Environmental Protection Technology Series
INFLUENCE OF TRICKLE AND SURFACE
IRRIGATION ON RETURN FLOW
QUALITY
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 7482Q
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
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The nine series are:
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This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
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tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-093
May 1977
INFLUENCE OF TRICKLE AND SURFACE IRRIGATION
ON RETURN FLOW QUALITY
by
Peter J. Wierenga
Department of Agronomy
New Mexico State University
Las Cruces, New Mexico 88003
Grant No. S-803156
(Formerly 13030 GLM)
Project Officer
James P. Law, Jr.
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
ii
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ABSTRACT
A field study was conducted to determine the effects of controlled surface
irrigation and trickle irrigation on the quality and quantity of irrigation
return flow. Trickle irrigation resulted in cotton yields C3-year averages)
which were 8.2 percent higher than those from the surface-irrigated plots,
and with trickle irrigation 24 percent less water was used than with surface
irrigation.
Data on soil salt accumulation in the surface-irrigated plots showed an
increase in salt concentration with depth to the clay-sand interface. Below
the clay-sand interface at 80-100 cm, a sharp decrease in salt concentration
was observed. It appeared that a larger change in soil salinity was produced
by altering irrigation frequency than by changing irrigation efficiency.
Irrigating when 50 percent of the soil water had been depleted was the irri-
gation frequency most conducive to salt retention by the soils.
It appeared that trickle irrigation was quite effective in controlling the
volume of return flow, while maintaining relatively low salinity levels in
the soil around the trickle emitters. Accumulated salts were readily moved
away from trickle lines by heavy preplant irrigations or intense rains.
The mean salt concentration of the irrigation return flow, as estimated from
deep soil solution samples, agreed well with the average salt concentration
of the groundwater to a depth of 11 m. Below 11 m the salt content of the
groundwater decreased. The quality of irrigation return flow entering the
Del Rio Drain agreed with the average concentration of the groundwater at
depths of 6 to 26 m, but not with the quality of the groundwater measured
at a single depth.
This report was submitted in fulfillment of Grant No. S-803156 (formerly
13030 GLM) by New Mexico State University under the sponsorship of the U.S.
Environmental Protection Agency. This report covers the period July 1, 1971,
to December 31, 1974, and work was completed as of February 28, 1975.
in
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CONTENTS
Page
List of Figures vi
List of Tables ix
Acknowledgments xviii
Sections
I Introduction 1
II Summary 3
III Conclusions 7
IV Recommendations 9
V Materials and Methods 11
VI Results and Discussion 32
VII References 105
VIII Publications 106
IX Appendix 107
X Glossary 156
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FIGURES
No. Page
1. Layout of experimental site and numbering of plots 12
2. Hydraulic conductivity as a function of water content at
several depths for the soils in plot 4 24
3. Ratio of evapotranspiration to pan evaporation for cotton as a
function of percent of growing season elapsed 29
4. Crop coefficient (Kc) used in the Jensen-Haise equation to
estimate evapotranspiration 31
5. Variation of soil-water tensions (cm of H20) at the 150- and
180-cm depths with time (plot 22) 33
6. Variation of the mean hydraulic gradient between the 150- and
180-cm depths for Treatment 9 33
7. Accumulative evapotranspiration estimated by ISS and smoothed
neutron data for 1974 (mean of all 25% depletion treatments) .... 40
8. Accumulative evapotranspiration estimated by ISS and smoothed
neutron data for 1974 (mean of all 50% depletion treatments) .... 40
9- Accumulative evapotranspiration estimated by ISS and smoothed
neutron data for 1974 (mean of all 75% depletion treatments) .... 41
10. ECe (mmhos/cm) versus total salts (meq/1) for saturation
extracts of field plot samples taken in May 1973 49
11. Soil salinity (g/lOOg of soil) response to depletion and years.
Parameters shown are depletion treatments applied 51
12. General trends in the total yield of cotton due to depletion
and efficiency (averages of 1972, 1973 and 1974). Parameters
shown are percent depletion 71
13. Comparison of salt contents of soil samples taken on (below)
trickle lines (dashed lines) and between trickle lines (solid
lines). The three graphs shown are for post harvest samples
taken in 1972, 1973 and 1974. Vertical arrow denotes average
depth to sand for the trickle treatments 79
vi
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FIGURES (Continued)
No. Page
14. Soil salinity differences due to sampling location (between
row minus below row) for the 0.2 and 0.6 bar trickle treat-
ments. The differences are for the means of the 1972, 1973
and 1974 post harvest samples 80
15. Soil salinity at the 5- and 10-cm depths as estimated by
salinity sensors for the 0.2 bar trickle treatment. Vertical
dashed lines denote total rainfall for month indicated.
Vertical solid lines denote irrigation on'date indicated 84
16. Soil salinity at the 25- and 40-cm depths as estimated by
salinity sensors for the 0.2 bar trickle treatment. Verti-
cal dashed lines denote total rainfall for month indicated.
Vertical solid lines denote irrigation on date indicated 85
17. Soil salinity at the 5- and 10-cm depths as estimated by
salinity sensors for the 0.6 bar trickle treatment. Verti-
cal dashed lines denote total rainfall for month indicated.
Vertical solid lines denote irrigation on date indicated 86
18. Soil salinity at the 25- and 40-cm depths as estimated by
salinity sensors for the 0.6 bar trickle treatment. Verti-
cal dashed lines denote total rainfall for month indicated.
Vertical solid lines denote irrigation on date indicated 87
19. Comparison of soil salinity around a trickle line in plot
before (top figure) and after (bottom figure) a 200-mm
preirrigation 88
20. Soil salinity distribution around two parallel trickle lines
in Plot T2 prior to a 120-mm rain in August 1973 89
21. Soil salinity distribution around two parallel trickle lines
in Plot T2 after a 120-mm rain in August 1973 90
22. Flow at Del Rio Drain sampling sites A and B in 1972. 94
23. Flow at Del Rio Drain sampling sites A and B in 1973 95
24. Flow at Del Rio Drain sampling sites A and B in 1974 96
25. Cumulative frequency distribution of flow rate as measured
at Del Rio Drain sites A and B (December 1971 through 1974) .... 97
26. Electrical conductivities of water samples from Del Rio
Drain sites A and B in 1972 99
27. Electrical conductivities of water samples from Del Rio
Drain sites A and B in 1973 100
vii
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FIGURES (Continued)
No. Page
28. Electrical conductivities of water samples from Del Rio
Drain sites A and B in 1974 101
29. Cumulative frequency distribution of water quality at
Del Rio Drain sites A and B (December 1971 through 1974) 102
viii
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TABLES
No. Page
1. Mean particle size distribution of soil near plot 4. All
values are the mean of three determinations 18
2. Bulk density values for the soil at the experimental site 19
3. Water contents, in % dry weight at 15 bars pressure for
27 surface-irrigated plots 20
4. Water contents, in % dry weight, at 15 bars pressure for
the six trickle-irrigated plots 22
5. Estimated root depths and available water for surface
irrigation treatments 22
6. Average water contents of the subsoil (surface-irrigated
plots) measured with a neutron probe during 1974 25
7. Summary of irrigation treatments and plots assigned to
each treatment 27
8. Irrigation and rainfall data for surface plots at the indicated
time intervals (1972) 36
9. Irrigation and rainfall data for surface plots at the indicated
time intervals (1973) 36
10. Irrigation and rainfall data for surface plots at the indicated
time intervals (1974) 37
11. Total amounts of water applied in cm (rainfall plus irriga-
tion) during the 1972, 1973 and 1974 growing seasons compared
with computed evapotranspiration (ET) in cm. Pan refers to ET
as estimated by evaporation pan and ISS refers to irrigation
scheduling service estimates of ET 37
12. Comparison of neutron probe measured water use with ISS
estimated water use, and total water actually applied for
1973 and 1974 39
13. Effect of depletion and efficiency treatment on measured
(neutron probe) and predicted (ISS) water use 39
Ix
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TABLES (Continued)
No. Page
14. Salt content of soil (g/lOOg of soil) in surface-irrigated
plots 1-10 and outside surface-irrigated plots 11-30.
(spring 1972 prior to planting) 43
15. Salt content of soil Cg/10Qg of soil) in surface-irrigated
plots (December 1972) 44
16. Salt content of soil (g/lOOg of soil) in surface-irrigated
plots (May 1973) 45
17. Salt content of soil (g/lOOg of soil) in surface-irrigated
plots (December 1973) 46
18. Salt content of soil (g/lOOg of soil) in surface-irrigated
plots (December 1974) 47
19- Salt content of soil (g/lOOg of soil) outside surface-
irrigated plots (December 1974) 48
20. Analysis of variance for soil salinity based on saturation
extracts from the surface-irrigated plots (Fall samples
1972, 1973 and 1974) 50
21. Treatment means of the salt contents of the soil (g/lOOg
of soil) in the surface-irrigated plots (December 1972). 52
22. Treatment means of the salt contents of the soil (g/100g
of soil) in the surface-irrigated plots (December 1973). 52
23. Treatment means of the salt contents of the soil (g/lOOg
of soil) in the surface-irrigated plots (December 1974). 53
24. Combined treatment means of the salt contents of the soil
(g/lOOg of soil) in the surface-irrigated plots for the
years 1972, 1973 and 1974 53
25. Mean salt contents (g/lOOg of soil) for the surface-irri-
gated plots by depth for each sampling period 54
26. Mean composition of saturation extracts (meq/1) of soils
from plots 1-20, irrigated by surface flooding (May 1973). 55
27. Mean composition of saturation extracts (meq/1) of soils
from plots 1-30, irrigated by surface flooding (May 1973). 55
28. Means and standard deviations of ionic composition of
saturation extracts of soils from plots 1-30, irrigated
by surface flooding (May 1973) 56
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TABLES (Continued)
No. Page
29. Mean electrical conductivities (mmhos/cm) Of soii solution
samples (1972 cropping season) and of saturation extracts
of samples taken at similar depths in the soil profile of
the surface-irrigated plots (December 1972) 59
30. Mean electrical conductivities (mmhos/cm) of soil solution
samples (1973 cropping season) and of saturation extracts
of samples taken at similar depths in the soil profile of
the surface-irrigated plots (December 1973); 60
31. Mean electrical conductivities (mmhos/cm) of soil solution
samples (1974 cropping season) and of saturation extracts
of samples taken at similar depths in the soil profile of
the surface-irrigated plots (December 1974) 61
32. Average chemical composition of soil solution extracted
from the surface-irrigated plots through suction cups
during the period January through April 1973, and chemical
composition of irrigation water, mean values (see Appendix
Table 23) 62
33. Analysis of variance for electrical conductivities (mmhos/
cm) of soil solution samples as listed in Tables 29, 30 and
31 64
34. Treatment means of the electrical conductivities (mmhos/cm)
of the soil solution samples extracted through suction cups
in 1972, 1973 and 1974 64
35. Average chemical composition (meq/1 except N(>3 in ppm) of
samples taken from test wells during 1972, 1973 and 1974 65
36. Analysis of variance for cotton yield for 1974 (surface-
irrigated plots) 66
37. Effects of irrigation efficiency and water depletion
treatments on the total yields of cotton for the surface-
irrigated plots (1974). Yields in kg/ha 67
38. Effects of irrigation efficiency on yield and quality of
cotton for the surface-irrigated plots (1974) 68
39. Effects of water depletion on yield and quality of cotton
for the surface-irrigated plots (1974) 68
xi
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TABLES (Continued)
No. Page
40. Analysis of variance for cotton yield for the surface-irri-
gated plots for the combined years 1972, 1973 and 1974 69
41. Effects of irrigation efficiency and water depletion treat-
ments on the total yields of cotton for the surface-irri-
gated plots. Yields in kg/ha 70
42. Partial analysis of variance for cotton quality factors for
the combined years 1972, 1973 and 1974 (surface-irrigated
plots) 72
43. Amounts (cm) of irrigation and rain water on trickle plots,
and calculated evapotranspiration (ISS). (1972 through 1974)... 73
44. Salt content of soil (g/lOOg of soil) in trickle-irrigated
plots (December 1972) 74
45. Salt content of soil (g/lOOg of soil) in trickle-irrigated
plots (May 1973) 75
46. Salt content of soil (g/lOOg of soil) in trickle-irrigated
plots (December 1973) 75
47. Salt content of soil (g/lOOg of soil) in trickle-irrigated
plots (December 1974) 76
48. Salt content of soil (g/lOOg of soil) outside trickle-irri-
gated plots (December 1974) 76
49. Analysis of variance for soil salinity based on saturation
extracts from the trickle-irrigated plots (fall samples
1972, 1973 and 1974) 78
50. Soil salinity (g/lOOg of soil) for sampling locations below
and between trickle lines as a function of depth 80
51. Soil salinity (g/lOOg of soil) for sampling locations below
and between trickle lines as a function of depth and salinity
differences between locations (between row minus below row).
Means of 1972, 1973 and 1974 post harvest samples 81
52. Mean composition of saturation extracts (meq/1) of samples
taken from below the trickle lines (May 1973) as a function
of depth 81
xii
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TABLES (Continued)
No. Page
53. Mean composition of saturation extracts (meq/1) of samples
taken in between the trickle lines (May 1973) as a function
of depth 82
54. Mean composition of saturation extracts (meq/1) of all samples
taken in the trickle plots (May 1973) as a function of depth ... 82
55. Effects of soil-water tension on yield and quality of
cotton from the trickle-irrigated plots (1974) 91
56. Effects of soil-water tension on yield (kg/ha) of cotton
from trickle-irrigated plots in 1972, 1973 and 1974 92
57. Analysis of variance for cotton yields for the combined
years 1972, 1973 and 1974. (Trickle-irrigated plots) 92
58. Mean composition of Del Rio Drain water (meq/1 except N03 in
ppm) at sites A and B during 1972, 1973 and 1974 103
59- Computed quality of return flow entering Del Rio Drain between
sites A and B. The quality of the test wells and of the
irrigation well is also presented 104
Appendix Tables
Appendix Table 1. ECe values (mmhos/cm) for saturation extracts
of soil samples taken outside of (or within) surface and
trickle-irrigated plots (spring 1972, prior to planting).
"S" and "E" following plot numbers designate "south of plot"
and "east of plot," respectively 108
Appendix Table 2. ECe values (mmhos/cm) for saturation extracts
of soil samples from surface and trickle-irrigated plots
(Dec. 1972). "R" and "C" following trickle plot numbers
designate "on the row" and "between two rows," respectively. . . . 109
Appendix Table 3. ECe values (mmhos/cm) for saturation extracts
of soil samples from surface and trickle-irrigated plots
(May 1973). "R" and "C" following trickle plot numbers
designate "on the row" and "between two rows," respectively. • • . 110
Appendix Table 4. ECe values (mmhos/cm) for saturation extracts
of soil samples from surface and trickle-irrigated plots
(Dec. 1973). "R" and "C" following trickle plot numbers
designate "on the row" and "between two rows," respectively. . . . HI
Appendix Table 5. ECe values (mmhos/cm) for saturation extracts
of soil samples from surface and trickle-irrigated plots
(Dec. 1974). "R" and "C" following trickle plot numbers
designate "on the row" and "between two rows," respectively. • • • 112
xiii
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TABLES (Continued)
No. Page
Appendix Table 6. ECe values Cramhos/cm) for saturation extracts of
soil samples taken outside of surface and trickle-irrigated
plots Oec. 1974). "E" and 'V following plot numbers design-
ate "east of plot" and "west of plot," respectively ...... 14,3
Appendix Table 7. Composition (meq/1). of saturation extracts of
soil samples taken from surface and trickle-irrigated plots
at a depth of 0-20 cm (Hay 1973) . "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively .....................
Appendix Table 8. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle-irrigated plots
at a depth of 20-40 cm (May 1973). "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively ..................... 115
Appendix Table 9. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle -irrigated plots
at a depth of 40-60 cm (May 1973) . "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively ..................... 116
Appendix Table 10. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle -irrigated plots
at a depth of 60-80 cm (May 1973) . "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively. .................... 117
Appendix Table 11. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle -irrigated plots
at a depth of 80-100 cm (May 1973). "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively ..................... 118
Appendix Table 12. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle-irrigated plots
at a depth of 100-120 cm (May 1973). "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively. .................... 119
Appendix Table 13. Composition (meq/1) of saturation extracts of
soil samples taken from surface and trickle-irrigated plots
at a depth of 120-140 cm (May 1973) . "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively ..................... 120
xiv
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(Continued)
No. Page
Appendix Table 14. Composition Cmeq/1) of saturation extracts of
soil samples taken from surface and trickle-irrigated plots
at a deptn of 140-160 cm (Hay 1973}. "R" and "C" following
trickle plot numbers designate "on the row" and "between two
rows," respectively 121
Appendix Table 15. Electrical conductivities (mmhos/cm) of soil
solution withdrawn from surface and trickle-irrigated plots
in 1972 122-
Appendix Table 16. Electrical conductivities (mmhos/cm) of soil
solution withdrawn from surface and trickle-irrigated plots
in 1973 123
Appendix Table 17. Electrical conductivities (mmhos/cm) of soil
solution withdrawn from surface and trickle-irrigated plots
in 1974 124
Appendix Table 18. Chemical composition (meq/1 except N03 in
ppm) of samples taken from test well #1 during the years
1972, 1973 and 1974 125
Appendix Table 19. Chemical composition (meq/1 except N03 in
ppm) of samples taken from test well #2 during the years
1972, 1973 and 1974 126
Appendix Table 20. Chemical composition (meq/1 except N03 in
ppm) of samples taken from test well #3 during the years
1972, 1973 and 1974 127
Appendix Table 21. Chemical composition (meq/1 except N03 in
ppm) of samples taken from test well #4 during the years
1972, 1973 and 1974 128
Appendix Table 22. Chemical composition (meq/1 except NC>3 in
ppm) of samples taken from test well #5 during the years
1972, 1973 and 1974 129
Appendix Table 23. Chemical composition (meq/1 except N03 in
ppm) of samples taken from the irrigation well during the
years 1972, 1973 and 1974 130
Appendix Table 24. Cotton yields in kg/ha for first, second and
total harvests for surface and trickle-irrigated plots
(1972, 1973 and 1974) 131
xv
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TABLES (Continued1
No. gage
Appendix Table 25. Percent lint of cotton from first and second
harvests for surface and trickle-irrigated plots C1972, 1973
and 1974) 132
Appendix Table 26. 2.5 percent span of cotton from first and
second harvests for surface and trickle-irrigated plots (1972,
1973 and 1974) 133
Appendix Table 27. Uniformity ratio of cotton from first and
second harvests for surface and trickle-irrigated plots (1972,
1973 and 1974) 134
Appendix Table 28. Micronaire of cotton from first and second
harvests for surface and trickle-irrigated plots (1972, 1973
and 1974) 135
Appendix Table 29. Strength of cotton from first and second
harvests for surface and trickle-irrigated plots (1972, 1973
and 1974) 136
Appendix Table 30. Elongation of cotton from first and second
harvests for surface and trickle-irrigated plots (1972, 1973
and 1974) 137
Appendix Table 31. Mean monthly composition (meq/1 except N(>3 in
ppm) of Del Rio Drain water at site A (1972) 138
Appendix Table 32. Mean monthly composition (meq/1 except N03 in
ppm) of Del Rio Drain water at site B (1972) 139
Appendix Table 33. Mean monthly composition (meq/1 except N(>3 in
ppm) of Del Rio Drain water at site A (1973) 140
Appendix Table 34. Mean monthly composition (meq/1 except NOj in
ppm) of Del Rio Drain water at site B (1973) 141
Appendix Table 35. Mean monthly composition (meq/1 except NOo in
ppm) of Del Rio Drain water at site A (1974) 142
Appendix Table 36. Mean monthly composition (meq/1 except N03 in
ppm) of Del Rio Drain water at site B (1974) 143
Appendix Table 37. Estimated EC (mmhos/cm) of return flow between
Del Rio Drain sampling sites A and B for 1972 as calculated
by the equation: ECB x flowB - ECA x
Flow is in m3/sec.
xvi
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TABLES CContinued)
No.
Appendix Table 38. Estimated Ca concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1972 as
calculated by the equation: [Ca-g] x flowg - [Ca^] x
Flow is in m /sec. (flows - flowA) . . . . . 145
Appendix Table 39. Estimated Mg concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1972 as
calculated by the equation: [MgB] x flowB - [Mg^] x flow^
Flow is in m3/sec. (flowB - flowA) . . . . . 146
Appendix Table 40. Estimated Na concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1972 as
calculated by the equation: [NaB] x flowB - [Na^] x flow^
Flow is in m3/sec. (flowg - flow^) ..... 147
Appendix Table 41. Estimated EC (mmhos/cm) of return flow between
Del Rio Drain sampling sites A and B for 19.73. Flow is in.
m3/sec.
Appendix Table 42. Estimated Ca concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1973.
Flow is in nr/sec ...................... 149
Appendix Table 43. Estimated Mg concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1973.
Flow is in m3/sec ...................... 150
Appendix Table 44. Estimated Na concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1973.
Flow is in m3/sec ...................... 151
Appendix Table 45. Estimated EC (mmhos/cm) of return flow between
Del Rio Drain sampling sites A and B for 1974. Flow is in
m3/sec.v ........................... 152
Appendix Table 46. Estimated Ca concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1974.
Flow is in m3/sec ...................... 153
Appendix Table 47. Estimated Mg concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1974.
Flow is in m3/sec ...................... 154
Appendix Table 48. Estimated Na concentrations (meq/1) of return
flow between Del Rio Drain sampling sites A and B for 1974.
Flow is in m3/sec ...................... 155
xvii
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ACKNOWLEDGMENTS
Many individuals contributed to the project and to the preparation of this
report. In particular, the author would like to thank Dr. Morris Finkner
and Dick Glaze from the Experimental Statistics Department for their help
in the analysis of the data.
The dedication of Susan Gomez who helped throughout the project with sample
analysis, data analysis, and finally report preparation, and of Buck Sisson
who helped during the final year of the project with field work, data
analysis, and the preparation of this report is very much appreciated.
Thanks are also due Ted Patterson and Dr. Terry Howell, Agricultural
Engineering, for their assistance and advice concerning the field work and
data analysis.
The author also wants to acknowledge the encouragement and help from
Dr. Arden A. Baltensperger, Chairman, Agronomy Department, and Eldon Hanson,
Chairman, Agricultural Engineering. The enthusiastic support of, and
valuable discussions with John Clark, Grant Director and Director of the
Water Resources Research Institute, were especially appreciated.
XVlll
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SECTION I
INTRODUCTION
Maintaining the quality of river water is a major problem in the Western
United States. In New Mexico, the salt concentration in the Rio Grande
increases progressively going downstream from Santa Fe, in the north, to El
Paso on the New Mexico-Texas border in the south. The greatest increases in
salt concentration occur in reaches where irrigated agriculture is practiced
(the rate of increase is more than twice that of non-irrigated reaches) and
is related to irrigation return flow.
Irrigation return flow originates when water in excess of evapotranspiration
is applied to the soil-plant system. The excess water is applied intention-
ally to leach soluble salts from the plant root zone and insure perennial
agriculture. That portion of the excess water flowing back to the river is
called irrigation return flow.
This report presents information from field studies which were conducted to
determine the effects of irrigation management on the quality of irrigation
return flow. By reducing the amount of water used for irrigation and
improving irrigation efficiency, the amount of water percolating through the
soil and entering the groundwater table or drains is reduced. Thus proper
management of irrigation water application is important for controlling the
quality of irrigation return flow.
The general objective of this project was to determine the effects of improved
irrigation methods, i.e., controlled surface irrigation and trickle irriga-
tion, on the quality and quantity of irrigation return flow.
The project objectives were:
1) to determine the effects of the depth and frequency of surface irri-
gation on water and solute transport within soil profiles.
2) to determine the effect of water management on composition and
quality of percolating water from field plots under trickle irriga-
tion and to determine the feasibility of minimizing percolation
losses by trickle irrigation.
3) to compare the results of this study with the quality of water in
the Del Rio Drain, and relate this to the quality of irrigation
water applied.
1
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The research was divided into three parts. Field plot experiments were con-
ducted at the New Mexico State University (NMSU) Plant Science Research
Center near Las Graces, New Mexico. For each plot, extensive determinations
of cotton yield, soil salinity, quality of percolating water, and crop water
use were made. In addition, measurements of the salt build-up around trickle
lines were made.
For part two, water sampling stations were established at two locations along
the Del Rio Drain. The quantity and quality of the water passing these two
stations were measured once a week throughout the experiment.
For part three of the project, a battery of two-inch wells was installed to
monitor the quality of the water in the subsoil in the plot area.
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SECTION II
SUMMARY
The salt concentration of the water in the Rio Grande in New Mexico increases
progressively as the river goes downstream from Santa Fe in Northern New Mexico
to El Paso, Texas. The greatest increases in salt concentration occur in
reaches where irrigation is practiced due to the return to the river of lower
quality drainage water (irrigation return flow) .
This report presents information from a 3-1/2 year field study which was con-
ducted to determine the effects of irrigation management on the quality of
drainage return flow. The general objective of the project was to determine
the effects of controlled surface irrigation and trickle irrigation on the
quality and quantity of irrigation return flow. The study consisted of three
parts. For part one, field plot experiments were conducted at the NMSU Plant
Science Research Center near Las Cruces, New Mexico. Some of the field plots
were irrigated by surface irrigation and others by trickle irrigation. Exten-
sive determinations were made of cotton yield, soil salinity, quality of
percolating water, and consumptive use of water for each plot. For part two,
water sampling stations were established at two locations along the Del Rio
Drain near the farm. The quantity and quality of the water passing these
two stations were measured once a week for the duration of the experiment.
For part three of the project, a battery of two-inch wells was installed to
monitor the quality of the water in the subsoil of the plot area.
Crop water use and deep percolation losses were estimated using three differ-
ent procedures. Because of the extreme heterogeneity of the soil at the
experimental site, both horizontally and with depth, percolation losses could
not be accurately calculated by multiplying hydraulic gradient by the
unsaturated hydraulic conductivity below the root zone. The abrupt layering
of the subsoil also resulted in unreliable water use data as obtained from
neutron probe readings. Climatological methods appeared most feasible to
estimate deep percolation losses. Based on the latter method, average deep
percolation losses of 19.3 cm in 1973 and 21.9 cm in 1974 were estimated for
the combined surface irrigation treatments. With a five-month growing season,
this amounted to an average downward flux of about 1.4 mm/day.
-------
During each project year, the amounts of water used on the trickle plots were
smaller than those used on the surface irrigated plots including the 100 per-
cent efficiency surface treatment. In 1973, the average amount of water
applied to the 100 percent efficiency treatment was 67.1 cm versus 54.3 cm
applied to the trickle plots, or about 20 percent less with trickle irriga-
tion. In 1974, these amounts were 77.5 cm versus 56.0 cm or a water savings
of 28 percent with trickle irrigation.
Irrigation treatments had no significant effect on cotton yield at the 5 per-
cent confidence level. However, for the surface irrigated plots, the 50 per-
cent depletion treatment yielded more cotton than did the 25 percent and 75
percent depletion treatments at the 90 percent and 100 percent levels of effi-
ciency. Yields tended to decrease with increasing percent efficiency with the
exception of the 50 percent depletion treatments. For 1972-1974, the mean
yield from all surface irrigated plots was 1090 kg lint cotton pe,r ha, versus
1180 kg/ha for all trickle irrigated plots. Thus the trickle plots produced
on the average 8.2 percent more lint cotton than the surface irrigated plots
and used 24 percent less irrigation water.
The salt distribution in all plots was measured after each irrigation season
by taking soil samples at 20-cm depth intervals to 160-cm. Saturation
extracts were prepared and the electrical conductivities Cand during one year
the composition) of the extracts determined. The large spatial variability of
soil salinity made it difficult to detect any statistically significant
differences due to surface irrigation treatments. Thus, soil salinity was
independent of efficiency treatments and depletion treatments applied. How-
ever, depletion had five times the effect on salinity that efficiency had,
indicating that for the study area, a greater change in salinity would be
produced by altering irrigation frequency than by altering irrigation effi-
ciency.
From 1972-1974, there was a slight increase in the salt content of the surface
irrigated plots, from an average of 0.173 g/lOOg of soil in the fall of 1972
to 0.189 g/lOOg in the fall of 1974. This increase in salt content was most
pronounced for the 50 percent depletion treatment. It was negative for the
25 percent depletion treatment.
-------
The salinity data indicated a large increase in soluble salts with depth to
about 100 cm, and then a decrease. The high salt concentration at the 60-100-
cm depth as compared with the salt concentration in the underlying sand was
mainly due to higher concentrations of Ca, Mg and SO,. Salt concentrations
at 60-100 cm were double those at 120-140 cm.
It proved to be extremely difficult to extract soil solution samples through
suction cups placed in the sandy subsoil below the root zone. As a result,
these data are somewhat incomplete, and the coefficients of variation are
high. The average electrical conductivity of the soil solution samples
collected over the three years was 7.89 mmhos/cm. This value was found to be
on the average 4.2 times higher than the mean conductivity of the saturation
extracts of soil samples taken at the same depth in the profile. The only
significant treatment effect on electrical conductivity of the soil solution
samples was depletion. The salt concentration of the percolation water from
the 75 percent depletion plots was significantly lower Cat the 5 percent
level of probability), than the salt concentration of the water from the 25
and 50 percent depletion plots. This agreed with the measurements on total
salt in the profile as determined from saturation extracts.
Treatment had no significant effect on the total salts accumulated in the
trickle-irrigated plots, but did affect the salt distribution around the
trickle lines. The plots in the drier trickle treatment accumulated salts
closer to the soil surface than did those in the 0.2 bar treatment. Salt
distribution around trickle lines was also measured with salinity sensors.
The sensors performed satisfactorily and provided a rapid measurement of the
response of salt distribution to irrigation or rainfall. The data showed
that preplant irrigations through trickle lines were very effective in moving
salts away from the lines, thus providing a seed bed of low salt concentra-
tion.
Excellent data were obtained on the quality of the groundwater at five levels
below the soil surface. The water quality of the monitoring wells changed,
with depth, from a mean electrical conductivity of 1.63 mmhos/cm at 5.8 m to
1.09 mmhos/cm at 22.9 m. Assuming a bulk density of 1.6 for the sandy sub-
soil, the saturated water content in this zone was calculated to be 38.9 per-
cent by volume. The volumetric water content in the unsaturated sandy subsoil
-------
averaged about 8 percent. On this basis, the electrical conductivity of the
water in the unsaturated zone should be 4.86 times the electrical conductivity
of the shallow groundwater. The observed ratio of these electrical conducti-
vities was 7.89/1.63 » 4.84, which is in excellent agreement.
Flow measurements at both sampling stations on the Del Rio Drain showed a
sharp increase in flow in early March, followed by a second relative peak in
flow rate in July-August during all three years of the study. The data
3
revealed that the increase in drain flow between the two sites was 0.11 m /sec
or +18 percent, during at least 50 percent of the time. No estimates were
available on the actual area drained by this section of the Del Rio Drain.
The mean salt content of the drain water was found to increase from 908 ppm
at site A to 953 ppm at site B 4.5 km downstream, an increase of 10 ppm/km of
drain. A frequency distribution of the salt concentration showed that 50 per-
cent of the time the salinity could be expected to increase at a rate of 0.86
percent per km of drain. The quality of water entering the drain between the
two measuring sites was calculated from the increase in concentration and flow
between the sites, and agreed fairly well with the mean quality of the water
sampled from the test wells and irrigation well. The quality of the water
from any one test well, however, did not adequately represent the quality of
the water entering the drain. Thus, in order to estimate the quality of the
water entering a drain, the saturated zone has to be sampled at several depths.
-------
SECTION III
CONCLUSIONS
1. As much, as 32 percent of the water applied to the surface irrigated plots
was lost by percolation to the subsoil. Drainage losses ranged from 32
percent of the total water applied on the treatment designed for 80 percent
water use efficiency to 21 percent of the water applied on the treatment
designed for 100 percent water use efficiency. Assuming a 5-month irri-
gation season, this resulted in average downward fluxes of 1.5 and 1.0
mm/day, respectively, for these treatments.
2. Total water use, as estimated with the irrigation scheduling system, agreed
closely with total amount of irrigation water applied to the trickle plots,
irrigated on the basis of tensiometer data.
3. For the stratified-heterogenous soils of the Mesilla Valley, it appeared
more reliable to estimate deep percolation losses with the water balance
method, based on estimates of consumptive use, than from soil hydraulic
conductivity and water content data.
4. Determining irrigation efficiency from frequent water content measurements
with the neutron probe was unreliable. This was due to rapid drainage
losses immediately following heavy irrigations, to uncertainty in the
neutron meter calibration curve near saturation for the clay-loam soil
in the upper 70 cm of the profile, and to systematic errors in water con-
tent measurements near the clay-sand interface at around 70 cm below most
of the field plots.
5. Surface irrigation treatments had no significant effect on cotton yields
at the 5 percent level of probability. However, yields tended to decrease
with increasing efficiency, and the 50 percent depletion treatment yielded
more than the 25 and 75 percent depletion treatments.
6. The trickle-irrigated plots used 20 percent less water than the surface-
irrigated plots in 1973 and 28 percent less water in 1974. Averaged over
all years and treatments, the trickle plots yielded 8.2 percent more lint
cotton than did the surface-irrigated plots. Thus, it appeared feasible
to minimize water losses with trickle irrigation while maintaining, at
least for three years, yields as good or better than those obtained with
surface irrigation.
-------
7. Surface and trickle irrigation treatments had no significant effect on
the economically important cotton quality parameters.
8. Soil salinity of the surface-irrigated plots was not affected signifi-
cantly (at the 5 percent level of probability) by irrigation treatments.
Treatment effects were largely obscured due to the large spatial vari-
ability of soil salinity over the experimental area. However, irrigating
when 50 percent of soil water had depleted caused a consistent trend
toward increasing total salt in the soil profile.
9. With preplant irrigation through the trickle system and rainfall in the
summer, a region of•relatively low salt content was maintained around
trickle lines. The drier trickle irrigation treatment accumulated more
salt close to the soil surface than did the wet irrigation treatment.
10. The quality of water in the upper part of the saturated zone appeared to
be in equilibrium with the quality of the water percolating from the
unsaturated zone above it.
11. The quality of the groundwater varied with depth from 5 to 23 m. Below
11 m, the salt content of the groundwater started to decrease. It was
35 percent less at 23 m than at 5 m. Due to this variation of salt
content with depth in the saturated zone, the quality of the return flow
entering the Del Rio Drain could not be estimated from the quality of
groundwater measured at one depth, only.
12. The quality of the return flow entering the Del Rio Drain between two
sampling stations was estimated from differences in the concentrations of
salt and differences in the flow rates measured at these two stations.
The calculated salt concentration of the return flow was in agreement
with the average concentration of the groundwater between 5 and 23 m.
The increase in drain flow between the two stations was found to be 0.11
3
m /sec, or -1-18 percent at least 50 percent of the time. The increase in
salt load was 0.86 percent per km length of drain 50 percent of the time.
-------
SECTION IV
RECOMMENDATIONS
1. The results of this study indicate that with proper irrigation management
salts may be retained in the soil profile. Because the long-term effects
of salt retention in layered field soils on yield have not been adequately
studied, it is recommended that such studies be initiated to evaluate the
long-term effects of improved water management practices on yields.
2. Field scale testing of trickle irrigation for high value crops such as
chile, lettuce and seed alfalfa is recommended. These tests should in-
clude water use measurements and monitoring of salt levels in the soil
around the trickle lines.
3. Prediction of irrigation needs on the basis of climatological data and of
crops and soils information is a practical method for reducing water
requirements in the Mesilla Valley thus reducing the volume of return
flow. However, a large-scale application of this method should be accom-
panied by a system of sampling representative fields for salt build-up in
the profile.
4. Due to the large variation in physical and chemical properties of the soils,
spatially and with depth, and because of the large amount of salt present
in the soils of the study area, changes in soil salinity or in return flow
quality are not easily detected in short-term experiments. It is there-
fore recommended that detailed field plot studies conducted under controlled
conditions to determine the long-term effects of irrigation management on
soil salinity and quality of return flow be continued.
5. Increased effort is needed to determine actual evapotranspiration data for
various crops and soils in the Mesilla Valley.
6. A network of shallow test wells should be established in the Mesilla Valley
to monitor the quality of shallow groundwater. At each location the ground-
water quality should be monitored at several depths.
7. The data from this study indicate considerable accumulation of salts
at or near the soils interface of clay over sand. Any accumulation of
salt in soil profiles will affect the quality of water percolating to the
water table and thus affect quality of return flow. In order to under-
stand the development of salinity profiles in stratified soils, detailed
studies of the simultaneous movement of water and salts are necessary. The
-------
presence of a sharp clay/sand interface has a great effect on soil-water
movement and was suspected to have an effect on the precipitation and
dissolution of salts.
Future studies should include development and testing of models to pre-
dict the effect of irrigation management on return flow quality. Such
models should include soil-water chemistry in the unsaturated zone as
well as water chemistry and water movement in the saturated zone. A com-
bination of intelligent data collection and model development will provide
a more rapid means of estimating effects of irrigation management on
quality of return flow than will any singular approach.
10
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SECTION V
MATERIALS AND METHODS
FIELD FACILITIES
The farm, prior to purchase by the University in 1970, had been under irriga-
tion for a long time. The crops grown in the study area were mainly cotton,
alfalfa, and chile. The farm was served by the Elephant Butte Irrigation
District, and the quality of the Rio Grande water at Las Cruces Dam was repre-
sentative of the water used for irrigation in the past.
Before installation of the plots, the field area was leveled then flood irri-
gated with approximately 20 cm of water. Soil samples were taken during con-
struction of the field plots in order to determine salt distribution with
depth prior to the start of irrigation treatments. Additional soil samples
were taken outside of each plot during the fall of 1974.
The project was located at the Plant Science Research Center of New Mexico
State University, about eight miles south and west of Las Cruces, New Mexico.
The soil at the site was heterogeneous which is characteristic of alluvial
soils in the Mesilla Valley. The soil profile consisted of about 30-cm silty
clay loam over 20 to 30 cm of clay, over a variable amount of silty loam. The
latter changed rather abruptly into a medium sand. The depth to the sand on
the two acre site varied from 60 to 120 cm below the soil surface. Root pene-
tration into the medium to fine sandy subsoil appeared to be almost negligible.
In Figure 1, the field plot layout at the experimental site is presented. The
experimental design consisted of thirty 7.3 x 7.3 meter plots and six 6.1 x
18.3 meter plots. The 7.3 x 7.3 meter plots were irrigated by surface irri-
gation and the 6.1 x 18.3 meter plots were irrigated by trickle or drip irri-
gation. Each surface-irrigated plot had its own alfalfa valve, which, was
connected through a 10-cm I.D. underground pipeline to the 20-cm I.D. irrigar-
tion well just outside the plot area.
A water flow meter was installed in the main line from the well in order to
meter the correct amount of water to each surface-irrigated plot. These plots
were separated from the surrounding soil by polyethylene plastic to a depth of
75 cm below the soil surface. The plastic around the plots served to prevent
horizontal water movement out of the plot area, which may otherwise have taken
11
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Figure 1. Layout of experimental site and numbering of plots.
-------
place due to the low permeability of the 4Q-60-cm layer. Wooden boards ex-
tending 20 cm above the soil surface and 10-cm below, covered with polyethy-
lene plastic, prevented surface runoff from the plots.
The trickle system consisted of 1-cm I.D. trickle lines at 1-m row spacing
and having Drip-Eze emitters (Controlled Water Emission Systems, El Cajon,
California) every 45 cm of trickle line. Initially the pressure in the
trickle lines was maintained at 1 atm. During the last two years, flow con-
trol valves were used to control the amount of water going to each plot. An
2
emission rate of 3.6 liters per hour (equivalent to 8 mm per cm per hour)
per emitter was used. For each trickle-irrigated plot, a separate positive
displacement water meter was used to measure the amount of water delivered.
The water meters were calibrated annually.
The irrigation well installation consisted of a 30-cm hole, 26-m deep, gravel
packed and screened with a 20-cm I.D. Wesco Keystone slotted screen extending
from 17 to 26 m. Water table depth was 3.7 m. The water lubricated vertical
turbine pump (bowls set at 17 m) delivered 19 I/sec (300 gpm) at a dynamic
head of 27 m. The pump was driven at approximately 3600 rpm with a 10 hp
(480v., 3-phase, 60Hz) electric motor.
A battery of five observation wells was installed to monitor quality changes
in the underlying aquifer and to monitor the water quality versus depth rela-
tionship within the shallow aquifer. The wells extended to depths of 5.8, 8.2,
11.0, 15.5 and 22.9 meters. The casings were 3.2-cm I.D. (1-1/4 inch) sche-
dule 200 PVC pipe, and each casing had a 60-cm section of slotted plastic well
screen at the bottom. The five wells were valved to a common manifold and
individually sampled with a pitcher pump. After 1-1/2 years, the pitcher pump
was replaced by a suction system with nylon tubing leading into separate
collection bottles. During each sampling, sufficient volumes of water were
removed from each well to assure a representative sample from the specified
sample depth.
Two sampling stations were established along the Del Rio Drain. The Del Rio
Drain runs approximately parallel to the Rio Grande for a distance of about
32 km and drains a large portion of the Mesilla Valley. It is one of the
eight major drains in the valley having continuous flow throughout the year.
The drain borders the experimental site to the east. One station, station B,
13
-------
was constructed adjacent to the plot area and the second station, station A,
was constructed 4.5 km upstream. Water samples were taken at the two stations
at weekly intervals starting in December 1971.
The flow rates at the sampling stations were also monitored. Staff gauges
were installed at culvert inlets near each sampling station. Foot bridges
from which current meter readings could be made were installed 10 meters up-
stream from the culverts. Current meter readings were taken weekly, and the
quantity of flow computed for each station. Stevens water stage recorders
were installed at each site to obtain a continuous record of stage and thus
of flow rate. A stage discharge curve for each site was constructed. Because
of vandalism, the water stage recorders were functional during only part of
the project. Flow meter readings, however, were made at weekly intervals
throughout the project.
FIELD MEASUREMENTS
Water content was measured with neutron probes manufactured by Trpxler Elec-
tronic Laboratories, Raleigh, North Carolina. The equipment consisted of a
Model 1255, 100 millicurie americium-beryllium probe and a Model 2651 digital
sealer. A calibration curve was constructed from neutron meter readings and
the water contents determined for gravimetric soil samples taken at the same
time and in the same general soil volume. Each time neutron readings were
made, the calibration curve was modified according to the neutron counts
obtained on a set of three standards provided by the manufacturer. It was
necessary to frequently calibrate all probes and meters against factory stan-
dards over the duration of the experiment because the use of different probes
and rate meters as well as instrument repairs shifted the calibration. By this
method, the water contents obtained before and after repairs, or the water
contents obtained with different probes were comparable.
Neutron readings were made near the center of each plot through aluminum
access tubes, 3.1 cm O.D. and 150 or 180 cm long. When not in use, each, tube
was closed by a rubber stopper to prevent its filling with water during irri-
gations.
Tensiometers were installed at two depths in each plot to determine the
hydraulic gradient "below the root zone of the cotton crop. It had been
observed, on adjacent cotton fields, that roots would not penetrate the sands
14
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underlying the clay loam. Since the sand was reached at a depth of 60 cm in
the first row of plots but was often as deep as 120 cm in the third row of
plots, it was decided to place the tensiometers at increasing depths from the
first row to the third row- Hence,in plots 1-10, triplicate tensiometers were
installed at 120 cm and at 150 cm below the soil surface. In plots 11-20 the
tensiometers were installed at depths of 135 and 165 cm, and in plots 21-30
and in the trickle plots, the tensiometers were installed at depths of 150
and 180 cm. This insured that the gradient was measured below the root zone.
All tensiometers were connected by buried nylon tubing to mercury manometers
placed in louvered instrument shelters outside the plots. A great deal of
effort was needed to keep the tensiometers, a total of 198, in operating con-
dition. The nylon tubing, where exposed to sunlight, became brittle and had
to be replaced each year. During the irrigation season the tensiometers were
read at regular time intervals. The data were punched on cards and the
hydraulic gradients calculated and averaged by computer for each treatment
over various time periods.
Suction cup samplers were installed to sample the quality of the water perco-
lating from the root zone to the groundwater table. The samplers consisted of
a variable length of 2.2-cm O.D. PVC tubing (schedule 80) attached to a ten-
siometer cup 5.8-cm long. Samplers were installed near the center of each
plot at a depth halfway in between that of the tensiometers. Thus,in row 1
(plots 1-10) the suction cups were placed at 135 cm; in row 2 (plots 11-20) at
150 cm; and in row 3 (plots 21-30) and in the trickle plots at 165 cm. A
hole slightly smaller than the outside diameter of the sampler was driven to
a depth of about 10 cm above the final depth of the sampler. The sampler was
then pushed in to its proper depth as specified above. All suction cups were
connected by buried vacuum lines to collection bottles outside of each plot.
A constant suction was maintained on the sample collection bottles by means of
an underground vacuum system connected to a central vacuum pump located in the
instrument van. Initially, a vacuum of about 0.6 atm was used to obtain soil
solution samples. However, frequently no sample was obtained probably due to
excessive evaporation. When a vacuum of about 0.15 atm was applied, better
results were obtained. Since a vacuum sometimes had to be applied for several
days in order to extract a sample, there may have been some concentrating
effect on the solution samples in the collection flasks. Mineral oil was
15
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initially added to the collection flasks to prevent evaporation from the
samples, but was found to interfere with the chemical analyses, and its use
was discontinued.
Several times during the experiment, soil samples were taken within the plots
at 20-cm depth intervals to 160 cm. These samples were taken at two locations
within each surface-irrigated plot and composited for analysis by depth.
Trickle plot soil samples were taken from four locations within each plot.
Two locations were selected below a trickle line and two locations were
selected in between two trickle lines, the two "below" samples for each depth
combined for analysis and the two "between" samples for each depth combined for
analysis. Saturation extracts were made from all samples and the electrical
conductivities (EC ) determined. Samples collected in the spring of 1973 were
subjected to a complete chemical analysis for water soluble anions and cations,
pH and electrical conductivity.
Soil samples were taken during the following periods:
1. Fall 1972 - inside plots; ECe only
2. Spring 1973 - inside plots; complete analysis
3. Fall 1973 - inside plots; EC only
4. Fall 1974 - inside and adjacent to plots; EC only
Salinity sensors from Soil Moisture Equipment Corp., Santa Barbara, California,
Model No. 5000-A, were used to measure salt distribution around trickle lines.
The salinity sensors were installed in 2.5-cm diameter holes which had been
punched to the desired depth. Contact was maintained between the ceramic
portion of the salinity sensor and the soil by means of a compression spring.
To insure that there was no water and salt movement to the sensor via the
installation hole, approximately 10 cm of the hole was backfilled with soil,
capped with polyethylene film, and the remainder of the hole backfilled with
original soil. The factory calibrated and temperature compensated salinity
sensors were used to obtain salinity readings in conjunction with a Model
5500 salinity bridge.
The first group of salinity sensors was installed in June 1972. Fifteen sen-
sors were installed in a symmetrical grid pattern around a trickle line in
plot T2 ("wet" treatment), and fifteen sensors were similarly installed around
a trickle line in plot T5 ("dry" treatment). For each of the two plots, the
16
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sensors were installed at depths of 10, 25, and 40 cm, and at distances of 0,
15, 30 and 45 cm from the trickle line on both sides. The grid coordinates
(distance from line, depth) in cm were: (0,10), (0,25), (0,40), (15,10), (15,
25), (15,40), (30,10), (30,25) and (45,25). On August 1, 1973, additional
salinity sensors were installed in each of the two plots to complete the grid
to a depth of 40 cm, to include a new depth of 5 cm and to encompass an adja-
cent trickle line.
A weather station was set up west of the experimental site to measure incoming
solar radiation, wind velocity, air temperature, relative humidity, rainfall,
pan evaporation, and maximum and minimum temperature.
Incoming solar radiation was measured with a pyrheliometer (Epply Laboratory
Inc., Newport, Rhode Island) which had a sensitivity of 8.3 millivolts per
-2 -1
cal cm min . During the first year of operation, the output from the
pyrheliometer was recorded on a data acquisition system (Non-Linear Systems,
Inc., Del Mar, California) and the millivolt readings punched on cards and
integrated by computer to obtain the total daily incoming solar radiation.
During the second year, a strip chart recorder was used to record the data
which were then integrated by computer. Near the end of the project, a
modified Thurtell integrator was used to record and accumulate incoming solar
radiation.
Wind velocity was measured at 2 m above the soil surface with an anemometer
(Belfort Instrument Co., Baltimore, Maryland, Cat. No. 5-349A, United States
Weather Bureau Spec. No. 450.6104) which was read daily in the morning.
Air temperature at 2 m was measured initially with a thermocouple and recorded
with the data acquisition system. During the last year of the project, air
temperature was measured with a hygrothermograph (Weather Measure Corporation,
Sacramento, California, Model No. H311). Daily maximum and minimum air
temperatures were measured with maximum and minimum thermometers.
Relative humidity was initially measured with a Brady Aray humidity sensor
(Thunder Scientific, Albuquerque, N.M.), and the output recorded on the data
acquisition system. The humidity sensor had performed satisfactorily under
laboratory conditions but failed in the field. During the last year of the
study, relative humidity was measured with the hygrothermograph which, after
initial calibration in the laboratory, was regularly checked in the field with
17
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a portable electric fan psychrometer. Rainfall was measured with a standard
8-inch rain gauge, and evaporation was measured with a U.S. Weather Bureau
Class A pan (Weather Measure Corporation, Sacramento, California, Model No.
H311). All transducers were housed in a standard United States Weather
Bureau Shelter.
PHYSICAL PROPERTIES OF THE SOIL
A particle size analysis was run on soil samples taken from three different
sites near plot 4 using the pipette method of Kilmer and Alexander (1949).
The results, which are presented in Table 1, indicate extensive layering of
the soil at the experimental site.
Table 1. MEAN PARTICLE SIZE DISTRIBUTION OF SOIL NEAR PLOT 4
Depth
(cm)
10-20
20-35
40-50
55-65
70-80
85-95
115-125
145-155
Sand
00
21.8
18.2
2.1
4.9
56.4
94.7
93.0
94.6
Clay
(%)
43.3
41.9
50.7
52.6
6.4
1.0
2.1
1.6
Silt
(%)
34.9
39.9
47.2
42.5
37.2
4.3
4.9
3.8
Texture
Clay
Silty clay
Silty clay
Silty clay
Sandy loam
Sand
Sand
Sand
Note: All values are the mean of three determinations
Samples were taken for bulk density determination with an Uhland core sampler
(Utah Research Foundation, Logan, Utah) and with a hydraulic soil auger (Gidd-
ings Manufacturing Company, Fort Collins, Colorado). Three locations around
plot 4, and also locations near plots 3, 28, and 29 were sampled. The results
are presented in Table 2.
Disturbed soil samples were saturated with .01N CaCl2, placed in rubber rings
on a pressure plate membrane (Soil Moisture Equipment Corp., Santa Barbara,
California), and a pressure of 15 atmospheres applied. After equilibration,
the samples were removed and their water contents determined. The results
are presented in Table 3 for the surface-irrigated plots and in Table 4 for
the trickle-irrigated plots. These data again clearly demonstrate the vari-
18
-------
Table 2. BULK DENSITY VALUES FOR THE SOIL AT THE EXPERIMENTAL SITE
Plot 3, East
(means of three values, Uhland sampler)
Depth (cm) 0-15
BD (g/cm3) 1.26
15-25
1.30
25-35
1.38
35-1*5
1.1*7
;45-55 55-65
1.3l* 1.'33
Plot 1*
(means of three values, Uhland sampler, sand at 60-cm)
Depth(cm) 0-20
BD Cg/cm3) 1.1*2
Depth (cm) 0-10
BD Cg/cm3)
Depth (cm) 0-10
BD (g/cm3) 1.36
Depth (cm) 0-15
BD Cg/cm3) 1.1*5
20-1*0
1.38
10-20
1.39
10-20
1.1+9
15-25
1.1*5
1*0-60
1.29
(10-cm
20-30
1.1*1
20-30
1.39
(5 -cm
25-35
1.1*9
60-75
1.51+
cores,
30-1*0
1.1*2
(10-cm
30-1*0
1.39
75-100 100-120 120-11*0 lUO-160
1.52 1.1*9 1.6l l,6l
Plot 28, West
Giddings auger ,
1*0-50 50-60
1.1*1 1.33
Plot 28, South
cores, Giddings
1*0-50 50-60
1.30
Plot 29, East
cores, Giddings auger,
35-1*5
1.31*
1*5-55 55-65
1.37 1.32
sand at 9£>-cm)
60-65 76-81 81-91 91-101
1.32 1.25 1.37 1.1*9
auger )
60-70
1.30
sand at 120-cm)
65-75 75-85 85-95 95-105 105-115
1.31 1.26 1.38 1.26 1.35
-------
Table 3. WATER CONTENTS, IN % DRY WEIGHT AT 15 BARS
PRESSURE FOR 27 SURFACE-IRRIGATED PLOTS
Plot No. 0-20 20-40
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
31.
22.
23.
22.
26.
25.
28.
6
6
1
5
8
7
5
28.1
31.
28.
28.
31.
25.
29.
24.
31.
28.
27.
29.
30.
33.
27.
22.
30.
28.
25.
31.
Mean plots
St.
27.
3
7
3
8
2
2
1
2
3
5
3
7
6
8
7
2
9
0
7
1-30
9
Dev. plots
3.
Mean plots
St.
27.
2
1-20
5
Dev. plots
3.
1
32.8
23.1
22.4
22.2
27.8
23.6
29.2
31.4
31.8
25.2
24.2
32.7
30.3
30.4
23.4
31.0
27.1
25.2
29.2
31.1
32.8
26.3
27.0
26.1
29.9
27.4
32.4
28.0
1-30
3.5
27.4
1-20
3.8
40-60
35.9
30.1
28.2
24.2
33.1
26.9
33.6
36.7
34.7
29.8
30.0
38.0
32.7
29.9
22.8
30.6
28.0
26.6
25.7
15.2
26.3
27.7
12.6
33.0
31.1
31.0
33.6
28.8
5.5
30.7
4.2
Depth (cm)
60-80 80-100 100-120
28.0
13.5
24.8
12.1
21.6
21.6
27.1
34.9
23.7
29.5
31.6
21.6
18.6
17.3
12.7
20.2
28.9
24.4
7.4
8.3
6.9
18.3
15.7
35.8
28.8
33.7
37.1
22.4
8.8
22.9
6.5
8.5
2.5
2.9
3.7
3.4
3.6
5.6
12.4
5.7
9.3
2.6
4.5
3.3
2.9
4.6
4.4
6.5
7.0
14.1
7.1
10.1
14.3
9.3
35.8
10.1
15.1
10.5
8.1
6.8
5.2
2.7
2
1
1
1
1
1
4
5
1
1
1
1
0
1
1
1
1
2
25
15
16
23
29
19
20
6
2
7
9
2
1
.1
.8
.7
.5
.5
.8
.3
.3
.8
.3
.2
.7
.9
.1
.9
.9
.3
.0
.7
.9
.2
.6
.8
.1
.5
.8
.9
.2
.1
.0
.1
120-140
1.5
1.6
1.4
1.0
1.8
1.6
1.7
3.1
1.9
1.1
0.9
1.4
1.6
0.7
1.3
1.9
1.1
1.5
12.3
16.3
9.7
8.3
24.5
22.0
9.1
6.7
3.3
5.2
6.6
1.5
0.5
140-160
1
1
1
1
1
2
1
1
1
1
1
1
1
0
2
1
1
1
3
2
3
3
3
17
10
8
1
3
3
1
0
.2
.5
.3
.5
.3
.5
.3
.8
.5
.6
.6
.3
.0
.8
.0
.7
.2
.7
.6
.2
.1
.0
.8
.7
.4
.6
.6
.0
.7
.5
.4
20
-------
ability of the subsoil at the experimental site. The first two rows of plots
are much more similar than the third row of plots, as shown by comparing the
standard deviation for all surface-irrigated plots with the standard devia-
tion for the first two rows only (plots 1-20). The standard deviation was
considerably decreased by excluding the data for the third row of plots.
The amount of plant available water in stratified soils is difficult to esti-
mate. At the experimental site, a variable thickness of clay loam is under-
lain by sand. A commonly accepted concept in soil physics is that a coarse-
textured subsoil causes overlying fine soils to "hold" more water after irri-
gation, than would be held by uniform fine-textured soils.
Plant available water was initially assumed to be the amount of water held by
the soil at water potentials between 1/3 atm and 15 atm. The data in Table 3
show that the amount of water held by the first 20 surface-irrigated plots at
15 atm was about 27.2 percent by weight for the upper 80 cm of soil. This is
equivalent to 38.1 percent by volume (assuming an average bulk density of
1.4). With a bulk density of 1.4, the porosity is 48 percent. Thus after a
heavy irrigation, the water content would be no more than 48 percent by
volume. The "available water", then, would at most be 48 - 38 = 10 percent.
For an 80-cm profile, this amounts to 8.0-cm water. The available water may
also be estimated from the difference in the water content of the profile one
or.two days after irrigation and the water content at the end of the growing
season, when the plants have used up most of the readily available water.
Using the latter procedure, estimates ranged from 12 to 15-cm available water
for an 80-cm soil profile, considerably above the values obtained from the
15 atm water content and the saturated water content.
For the purpose of the irrigation scheduling program, the available water was
estimated to be 5 cm per 30 cm of soil. This amounted to 13.3-cm for an 80-cm
profile. The depth of the profile was assumed to be the same as the depth to
the sand. Since this depth was different for each plot, the mean rooting
depths for each treatment were calculated separately. The mean estimated root
depths and the estimated available water are given in Table 5 for each treat-
ment.
Hydraulic conductivity as a function qf water content was determined following
the procedure described by Nielsen et al. (1964) and van Bavel et al. (1968).
21
-------
Table 4. WATER CONTENTS, IN % DRY WEIGHT, AT 15 BARS
PRESSURE FOR THE SIX TRICKLE-IRRIGATED PLOTS
Plot No.
1 row
1 center
2 row
2 center
3 row
3 center
4 row
4 center
5 row
5 center
6 row
6 center
Mean
St. Dev.
0-20
28.6
28.7
23.3
21.5
21.7
35.2
35.1
24.5
31.7
30.6
30.1
21.0
27.7
5.2
20-40
29.3
28.5
20.8
21.9
22.9
36.6
36.0
23.4
21.7
30.7
25.8
23.7
26.8
5.5
40-60
28.5
23.1
22.5
12.0
13.9
30.5
25.2
27.7
31.8
24.9
18.5
15.9
22.9
6.5
Depth (cm)
60-80 80-100
7.5
15.8
6.6
5.9
4.4
8.1
11.4
11.5
18.0
15.2
7.1
6.4
9.8
4.5
10.1
21.7
9.4
11.3
4.7
16.7
5.0
10.6
15.5
16.3
9.8
10.6
11.8
5.0
100-120
15.5
12.0
11.6
17.9
9.2
21.0
8.6
17.8
16.6
15.9
12.0
17.4
14.6
3.9
120-140
5.3
4.7
4.3
4.0
6.2
8.8
3.8
6.8
8.9
8.3
10.0
10.1
6.8
2.4
140-160
10.4
6.9
5.6
6.0
3.2 .
6.0
1.7
9.0
2.2
10.0
5.5
8.7
6.3
2.9
Table 5. ESTIMATED ROOT DEPTHS AND AVAILABLE WATER
FOR SURFACE IRRIGATION TREATMENTS
Treatment No.
1
2
3
4
5
6
7
8
9
Root depth
(cm)
72
68
70
71
72
69
68
75
69
Available water
(cm)
12.0
13.3
11.7
11.8
12.0
11.5
11.3
12.5
11.5
22
-------
The soil profile was thoroughly wetted by applying 45 cm of water. Following
infiltration, the soil surface was covered with black polyethylene plastic.
Cumulative water loss from the soil by drainage was measured with a neutron
probe at time intervals varying between one half day and several days. Simul-
taneously, the hydraulic gradients in the subsoil were obtained from tensio-
meter readings. From estimated drainage fluxes and hydraulic gradients,
values of hydraulic conductivity were calculated.
Graphs depicting the change in hydraulic conductivity with water content are
presented in Fig. 2 for four different depths in plot 4. The figure shows
that the hydraulic conductivity in the sandy subsoil (below 75~cm) changes
very rapidly with water content. Therefore, in order to estimate deep perco-
lation losses, accurate measurements of the water content were required in
addition to knowledge of the hydraulic conductivity-water content relation-
ships for every plot.
An indication of the variability in water content of the subsoil in the field
can be obtained from the data in Table 3, where the water contents at 15 atm
pressure are presented. In Table 6, the water contents are presented for the
depth in each plot where the hydraulic gradient was measured. The water con-
tents were obtained from neutron probe data taken during the period February
through December 1974. During this period the water content of the sand at
125 to 150 cm remained nearly constant. However, the plot-to-plot variation
was relatively large, particularly in the third row of plots. For the first
two rows, the mean was about 12 percent by volume and the standard deviation
about the mean was 3.5 percent by volume. It is obvious from Fig. 2 that the
hydraulic conductivity changed orders of magnitude over the range of water
contents presented in Table 6. This made it impossible to obtain representa-
tive hydraulic conductivity values for each plot from measurements taken in
only one or two plots.
LABORATORY PROCEDURES
All water samples and soil solution samples taken in the field were brought
to the laboratory for analysis. The procedures for analysis were basically
those described in "Methods for Chemical Analysis of Water and Wastes"
(Environmental Protection Agency, 1971).
Electrical conductivity was determined using a Barnstead conductivity bridge.
23
-------
1
O
o
8
O
1 io<
o
v|
1 x
1 x
II
x xx
120-150 cm
75- 90 cm
90-l20cm
f / /
i / /
x f*
* ^
|X *
1
.*
XX
si
y
/
*
60-75 cm
5.0 10.0 15.0 20.0 25.0
WATER CONTENT (% OF VOLUME)
30.0
Figure 2. Hydraulic conductivity as a function of water content at
several depths for the soils in plot 4.
24
-------
Table 6. AVERAGE WATER CONTENTS OF THE SUBSOIL (SURFACE-IRRIGATED
PLOTS) MEASURED WITH A NEUTRON PROBE DURING 1974
Plot no.
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Mean plots
1-30
St. dev. plots
1-30
Mean plots
1-20
St. dev. plots
Water content
125 cm
8.58
9.29
8.59
11.16
15.63
13.62
15.21
14.10
17.94
7.50
9.30
18.57
11.31
9.37
10.20
10.28
12.58
11.95
24.60
24.97
40.43
19-75
50.78
49.81
8.92
16.50
10.95
17.11
11.83
11.95
3.27
(yolujne percent) at:
150 cm
10.40
11.84
9.19
11.09
11.26
12.86
15.98
13.92
14.64
8.34
25.99
14.24
12.47
11.50
9.93
10.16
11.95
15.49
13.29
19.71
21.35
10.92
34'. 22
23.08
9.30
10.66
8.75
14.17
5.99
12.85
3.92
180 cm
_
—
—
—
-
-
-
—
—
-
-
-
-
-
-
-
-
-
11.81
27.82
21.85
11.43
40.86
8.71
8.42
14.46
9.96
17.26
10.99
-
-
1-20
25
-------
The pH was determined with a digital pH meter. An atomic absorption-flame
emission spectrophotometer was utilized in the analysis of the cations, sodium
and potassium concentrations determined by flame emission and calcium and
magnesium determined by atomic absorption. Procedures described in "Analytical
Methods for Atomic Absorption Spectrophotometry" (Perkin-Elmer, 1971) were
used for these determinations. Sulfate concentrations were determined by the
nitrochromeazo titrimetric method developed by- Rasnick and Nakayama (1973) .
Carbonate and bicarbonate concentrations were determined by titration with
0.01 N sulfuric acid in the presence of phenolphthalein and methyl orange
(U.S. Salinity Laboratory* 1954). Chloride analysis was completed on a
Buchler-Cotlove chloridometer (Cotlove et al. 1958). Nitrate analyses were
done spectrophotometrically (Lambert and Dubois, 1971).
EXPERIMENTAL DESIGN OF FIELD PLOT STUDY
The main treatment effects on the surface irrigated plots were frequency of
irrigation and water application efficiency where water application efficiency
is defined as the percentage of the water applied that is actually stored in
the root zone for use by the crops (Willardson, 1972). Frequency was deter-
mined on the basis of the amount of "available" water in the soil profile,
where "available" water was defined as discussed above. Treatments included
the scheduling of an irrigation when 25, 50 or 75 percent of the available
water was depleted from the root zone at a predetermined efficiency. Three
field water application efficiencies were selected: 50, 75 and 100 percent
for the first year of study, and 80, 90 and 100 percent efficiency for the
last two years of study. At 50 percent efficiency, half of the applied water
was lost by deep percolation, while ideally none was lost at 100 percent effi-
ciency. The main treatment effects consisted of combinations of three fre-
quencies of irrigation with three field water application efficiencies,
resulting in a total of nine treatments. Each treatment was block randomized
with three replications per treatment, resulting in 27 surface-irrigated plots.
Of the six trickle irrigated plots, three were irrigated to maintain a soil
water tension of less than 0.2 bars at a depth of 15 cm. In the other three
plots the soil water tension at a depth of 15 cm was kept at 0.6 bars or less.
Table 7 summarizes the plots in each treatment and the treatments as applied
during 1973 and 1974.
26
-------
Table 7. SUMMARY OF IRRIGATION TREATMENTS AND PLOTS
ASSIGNED TO EACH TREATMENT
Treatment
number
1
2
3
4
5
6
7
8
9
02
06
Depletion
(%)
Surface-irrigated
25
50
75
25
50
75
25
50
75
Trickle -irrigated
0.2 atm
0.6 atm
Efficiency
(%)
plots
80
80
80
90
90
90
100
100
100
plots
_^
— —
Plot
numbers
2,14,29
5,20,25
6,16,21
10,18,24
1,15,30
3,11,23
9,12,26
8,17,27
7,13,22
3,4,5
1,2,6
CROP MANAGEMENT
After preirrigation with 15 to 25 cm of water, the surface and trickle-irri-
gated plots were planted with cotton, Acala 1517-70. All plots were planted
without bedding on a 1-m row spacing using a small hand planter. Planting was
during the last two weeks of April or the first week of May. Fertilizer was
applied in a shallow trench next to each cotton row during the first week of
June. Amounts applied were 134 kg N/ha and 67 kg P~0,-/ha.
Yields were estimated from the cotton obtained by hand picking the center five
rows on each surface -irrigated plot and the center four rows on the trickle-
irrigated plots. Total row length harvested was 30.5 m (100 ft) on the sur-
face-irrigated plots and 61 m (200 ft) on the trickle-irrigated plots. All
plots were harvested twice. The first harvest was generally during the first
two weeks of October, and the second harvest was about four weeks later. After
the second harvest, the cotton stalks were manually removed from the soil.
Cultivation of the plots was limited to rototilllng the surface-irrigated plots
after preirrigation and before planting. Although this procedure is different
from what the farmers in the area use, the small size of the plots made it
27
-------
impossible to use standard farming practices. Following preirrigations, the
soil in the trickle plots was in excellent condition, so no rototilling or
tillage was necessary.
After planting in 1973 and 1974, a sandcap was applied over the rows to aid in
germination and to prevent severe crusting of the surface soil. This proce-
dure was used for the surface-irrigated plots only as there was never any
surface crust formation on the trickle-irrigated plots or problems with
germination.
IRRIGATION MANAGEMENT
The scheduling of irrigation water for the various treatments was based upon
climatological data and on soil and crop data from the experimental plots.
During the 1972 season, irrigation intervals and amounts were determined by
pan evaporation data, corrected with a stage of growth dependent crop coeffi-
cient and adjusted for rainfall. The coefficients based on stage of growth
had been developed for use on the Salt River Project in Arizona, and were
modified slightly because of the cooler nights in Las Cruces. The shape of the
modified relationship is shown in Fig. 3.
During the 1973 and 1974 seasons, irrigation intervals and amounts were based
on the Irrigation Scheduling Service (ISS) of the Bureau of Reclamation. This
program, originally developed by Jensen (Jensen et al. 1972), schedules irri-
gations from meterological data combined with soil, crops and experimental
information.
A weather station was established at the Plant Science Research Center adja-
cent to the study area, and the following measurements were made: incoming
solar radiation, temperature, humidity, daily wind run at 2 m, pan evaporation
and rainfall" (see under climatic data). The Bureau of Reclamation u'sed these
same data for scheduling irrigations on farms in the vicinity of the Plant
Science Research Center.
The Jensen-Haise equation was used for computing evapotranspiration. It has
the form:
ETP = C (T - T ) R CD
where T is the mean daily air temperature in °F, R is the daily solar incoming
s
radiation in inches evaporation equivalent, and C and T are coefficients.
L. 2v
28
-------
1.0
.8
to
CO
M Q.
LUJUJ
Q
I
.6
.4
.2
10
20 30 40 50 60 70
% OF GROWING SEASON ELAPSED
80
90
Figure 3. Ratio of evapotranspiration to pan evaporation for cotton as a function
of percent of growing season elapsed.
-------
The values for C and T used in tke El Paso - Las Cruces area are .0066 and
t. X
-24, respectively. Therefore, equation (1) becomes:
ETP = 0.0066 CT + 24) R (2)
s
To get the actual daily evapotranspiration CET) for cotton, ETP is multiplied
by a crop coefficient, K , and a soil moisture coefficient, Ka> as follows:
ET = K x K x ETP C3)
c a
The value of the crop coefficient K varies with the stage of growth of each
c
crop. The K curve used for cotton in the local area is presented in Fig. 4.
The soil moisture coefficient reflects the availability of soil moisture at
the time of computation. The adjustment is small when soil moisture is high
and becomes greater as the available soil moisture decreases according to:
_ In (AM + 1) f4v
a ~ In (101) W
where AM is the percent of available moisture in the root zone. The maximum
available moisture in the root zone and the maximum rooting depths for each
surface treatment used in the program are listed in Table 5.
The increase in evaporation from the wet soil surface immediately following an
irrigation or rainfall was accounted for in the following manner:
1. Adjusted ET = Computed ET + (Percent x Adjustment)
2. Adjustment =(0.9-K K)x ETP
c a
3. No adjustment the day of rain or after 4 days following rain, and
no adjustment if K K > 0.9.
c a —
4. First day after rain: 80 percent x adjustment
Second day after rain: 50 percent x adjustment
Third day after rain: 30 percent x adjustment
5. Adjustment following an irrigation is the same; also no ET
computed for the day of the irrigation.
The effective cover date at which the crop began to require water at the peak
rate was taken to be August 7 in 1973, and August 13 in 1974. A 60-cm root
zone was assumed at planting. Increases in the depth of the root zone were
made in 15-cm increments, until the maximum depth was reached at 80 percent of
the time from planting to effective cover. Effective precipitation was assumed
to be the total precipitation from rains greater than 2.5-mm.
30
-------
COTTON
Computer curve #10
_L
_L
20 40 60
Plant to effective cover, %
80
100
20 40 60
Days after effective cover.
8O
Figure 4. Crop coefficient (K ) used in the Jensen-Haise equation to
estimate evapotranspiration.
-------
SECTION VI
RESULTS AND DISCUSSION
The results of this study will be discussed according to the objectives stated
in the introduction. First, the effects of surface irrigation treatments on
water and solute movement within the soil profile will be discussed. Included
will be the data obtained from the five deep wells, and also the effect of
irrigation treatments on cotton yield. The second objective, i.e., to deter-
mine the effects of water management on composition and quality of percolating
water in plots under trickle irrigation,will be discussed next.
In the third section, the quality of the water in the Del Rio Drain will be
discussed and compared with the quality of the water percolating from the field
plots and with the quality of the water from the deep wells, the irrigation
well, and from the Rio Grande during the irrigation season.
SURFACE IRRIGATION
Percolation Losses
From Soil Hydraulic Properties - Percolation losses during the experiment were
to be determined from knowledge of the hydraulic conductivity and the hydraulic
gradient as measured in each plot. During each of the three crop years, the
hydraulic gradients were measured with triplicate tensiometers placed at two
depths well below the root zone in each plot.
The tensiometers were connected to mercury manometers outside of each plot.
From the manometer readings, soil-water tensions were calculated for each depth
below the soil surface. The hydraulic gradients were computed directly from
soil-water tensions.
An example of the variation in soil-water tension with time is presented in
Fig. 5 for Plot 22 for the 1973 crop year.
The data for Plot 22 show a fairly constant soil-water tension at both depths
until the end of August. After September 1, though there was no irrigation,
the cotton was apparently still using water causing a gradual increase in soil-
water tension at 150 and 180 cm.
Figure 6 shows the hydraulic gradient averaged for plots 7, 13, and 22 (Treat-
ment 9) at various time intervals during the 1973 crop year. There is consid-
erable variation in the gradient. During July and August, the gradient was
32
-------
E
u
I
tr.
LU
Sf
150 r
100
50
0
/^.4fl$N..A
°cp-q#>-'
*tg
§<%>
150cm i
1
~JJUJ-»'-v»'- I
,<*"«n I80cm
JULY
AUGUST SEPTEMBER OCTOBER
Figure 5.
Variation of soil-water tensions (cm of H20) at the
150- and 180-cm depths with time (plot 22). „
£ 2.54r
JULY
AUGUST SEPTEMBER OCTOBER
Figure 6. Variation of the mean hydraulic gradient between
the 150- and 180-cm depths for Treatment 9.
33
-------
approximately unity with a slow increase in September due to drying of the
soil above the tensiometers. A gradient of unity means downward movement of
soil-water at a rate equal to the hydraulic conductivity of the soil at the
prevalent water content.
No significant differences were found between the average hydraulic gradients
of the treatments. Therefore, the monthly gradients of the treatments were
averaged for all plots. The results for 1973 and 1974 were:
1973 1974
June -0.86 -0.61
July -1.10 -0.78
August -0.84 -0.90
September -0.58 -0.76
At all times and for all plots the hydraulic gradients were near unity, as
expected, and directed downward, indicating some downward movement of water.
The hydraulic conductivity of the sandy subsoil at the experimental-site varied
widely with water content (Figure 2). Small changes in water content
result in large changes in hydraulic conductivity. As a result, the water con-
tent of the soil layer where the hydraulic gradient is measured needs to be
known very precisely. The precision of the neutron probe was usually within
+_ 1 percent by volume. However, a one percent variation in water content may
lead to errors of 200 to 500 percent in estimates of hydraulic conductivity
(Fig. 2).
A further complication is that the hydraulic properties of the subsoil at the
experimental site vary widely from plot to plot, as evidenced from the data in
Tables 1, 3 and 6.
For example, during the 1974 irrigation season, the mean water content of the
first two rows of plots (plots 1-20) at 125-150 cm was 12.5 percent by volume
with a standard deviation of about 4 percent by volume (Table 6).
Although during the year the water content at tensiometer depths in each plot
remained fairly constant, the large plot-to-plot variations in water content
caused the spatial variability of the hydraulic conductivity over the experi-
mental site to be great. For these reasons it became impossible to accu-
rately estimate deep percolation losses from each plot, using conductivity
relationships obtained for a number of test plots.
34
-------
In conclusion, estimates could not be made of the deep percolation losses from
each treatment using the concept of conductivity times gradient. Although the
hydraulic gradients were close to unity during a large part of the irrigation
season, the uncertainties in the measured water contents and in the hydraulic
conductivities corresponding to these water contents precluded calculation of
deep percolation losses for treatments with the necessary precision.
From climatological data - The first year, a Class A evaporation pan was used
in estimating crop water use (ET), while during the second and third year, the
Irrigation Scheduling Service (ISS) of the Bureau of Reclamation was used (See
Irrigation Management, page 28) to estimate ET.
By comparing actual amounts of water applied, irrigation + rainfall, with esti-
mated crop water use (ET), deep percolation losses could be determined.
In order to present the irrigation and rainfall data in a uniform manner, the
irrigation season is divided into three segments: preirrigation, seeding to
stand establishment, and stand establishment to harvest taken to be October 31.
The irrigation and rainfall data for these time segments are presented in
Tables 8, 9 and 10 for 1972, 1973 and 1974, respectively. These irrigation
and rainfall data show considerable variation from year to year in the quantity
of water applied during seedling emergence. This variation was mainly caused
by the presence or absence of rainfall. The variation in water applied from
stand establishment to harvest is due largely to the change from evaporation
pan to ISS in estimating crop water use and the change in treatments from 1972
to 1973.
In establishing a stand in 1974, it was found that frequent irrigation was
necessary to keep the soil from forming a crust during a period of unusually
high winds and high air temperatures. In the other years small rains greatly
reduced the quantity of irrigation water required to obtain seedling emergence.
Thus, to provide reasonable comparisons of irrigation efficiencies from year to
year, columns titled "Total" in Tables 8, 9 and 10 were used to construct Table
11.
In Table 11, the total amounts of irrigation and rainfall (from stand establish-
ment to harvest) are presented together with the computed evapotranspiration
from pan data (1972) and from the ISS program (1973 and 1974).
35
-------
Table 8. IRRIGATION AND RAINFALL DATA FOR SURFACE
PLOTS AT THE INDICATED TIME INTERVALS (1972)
Seeding
to
stand estab.
Treat-
ment No
1
2
3
4
5
6
7
8
9
Preirrigation
(cm)
20. 5
20.7
20.5
20.4
20.5
20.6
20.5
20.6
20.8
Irrigation
(cm)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Rain
(cm)
4.1
4.1
4.1
4.1
4.1
4.1
4.1
4.1
4.1
Stand estab. to
harvest
Irrigation
(cm)
72.0
72.6
68.3
51.4
54.1
48.5
42.7
42.1
39.1
Raina
(cm)
22.6
22.6
22.6
22.6
22.6
22.6.
22.6
22.6
22.6
Totalb
(cm)
106.6]
108.5)105
102. 6J
85.8]
88.7) 85
82. 6J
76.61
77.2) 75
73. 2j
.9
.7
.7
To October 31, only rains of intensity greater than 0.25 cm considered.
Total = total water applied (irrigation plus rainfall) from stand
establishment to harvest + final soil-water depletion (plant available
water, Table 5, page 22).
Table 9. IRRIGATION AND RAINFALL DATA FOR SURFACE
PLOTS AT THE INDICATED TIME INTERVALS (1973)
Seeding to
stand estab.
Stand estab. to
harvest
Treat-
ment K[0
1
2
3
4
5
6
7
8
9
Preirrigation
(cm)
11
10
11
11
11
14
13
15
11
.9
.3
.1
.8
.9
.1
.9
.6
.6
a
Irrigation
(cm)
7
9
7
8
8
8
7
7
7
.5
.6
.0
.0
.1
.2
.4
.3
.3
Rain
(cm)
1.
1.
1.
1.
1.
1.
1.
1.
1.
8
8
8
8
8
8
8
8
8
Irrigation Rain
(cm) (cm)
53
54
45
44
48
37
41
33
35
.7
.0
.1
.0
.3
.9
.9
.9
.0
18.4
18.4
18.4
18.4
18.4
18.4
18.4
18.4
18.4
Total0
(cm)
84.1
85.7
75.2
74.2
78.7
67.8
> 81.7
> 73.6
71.61
64.8? 67.1
64. 9J
Preirrigation does not include the 0.4-cm rain that occurred.
To October 31, only rains of intensity greater than 0.25 cm considered.
Q
Total = total water applied (irrigation plus rainfall) from stand
establishment to harvest + the final soil-water depletion (plant
available water, Table 5). •
36
-------
Table 10. IRRIGATION AND RAINFALL DATA FOR SURFACE
PLOTS AT THE INDICATED TIME INTERVALS (1974)
Seeding to
stand estab.
Stand estab. to
Treat-
mentNo.
1
2
3
4
5
6
7
8
9
Preirrigation
(cm)
16
16
16
16
16
16
16
16
16
.5
.5
.5
.5
.5
.5
.5
.5
.5
Irrigation
(cm)
16
15
15
15
15
15
15
15
15
.0
.3
.4
.4
.3
.4
.4
.3
.2
Rain
(cm)
0
0
0
0
0
0
0
0
0
Irrigation Rain
(cm) (cm)
49
45
47
45
37
43
44
37
40
.4
.8
.0
.9
.4
.4
.9
.0
.0
25
25
25
25
25
25
25
25
25
.1
.1
.1
.1
.1
.1
.1
.1
.1
Total0
(cm)
86.5}
84.3>
83. 8J
82.8]
74. 5)
80. OJ
81.31
74. 6>
76. 6J
84.9
79.1
77.5
a
Estimated. The 40.6-cm irrigation to determine hydraulic properties of
the soils is not included here.
To October 31, only rains of intensity greater than 0.25 cm considered.
•»
"Total = total water applied (irrigation plus rainfall) from stand
establishment to harvest + the final soil water depletion (plant avail-
able water, Table 5).
Table 11. TOTAL AMOUNTS OF WATER APPLIED IN CM (RAINFALL PLUS IRRIGA-
TION) DURING THE 1972, 1973 AND 1974 GROWING SEASONS COMPARED
WITH COMPUTED EVAPOTRANSPIRATION (ET) IN CM. PAN REFERS TO
ET AS ESTIMATED BY EVAPORATION PAN AND ISS REFERS TO
IRRIGATION SCHEDULING SERVICE ESTIMATES OF ET
Treat-
ment No.
1
2
3
4
5
6
7
8
9
1972a
Applied
106.6
108.5
102.6
85.8
88.7
82.6
76.6
77.2
73.2
ET(PAN)
55.1
55.1
55.1
55.1
55.1
55.1
55.1
55.1
55.1
1973a
Applied
84.1
85.7
75.2
74.2
78.7
67.8
71.6
64.8
64.9
ETQSS)
54.6
54.6
54.6
54.1
56.6
54.6
53.6
55.6
54.6
1974a
Applied
86.5
84.3
83.8
82.8
74.5
80.0
81.3
74.6
76.6
ET(ISS)
57.9
58.7
59.4
57.9
56.9
59.2
57.9
59.7
59.4
Average
89.1
55.1
74.1
54.8
80.5
58.6
a Post irrigation rainfall for 1972, 1973 and 1974 are 13.9 cm, 10.6 cm,
and 17.4 cm, respectively.
37
-------
Assuming that deep percolation losses are equal to amounts applied minus
estimated ET, these data show that the amounts of water lost by deep percola-
tion varied in 1973 from a high of 36 percent from Treatment 2, to a low of
14 percent from Treatment 8, as estimated by ISS. During the 1974 irri-
gation season, calculated deep percolation losses were 31 percent from the 80
percent efficiency treatment, and 24 percent from the 100 percent efficiency
treatment. Averaged for all treatments,the depths of water lost by deep
percolation were 19.3 cm in 1973 and 21.9 cm in 1974 (Table 11). Thus, on the
average in 1973 and 1974, 20.6 cm of water was lost over a 5 month period.
This amounts to a downward flux of 0.14 cm/day. Since hydraulic gradients
were close to one during most of the irrigation season, the flux was approxi-
mately equal to the hydraulic conductivity at the prevailing water content.
Hydraulic conductivities as small as 0.14 cm/day could not be measured in situ.
It is also clear from Fig. 2 that, in this range of conductivities, small
errors in the determination of water content produced very large errors in
estimated fluxes.
From Neutron Probe Data - The water contents in the plots were measured with
the neutron probe at short time intervals, particularly during the last year
of the three year study. During the 1974 growing season, the water content in
each plot was determined more than 45 times. From the differences in water
content with time, water use by the crop can be calculated if deep percolation
losses are known or are negligibly small. Table 12 lists 1973 and 1974 crop
water use as estimated by neutron probe, amounts of water applied (irrigation
and rain), and ISS computed ET.
The data in Table 12 show that although the predicted evapotranspiration data
are nearly the same for all treatments, the measured water use data show large
differences. This table shows that differences in water use measured with the
neutron probe are somewhat larger between depletions than between efficiencies,
indicating that depletion treatments had more effect on leaching than did
efficiency treatments. The cumulative water use estimated by ISS and from
neutron probe data in 1974 are also presented in Figures 7, 8 and 9 for the
25, 50 and 75 percent depletion treatments, respectively.
38
-------
Table 12. COMPARISON OF NEUTRON PROBE MEASURED WATER USE WITH ISS
ESTIMATED WATER USE, AND TOTAL WATER ACTUALLY APPLIED
FOR 1973 AND 1974
Deple- Effi-
Treat- tion ciency
ment No. % %
1
2
3
4
5
6
7
8
9
Mean
25
50
75
25
50
75
25
50
75
80
80
80
90
90
90
100
100
100
Measured
(cm)
71.0
64.2
59.5
80.1
66.3
57.7
63.6
50.4
50.0
62.5
1973
Applied*1
(cm)
84.1
85.7
75.2
74.2
78.7
67.8
71.6
64.8
64.9
74.1
ET(ISS)
(cm)
54.6
54.6
54.6
54.1
56.6
54.6
53.6
55.6
54.6
54.8
Measured
(cm)
89.8
74.6
63.1
78.3
69.5
54.4
81.5
67.4
59.3
70.9
1974
Applied3-
(cm)
86.5
84.3
83.8
82.8
74.5
80.0
81.3
74.6
76.6
80.5
ET(ISS)
(cm)
57.9
58.7
59.4
57.9
56.9
59.2
57.9
59.7
59.4
58.6
Applied water includes post irrigation rains of 10.6-cm and 17.4-cm for
1973 and 1974, respectively.
Table 13. EFFECT OF DEPLETION AND EFFICIENCY TREATMENT ON MEASURED
(NEUTRON PROBE) AND PREDICTED (ISS) WATER USE
1973
1974
Treat- Measured Applied ET(ISS)
ments Depletion % (cm) (cm) (cm)
Measured Applied ET(ISS)
(cm) (cm) (cm)
1,4,7
2,5,8
3,6,9
25
50
75
71.6
60.3
55.7
76.6
76.4
69.3
54.1
55.6
54.6
83.2
70.4
58.9
83.5
77.8
80.1
57.9
58.4
59.3
Efficiency 2
1,2,3
4,5,6
7,8,9
80
90
100
64.9
68.0
54.7
81.7
73.6
67.1
54.6
55.1
54.6
75.8
67.4
69.4
84.9
79.1
77.5
58.7
58.0
59.0
The measured water use (neutron probe) was less than the total amount of water
applied. In 1973, the difference between measured use and total water applied
was 20 percent and in 1974, the difference was 26 percent. These differences
probably arise from systematic errors in water contents as measured with the
neutron probe, the plot surfaces not being perfectly level, and rapid drain-
age losses immediately following heavy irrigation.
39
-------
*c
o
*SM^
O
^
9=
CL
Z
tr
£
Q.
§
UJ
80
70
60
50
40
30
20
10
n
-
MEAN OF ALL 25% DEPLETION TREATMENTS
—
x
X NEUTRON PROBE
o ISS X
O
X
X
_ o
o
X
-
X o
X o
w
Xo
v X o
x o
ly 1 ° 1 1 1 1 1 1 1 1 1 1 1
APR MAY JUN JUL AUG SEP
Figure 7. Accumulative evapotranspiration estimated by ISS and
smoothed neutron probe data for 1974 (mean of
all 25% depletion treatments).
'e
Z
o
,
<£
on
CL
V)
z
tr
^
CL
§
LJ
80
70
60
50
40
30
20
10
n
-
MEAN OF ALL 50% DEPLETION TREATMENTS
X
X NEUTRON PROBE
- ° ISS
o
X
-
o
X
o
x
o
X
o
X
X o
X o
X o
•^ 1 6 i
APR MAY JUN JUL AUG SEP
Figure 8. Accumulative evapotranspiration estimated by ISS
and smoothed neutron probe data for 1974 (mean of
all 50% depletion treatments).
40
-------
"g
£>
Z
o
-------
In Appendix Tables 1-6, electrical conductivities of the saturation extracts
(mmhos/cm) are presented.
The data in Tables 14-19 are presented in g per 100 g soil. The amount of
salt per 100 g soil was calculated from:
g salts/100 g soil = (ml H20/100 g soil) X (g/l)/1000 CD
where:
g/1 = mmhos/cm X 14.3 X 0.07 (2)
A complete chemical analysis was made on the saturation extracts of the soil
samples collected during May 1973. From the equivalent weights of the con-
stituent ions in the extracts, an average milliequivalent weight of 0.070 was
found for the conversion of meq/1 to g/1. By further plotting ECe (mmhos/cm)
versus total salts in milliequivalents per liter, a correlation was obtained
between EC and concentration in meq/1 (Figure 10), with a slope of 14.3.
An analysis of variance based on saturation extracts of soil samples from the
surface irrigation treatments is presented in Table 20. The data in Tables
14-19, and Appendix Tables 1-6 show considerable variation in salinity not only
with depth, but also in the horizontal plane. The significant variation by
depth was expected since the soil profiles are sharply stratified. This
stratification is a natural property of these soils, and not under experi-
mental control. An index of variation is the standard deviation about the
mean soil salinity. For depths greater than 100 cm, the standard deviation
was typically as large as the mean. It may be noted that spatial variation
appeared to be greater in the subsoil than in the topsoil.
The large spatial variation in soil salinity (indicated by the large coeffi-
cients of variation associated with various error terms) made it difficult to
detect any statistically significant differences due to irrigation treatments.
Table 20 shows that the only factors having a significant effect on soil
salinity were depth and the year X depletion interaction. Soil salinity was
independent of the efficiency treatments, which was not too surprising consi-
dering the relatively small differences in the amounts of water applied on
the three efficiency treatments and the extreme natural variability of the
experimental site. Although depletion was not significant, the data in Table
42
-------
Table 14. SALT CONTENT OF SOIL (g/lOOg OF SOIL) IN SURFACE-IRRIGATED PLOTS 1-10
AND OUTSIDE SURFACE-IRRIGATED PLOTS 11-30 (SPRING 1972 PRIOR TO PLANTING)
co
Plot No.
P 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
PllSa
P12S
P13S
P14S
P15S
P16S
P17S
P18S
P19S
P21S
P22S
P23S
P24S
P25S
P26S
P27S
P28S
P29S
Mean
Std. Dev.
0-20
.13
.19
.15
-
.11
.20
.18
.13
.35
.21
.23
.21
.20
.13
.13
.14
.21
.21
.07
.07
.12
.15
.36
.22
.23
.19
.16
.18
.069
Depth (cm)
20-40
.15
.22
.32
-
.18
.58
.29
.16
.55
.49
.33
.38
.44
.19
.19
.22
.38
.39
.08
.05
.06
.15
.46
.41
.35
.30
.23
.29
.15
40-60
.48
.29
.50
—
.40
.39
.55
.29
.41
.57
.33
.29
.32
.36
.30
.43
.43
.60
.05
.03
.03
.39
.37
.46
.54
.53
.34
.37
.15
60-90
.04
.02
.06
-
.11
.15
.39
.10
.28
.15
.08
—
.19
.12
.13
.24
.10
.29
.04
.02
-
.15
.45
.37
.18
.30
.43
.18
.13
S designates south of plot.
-------
Table 15. SALT CONTENT OF SOIL Cg/100g OF SOIL) IN SURFACE-
IRRIGATED PLOTS (DECEMBER 1972)
Plot No.
P 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P14
P15
P16
P17
P18
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
Mean
Std.Dev.
0-20
0.09
0.08
0.10
0.06
0.08
0.12
0.09
0.13
0.10
0.11
0.16
0.15
0.11
0.13
0.09
0.11
0.10
0.09
0.12
0.07
0.09
0.22
0.20
0.24
0.11
0.13
0.11
0.12
0.043
20-40
0.17
0.13
0.20
0.12
0.15
0.16
0.15
0.23
0.28
0.21
0.30
0.32
0.14
0.28
0.18
0.17
0.15
0.21
0.15
0.14
0.15
0.26
0.24
0.33
0.17
0.15
0.11
0.19
0.063
40-60
0.34
0.38
0.41
0.17
0.36
0.27
0.41
0.46
0.51
0.37
0.41
0.50
0.41
0.54
0.34
0.45
0.34
0.35
0.11
0.17
0.12
0.48
0.39
0.44
0.33
0.33
0.22
0.36
0.12
Depth
60-80
0.28
0.20
0.44
0.15
0.41
0.26
0.30
0.41
0.41
0.42
0.36
0.33
0.23
0.21
0.15
0.31
0.31
0.42
0.09
0.13
0.10
0.39
0.38
0.43
0.28
0.52
0.23
0.30
0.12
(cm)
80-100
0.12
0.10
0.18
0.12
0.11
0.14
0.14
0.19
0.22
0.13
0.13
0.11
0.14
0.11
0.09
0.05
0.15
0.23
0.08
0.05
0.09
0.27
0.23
0.50
0.20
0.23
0.13
0.16
0.090
100-120
0.06
0.06
0.07
0.05
0.09
0.06
0.05
0.11
0.15
0.08
0.07
0.08
0.07
0.06
0.04
0.03
0.05
0.11
0.08
0.06
0.10
0.31
0.39
0.45
0.17
0.15
0.07
0.11
0.11
120-140
0.03
0.05
0.06
0.04
0.05
0.04
0.05
0.06
0.12
0.06
0.05
0.07
0.02
0.05
0.03
0.03
0.05
0.09
0.08
0.04
0.07
0.42
0.29
0.16
0.11
0.06
0.04
0.082
0.086
140-160
0.03
0.05
0.10
0.03
0.04
0.03
0.06
0.05
0.12
0.12
0.04
0.06
0.04
0.05
0.02
0.03
0.05
0.06
0.02
0.04
0.02
0.04
0.03
0.29
0.10
0.05
0.03
0.060
0.055
-------
Table 16. SALT CONTENT OF SOIL (g/lOOg OF SOIL) IN SURFACE-
IRRIGATED PLOTS CHAY 1973)
Plot No.
P 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P14
P15
P16
P17
P18
P20
P21
P22 "
P23
P24
P25
P26
P27
P29
P30
Mean
Std.Dev.
0-20
0.07
0.10
0.10
0.06
0.09
0.06
0.09
0.11
0.10
0.13
0.13
0.15
0.09
0.10
0.10
0.13
0.11
0.09
0.11
0.10
0.10
0.17
0.13
0.15
0.11
0,10
0.12
0.11
0.025
20-40
0.08
0.13
0.15
0.07
0.07
0.07
0.09
0.11
0.12
0.18
0.10
0.14
0.08
0.12
0.09
0.14
0.16
0.09
0.09
0.08
0.12
0.35
0.17
0.22
0.10
0.11
0.15
0.13
0.058
40-60
0.29
0.36
0.29
0.09
0.12
0.16
0.20
0.20
0.28
0.55
0.36
0.50
0.30
0.26
0.08
0.26
0.37
0.31
0.11
0.07
0.20
0.24
0.40
0.26
0.31
0.23
0.19
0.26
0.12
60-80
0.27
0.29
0.47
0.13
0.27
0.27
0.43
0.49
0.45
0.70
0.55
0.31
0.36
0.40
0.16
0.32
0.51
0.37
0.09
0.08
0.10
0.36
0.40
0.49
0.65
0.46
0.39
0.36
0.16
Depth (cm)
80-100
0.17
0.16
0.16
0.06
0.10
0.10
0.23
0.26
0.22
0.34
0.15
0.19
0.14
0.15
0.16
0.16
0.21
0.21
0.09
0.09
0.12
0.41
0.28
0.60
0.41
0.45
0.24
0.22
0.13
100-120
0.09
0.13
0.08
0.03
0.03
0.05
0.19
0.16
0.08
0.07
0.07
0.09
0.05
0.05
0.06
0.07
0.07
0.08
0.12
0.13
0.14
0.43
0.43
0.31
0.20
0.36
0.13
0.14
0.11
120-140
0.05
0.13
0.06
0.02
0.05
0.06
0.08
0.10
0.06
0.07
0.06
0.06
0.04
0.05
0.03
0.05
0.05
0.05
0.07
0.10
0.11
0.31
0.25
0.48
0.28
0.26
0.08
0.11
0.11
140-160
0.04
0.07
0.05
0.02
0.03
0.05
0.07
0.06
0.08
0.07
0.04
0.05
0.10
0.04
0.03
0.05
0.04
0.07
0.04
0.03
0.05
0.10
0.20
0.28
0.33
0.45
0.06
0.092
0.10
-------
Table 17. SALT CONTENT OF SOIL (g/lOOg Of SOIL) IN SURFACE-
IRRIGATED PLOTS (DECEMBER 1973)
05
Plot No.
P 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P14
P15
P16
P17
P18
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
Mean
Std. Dev.
0-20
0.08
0.10
0.18
0.11
0.07
0.06
0.10
0.11
0.13
0.19
0.12
0.15
0.05
0.12
0.10
0.12
0.17
0.18
0.13
0.09
0.09
0.13
0.23
0.25
0.15
0.10
0.13
0.13
0.048
20-40
0.12
0.14
0.15
0.06
0.09
0.16
0.14
0.14
0.23
0.21
0.15
0.18
0.16
0.15
0.11
0.18
0.31
0.25
0.13
0.10
0.12
0.15
0.33
0.33
0.21
0.11
0.16
0.17
0.069
40-60
0.27
0.48
0.49
0.43
0.18
0.25
0.33
0.33
0.48
0.52
0.61
0.47
0.35
0.31
0.43
0.42
0.29
0.50
0.20
0.06
0.12
0.28
0.38
0.44
0.42
0.23
0.19
0.35
0.14
Depth
60-80
0.24
0.31
0.30
0.19
0.23
0.31
0.38
0.32
0.38
0.39
0.48
0.54
0.17
0.25
0.27
0.31
0.50
0.38
0.15
0.08
0.07
0.44
0.44
0.48
0.40
0.49
0.38
0.33
0.13
(cm)
80-100
0.13
0.08
0.11
0.05
0.05
0.13
0.17
0.30
0.12
0.14
0.14
0.14
0.11
0.12
0.10
0.17
0.10
0.15
0.14
0.08
0.10
0.05
0.56
0.48
0.29
0.44
0.24
0.17
0.13
100-120
0.06
0.05
0.06
0.03
0.02
0.05
0.06
0.08
0.07
0.09
0.05
0.08
0.03
0.05
0.05
0.07
0.05
0.08
0.16
0.09
0.13
0.14
0.55
0.54
0.14
0.36
0.14
0.12
0.14
120-140
0.03
0.06
0.05
0.03
0.02
0.05
0.05
0.05
0.09
0.07
0.05
0.08
0.03
0.04
0.03
0.05
0.05
0.04
0.11
0.05
0.07
0.05
0.50
0.33
0.04
0.27
0.07
0.088
0.11
140-160
0.05
0.06
0.05
0.03
0.02
0.04
0.06
0.04
0.07
0.04
0.15
0.07
0.04
0.04
0.03
0.04
0.05
0.04
0.03
0.03
0.02
0.03
0.21
0.09
0.03
0.43
0.05
0.068
0.084
-------
Table 18. SALT CONTENT OF SOIL C&/lQOg OF SOIL) IN SURFACE-
IRRIGATED PLOTS (DECEMBER 1974)
Plot No.
P 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P14
P15
P16
P17
P18
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
Mean
Std. Dev.
0-20
0.08
0.13
0.09
0.11
0.10
0.08
0.08
0.07
0.11
0.17
0.17
0.21
0.11
0.20
0.14
0.11
0.17
0.10
0.29
0.08
0.09
0.10
0.20
0.28
0.13
0.08
0.11
0.13
0.059
20-40
0.15
0.24
0.21
0.17
0.17
0.16
0.19
0.15
0.24
0.25
0.24
0.31
0.17
0.23
0.30
0.24
0.28
0.23
0.18
0.13
0.13
0.26
0.29
0.40
0.32
0.21
0.28
0.23
0.066
40-60
0.24
0.36
0.48
0.37
0.39
0.26
0.40
0.26
0.36
0.33
0.35
0.42
0.32
0.26
0.28
0.39
0.40
0.36
0.27
0.16
0.24
0.29
0.36
0.46
0.44
0.21
0.36
0.34
0.080
Depth
60-80
0.39
0.26
0.33
0.28
0.33
0.31
0.42
0.34
0.37
0.35
0.43
0.48
0.31
0.33
0.40
0.39
0.47
0.41
0.17
0.13
0.10
0.29
0.39
0.49
0.51
0.45
0.51
0.36
0.11
Con)
80-100
0.25
0.04
0.13
0.09
0.06
0.38
0.18
0.20
0.14
0.25
0.12
0.16
0.14
0.21
0.13
0.19
0.12
0.14
0.14
0.10
0.10
0.12
0.48
0.43
0.49
0.24
0.20
0.19
0.12
100-120
0.05
0.04
0.06
0.03
0.02
0.09
0.05
0.18
0.06
0.11
0.06
0.08
0.03
0.21
0.06
0.10
0.05
0.06
0.14
0.11
0.13
0.12
0.44
0.47
0.17
0.26
0.07
0.12
0.11
120-140
0.03
0.04
0.03
0.03
0.02
0.04
0.04
0.06
0.05
0.04
0.04
0.11
0.03
0.19
0.03
0.08
0.05
0.04
0.11
0.10
0.09
0.05
0.43
0.36
0.04
0.08
0.03
0.083
0.097
140-160
0.03
0.03
0.06
0.04
0.02
0.03
0.05
0.05
0.04
0.03
0.05
0.13
0.03
0.05
0.03
0.04
0.04
0.03
0.03
0.08
0.02
0.01
0.42
0.10
0.03
0.06
0.03
0.059
0.076
-------
CO
Table 19. SALT CONTENT OF SOIL Cg/100g OF SOIL) OUTSIDE
SURFACE-IRRIGATED PLOTS (DECEMBER 1974)
Plot No.
P 1ES
P 3E
P 5E
P 7E
P 9E
P11E
P13E
P15E
P17E
P19E
P21E
P23E
P25E
P27E
P29E
Mean
Std. Dev.
Q-20
0.26
0.36
0.14
0.19
0.28
0.34
0.34
0.19
0.20
0.26
0.10
0.3.6
0.11
0.16
0.30
0.23
0.085
20-40
0.25
0.21
0.18
0.17
0.31
0.31
0.35
0.22
0.18
0.23
0.09
0.10
0.11
0.12
0.35
0.21
0.088
40-60
0.42
0.35
0.32
0.31
0.41
0.42
0.46
0.27
0.33
0.39
0.08
0.06
0.06
0.06
0.43
0.29
0.15
Depth (cm)
60-80 80-100
0.13
0.18
0.16
0.20
0.28
0.39
0.51
0.26
0.13
0.21
0.07
0.06
0.06
0.05
0.43
0.21
0.14
0,04
0.15
0.06
0.10
0.22
0.43
0.27
0.08
0.10
0.08
0.06
0.08
0.05
0.07
0.49
0.15
0.14
100-120
0.04
0.05
-
0.05
0.13
0.40
0.10
0.03
0.03
0.04
0.05
0.06
0.06
0.07
0.32
0.10
0.11
120-140
0.04
0.05
-
0.08
0.05
0.21
0.07
0.06
0.03
0.04
0.01
0.02
0.03
0.04
0.28
0.072
0.075
140-160
0.04
-
—
0.04
-
0.02
0.07
0.07
0.04
0.05
0.01
0.02
0.01
0.02
0.11
0.041
0.029
E designates east of plot.
-------
CO
200
ISO
160
c- 140
x.
| 120
w 100
80
60
40
20
I I I I I I
I I
I 23456789 10 II 12
mmhos/cm
Figure 10. EC (mmhos/cm) versus total salts (jneq/1) for saturation extracts
of field plot samples taken in May 1973.
-------
Table 2Q. ANALYSIS OF VARIANCE FOR SOIL SALINITY BASED ON SATURATION
EXTRACTS FROM THE SURFACE-IRRIGATED PLOTS (FALL SAMPLES
1972, 1973 AND 1974)
Source of
Variation
Replication
Years (Y)
Error A
Depths (D)
Error B
Depletion (Depl)
Efficiency (E)
Depl X E
Error C
Y X D
Error D
Y X Depl
Y X E
Y X Depl X E
Error E
D X Depl
D X E
D X Depl X E
Error F
Y X D X Depl
Y X D X E
Y X D X Depl X E
Error G
Degrees of
freedom
2
2
4
7
14
2
2
4
16
14
28
4
4
8
32
14
14
28
112
28
28
56
224
F. Value
-
1.816
c.v. = 49.18
16.48b
c.v. - 131.9
2.062
0.4009
0.8159
c.v. = 167.5
2.012
c.v. = 31.92
2.954a
1.344
0.6243
c.v. = 49.27
1.107
0.9099
0.7541
c.v. = 46.66
0.8311
0.8023
1.216
c.v. = 29.65
a' Denotes significance at the 5% and 1% level of probability, res-
pectively, c.v. denotes coefficient of variation (%) .
50
-------
20 show that it had five times the effect that efficiency had. This agrees
with what was earlier observed from water use data estimated by neutron probe.
Differences between water applied and estimated water use were larger among
depletion treatments than among efficiency treatments, indicating that deple-
tion treatments would have more effect on leaching. This trend implies that,
for the soils in the study area, it may be possible to control soil salinity
by altering the irrigation frequency.
The only factor besides depth having a significant effect on soil salinity was
the year X depletion interaction, implying that soil salts accumulated (or
leached) depending on the depletion treatment and the year the treatment was
applied. The year X depletion interaction is shown graphically in Figure 11.
.23
.22
_j .21
% -20
t .19
o»
O
O
X
O>
18
17
16
15
,14
x 50% DEPL.
25% DEPL.
a 75% DEPL.
_L
_L
1972 1973 1974
Figure 11. Soil salinity (g/lOOg of soil) response to depletion and
years. Parameters shown are depletion treatments applied.
The strong tendency for salt build-up that occurred at 50 percent depletion
indicates that it is possible to increase soil salinity (maintain a positive
salt balance) by utilizing proper irrigation management.
The treatment means of the salt contents of the soil after harvest in 1972,
1973 and 1974 are presented in Tables 21, 22 and 23. The three-year treatment
means are presented in Table 24.
51
-------
Table 21. TREATMENT MEANS OF THE SALT CONTENTS OF THE SOIL
Cg/lOOg OF SOIL) IN THE SURFACE-IRRIGATED PLOTS (DECEMBER 1972)
Efficiency
percent 0-20
80
90
100
.10
.12
.13
20-40
.16
.20
.22
40-60
.32
.37
.38
Depth (cm)
60-80 80-100 100-120
.28
.31
.31
.14
.15
.17
.11
.10
.12
120-140
.08
.10
.07
140-160
.04
.06
.08
All
depths
.15
.18
.18
Depletion %
25 .14 .22 .42 .36 .21 .16 .11 .08 .21
50 .11 .18 .36 .28 .14 .11 .08 .05 .16
75 .10 .18 .30 .26 .11 .07 .06 .05 .14
All
treatments .12 .19 .36 .30 .15 .11 .08 .06 .17
Table, 22. TREATMENT MEANS OF THE SALT CONTENTS Of THE.
Cg/lOOg OF SOIL) IN THE SURFACE-IRRIGATED PLOTS (DECEMBER 19J3)
Efficiency
percent
80
90
100
Depletion
25
50
75
Q-20
.12
.13
.13
%
.13
.13
.12
20-40
.15
.18
.17
.19
.18
.14
40-60
.35
.33
.37
.39
.36
..30
Depth (cm)
60-80 80-100 100^120
.29
.33
.36
.40
.33
.26
.18
.12
.20
.20
.21
.11
.15
.09.
.13
.15
.13
.08
120-140
.12
.06
.08
.11
.09
.06
140-160.
.10
.04
.06
.11
.06
.03
AH
depths
.18
.16
.19
.21
.19
.14
All
treatments .13 .17 .35 .33 .17 .12 .09 .07 .18
52
-------
Table 23. TREATMENT MEANS OF THE SALT CONTENTS OF THE SOIL
Cg/lOOg OF SOIL) IN THE SURFACE-IRRIGATED PLOTS CDECEMBER 1974)
Efficiency
percent
80
90
100
Depletion 5
25
50
75
All
treatments
0-20
.14
.12
.14
I
.14
.12
.14
.13
20-40
.22
.23
.24
.24
.24
.20
.23
40-60
.32
.33
.35
.33
.35
.32
.33
Depth (cm)
60-80 80-100 100-120
.33
.35
.39
.38
.40
.29
.36
.16
.17
.25
.17
.25
.16
.19
.12
.10
.15
.14
.13
.09
.12
120-140
.09
.06
.10
.08
.10
.06
.08
140-160
.08
.04
.06
.04
.08
.05
.06
All
depths
.18
.17
.21
.19
.21
.16
.19
Table 24. COMBINED TREATMENT MEANS OF THE SALT CONTENTS OF THE
SOIL Cg/lOOg OF SOIL) IN THE SURFACE-IRRIGATED PLOTS FOR THE
YEARS 1972, 1973 AND 1974
Efficiency
percent
80
90
100
Depletion
25
50
75
0-20
.12
.12
.13
%
.14
.12
.12
20-40
.18
.20
.21
.22
.20
.18
40-60
.33
.34
.37
.38
.36
.30
Depth (cm)
60-80 80-100 100-120
.30
.33
.36
.38
.34
.27
.16
.15
.21
.20
.20
.13
.13
.10
.13
.15
.12
.08
120-140
.10
.07
.08
.10
.09
.06
140-160
.07
.05
.07
.08
.06
.04
All
depths
.17
.17
.20
.21
.19
.15
All
treatments .13 .20 .35 .33 .17 .12 .08 .06 .18
53
-------
The mean salt contents for each, year are presented in Table 25. Included in
this table are the mean salt contents of the samples taken outside of the plots
at the beginning of the experiment and at the end of the experiment. This
table shows relatively small changes in total salt content of the profiles over
the duration of the project. This is probably due to precipitation and to
leaching of salts below the 160-cm depths.
Table 25. MEAN SALT CONTENTS (g/lOOg OF SOIL) FOR THE SURFACE-
IRRIGATED PLOTS BY DEPTH FOR EACH SAMPLING PERIOD
Depth (cm)
0-20 20-40 40-60 60-80 80-100 100-120
aSpring '72
Fall, '72
Spring '73
Fall, '73
Fall, '74
bFall, '74
.18
.12
.11
.13
.13
.23
.29
.19
.13
.17
.23
.21
.37
.36
.26
.35
.34
.29
.18
.30
.36
.33
.36
.21
mum
.16
.22
.17
.19
.15
_
.11
.14
.12
.12
.10
120-140
_
.08
.11
.09
.08
.07
140-160
*_.
.06
.09
.07
.06
.04
All
depths
M
.17
.18
.18
.19
.16
«
Soil samples taken within surface irrigated plots 1-10 and outside
of surface-irrigated plots 11-30.
Soil samples taken outside of plots.
Composition of Saturation Extracts - The saturation extracts made from soil
samples taken during May 1973 were analyzed for chemical composition (a total
of 2904 independent chemical determinations). The results, presented in appen-
dix Tables 7-14, are summarized in Tables 26-28. Table 26 presents the mean
composition of the saturation extracts of soil samples from the first two rows
of plots. Table 27 presents the mean composition of the saturation extracts
of soil samples from all surface-irrigated plots, and Table 28 presents some
of the means from Table 27 together with their standard deviations. This
table shows the large variation in chemical composition between plots as evi-
denced by the large standard deviations. In general, the data show a large
increase in soluble salts with depth to about 100 cm, and then a decrease.
The mean quantities of water which were used for making the saturation extracts
are presented in column two of Tables 26 and 27. The amounts vary from 83 ml
per 125 g of soil at 40-60 cm (clay-loam) to 26 ml per 125 g of soil at 140
160 cm. Since the clay loam and sand have bulk densities of 1.4 and 1.5,
54
-------
Table 26. MEAN COMPOSITION OF SATURATION EXTRACTS (ifteq/15 OF SOILS FROM PLOTS
1-20, IRRIGATED BY SURFACE FLOODING (MAY 1973)
Depth
(cm)
0-20
20-40
40-60
60-80
80-100
100-120
120-140
140-160
ml/125g mmhos
of soil /cm
71.6 1.8
73.1 1.9
83.4 4.1
70.8 6.4
28.3 7.6
25.0 4.0
25.7 2.9
25.9 2.7
I
Cations
23.1
25.3
58.5
94.2
108.9
54.2
36.2
33.3
Ca
9.3
8.8
25.3
41.6
41.6
19.8
11.8
11.7
Table 27. MEAN COMPOSITION OF
1-30, IRRIGATED
Depth
(cm)
0-20
20-40
40-60
60-80
80-100
100-120
120-140
140-160
ml/125g mmhos
of soil /cm
70.8 1.9
73.1 2.1
78.0 4.1
69.6 6.2
38.0 7.1
34.9 4.6
33.6 3.6
30.6 3.3
I
Cations
24.7
28.5
58.0
90.5
102.3
62.0
48.1
43.5
Ca
9.9
10.7
25.5
39.7
39.9
23.4
17.7
16.5
Mg
2.4
2.7
7.9
13.4
15.2
6.1
3.9
3.3
SATURATION
BY SURFACE
Mg
2.6
3.0
7.6
12.9
14.2
7.3
5.4
4.6
Na
10.5
12.9
24.3
38.0
50.8
27.5
19.9
17.7
EXTRACTS
K
1.0
0.9
1.1
1.2
1.3
0.8
0.7
0.7
Cl
2.5
2.1
3.1
5.9
14.1
7.0
4.9
4.3
(meq/1) OF
FLOODING (MAY
Na
11.1
13.9
23.6
36.7
46.9
30.4
24.1
21.6
K
1.0
1.0
1.2
1.3
1.3
1.0
0.9
0.8
1973)
Cl
2.6
2.6
3.7
6.5
12.8
8.5
6.4
5.9
co3
0
0
0
0
0
0
Q
0
HC03
11.7
10.6
8.4
7.4
7.1
6.4
5.8
5.9
SOILS FROM
co3
0
0
0
0
0
0
0
0
HC03
12.2
11.3
9.8
8.4
8.3
7.7
7.0
6.7
S°4
8.9
12.1
45.2
79.3
83.4
39.0
24.7
22.4
PLOTS
S°4
9.7
13.7
43.1
73.8
77.0
43.6
33.0
29.1
N03
0.1
0.1
0.1
0.6
3.6
1.2
0.9
0.7
N03
0.1
0.1
0.1
0.7
2.8
1.3
0.9
0.7
-------
Ol
O5
Table 28. MEANS AND STANDARD DEVIATIONS OF IONIC COMPOSITION OF SATURATION
EXTRACTS OF SOILS FROM PLOTS 1-30, IRRIGATED BY SURFACE FLOODING (MAY 1973)
0-20
Mean St. Dev.
ECe > mmhos / cm
Cations
Ca (meq/1)
Mg (meq/1)
Na (meq/1)
K (meq/1)
Cl (meq/1)
CC>3 (meq/1)
HC03 (meq/1)
804 (meq/1)
N03 (meq/1)
1.9
24.7
9.9
2.6
11.1
1.0
2.6
0
12.2
9.7
0.1
0.5
6.2
3.0
0.8
2.7
0.2
0.9
0
3.2
4.1
0.2
60-80
Mean St. Dev.
6.2
90.5
39.7
12.9
36.7
1.3
6.5
0
8.4
73.8
0.7
1.7
26.1
13.7
4;5
11.8
0.3
3.6
0
2.7
25.7
0.9
140-160
Mean St. Dev.
3.3
43.5
16.5
4.6
21.6
0.8
5.9
0
6.7
29.1
0.7
1.8
29.9
14.7
3.6
12.2
0.4
4.0
0
2.3
24.0
1.3
-------
respectively, and average field water contents of 40 percent and 8 percent,
respectively, factors of 2.2 and 3.9 were obtained for converting extract
concentrations to field concentrations for these two soils. Converting the
anion and cation concentrations to field moisture contents, it was found
that the large salt concentration at the 60- to 100-cm depth, as compared with
salt concentration of the sand, was mainly due to higher concentrations of Ca,
Mg and SO,. The latter concentrations at the 60- to 100-cm depth were about
double those at the 120- to 140-cm depth. The concentrations of the other
anions and cations at those two depths were about the same.
It appeared that there was considerable gypsum present at the 60- to 100-cm depth
at the interface between the clay-loam and sand. Whether this gypsum originated
from the soil or from the irrigation water was not clear. If it could be shown
that the gypsum in irrigation water does precipitate at or above the clay-sand
interface in layered soil profiles, this would be of considerable interest in
studying the quality of irrigation return flow. Such a process would reduce
the total salt concentration of the return flow. On the other hand, precipi-
tation of gypsum has a negative effect on the sodium adsorption ratio of the
soil solution. For example, after converting to field water contents, the
SAR of the soil solution at 60-80 cm was 10.7, but at 120-140 cm it was 14.0,
considerably higher.
Quality of Percolation Water
Composition of Soil Solution - The electrical conductivities of soil solution
samples withdrawn with suction cups in 1972, 1973 and 1974 are presented in
Appendix Tables 15, 16 and 17. Because of the low water content of the sandy
subsoil and the very low hydraulic conductivity of the soil around the cups,
suction often had to be applied for several days in order to get a sufficient
sample volume for chemical analysis. No samples were obtained from some of
the suction cups.
The data from the January - April 1973 sampling period were almost complete.
During this period, all plots were irrigated with 40 cm of water then covered
with plastic in order to determine hydraulic conductivity of the subsoil. As
a result, the subsoil was relatively wet, and a suction sample could be
obtained from all plots. A complete chemical analysis was made of these
samples.
57
-------
For each, plot, electrical conductivities of soil solution samples taken during
the year are presented along with, the mean conductivity and standard deviation
for all plots (Tables 29, 30 and 31). The average chemical composition of the
soil solution samples withdrawn from the subsoil in the period January through
April 1973 is presented in Table 32, together with the composition of the
water from the irrigation well. The data in Tables 29-32 show that the average
electrical conductivity of samples removed through the suction cups during the
three years of study was 7.89 mmhos/cm, which is 6.5 times higher than the
salt concentration from the irrigation well. Rhoades et al. CL973) presented
compositions of drainage waters from lysimeters irrigated with synthesized
river waters from the Western U.S.A. Since, after multiplication by a factor
of 1.4, their water No. 3 is almost identical in composition to the well water
used in the present experiment, we may compare their results with ours.
Rhoades et al. (1973) measured the salt concentration of the drainage water
from the lysimeters irrigated with No. 3 water at leaching fractions of 0.1,
0.2 and 0.3. At these leaching fractions,their observed ratios of EC, /EC.
were 6.2, 3.4 and 2.9, respectively. Inasmuch as the average ratio of
EC, /EC. for our field plots is 6.5, it appears that, based on this data,
<1W 1W
the fraction of applied water that percolated to the subsoil was around 10
percent.
The composition of the drainage water as a function of leaching fraction was
also presented by Rhoades et al. (1973). Their ratio of the concentration of
each ion in the drainage water to the concentration of each ion in the irri-
gation water was different in each case. Nevertheless, their ratios obtained
from the lysimeters irrigated at a leaching fraction of between 0.1 and 0.2
were very similar to the ratios obtained for the various ions in the present
field experiment.
Based on this information, it appears that the leaching fraction on the
field plots has averaged between 0.1 and 0.2 during the past three years. On
the average then, 15 percent of the applied water should have percolated to
the subsoil. This is considerably less than that computed from neutron probe
data and from climatological data. Work presently underway will hopefully
provide data to reconcile these differences in the estimation of the fraction
of the water that actually percolated to the subsoil.
58
-------
Table 29. MEAN ELECTRICAL CONDUCTIVITIES (mmhos/cm) OF SOIL SOLUTION
SAMPLES (1972 CROPPING SEASON) AND OF SATURATION EXTRACTS OF SAMPLES
TAKEN AT SIMILAR DEPTHS IN THE SOIL PROFILE OF THE SURFACE-
IRRIGATED PLOTS (DECEMBER 1972)
EC (mmhos/cm) of soil
Plot No. solution
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Mean, plots 1-20
Std. Dev. plots
1-20
Mean, plots 1-30
Std. Dev. plots
1-30
7.9
10.3
-
8.7
5.5
4.8
6.3
-
12.0
9.9
11.5
-
6.5
11.2
7.2
7.8
9.4
12.8
3.0
2.0
4.6
—
5.4
8.9
10.7
9.5
11.3
8.79
2.48
8.14
2.98
ECe Gpihos/cm) of sat-
uration extract Ratio
1.36
1.74
2.68
1.66
2.12
1.48
2.06
2.66
5.58
6.12
1.82
3.10
1.52
2.06
1.16
1.26
2.08
2.62
0.82
1.26
1.02
1.52
1.44
3.44
2.61
2.34
1.74
2.39
1.37
2.19
1.24
5.81
5.92
-
5.24
2.59
3.24
3.06
-
2.15
1.62
6.32
-
4.28
5.44
6.21
6.19
4.52
4.88
3.66
1.59
4.51
-
3.75
2.59
4.10
4.06
6.49
4.50
4.27
59
-------
Table 30. MEM ELECTRICAL CONDUCTIVITIES (mmhos/cm) OF SOIL SOLUTION
SAMPLES (1973 CROPPING SEASON) AND OF SATURATION EXTRACTS OF SAMPLES
TAKEN AT SIMILAR DEPTHS IN THE SOIL PROFILE OF THE SURFACE-
IRRIGATED PLOTS (DECEMBER 1973)
EC (mmhos/cm) of soil
Plot No. solution
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Mean plots 1-20
Std. Dev., plots
1-20
Mean plots 1-30
Std. Dev., plots
1-30
9.6
10.8
-
7.3
5.4
8.0
8.8
8.8
11.3
9.9
13.8
10.0
4.5
7.7
9.6
9.1
8.5
7.8
4.5
4.4
4.9
2.5
6.4
5.2
7.0
12.9
6.5
8.88
2.16
7.89
2.76
ECe (mmhos/on) of sat-
uration extract Ratio
1.50
2.62
2.32
1.16
0.98
2.00
2.16
2.36
4.26
1.98
6.48
3.16
1.82
1.96
1.12
1.78
1.92
1.68
1.40
1.10
0.84
1.50
6.88
3.50
1.22
6.98
2.62
2.29
1.30
2.49
1.73
6.40
4.12
-
6.29
5.51
4.00
4.07
3.73
2.65
5.00
2.13
3.16
2.47
3.93
8.57
5.11
4.43
4.64
3.21
4.00
5.83
1.67
0.93
1.49
5.74
1.85
2.48
4.48
3.98
60
-------
Table 31. MEAN ELECTRICAL CONDUCTIVITIES Gnmhos/cm) OF SOIL SOLUTION
SAMPLES CL974 CROPPING SEASON) AND OF SATURATION EXTRACTS OF SAMPLES
TAKEN AT SIMILAR DEPTHS IN THE SOIL PROFILE OF THE SURFACE-
IRRIGATED PLOTS (DECEMBER 1974)
EC (mmhos/cm) of soil
Plot No. solution
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Mean plots 1-20
Std Dev., plots
1-20
Mean, plots 1-30
Std Dev., plots
1-30
9.7
8.1
-
8.4
4.4
9.0
9.4
8.7
7.3
8.4
6.5
10.3
4.6
7.6
6.9
10.3
8.2
6.2
4.0
3.5
5.0
3.0
7.8
8.4
5.6
6.8
20.8
7.88
1.75
7.65
3.38
ECe (mmhos/cm) of sat-
uration extract Ratio
1.30
1.66
1.51
1.58
1.10
1.73
1.85
2.52
2.34
1.44
2.24
4.28
1.21
2.49
1.42
2.15
1.88
1.36
1.54
2.68
0.91
0.68
6.34
3.86
1.41
2.92
1.45
1.89
0.74
2.07
1.19
7.46
4.88
-
5.32
4.00
5.20
5.08
3.45
3.12
5.83
2.90
2.41
3.80
3.05
4.86
4.79
4.36
4.56
2.60
1.31
5.49
4.41
1.23
2.18
3.97
2.33
14.32
4.42
4.34
61
-------
Table 32. AVERAGE CHEMICAL COMPOSITION OF. SOU SOLUTION EXTRACTED FROM
THE SURFACE-IRRIGATED PLOTS THROUGH SUCTION CUPS DURING THE PERIOD
JANUARY THROUGH APRIL 1973, ANfi CHEMICAL COMPOSITION OF
IRRIGATION WATER, MEAN VALUES CSEE APPENDIX TABLE 23)
EC x 10-3, mmhos/cm
PH
Ca, raeq/1
Mg, meq/1
Na, meq/1
K, meq/1
Cl, meq/1
C03, meq/1
HC03, meq/1
804, meq/1
N03 , ppm
P04, ppm
Sum cations
Sum anlons
Mean concentration
of tne solution at
120-150 cm
8.23
—
29.0
15.5
52.9
0.6
37.6
-
5.9
36.2
502
O.Q
98. Q
87.8
Standard
deviation
3.02
-
9.0
5.9
27.6
0.3
21.9
-
1.0
14.1
200
—
Concentration
irrigation
water
1.22
7.7
5.7
1.7
5.5
0.2
2.5
0.2
5.0
5.6
0.8
—
13.1
13.3
The data in Tables 29, 30 and 31 show much variation in the electrical conduc-
tivity of the soil solution for different plots and sampling periods. The
reason for the large variation in soil salinity between plots is not clear.
It is probably a result of the variation in physical and chemical properties
of the soil material within the plot area. The electrical conductivities of
saturation extracts of soil samples taken at the depths of the suction cups
as well as the ratio of conductivity of soil solution to conductivity of
saturation extract are shown in Tables 29-31. The average ratio of EC/EC
for all three years was 4.2 which is within the range of values given in the
U.S. Salinity Handbook for medium to coarse textured soils.
62
-------
The analysis of variance for the electrical conductivities (mmhos/cm) of the
soil solution samples, as listed in Tables 29, 30 and 31, is presented in
Table 33. The treatment means for depletion are presented in Table 34. The
only significant effect among treatments was the depletion treatment. Thus,
the salt concentration of the percolation water from the 75 percent depletion
plots was significantly lower than that from the 25 and 50 percent depletion
plots. This observation agrees with what was earlier observed for total salt
in the soil profile, i.e., that depletion had five times the effect in changing
the salt concentration of the soil profile that efficiency had.
There are several possible reasons for this result. First of all, the
differences in the amounts of water applied to the 80, 90 and 100 percent
design efficiency treatments are not large as a result of rainfall and pre-
irrigation being the same for all treatments. On the other hand, the spatial
variability in salinity and soil physical properties on the experimental site
was quite large. Therefore, a larger number of replications was necessary to
obtain significant differences than originally anticipated. Secondly, the
soil at the experimental site cracks considerably upon drying. This cracking
was much more pronounced on the less-frequently irrigated plots. Water perco-
lation through these cracks could have reduced the soil salinity in the sub-
soil of the 75 percent irrigation depletion treatment. On the 50 percent
depletion treatment, cracking was less evident, while the soil in the 25 per-
cent depletion treatment appeared moist during most of the irrigation season
and did not crack to any extent. A third reason could be the effect of
differences in leaching efficiency on frequently versus less frequently irri-
gated plots.
The data in Table 32 show that the nitrate concentration of the deep percola-
tion water is relatively high at 8.1 meq/1 or 502 ppm. High rates of fertili-
zation and the lack of reducing conditions were the most probable reasons for
this, as nitrate concentrations in the saturated zone and in the Del Rio
Drain were considerably lower. The relatively high standard deviation about
the mean for the various ions in the soil solution suction samples is again
due to the large variation in the physical and chemical properties of the
soil material over the plot area.
63
-------
Table 33. ANALYSIS OF VARIANCE FOR ELECTRICAL CONDUCTIVITIES
(mmhos/cm) OF SOIL SOLUTION SAMPLES AS LISTED IN
TABLES 29, 30 AND 31
Degrees of freedom
Total 80-6=74
Replication 2
Years 2
Error A 4
Depletion 2
Year x depletion 4
Efficiency 2
Year x efficiency 4
Depletion x efficiency 4
Error B 16
Year x depletion x 8
efficiency
Error C 32-6=26
MS
23.526
1.450
4.490
46.?29
16.023
10.429
5.6012
6.6083
12.1981
3.7105
6.70300
F
-
0.3229
c.v. = 26.91%
3.7898a
1.314
0.85497
0.4592
0.5417
c.v. = 44.35%
0.5535
c.v. = 32.88%
Significant at the 5% level of probability.
Note: degrees of freedom for Error C reduced by 6 to correct for the
6 missing values.
Table 34. TREATMENT MEANS OF THE ELECTRICAL CONDUCTIVITIES
(mmhos/cm) OF THE SOIL SOLUTION SAMPLES EXTRACTED THROUGH
SUCTION CUPS IN 1972, 1973 AND 1974
1972
1973
1974
Mean
25
9.73
8.70
6.84
8.42a
Percent depletion
50
9.12
7.80
9.53
8.82a
75
5.44
7.17
6.53
6.38b
a b
Water Quality in Test Wells
The electrical conductivities and chemical constituents of waters sampled from
the five test wells during 1972, 1973 and 1974 are presented in Appendix Tables
18 through 22. The chemical composition of water from the 20-cm I.D. well
used for irrigating the plots is presented in Appendix Table 23.
64
-------
Table 35. AVERAGE CHEMICAL COMPOSITION (meq/1 EXCEPT NO- in ppm) OF SAMPLES
TAKEN FROM TEST WELLS DURING 1972, 1973 AND 1974
05
OI
Well
1
1
1
1
2
2
2
2
3
3
3
3
4
4
4
4
5
5
5
5
Irr.
Irr.
Irr.
Irr.
Year
1972
1973
1974
Mean
1972
1973
1974
Mean
1972
1973
1974
Mean
1972
1973
1974
Mean
1972
1973
1974
Mean
1972
1973
1974
Mean
Depth
Cm)
22.9
22.9
22.9
22.9
15.5
15.5
15.5
15.5
11.0
11.0
11.0
11.0
8.2
8.2
8.2
8.2
5.8
5.8
5.8
5.8
26.0
26.0
26.0
26.0
ECX103
1.14
1.07
1.05
1.09
1.51
1.45
1.37
1.44
1.60
1.49
1.74
1.61
1.46
1.53
1.89
1.63
1.50
1.40
2.00
1.63
1.39
1.28
1.16
1.28
pH
7.60
7.43
8.04
7.52
7.37
8.07
7.48
7.36
8.03
7.51
7.35
8.00
7.27
7.41
7.94
7.85
7.35
7.91
Total
Cations
11.38
11.10
11.50
11.33
16.48
15.96
15.00
15.81
17.03
16.34
19.37
17.58
15.14
16.97
20.84
17.65
15.64
15.54
22.34
17.84
12.02
13.27
13.15
12.81
Total Ca
Mg
Na
Anions
11.71
11.29
11.41
11.47
16.70
16.17
15.34
16.07
17.20
16.35
19.10
17.55
15.44
16.50
21.08
17.67
16.17
14.86
22.30
17.78
12.51
13.96
12.94
13.14
5.13
5.29
6.08
5.50
8.27
7.89
6.84
7.67
8.09
7.47
9.27
8.28
6.94
7.80
9.32
8.02
6.71
6.80
10.50
8.00
4.75
5.75
5.91
5.47
1.60
1.54
1.69
1.61
2.23
2.10
1.96
2.10
2.38
2.30
2.78
2.49
2.34
2.59
3.18
2.70
2.94
2.63
3.85
3.14
1.87
1.82
1.55
1.75
4.47
4.08
3.56
4.04
5.75
5.75
5.98
5.83
6.31
6.33
7.08
6.57
5.63
6.33
8.08
6.68
5.69
5.80
7.64
6.38
5.21
5.49
5.50
5.40
K
Cl
co3
HC03
so4
meq/1
0,18
0.18
0.17
0.18
0.23
0.22
0.22
0.22
0.24
0.24
0.25
0.24
0.23
0.25
0.27
0.25
0.30
0.30
0.34
0.31
0.19
0.22
0.19
0.20
2.74
2.72
2.95
2.80
3.46
3.26
2.80
3.17
3.45
3.22
4.46
3.71
3.10
3.13
4.71
3.65
3.31
3.24
5.35
3.97
2.80
2.65
2.39
2.61
0.26
0.20
0.05
0.17
0.08
0.35
0.08
0.17
0.01
0.33
0.07
0.14
0.02
0.20
0.02
0.08
0.18
0.29
0.02
0.16
0.41
0.20
0.07
0.23
3.78
3.84
3.64
3.75
6.11
5.90
5.86
5.96
6.35
6.03
5.97
6.12
5.73
6.79
6.45
6.32
5.98
5.88
6.07
5.98
3.65
5.03
5.27
4.65
4.91
4.51
4.77
4.73
7.05
6.64
6.60
6.76
7.39
6.75
8.60
7.58
6.58
6.35
9.89
7.61
6.70
5.43
10.85
7.66
5.66
6.05
5.20
5.64
N03
ppm
0.08
1.27
0.23
0.53
0.14
1.52
0.34
0.67
0.14
1.55
0.31
0.67
0.00
1.29
0.55
0.61
0.00
1.02
0.79
0.60
0.00
1.67
0.35
0.67
-------
Chemical composition data obtained from each, test well and the irrigation well
were averaged for each year. The averages are presented in Table 35. The mean
chemical composition of the water from the irrigation well was similar to the
average chemical composition of the test wells at 15.5 and 22.9 m, indicating
that most of the water from the irrigation well was withdrawn from depths in
this range.
Cotton Yields and Quality
Yield and Quality for 1974 - 1974 cotton yields are presented in Appendix
Table 24 and the cotton quality data for the first and second harvests are
presented in Appendix Tables 25-30.
The analysis of variance for cotton yield for the surface irrigated plots
is presented in Table 36. 1974 was the first year of the experiment during
which both the depletion and efficiency treatments significantly affected
cotton yields.
Table 36. ANALYSIS OF VARIANCE FOR COTTON YIELD FOR 1974
(SURFACE-IRRIGATED PLOTS)
Source of
variation
Replication
Harvest date
Error A
Percent depletion
Efficiency
Percent depletion x efficiency
Error B
Harvest date x percent depletion
Harvest date x efficiency
Harvest date x percent depletion
x efficiency
Error C
Degrees of
freedom
2
1
2
2
2
4
16
2
2
4
16
F value
b
1060.
4.85a
5.16a
0.510
1.40
2.32
0.238
Coefficient of variation = 11.9%; mean = 1030 kg/ha.
' Significant at the 5% and 1% level of probability, respectively.
66
-------
The average yields for the treatments are presented in Table 37. The average
total yield Cfirst harvest + second harvest) was 1030 kg/ha.
This yield was slightly below the 1120 kg/ha average for the New Mexico Experi-
ment Station but considerably higher than the average yield for the Mesilla
Valley of 560 to 700 kg/ha. During the 1974 growing season, an infestation of
Verticillium wilt was observed to some degree in all plots. The disease was
more severe in the trickle plots than in the surface-irrigated plots.
Highest cotton yields were obtained for the 80 percent efficiency treatment
and the 50 percent depletion treatment. The lack of a significant depletion
X efficiency interaction indicates that the differences in yield due to the
efficiency treatments will be similar across all of the depletion treatments.
Table 37. EFFECTS OF IRRIGATION EFFICIENCY AND WATER DEPLETION
TREATMENTS ON THE TOTAL YIELDS OF COTTON FOR THE SURFACE-
IRRIGATED PLOTS C1974)
Water
depletion %
25
50
75
Average
Irrigation efficiency (%)
80 90 100
1050
1140
1080
1090a
(kg/ha)
1020
1130
941
1030ab
930
1030
930
963b
Average
1000a
1100b
986a
1030
Means followed by common letter are not significantly different at
the 5% or less level of probability.
Table 38 presents the effects of irrigation efficiency on the yield and quality
of cotton from the surface irrigation treatments. The irrigation efficiency
treatments significantly affected only yield during the 1974 season.
The effect of varying the soil-water depletion on yield and quality are pre-
sented in Table 39. Although the depletion treatments significantly affected
the 2.5% span of the second harvest, these yields were so low as to negate any
economic differences that may have occurred. The highest micronaire resulted
from the 75 percent depletion treatment, but this was opposite to what happened
67
-------
Table 38. EFFECTS OF IRRIGATION EFFICIENCY ON YIELD AND QUALITY OF
COTTON FOR THE SURFACE-IRRIGATED PLOTS (3.974)
Irrigation
efficiency
80
90
100
Yield Lint
(%) kg/ha %
890a
851ab
784b
2.5%
span
Unif .
ratio MIC Strength
1st harvest
37.5
37.5
37.2
1.19
1.17
1.18
46.8
47.3
46.6
4.0
3.8
3.9
22.2
21.7
21.6
Elongation
6.3
6.1
6.2
2nd harvest
80
90
100
80
90
100
202
179
179
1st
1090a
1030ab
963b
38.6
38.4
38.1
and
38.0
38.0
37.7
1.18
1.18
1.17
46.2
46.7
46.1
2nd harvests
1.18
1.17
1.18
46.5
47.0
46.3
3.7
3.7
3.7
combined
3.8
3.8
3.8
21.2
21.4
21.5
21.7
21.6
21.5
6.8
6.7
6.6
6.6
6.4
6.4
Means followed by common letter are not significantly different at the
5% or less level of probability.
Table 39. EFFECTS OF WATER DEPLETION ON YIELD AND QUALITY OF
COTTON FOR THE SURFACE-IRRIGATED PLOTS C1974)
Depletion
CO
25
50
75
25
50
75
25
50
75
Yield
kg/ha
834ab
890a
801b
168
207
185
1000a
1100b
986a
Lint
%
37.6
37.1
37.5
38.8
38.1
38.2
1st
38.2
37.6
37.8
2.5% Unif.
span ratio MIC Strength
1st harvest
1.17 46.8
1.18 47.0
1.19 47.0
2nd harvest
1.17a 46.9
1.17a 45.8
1.20b 46.3
and 2nd harvests
1.17 46.8
1.17 46.4
1.19 46.7
3.6a 21.5
3. gab 22.0
4.1b 21.9
3.7 21.2
3.6 21.2
3.8 21.7
combined
3.7 21.4
3.8 21.6
4.0 21.8
Elongation
6.1
6.2
6.3
6.7
6.8
6.6
6.4
6.5
6.4
Means followed by common letter are not significantly different at the
5% or less level of probability.
68
-------
in 1973. In 1973 the highest micronaire occurred at 25 percent depletion and
in 1972 the highest micronaire occurred at 50 percent depletion.
Yield and Quality for the Combined Years 1972. 1973 and 1974 - The individual
plot yields are presented in Appendix Table 2n. An analysis of variance for
cotton yield is presented in Table 40 for the surface-irrigated plots.
Table 40. ANALYSIS OF VARIANCE FOR COTTON YIELD FOR THE
SURFACE-IRRIGATED PLOTS FOR THE COMBINED YEARS
1972, 1973 AND 1974
Source of Degrees of
variation freedom
Replication
Years
Error A
Harvest date
Error B
Year X harvest date
Error C
Efficiency
Depletion
Efficiency X depletion
Error D
Year X efficiency
Year X depletion
Year X efficiency X depletion
Error E
Harvest date X efficiency
Harvest date X depletion
Harvest date X efficiency X depletion
Error F
Year X harvest X efficiency
Year X harvest X depletion
Year X harvest X depletion X efficiency
Error G
Total
2
2
4
1
2
2
4
2
2
4
16
4
4
8
32
2
2
4
16
8
8
8
32
-161
F value
104. 00 b
— __
459, 500. 00 b
74.13b
3.14
3.03
1.42
0.34
1.45
0.88
0.21
1.31
0.58
0.74
0.38
0.42
Coefficient of variation « 18.3%; mean = 1090 kg/ha
a' Significant at the 5 and 1% level of probability, respectively.
69
-------
Yield varied significantly between years and harvests. The yield differences
resulting from years were due to natural variation in weather patterns,
seeding dates, disease and insect infestations. The yield differences due to
harvest date were of little importance since the harvest date is established
by the availability of field labor and not soil-water management. The effi-
ciency and depletion treatments, while significant at the 10 percent level,
were not significantly different at the 5 percent level of probability. The
average yields per treatment for 1972, 1973 and 1974, and for these years
combined, are presented in Table 41. The general trends due to the effects
of efficiency and depletion on yield are presented also, in Figure 12.
Table 41. EFFECTS OF IRRIGATION EFFICIENCY AND WATER DEPLETION
TREATMENTS ON THE TOTAL YIELDS OF COTTON FOR THE SURFACE-
IRRIGATED PLOTS. YIELDS IN kg/ha
Water
depletion %
25
50
75
Average
25
50
75
Average
25
50
75
Average
25
50
75
Average
Irrigation efficiency (%)
80 90 100
930
842
1070
946
1490
1390
1340
1400
1050
1140
1080
1090
1972,
1160
1120
1160
1150
1972
752
961
976
896
1973
1270
1410
1280
1320
1974
1020
1130
941
1030
1973 and 1974
1010
1170
1070
1080
803
1000
888
897
1180
1390
1300
1290
930
1030
930
963
(combined)
969
1140
1040
1050
Average
828
935
977
913
1310
1390
1310
1340
1000
1100
984
1030
1050
1140
1090
1090
70
-------
In general, the 5Q percent depletion treatment yielded more than the 25 per-
cent and 75 percent depletion treatments at the 90 percent and 100 percent
levels of efficiency. As can be seen in Figure 12, yields tended to decrease
with increasing efficiency with the exception of the 50 percent depletion
treatments. Although variations in yield could not be statistically attri-
buted to the treatments applied, these general trends persisted throughout
the three-year study. The coefficient of variation averaged 18.3 percent
for the three years. This indicates that with the three replication design
employed, the smallest difference that could be detected would, on the average,
be about 200-220 kg/ha, whereas the difference between the 100 percent and
80 percent efficiency treatments averaged 129 kg/ha. In order to detect a
110 kg/ha difference, at least 14 replications would be required.
I200
UJ
>-
1150
MOO
1050
1000
950J-
50%DEPL.
75%DEPL
25%DEPL.
80 90
EFFICIENCY %
100
Figure 12. General trends in the total yield of cotton due to depletion and
and efficiency (averages of 1972, 1973 and 1974). Parameters shown
are percent depletion.
71
-------
The cotton quality data from the individual plot harvests are presented in
Appendix Tables 25-30. A summary of the analysis of variance for these data
is presented in Table 42.
Table 42. PARTIAL ANALYSIS OF VARIANCE FOR COTTON QUALITY FACTORS FOR
THE COMBINED YEARS 1972, 1973 AND 1974 (SURFACE-IRRIGATED PLOTS)
Source of
variation
Years
Harvest date
Efficiency
Depletion
Efficiency x depletion
Year x efficiency
Year x depletion
Year x depletion x
efficiency
Lint
%
b
a
ns
ns
ns
ns
ns
ns
2.5%
span
b
ns
ns
ns
ns
ns
ns
ns
Unif.
ratio
b
b
a
b
ns
a
ns
ns
MIC
ns
b
ns
a
a
ns
ns
ns
Strength
b
b
ns
ns
ns
ns
ns
a
Elongation
b
ns
ns
ns
b
ns
ns
ns
a,b denote significant differences at the 5 percent and 1 percent levels
of probability, respectively.
ns denotes no significant difference.
Between years, significant differences were found for lint percent, 2.5% span,
uniformity ratio, strength and elongation (See Glossary.) Of these, only
the uniformity ratio was significantly affected by the treatments applied.
This implies that the lint percent, 2.5% span, strength and elongation are
influenced more by fluctuations in seasonal weather patterns than by irriga-
tion management.
The two quality factors, lint percent and 2.5% span, primarily determine the
value of the cotton crop. (Although, if MIC is less than 3.0, the cotton is
discounted.) The significant interaction shown for strength is difficult to
interpret since neither efficiency nor depletion affected this factor directly.
This is the only significant third order interaction present. It indicates
that fiber strength depends, in a complicated fashion, on weather conditions
and soil moisture history.
The uniformity ratio was affected by both efficiency and depletion treatments.
72
-------
Since the year x depletion interaction is nonsignificant, the effect of deple-
tion was similar in all years and the highest uniformity ratio was produced
at 25 percent depletion each year.
While the quality data are interesting, most are of minor importance since
the economic value of the crop is determined primarily by yield, lint percent,
and 2.5% span.
TRICKLE IRRIGATION
Effects on Water Use and Deep Percolation
The amounts of irrigation and rain water received by the trickle plots during
1972, 1973 and 1974 are presented in Table 43.
Table 43. AMOUNTS OF IRRIGATION AND RAIN WATER ON TRICKLE PLOTS,
AND CALCULATED EVAPOTRANSPIRATION CESS) (1972 THROUGH 1974)
Treatment
0.2 bar
0.6 bar
0.2 bar
0.6 bar
0.2 bar
0.6 bar
Irrigation
(cm)
38.6
13.8
35.2
32.2
35.7
26.2
Total water applied3
Rain
(cm)
1972
26.7
26.7
1973
20.6
20.6
1974
25.1
25.1
Total
(cm)
65.3
40.5
55.8
52.8
60.8
51.3
Computed
(cm)
55.1
55.1
54.9
54.9
58.7
58.7
3From stand establishment to harvest (October 31)
bComputed from pan in 1972 and by ISS in 1973 and 1974 (Table 11).
Comparing the data in Table 43 with those in Tables 8, 9 and 10, it is clear
that during each project year the amounts of water used on the trickle plots
were smaller than those used on the surface-irrigated plots, including the
100 percent efficiency surface treatment. In 1973, the average amount of water
applied to the 100 percent efficiency surface treatment was 67.1 cm versus
73
-------
54.3 cm, or 20 percent less water, to the. trickle plots. In 1974, these
amounts were 77.5 cm versus 56.0 cm, or 28 percent less irrigation water on
the trickle plots than on the surface-irrigated plots.
Comparing the amounts of water applied to the trickle plots (Table 43) with
the average water use as calculated with ISS for the surface-irrigated plots,
it appears that in 1973 and 1974 the correct amounts of water were used on
the 0.2 bar trickle treatment. The amounts of water applied to the 0.6 bar
trickle plots were less than water use as calculated with ISS.
The total amount of water use as predicted with ISS was fairly close to that
determined with tensiometers in the trickle-irrigated plots providing added
confidence to the use of ISS for scheduling irrigations.
Effects on Soil Salinity
Concentration of Saturation Extracts - The results of the analyses of the
saturation extracts of soil samples from the trickle-irrigated plots are pre-
sented in Appendix Tables 1-6. The same results, expressed in g of salt per
100 g of dry soil are presented in Tables 44-48.
Table 44. SALT CONTENT OF SOIL (g/lOOg OF SOIL) IN TRICKLE-
IRRIGATED PLOTS (DECEMBER 1972)
Plot No.
Depth (cm)
0-20 20-40 40-60 60-80 80-100 100-120 120-140 140-160
Tl, row
Tl, center
T2, row
T2, center
T3, row
T3, center
T4, row
T4, center
T5, row
T5, center
T6, row
T6, center
Mean
St. Dev.
Mean, row
Mean, center
0.17
0.18
0.17
0.16
0.07
0.27
0.06
0.15
0.11
0.15
0.15
0.15
0.15
0.056
0.12
0.18
0.14
0.12
0.14
0.11
0.09
0.17
0.11
0.16
0.23
0.17
0.15
0.14
0.14
0.038
0.14
0.14
0.05
0.04
0.10
0.09
0.09
0.10
0.15
0.18
0.11
0.08
0.19
0.19
0.11
0.052
0.12
0.11
0.04
0.06
0.12
0.06
0.09
0.09
0.21
0.20
0.12
0.11
0.09
0.07
0.10
0.053
0.11
0.097
0.05
0.05
0.14
0.06
0.07
0.10
0.09
0.12
0.16
0.11
0.12
0.09
0.098
0.035
0.11
0.089
0.05
0.03
0.09
0.06
0.08
0.08
0.09
0.12
0.15
0.09
0.10
0.09
0.085
0.031
0.092
0.078
0.03
0.02
0.04
0.02
0.08
0.06
0.05
0.06
0.08
0.06
0.07
0.05
0.051
0.019
0.056
0.046
0.03
0.02
0.03
0.05
0.03
0.02
0.03
0.02
0.05
0.04
0.04
0.04
0.033
0.010
0.034
0.031
74
-------
Table 45. SALT CONTENT OF SOIL (g/10Qg OF SOIL) IN TRICKLE-
IRRIGATED PLOTS CMAY 1973)
Plot No.
Tl, row
Tl, center
T2, row
T2, center
13, row
T3, center
T4, row
T4, center
T5, row
T5, center
T6, row
T6, center
Mean
Std. Dev.
Mean, row
Mean, center
0-20
0.08
0.09
0.06
0.15
0.09
0.19
0.07
0.16
0.10
0.22
0.08
0.13
0.12
0.052
0.080
0.16
20-40
0.07
0.13
0.08
0.12
0.10
0.17
0.09
0.11
0.09
0.14
0.07
0.14
0.11
0.031
0.085
0.14
40-60
0.08
0.09
0.12
0.07
0.15
0.16
0.12
0.15
0.10
0.11
0.07
0.12
0.11
0.031
0.11
0.12
60-80
0.08
0.10
0.05
0.07
0.05
0.10
0.23
0.15
0.07
0.08
0.06
0.06
0.092
0.051
0.088
0.095
Depth.
80-100
0.08
0.12
0.09
0.11
0.06
0.09
0.15
0.13
0.11
0.09
0.09
0.12
0.10
0.025
0.098
0.11
Ccm)
100-120
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.11
.09
.12
.14
.12
.10
.18
.14
.19
.15
.11
.14
.13
.021
.14
.13
120-140
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.05
.05
.06
.06
.10
.08
.10
.08
.12
.09
.09
.09
.081
.024
.087
.076
140-160
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.07
.05
.07
.08
.06
.07
.04
.04
.07
.07
.06
.07
.063
.014
.064
.062
Table 46. SALT CONTENT OF SOIL (g/lOOg OF SOIL) IN TRICKLE-
IRRIGATED PLOTS (DECEMBER 1973)
Plot No.
Tl, row
Tl, center
T2, row
T2, center
T3, row
T3, center
T4, row
T4, center
T5, row
T5, center
T6, row
T6, center
Mean
Std. Dev.
Mean, row
Mean, center
0-20
0.14
0.12
0.11
0.03
0.08
0.12
0.09
0.13
0.07
0.09
0.11
0.09
0.099
0.030
0.099
0.099
20-40
0.11
0.13
0.12
0.05
0.10
0.13
0.13
0.15
0.09
0.11
0.15
0.12
0.12
0.026
0.12
0.12
40-60
0.08
0.14
0.08
0.06
0.05
0.08
0.12
0.17
0.07
0.11
0.28
0.15
0.12
0.064
0.11
0.12
60-80
0.16
0.16
0.11
0.11
0.07
0.08
0.14
0.18
0.11
0.12
0.14
0.09
0.12
0.034
0.12
0.12
Depth
80-100
0.12
0.19
0.11
0.09
0.09
0.12
0.10
0.09
0.14
0.09
0.23
0.30
0.14
0.066
0.13
0.14
(cm)
100-120
0.10
0.15
0.08
0.12
0.08
0.08
0.18
0.12
0.07
0.06
0.24
0.25
0.13
0.064
0.12
0.13
120-140
0.09
0.04
0.04
0.05
0.03
0.02
0.03
0.07
0.05
0.05
0.13
0.21
0.067
0.054
0.062
0.073
140-160
0.04
0.05
0.01
0.01
0.04
0.05
0.02
0.04
0.02
0.02
0.08
0.12
0.042
0.033
0.036
0.049
75
-------
Table 47. SALT CONTENT OF SOIL (g/lOQg OF SOIL) IN TRICKLE-
IRRIGATED PLOTS GDECEMBER 1974)
Plot No.
Tl, row
Tl, center
T2, row
T2, center
T3, row
T3 , center
T4, row
T4, center
T5, row
T5, center
T6, row
T6, center
Mean
Std. Dev.
Mean, row
Mean, center
0-20
0.07
0.11
0.08
0.14
0.07
0.06
0.09
0.19
0.05
0.10
0.06
0.14
0.096
0.042
0.069
0.12
20-40
0.09
0.14
0.12
0.17
0.08
0.15
0.06
0.24
0.06
0.17
0.12
0.19
0.13
0.055
0.088
0.18
40-60
0.11
0.20
0.17
0.15
0.07
0.09
0.08
0.28
0.04
0.13
0.19
0.34
0.15
0.088
0.11
0.20
60-80
0.13
0.27
0.13
0.07
0.08
0.08
0.14
0.19
0.08
0.12
0.28
0.22
0.15
0.074
0.14
0.16
Depth.
80-100
0.23
0.21
0.19
0.14
0.10
0.11
0.18
0.20
0.13
0.17
0.20
0.29
0.18
0.054
0.17
0.19
(cm)
100-120
0.09
0.17
0.17
0.17
0.13
0.15
0.18
0.17
0.16
0.18
0.30
0.30
0.19
0.055.
0.19
O.o9
120-140
0.14
0.10
0.18
0.12
0.07
0.06
0.18
0.12
0.10
0.11
0.33
0.34
0.15
0.091
0.17
0.14
140-160
0.06
0.05
0.06
0.04
0.03
0.05
0.06
0.03
0.07
0.09
0.21
0.21
0.079
0.061
0.080
0.077
Table 48. SALT CONTENT OF SOIL (g/100 g OF SOIL) OUTSIDE
TRICKLE-IRRIGATED PLOTS CDECEMBER 1974)
Plot No.
Tlwa
T2W
T3W
T1ED
T2E
T3E
T4E
T5E
T6E
Mean
Std. Dev.
0-20
0.04
0.05
0.08
0.09
0.04
0.10
0.03
0.12
0.16
0.077
0.043
20-40
0.10
0.16
0.16
0.10
0.06
0.14
0.06
0.14
0.19
0.12
0.045
40-60
0.13
0.12
0.17
0.08
0.11
0.12
0.08
0.14
0.31
0.14
0.067
60-80
0.09
0.08
0.06
0.09
0.07
0.07
0.11
0.09
0.14
0.089
0.022
Depth
80-100
0.09
0.06
0.06
0.10
0.11
0.10
0.08
0.10
0.18
0.098
0.037
(cm)
100-120
0
0
0
0
0
0
0
0
0
0
0
.06
.07
.11
.06
.07
.12
.11
.08
.26
.11
.062
120-140
0
0
0
0
0
0
0
0
0
0
0
.06
.07
.12
.09
.07
.08
.07
.05
.21
.091
.049
1 AO-1 60
0
0
0
0
0
0
0
0
0
0
__.
.05
.07
.04
.04
.03
.03
.06
.18
.063
.049
W designates west of plot.
E designates east of plot.
76
-------
The trickle-irrigated plots were sampled for soil salinity differently than
were the surface-irrigated plots. Samples were taken immediately on the
trickle lines and also at the mid-point between trickle lines.
The analysis of variance for the trickle plot salinity data for fall 1972,
1973 and 1974 is presented in Table 49. Because of the effect of location,
the analysis of variance is somewhat more complicated than that shown in Table
20 for the surface-irrigated plots. Also in comparing the two tables, the co-
efficients of variation associated with the error terms B are dissimilar.
This indicates that the natural variation in salinity by depth was less in the
trickle-irrigated plots than in the surface-irrigated plots.
Table 49 implies that not only did salinity levels vary significantly between
years and between depths, but the significant year x depth interaction indi-
cates that soil salts were distributed differently by depth in different
years. Of more interest is the interaction of year x depth x location (loca-
tion refers to samples taken between or on trickle lines). This three-way
interaction is depicted in Figure 13 where salt distribution by depth is
compared graphically during each year for the two locations.
These illustrations show that the 120-mm preharvest rain in 1973 moved con-
siderable quantities of salts from shallow depths deep into the profile.
This is reflected in the increase in salinity in the subsoil and the decrease
in salinity near the surface. Late season rains in 1973 and 1974 also contri-
buted to the downward movement of salts in the profile. Surface salinity
would have been much higher between the rows if it were not for these rains
since salt crusts were observed on the soil surface prior to the rains.
The nonsignificant year x treatment interaction indicates that soil salts
accumulated (or leached) at almost the same rate under the wet and dry
trickle treatments. However, the significant location x treatment and depth
x location x treatment interactions imply that the soil salinity profiles
were modified depending on the soil-water treatment and distance from the
trickle lines. These interactions are shown in Figure 14 where the soil
salinity differences - between row minus below row ("below row" also
77
-------
Table 49- ANALYSIS OF VARIANCE FOR SOIL SALINITY BASED ON SATURATION
EXTRACTS FROM THE TRICKLE-IRRIGATED PLOTS (FALL
SAMPLES 1972, 1973 AND 1974]
Source of variation Degrees of freedom F value
Replication
Years (Y)
Error A
Depths CD)
Error B
Location (L)
Error C
Treatment (T)
Error D
Y X D
Error E
Y X L
Error F
Y X T
Error G
D X T
Error H
D X L
Error I
L X T
Error J
Y X D X L
Error K
Y X D X T
Error L
D X L X T
Error M
Y X L X T
Error N
Y X D X L X T
Error 0
2
2
4
7
14
1
2
1
2
14
28
2
4
2
4
7
14
7
14
1
2
14
28
14
28
7
14
2
4
14
28
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
-
8.45 a
= 70.2%
10.26 b
= 48.2%
1.69 ns
= 66.9%
0.50 ns
= 232%
8.08 b
= 30.0%
10.53 b
= 20.9%
4.84 ns
= 71.4%
0.54 ns
- 55.7%
2.14 ns
= 31.2%
36.51 a
= 12.4%
3.16 b
= 23.4%
1.45 ns
= 35.1%
2.79 a
= 19.4%
0.10 ns
= 47.1%
1.10 ns
= 26.2%
a,b denote significance at the 5% and 1% level of probability,
respectively, ns denotes no significant difference.
designated "on row") - are graphically displayed. These results indicate
that, at depths of less than 70 cm, in the 0.2 bar treatment more salts were
found between the rows than on the rows, whereas in the 0.6 bar treatment the
salts were distributed fairly uniformly. The data in Figures 13 and 14 are
also given in Tables 50 and 51.
78
-------
.20
u.
O
.15
.10
".05
1972
'\
"^^xN BELOW
BETWEEN**^
i i i i
10 30 50 70 90 110 130 150
DEPTH (cm)
..20
3
b.
O
.15
O .10
v
w.05
1973
BETWEEN
m^^*1 ^ m»O»ocl
•«•• •' \
BELOwV
tO 30 50 70 90 110 130 ISO
DEPTH tern)
.20
.15
O .10
Q
*.05
r BETWEEN,
x^n I9?4
-"'BELOW
10 30 50 70 90 110 130 ISO
DEPTH (cm)
Figure 13. Comparison of salt contents of soil samples taken on (.below)
trickle lines (dashed lines) and between trickle lines (solid lines).
The three graphs shown are for post harvest samples taken in
1972, 1973 and 1974. Vertical arrow denotes average depth
to sand for the trickle treatments.
79
-------
The results also indicate that some of the percolating salts can accumulate
in the sands underlying the experimental site. Since the rooting depth of
cotton appears to be restricted to the soil profile above the sand, prob-
ably as a result of the sharp interface between the clay loam and the under-
lying sand, any salt accumulation in the sands would not be detrimental to
cotton production.
Table 50. SOIL SALINITY (g/lOOg OF SOIL) FOR SAMPLING LOCATIONS
BELOW AND BETWEEN TRICKLE LINES AS A FUNCTION OF DEPTH
Location
Below
Between
Below
Between
Below
Between
0-20
0.12
0.18
0.10
0.10
0.07
0.12
20-40
0.14
0.14
0.12
0.11
0.08
0.07
40-60
0.11
0.11
0.11
0.12
0.11
0.20
60-80
0.11
0.10
0.12
0.12
0.13
0.15
Averages of
Below
Between
0.10
0.13
0.11
0.14
0.11
0.14
0.12
0.13
Depth (cm)
80-100 100-120 120-140
1972
0.11
0.09
1973
0.13
0.14
1974
0.17
0.19
1972,
0.14
0.14
0.09
0.08
0.13
0.13
0.19
0.19
1973 and
0.13
0.13
0.06
0.04
0.06
0.07
0.17
0.14
1974
0.09
0.09
140-160
0.03
0.03
0.04
0.05
0.08
0.08
0.05
0.05
0.2 bar
10 30 50 70 90 110
DEPTH (cm)
130 150
Figure 14. Soil salinity differences due to sampling location (between
row minus below row) for the 0.2 and 0.6 bar trickle treatments.
The differences are for the means of the 1972, 1973 and 1974
post harvest samples.
80
-------
Table 51. SOIL SALINITY (g/lOOg OF SOIL) FOR SAMPLING LOCATIONS BELOW AND
BETWEEN TRICKLE LINES AS A FUNCTION OF DEPTH AND SALINITY DIFFERENCES
BETWEEN LOCATIONS (BETWEEN ROW MINUS BELOW ROW). MEANS OF 1972,
1973 AND 1974 POST HARVEST SAMPLES.
Depth (cm)
Location 0-20 20-40 40-60 60-80 80-100 100-120 120-140 140-160
Between
Below
Difference
Between
Below
Difference
0
0
0
0
e
0
.14
.08
.06
.13
.12
.01
0.16
0.10
0.06
0.13
0.13
O.OQ
0
0.13
0.09
0.04
0
0.15
0.14
0.01
.2 BAR
0.13
0.12
0.01
.6 BAR
0.12
0.13
-0.01
TREATMENT
0
0
0
.12
.11
.01
0.12
0.12
0.00
0
0
0
.07
.07
.00
0.04
0.04
0.00
TREATMENT
0
0
0
.16
.15
.01
0.15
0.15
0.00
0
0
-0
.10
.12
.02
0.06
0.06
0.00
Composition of Saturation Extracts - The saturation extracts of the soil
samples taken from the trickle-irrigated plots in the spring of 1973 were
analyzed for chemical composition (See Appendix Tables 7-14). The results
of these analyses are summarized in Tables 52, 53 and 54. Table 52 presents
the mean composition of saturation extracts of samples taken from below the
trickle lines (May, 1973). Table 53 presents the mean composition of the
samples from in between the trickle lines and Table 54 combines the data
from Tables 52 and 53.
Table 52. MEAN COMPOSITION OF SATURATION EXTRACTS (meq/1) OF SAMPLES
TAKEN FROM BELOW THE TRICKLE LINES (MAY 1973) AS A FUNCTION OF DEPTH
Depth
(cm)
0-20
20-40
40-60
60-80
80-100
100-120
120-140
140-160
mmhos
/cm
1.3
1.5
1.8
2.4
2.9
3.8
3.2
2.6
£
Cations
18.3
20.3
24.0
34.7
41.9
54.6
44.9
36.7
Ca
6.3
7.5
8.4
14.8
16.6
24.2
19.5
13.9
Mg
2.1
2.5
3.2
4.3
5.3
7.2
5.9
4.8
Na
9.2
9.6
11.7
14.9
19.3
22.5
18.7
17.2
K
0.7
0.7
0.7
0.7
0.6
0.8
0.8
0.7
Cl
1.8
2.3
2.7
4.2
6.2
11.6
11.2
8.1
C03
0
0
0
0
0
0
0
0
HC03
8.3
8.3
7.3
7.9
6.9
6.5
6.8
6.9
S04
6.1
8.5
12.1
19.5
22.4
29.9
22.8
17.7
N03
0.7
1.1
1.0
1.4
3.8
2.2
1.6
1.4
81
-------
Table 53. MEAN COMPOSITION OF SATURATION EXTRACTS (meq/1) OF SAMPLES TAKEN
IN BETWEEN THE TRICKLE LINES (MAY 1973) AS A FUNCTION OF DEPTH
Depth mmhos £
(cm) /cm Cations Ca Mg Na K Cl C03 HC03 804 N03
0-20
20-40
40-60
60-80
80-100
100-120
120-140
140-160
2.5
2.1
2.1
2.7
3.0
3.4
2.8
2.6
33.0
29.2
28.9
36.4
40.5
46.4
39.7
33.7
13.7
11.9
11.4
14.7
16.1
20.0
15.7
14.7
3.8
3.5
3.7
4.6
4.6
6.0
5.4
4.7
14.6
12.9
13.0
16.3
19.1
19.7
17.9
16.1
0.9
1.0
0.8
0.8
0.7
0.8
0.8
0.8
5.8
4.4
4.5
6.8
7.1
8.9
8.7
7.5
0
0
0
0
0
0
0
0
8.3
8.4
7.2
6.5
7.6
6.6
6.9
6.3
13.7
12.2
12.4
17.0
20.1
25.2
19-7
18.5
2.8
3.4
2.4
3.6
3.0
3.4
1.6
1.4
Comparing the data in Tables 52 and 53, it may be seen that in the upper 60
cm of soil the concentrations of Ca, Na, Cl, 804 and N03 were less below (on)
the trickle line than in between trickle lines. The lower concentrations of
chlorides below the trickle lines indicate considerable leaching around
trickle lines and some salt accumulation in between trickle lines. There
was no difference in bicarbonate concentration below and in between trickle
lines.
Table 54. MEAN COMPOSITION OF SATURATION EXTRACTS (meq/1) OF ALL
SAMPLES TAKEN IN THE TRICKLE PLOTS (MAY 1973) AS A FUNCTION OF DEPTH
Depth
(cm)
0-20
20-40
40-60
60-80
80-100
100-120
120-140
140-160
mmhos
/cm
1.9
1.8
1.9
2.5
2.9
3.6
3.0
2.6
£
Cations
25.7
24.8
26.5
35.5
41.2
50.1
42.3
36.5
Ca
10.0
9.7
9.9
14.8
16.3
21.9
17.6
14.2
Mg
3.0
3.0
3.5
4.5
5.0
6.5
5.6
4.8
Na
11.9
11.3
12.4
15.6
19.2
20.9
18.3
16.8
K
0.8
0.9
0.7
0.7
0.6
0.8
0.8
0.7
Cl
3.8
3.3
3.6
5.5
6.7
10.1
10.0
7.9
co3
0
0
0
0
0
0
0
0
HC03
8.3
8.3
7.3
7.2
7.3
6.5
6.9
6.7
so4
9.9
10.3
12.2
18.3
21.2
27.3
21.3
18.0
N03
1.8
2.2
1.7
2.5
3.4
2.9
1.6
1.4
Salt Distribution Around Trickle Lines - Salinity sensor readings were made at
regular intervals to monitor possible salt accumulation around trickle lines.
For each depth in each trickle plot, the data were averaged and plotted versus
82
-------
time (J^g. 15-18}. Before August 1, 1973, the number of salinity sensors
in each, plot were 0 at 5 cm, 5 at 1Q cm, 7 at 25 cm and 3 at 40 cm. After
August 1, there were 14 sensors at each of these depths (See Materials and
Methods). Thus, in constructing Figures 15-18, 5 values were used to
compute the average salinity at 10 cm before August 1, and 14 values were
used for computing the average values after this date. Rainfall and irri-
gation data are also presented in Figures 15-18. The data for Plots T5
(Figures 15 and 16) and T2 (Figures 17 and 18) show the same general trends.
For both plots, the salinity level responded rather quickly to irrigation or
rainfall. For example, preplant irrigations with 20 cm of water during
early March 1973 produced a large decrease in soil salinity at all levels
in the soil profile. This is shown even more clearly in Figure 19, where
the salt distribution in the soil around a trickle line is presented. Pre-
irrigation through a trickle line was apparently very effective in moving
salt away from the line. Even as far as 45 cm from the trickle line there
was a substantial decrease in soil salinity.
An example of leaching by rainfall is shown in Figures 20 and 21. Figure 20
shows the salt distribution around two parallel trickle lines on August 16,
1973. There was clearly some salt accumulation near the soil surface in
between trickle lines as a result of irrigation with water which had an
electrical conductivity of 1.4 mmhos/cm. However, an unusually large rain-
storm of 120 mm effectively moved the salts deep into the profile. There was
some runoff from the area, so it is not certain whether the whole 120 mm
leached through the profile or only a part of it.
The leachings of the soil profile by irrigation and rainfall (Figures 15-18)
were followed by substantial decreases in the salt concentration. The average
salt level had a tendency to increase during July and August when irrigation
and crop water use were intensive. The fall rains in 1973 and 1974, however,
were apparently sufficient to leach out most of the salts accumulated during
the previous months.
83
-------
WET TRICKLE TREATMENT (0.2 bars)
8
6
4
2
8
6
4
2
i
<"'
III'
1
I
ll
J'
SEP,
°"!
(
1
1
Q
JUL. 1 SEP. 1
NOV. 1
j
i
•\
\
o*"»«
i
NOV. 1
1972
i
i
i
]
}
1
1 i
JAN. 1 MAR
).o-— °"""""°
152mm1
1
SJC
f
i
j | ll
| | I i|
' ' 11
1 i I
'
'
o
II 1 1 I
1
1
DEPTH 5cm
\
\
i 1 i
MAY 1 JUL. 1 SEP. 1 NOV. 1 JAN. 1 MAR. 1
V
/*
DEPTH 10 cm
i'.
\
* %
-O O»w
*"OOO».O% DO* **"*"••« __.
0 ^ >.0...— — —•
254mm 108mm' H5mmr
I i i i
j
-
-
.
pCL
~-/\_ -
i i i i
MAY 1 JUL. 1 SEP 1 NOV. 1
>«M
-
_
-
..0...0.0' | *•.„
4:
101mm'
1 I 1 1 1 I 1 1
10
2C
3C
4(
e\f
Dl
6C
7C
8(
9(
JAN 1 MAR 1 MAY 1 JUL 1 SEP. 1 NOV. 1 JAN. 1 MAR 1 MAY. JUL. SEP. 1 NOV. 1 JAN. 1
1973
1974
3)
2J
O
i
Figure 15. Soil salinity at the 5- and 10-cm depths as estimated by salinity sensors for the 0.2
bar trickle treatment. Vertical dashed lines denote total rainfall for month indicated.
Vertical solid lines denote irrigation on date indicated.
-------
WET TRICKLE TREATMENT (O.2 bars)
oo
en
1
1
8
I6
3
11
1
1
§
•\
.
-
fo
i
i i i
i *
t | t
j j
: '
i
M
4 \ . ^
j ^. . _or
,
v
1
1
1
1
1
,
O
1
1
1
1
mil
n
i I
! 1
ill
II
if I
j f
_o
!
DEPTH 25cm
fX
'•°*Oa
/
»•"
SEP. 1 NOV. 1 JAN. 1 MAR. j MAY 1 JUL.
-
-
-
oo
u
i ;
1
}
/\
k \
\
\ J °"°**«»o»«**O
V ^
.
\
<
I52mmr;
i
r254mm
i 1 i i
*•»«•»
*^*-B ,,mmmr'
,
SEP. 1 NOV. 1 JAN. 1
j
0.0
M.— —
MAR.I
DEPTH 40cm
Sto.M__.~~0WM_<
0
I08mmr
i
1 1 1
••"•-«»,
H5mmT
III
in
^te^--°— io
— °-«- ^^
^^O»or^
1 1 1
MAY 1 JUL. 1 SEP. 1 NOV. 1
•»•
A.—O
^. o-o»-^
— o--*
101mm*
ii i i i
-
-
-
%
a
>o I
i
20 §
30 H
5
40 g
5o|
1
=f
603
70
80
90
JUL. I SEP. I NOV. I JAN. I MAR. I MAY) JUL. I SEP. I NOV. I JAN. I MAR. I MAY. I JUL. I SEP. I NOV. I JAN. I
1972 1973 1974
Figure 16. Soil salinity at the 25- and 40-cm depths as estimated by salinity sensors for the
0.2 bar trickle treatment. Vertical dashed lines denote total rainfall for month
indicated. Vertical solid lines denote irrigation on date indicated.
-------
DRY TRICKLE TREATMENT (0.6 bars)
ao
a>
I 6
|6
S
1,
-
-
1
-
1
1
1
1
i
SEP.I NOV.I
-
t
'f'
\
,
JAN.I
i
MAR
W o
\>«« 0»°~""0»«~»ft
1
id
.
'
M,
1 i
! '
DEPTH 5cm
\
\
\
o..~....o..~..^ . ...._
ii iii
\Y 1 JUL. 1 SEP. 1 NOV. 1 JAN. 1 MAR. 1
fr DEPTH 10 cm
^J] J
mm*
k/
s
-
_
• \/\
/ \
/ \
f o— »o
,0~_.0.0
1 1 1 1
AY 1 JUL. SEP. 1 NOV. 1
-
/•--•*-„
254mm TIO8mm IwSmm
i i i i i I i i i i i
i
20 §
30
O
40
60 I
70
80
90
JUL. I SEP I NOV.I JAN. I MAR. I MAY. I JUL. I SEP.I NOV.I JAN. I MAR. I MAY. I JUL. I SEP.I NOV.I JAN I
1972 1973 1974
Figure 17. Soil salinity at the 5- and 10-cm depths as estimated by salinity sensors for the
0.6 bar trickle treatment. Vertical dashed lines denote total rainfall for month
indicated. Vertical solid lines denote irrigation on date indicated.
-------
DRY TRICKLE TREATMENT (0.6 bars)
ao
-a
8
6
4
2
8
6
4
2
n
.
-°«
If
0<
f
\ \
I !
i i
i
i
«/""* **°*
> >
o
1 1
SEP.I NOV.I JAN.I MAR
i
*
i
*«*°%
°°o*°N^,* "
;
I
k
(
;
152mm s
S
M
«.0
1
j
j
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10 5
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70
80
90
JUL.I SEP.I NOV.I JAN. I MAR. I MAY. I JUL.I SEP.I NOV.I JAN.I MAR.I MAY. I JUL.I SEP.I NOV.I JAN. I
1972 1973 1974
Figure 18. Soil salinity at the 25- and 4Q-cm depths as estimated by salinity sensors for
the 0.6 bar trickle treatment. Vertical dashed lines denote total rainfall for month
indicated. Vertical solid lines denote irrigation on date indicated.
-------
TRICKLE LINE
3 5 mmhos/cm
4.4 3.9V2{5 3.0 4.2
4i2 4.9^5.7 6.
BEFORE
LEACHING
MARCH 1,1973
45 30 15 0 15 30 45
DISTANCE-cm
§ 10
SI 25
8
40
3 mmhos/cm
-TRICKLE LINE
3
4.9 4.1 \2.8 2.4
1.6 15 1.6 2.
.AFTER
LEACHING
MARCH 26,1973
45 30 15 0 15 30 45
DISTANCE-cm
Figure 19. Comparison of soil salinity around a trickle line in plot
before (top figure) and after (bottom figure) a 200-mm preirrigation.
88
-------
00
mmhos/cm
100 cm
2 3
10
5 -
-------
0
5
10
mmhos/cm
100 cm
E
o
I
I
I- «c
Q_ 25
UJ
o
40
-
-------
It appeared that preirrigation and rain were effective in preventing heavy
salt accumulations around trickle lines. This was the case even though all
trickle lines were kept at the same location for three successive growing
seasons and no tillage (no mixing of soils and salts) was performed.
Effects on Cotton Yields and Quality
Yield and Quality in 1974 - The 1974 cotton yields are presented in Appendix
Table 24 and the cotton quality data for the first and second harvests are
presented in Appendix Tables 25-30. The average yield and quality data for
each of the two trickle treatments are presented in Table 55 for 1974.
Table 55. EFFECTS OF SOIL-WATER TENSION ON YIELD AND QUALITY
OF COTTON FROM THE TRICKLE-IRRIGATED PLOTS (1974)
Tension
bars
.2
.6
.2
.6
.2
.6
Yield
kg/ha
969
974
95
99
1060
1070
Lint
%
36.3
37.1
39.9
39.6
1st
38.1
38.3
2.5%
span
1st
1.20
1.17
2nd
1.16
1.14
Uniformity
ratio MIC
harvest
45.7
46.3
harvest
47.4
45.0
3.30
3.27
3.30
3.07
Strength
20.7
21.4
20.3
20.6
Elongation
6.30
6.27
6.27
6.43
and 2nd harvests combined
1.18
1.16
46.6
45.6
3.30
3.17
20.5
21.0
6.28
6.35
The treatments applied to the trickle plots had no significant effect during
the 1974 season. This is due in part to the heavy infestation of Verticillium
wilt that occurred during 1974.
Yield of Cotton for the Combined Years 1972. 1973 and 1974 - The cotton yields
from the trickle plots for the years 1972, 1973 and 1974 are presented in
Table 56. The analysis of variance for the yield data is presented in Table
57. The analysis of variance showed that treatment had no significant effect
on cotton yield.
91
-------
Table 56. EFFECTS OF SOIL-WATER TENSION ON YIELD (kg/ha) OF COTTON
FROM TRICKLE-IRRIGATED PLOTS IN 1972, 1973 AND 1974
Treatment
Year 0.2 bar 0.6 bar Mean
1972 1250 1120 1180
1973 1240 1370 1300
1974 1060 1070 1060
Mean 1180 1190 1180
Table 57. ANALYSIS OF VARIANCE FOR COTTON YIELDS FOR THE COMBINED
YEARS 1972, 1973 AND 1974
(TRICKLE-IRRIGATED PLOTS)
Source of variation Degrees of freedom F value
Replication
Years (Y)
Error A
Harvest (H)
Error B
Y X H
Error C
Treatment (T)
Error D
Y X T
Error E
H X T
Error F
Y X H X T
Error G
2
2
4
1
2
2
4
1
2
2
4
1
2
2
4
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
c.v.
_
5.71
= 14.6%
53.6
m 40.4%
7.47
= 33.2%
0.001
= 13.6%
2.88
- 11.4%
39.9
= 16.3%
23.0
= 13.2%
92
-------
Comparing the data in Table 56 with, those in Table 39 showed that the mean
yield from the trickle-irrigated plots was 1180 kg/ha versus 1090 kg/ha
from the surface-irrigated plots. Thus, the trickle plots produced on the
average 8.2 percent more lint cotton than the surface-irrigated plots and
used about 24 percent less irrigation water.
Quantity of Drain Flow - Figures 22, 23, and 24 show drain flow at sampling
stations A and B on the Del Rio Drain. During all three years of the study,
the early March time period is marked by a sharp increase in flow at both
stations. Since preirrigations are initiated at this time of the year, the
flow increases could be expected. With the exception of 1972, the increase
in drain flow persisted throughout the growing season. A second relative
peak in flow rate occurred in July-August, followed by an erratic decline
to the winter flow rates.
Figure 25 presents a cumulative frequency distribution for drain flow at sites
A and B. Although the Mesilla Drain Cestimated length 26 km) enters between
the sites, this drain contributes little or nothing to the flow of the Del Rio
Drain (estimated length above sites A and B is 42 km).
Figure 25 indicates that during the period December 1971 through 1974, the
increase in drain flow between A and B was less than 0.25 nr/sec, 100 percent
o
of the time, less than 0.11 m /sec, 50 percent of the time and less than
o
0.05 m /sec 10-15 percent of the time. These data indicate that at least 50
3
percent of the time an increase in flow rate of 18 percent or .11 m /sec
could be expected between the two sites.
3 3
A flow rate of .11 m /sec is equivalent to 9500 m /day. The distance between
sites A and B is 4.5 km. Assuming that an area 1 km wide is drained on both
sides of the drain, it follows that the downward flux of water in this area
would be equivalent to 1 mm/day. These losses were of the same order of
magnitude as the drainage losses estimated at the experimental site.
The proximity of the Rio Grande to the Del Rio Drain, however, makes the
above interpretation very uncertain. Also, the precise area drained by the
Del Rio Drain is unknown, and could easily be much larger or smaller than
2
the 2 x 4.5 km used here.
93
-------
l.75r
1.50
ro
UJ
1.25
1.00
I -7S
.50
.25
—• '
,
v'
«> SITE A
x SITE 8
\\
0
JAN.I FEB.I MAR.I APR.I MAY I JUN.I JUL.I AUG.I SEP.I OCT.I NOV.I DEC.I
Figure 22. Flow at Del Rio Drain sampling sites A and B in 1972.
-------
CO
en
o
q>
v»
l.75r
1.50-
1.25
2
1.00
.75
.50
.25
o SITE A
x SITE B
\ x
v-
JAN. I FEB. I MARJ APR. I MAY I JUN.I JUL. I AUG. I SEP. I OCT. I NOV. 1 DEC. I
Figure 23. Flow at Del Rio Drain sampling sites A and B in 1973.
-------
l.75r
to
* SITE B
JAN. I FEB. I MAR. I APR. I MAY I JUN. I JUL. I AUG. I SEP. I OCT. I NOV. I DEC. I
Figure 24. Flow at Del Rio Drain sampling sites A ane B in 1974.
-------
co
20 40 60 80
FREQUENCY (percent)
100
Figure 25. Cumulative frequency distribution of flow rate as measured at Del Rio Drain
sites A and B (December 1971 through 1974).
-------
Quality of Drain Flow - Figures 26, 27 and 28 show the electrical conductiv-
ities of drainage waters at Del Rio Drain -sites A and B. In general, there
appeared to be an inverse correlation between drain flow and the electrical
conductivities of the water in the Del Rio Drain. When the drain flow
increased in early spring, after the start of the irrigation season, the con-
ductivity of the drain water decreased. A decrease in drain flow in the fall,
on the other hand, resulted in a gradual increase in salinity of the drain
water (Figs. 26 and 27). No further analysis of the correlation between drain
flow and drain water quality was made due to lack of groundwater data.
At regular time intervals, the water samples from Del Rio Drain sites A and B
were analyzed for chemical composition. The results of these analyses are
presented in Appendix Tables 31 through 36. Yearly averages of the chemical
constituents of the samples from sites A and B are presented in Table 58.
Based on the equivalent weights of the various salts listed in Table 58, the
mean salt content at site A during 19/2-1974 was 908 ppm. At site B it was
953 ppm, an increase of 45 ppm (equivalent to 10 ppm per km of drain).
The degradation of water quality taking place between sites A and B is further
shown in Figure 29.
During the period December 1971 through 1974, the salinity of the drain water
always (100 percent of the time) increased at least 3.4 percent (or 0.75
percent/km of drain) between the sites. Figure 29 also indicates that 50
percent of the time salinity could be expected to increase at a rate of 0.86
percent/km of drain.
The results (not shown here) of a frequency distribution of sodium adsorption
ratio (SAR) for sites A and B indicate that there was no difference in SAR
between the sites. These data imply that the relative cation composition is
unchanged over this segment of the drain. This is also evident from the data
in Table 58.
The data on drain flow and quality at sites A and B were also used to compute
the quality of the return flow entering the Del Rio Drain between A and B.
The results of these calculations are presented in Appendix Tables 37-48 and
summarized in Table 59 along with the chemical composition of the five test
wells and irrigation well.
98
-------
co
50
1.8
1.7
1.6
1.5
E
o
8 1.4
E
E
1.3
1.2
1.0
SITE A
SITE B
,—X—X
JAN. I FEB. I MAR. I APR. I MAY I JUN.I JUL. I AUG. I SEP. I OCT. I NOV. I DEC. I
Figure 26. Electrical conductivities of water samples from Del Rio Drain sites A and B in 1972.
-------
o
o
1.8 r
1.7
1.6
1.5
E
o
8 1.4
£
E
E
1.3
1.2
I.I
1.0
•*x,
x x-x
X
4,
*o t\ t » ' » p~o»o
vv v y
SITE A
SITE B
-------
1.8
1.7
1.6
1.5
I
§ 1,4
E
1.3
1.2
I.I
1.0
SITE A
SITE B
\/vd
_L
JAN I FEB. I MAR. I APR. I MAY I JUN. I JUL. I AUG. I SEP. I OCT. I NOV. I DEC. I
Figure 28. Electrical conductivities of water samples from Del Rio Drain sites A and B in 1974.
-------
O
CO
- 1400
Q.
Q.
CO
<
CO
o
LU
O
CO
CO
<
O
1200
1000
0
• SITE A
• SITE B
0
20 40 60 80
FREQUENCY (percent)
100
Figure 29. Cumulative frequency distribution of water quality at Del Rio Drain sites
A and B (December 1971 through 1974).
-------
o
CO
Table 58. MEAN COMPOSITION OF DEL RIO DRAIN WATER
(meq/1 EXCEPT N03 in ppm) AT SITES A AND B DURING 1972, 1973 and 1974
A-1972
A-1973
A-1974
Mean
B-1972
B-1973
B-1974
Mean
EC
1.32
1.25
1.21
1.26
1.37
1.31
1.26
1.31
Cations
13.10
13.06
13.51
13.22
13.48
13.63
14.23
13.78
Anions
13.43
13.10
13.16
13.23
14.04
13.67
14.06
13.92
Ca
5.13
5.26
5.51
5.30
5.24
5.43
5.89
5.52
Mg
1.76
1.65
1.62
1.68
1.82
1.74
.1.67
1.74
Na
5.99
5.92
6.15
6.02
6.20
6.23
6.44
6.29
K
.21
.24
.24
.23
.22
.24
.24
.23
Cl
3.51
3.39
3.42
3.44
3.57
3.49
3.51
3.52
co3
.38
.38
.13
.30
.47
.37
.15
.33
HC03
3.41
3.62
3.90
3.64
3.50
3.80
4.23
3.84
S04
6.12
5.68
5.69
5.83
6.49
5.98
6.15
6.21
N03 in
ppm
.24
1.91
.72
.96
.41
1.87
1.09
1.12
-------
Table 59. COMPUTED QUALITY OF RETURN FLOW ENTERING DEL RIO DRAIN
BETWEEN SITES A AND B. THE QUALITY OF THE TEST WELLS AND
OF THE IRRIGATION WELL IS ALSO PRESENTED
EC
mmhos/cm
Return flow (1972)
Return flow (1973)
Return flow (1974)
Return flow (all years) .
Well #1 (22.9 m)
Well #2 (15.5 m)
Well #3 (11.0 m)
Well #4 ( 8.2 m)
Well #5 ( 5.8 m)
Irrigation well (26.0 m)
All wells
1.54
1.53
1.52
1.53
1.09
1.44
1.61
1.63
1.63
1.28
1.45
Ca
meq/1
5.25
6.76
7.46
6.49
5.50
7.67
8.28
8.02
8.00
,5.47
7.16
Mg
meq/1
2.01
2.03
1.88
1.97
1.61
2.10
2.49
2.70
3.14
1.75
2.30
Na
meq/1
6.97
7.39
7.65
7.34
4.04
5.83
6.57
6.68
6.38
5.40
5.82
The data in Table 59 show; a fairly good agreement between the computed quality
of the return flow- entering between sites A and B and the average of the
quality of the observation wells and the irrigation well. The quality of the
irrigation return flow, however, is quite different from the quality of water
measured at any single depth, except for well #2. The water quality of well
#2 at 15.5 m is very close to the mean quality for all wells and seems to
represent the irrigation return flow quality the best.
The significant variation of water quality in the saturated zone with depth
would be of great importance in predicting the quality of irrigation return
flow. Models for predicting the quality of irrigation flow are frequently
evaluated with data from observation wells and irrigation wells, which are
usually collected for a single depth. The data in Tables 35 and 59 indicate
that the water quality data from a single depth in the saturated zone may
not adequately represent the quality of return flow entering a drainage
canal.
104
-------
SECTION VII
REFERENCES
1. Cotlove, E., H. U. Trantham and R. L. Bowman. 1958. An instrument for
and method for automatic, rapid, accurate, and sensitive titration
of chloride in biological samples. J. Lab. Clin. Med. 50:358-371.
2. Jensen, M. E. 1972. Programming irrigation for greater efficiency. Ijn
D. Hillel (ed.) Optimizing the soil physical environment toward
greater crop yields. Academic Press, New York. pp. 133-161.
3. Kilmer, V. J., and L. T. Alexander. 1949. Methods of making mechanical
analysis of soils. Soil Sci. 68:15-24.
4. Lambert, R. S., and R. J. Dubois. 1971. Spectrophotometric determina-
tion of nitrate in the presence of chloride. Anal. Chem. 43:955-957.
5. Nielsen, D. R., J. M. Davidson, J. W- Biggar and R. J. Miller. 1964.
Water movement through Panoche clay loam soil. Hilgardia 35(17):
491-506.
6. Perkin-Elmer Corporation. 1971. Analytical methods for atomic absorp-
tion spectrophotometry. The Perkin-Elmer Corporation, Norwalk, Conn.
7. Rasnick, B. A., and F. S. Nakayama. 1973. Nitrochromeazo titrimetric
determination of sulfate in irrigation and other saline waters. Comm.
Soil Sci. Plant Anal. 4:171-174.
8. Rhoades, J. D., R. D. Ingvalson, J. M. Tucker and M. Clark. 1973. Salts
in irrigation drainage waters: I. Effects of irrigation water compo-
sition, leaching fraction, and time of year on the salt compositions
of irrigation drainage waters. Soil Sci. Soc. Amer. Proc. 37:770-774.
9. U.S. Environmental Protection Agency. 1971. Methods for chemical analy-
sis of water and wastes. Methods Development and Quality Assurance
Research Laboratory, National Environmental Research Center, Cincinnati,
Ohio. 316 pp.
10. U.S. Salinity Laboratory Staff. 1954. Saline and alkali soils. USDA
Agr. Handbook No. 60. L. A. Richards (ed.), Superintendent of Docu-
ments, U.S. Government Printing Office, Washington, D.C. p. 98.
11. van Bavel, C.H.M., G. B. Strick and K. J. Brust. 1968. Hydraulic pro-
perties of a clay loam soil and the field measurement of water uptake
by roots: I. Interpretation of water content and pressure profiles.
Soil Sci. Amer. Proc. 32:310-317.
12. Willardson, L. S. 1972. Attainable irrigation efficiencies. J. Irrig.
and Drainage Division 98:239-246.
105
-------
SECTION VIII
PUBLICATIONS
Patterson, T. C. and P. J. Wierenga. 1973. Influence of trickle irri-
gation on irrigation return flow. Paper No. 73-2506. American Soc.
of Agricultural Engineers. St. Joseph., Michigan.
Patterson, T. C. and P. J. Wierenga. 1974. Irrigation return flow as
influenced by drip irrigation. Proceedings of the International
Drip Irrigation Congress. San Diego, California. July 7-14, 1974.
p. 376-381.
van de Pol, R. M. 1974. Solute movement in a layered field soil. M.S.
thesis, New Mexico State Univ., Las Cruces. 125 p. (partial support
from this project).
van Genuchten, M. Th. 1975. Mass transfer studies in sorbing porous
media. Ph.D. thesis, New Mexico State Univ., Las Cruces. 161 p.
(partial support from this project).
Wierenga, P. J. and T. C. Patterson. 1972. Irrigation return flow
studies in the Mesilla Valley. In Managing irrigated agriculture
to improve water quality. Proceedings National Conference on
Managing Irrigated Agriculture to Improve Water Quality. May 16-18,
1972.
Wierenga, P. J. and T. C. Patterson. 1973. Quality and quantity of
return flow as influenced by trickle and surface irrigation. New
Mexico Water Resources Research Institute Report No. 014. Las
Cruces. 40 pp.
Wierenga, P. J. 1973. Irrigation management and its effect on the
quality of drainage return flow. Abstract in Science and Man in
the Americas Desert and Arid Lands Central Theme, AAAS, Mexico
City, June 20 - July 4, 1973.
Wierenga, P. J. and T. C. Patterson. 1974. Quality of irrigation
return flow in the Mesilla Valley. Proceedings of the 10th Inter-
national Congress of Soil Science, Moscow, USSR. August 12-20,
1974. Volume X. p. 216-222.
Wierenga, P. J. and T. C. Patterson. 1974. Quality and quantity of
return flow as influenced by trickle and surface irrigation. New
Mexico Water Resources Research Institute Report No. 042. Las
Cruces. 42 pp.
106
-------
SECTION IX
APPENDIX
Tables Page
1-6 Electrical conductivities of saturation extracts of soil
samples taken from surface and trickle-irrigated plots
(1972 through 1974} 108
7-14 Chemical composition of saturation extracts of soil
samples taken from surface and trickle-irrigated plots
(May 1973) 114
15-17 Electrical conductivities of soil solution withdrawn from
surface and trickle-irrigated plots (1972 through 1974). 122
18-23 Chemical composition of water samples taken from test
wells and irrigation well at Plant Science Farm (1972
through 1974) 125
24-30 Cotton yield and quality data for surface and trickle -
irrigated plots (1972 through 1974) 131
31-36 Chemical composition of water samples taken at sampling
sites A and B on the Del Rio Drain (1972 through 1974). 138
37-48 Estimated quality of return flow between sampling sites
A and B on the Del Rio Drain (1972 through 1974) 144
107
-------
Appendix Table 1. EC VALUES (mmhos/cm) FOR SATURATION EXTRACTS OF
SOIL SAMPLES TAKENeOUTSIDE OF (OR WITHIN) SURFACE AND TRICKLE-
IRRIGATED PLOTS (SPRING 1972, PRIOR TO PLANTING). "S" AND
"E" FOLLOWING PLOT NUMBERS DESIGNATE "SOUTH OF PLOT" AND
"EAST OF PLOT," RESPECTIVELY
DEPTH (CM)
PLOT NO. 0-20 20-40 40-60
SURFACE-IRRIGATED PLuTS
6C-90
P 1
P 2
P 3
P b
P 7
P 8
P °
P10
PUS
P12S
H3S
PUS
F15S
P16S
P17S
Pies
PIPS
P21S
P2?S
P23S
F24S
P25S
P26S
P27S
P28S
P20S
1 .96
2.V«
2.21
1.93
3.43
2.97
2.23
5.41
3.11
3.25
3.17
3.10
1.90
2.15
2. CO
3.35
3.42
1 .20
1.20
2.02
2.34
4.41
3.53
3.36
2.74
2.70
2.36
3.10
4.85
2.ai
8.10
4.43
2,^7
7.97
5.43
4.37
4.37
5.21
2.4«
2.71
3.14
5.51
5. IS
1.42
1.22
1.20
2.00
5.10
4. 70
5.20
4.00
3.38
7.39
6.C2
7.74
5.79
6.83
7.78
4.35
8.74
6.20
5.98
6.93
5.97
4.32
4.50
4. o5
6 . 30
6,96
1 .40
1.14
1.00
4.04
5.3?
'+.^0
6.04
5.56
4.34
1.45
0.96
2.70
3.52
6.42
10.27
4.29
9.g6
6.45
2.76
5.23
4.06
5.00
5.15
4.52
7.36
1.14
0.90
3.34
5.22
3.9C
6.40
6.06
5.42
MEAN= 2.77
STO. D5V.= 0.94-
GENFRAL
3.95 5.39 4.70
1.82 1.97 2.46
C£PTHS= 4.20 N'MHOS/CM
PLOTS
T 2E
T 3
T 3E
T 5
T 6
1.29
1.02
1.31
1.78
2.85
I.IP
1.16
2.22
1.94
4.23
1.22
1.39
3.59
2.11
4.94
1.48
3.61
1.85
5.02
VEAN= 1.75 2.15 2.65 2.99
STO. DEV.= C.70 1.25 1.59 1.64
GENERAL MEAN, ALL OEPTHS= 2.38 MMHJS/CM
108
-------
Appendix Table 2. ECe VALUES (mmfios/cm) FOR SATURATION EXTRACTS OF
SOIL SAMPLES FROM SURFACE AND TRICKLE-IRRIGATED PLOTS (Dec. 1972)
"R" AND "C" FOLLOWING TRICKLE PLOT NUMBERS DESIGNATE "ON THE
ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
DEPTH (CKJ
PLOT NO. 0-20 20-40 40-60 60-80 80-100
SURFACE-IRRIGATED PLOTS
100-120 120-140 140-160
P10
PI I
P12
Pi 3
P14
P15
Plfc
P17
PI 8
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
1.46
1.36
1.56
1.04
1.12
1.78
1.42
1.96
1.72
1.80
2.32
1.96
1.90
1.96
1.30
1.64
1.98
1.62
2.15
1.16
1.43
3.52
2.62
3.48
1.66
2.08
1.82
2.90
1 .98
2.92
1.7?
2.22
2.58
2.18
3.48
4.44
3.44
4.36
4.18
2.14
3.78
2.68
2.56
2.84
3.40
3.16
2.28
2.34
4.04
3.22
4.30
2.59
2.34
1.70
5.C8
4.60
5.36
3.50
4.84
4.14
4.88
5.90
6.32
5.12
5.56
6.16
5.92
7.18
4.60
6.52
5. BO
5.02
3. 18
3.40
2.98
7.27
4.56
5.00
4.40
4.10
2.62
5.0ft
5.66
6.7C
3.58
5.33
4.16
5.32
6.54
7. 08
5.92
6.04
7.46
5.32
5.76
4.46
6.86
5.60
5.80
2.70
2.74
3.27
6.44
4.62
5.38
2.91
7.04
2.89
4.26
4.58
7.32
4.24
3.72
4.2C
5.02
6.56
8.48
5.60
5.78
5.36
6.42
4.38
3. (30
2.LO
6.52
7.26
2.29
1.5S
2.40
5.62
4.46
5.16
2.6*
7.76
4.20
2.56
2.52
3.16
2.44
3.16
2.54
2.26
5.30
7.78
3.72
?.04
3.90
3.C8
2.56
1.70
1.36
2.06
5.72
2.02
1.5C
1.B7
5.31
5.14
4.16
2.38
6.76
3.30
1.36
1.74
2.68
1.66
2.12
1.48
2.06
2.66
5.58
3. 12
2.10
3.36
l.OS
•2.14
1.48
1.26
2.14
3.96
2.42
1.7C
1.90
6.32
5.56
3.88
2.41
2.96
1.80
1 .24
2.20
4.48
1.20
1 .90
1 .28
2.56
2.28
5.78
6.12
1.82
3.10
1.52
2.06
1 .16
1.26
2.08
2.62
0.82
1.26
1.02
1 .52
1.44
3.44
2.61
2 .34
1 .74
MFAN = 1.64 2.95 4.96 5.24 4.88 3.38 2.65 2.25
STD. DEV.= 0.60 0.83 1.21 1.45 1.80 1.64 1.43 1.35
GENERAL MEAN, ALL CEPTHS AND TREATMENTS= 3.52 MMHCS/CM
PLOTS
T
T
T
T
T
T
T
T
T
T
T
T
I R
1C
2R
2C
3R
3C
4R
4C
5R
5C
6R
6t
2.80
3. 02
3.02
2.72
1.06
4.70
0.94
2.32
1.62
2.40
2.44
2.28
2.20
1.82
2.24
1.70
1.34
2.80
1.60
2.64
3.40
2.68
2.16
2.06
1.44
1.28
1.90
1.70
2.52
2.48
2.68
3.4H
2.52
2.16
3.04
3.08
1.34
l.°52
3.18
1 .50
2.72
2.92
4.10
4.52
2.90
2.74
2.86
1.94
1.34
1.32
3. 60
1.68
2.3*
2.58
2.88
3.3C
3.92
2.74
3.C6
2.14
1.30
1.10
2.24
1.40
2.16
2.06
2.64
2.10
3.58
2.30
2.34
1.96
0.90
1. 18
1.46
0.82
2.22
1.74
1.50
2.12
2.64
1.80
1.86
1.64
1 .32
1.02
1 .36
1 .58
1.06
0.90
1.18
0.94
2.29
1.52
1.36
1.22
MEAN = 2.44 2.22 2.35 2.69 2.57
STO. OEV.= C.99 0.?8 0.68 0.99 0.85
GENERAL MEAN, ALL DEPTHS AND TRE4T,*fNTS= 2.18
2.18
0.72
1.66
0.53
1.31
0.38
109
-------
Appendix Table 3. ECe VALUES (nunfios/cm) FOR SATURATION EXTRACTS OF
SOIL SAMPLES FROM SURFACE AND TRICKLE-IRRIGATED PLOTS CMAY 1973).
"R" AND "C" FOLLOWING TRICKLE PLOT NUMBERS DESIGNATE "ON THE
ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
DEPTH (CM)
PLOT NO. 0-20 20-40 40-60 60-80 RO-100
StmACe-!fiRir,AT£D PLOTS
100-120 120-140 140-160
P \
P 2
P 3
P 5
P 6
P 7
P 8
P 9
PIO
Pll
P12
PL3
P14
P15
P16
P17
P18
P20
021
P22
P23
P24
P25
P?6
P27
P29
t>30
1 .24
1 .57
l.fll
1.01
1.54
1.06
1 .64
?.C5
1. 63
2. CB
2.42
2.66
1.63
1.73
1.68
2.29
1.98
1.67
1.56
1.77
1,76
3.13
2.26
2.61
1.93
1.79
2.21
L. 2C-
2.32
2.54
1.26
1.30
1.32
1.53
1.92
1.96
2.85
1.65
2.36
1.39
2.C8
1.60
2.44
2.77
1.60
1.44
1.38
2.C1
5.80
2.78
3.50
1.63
1.98
2.91
3.95
4,84
4.12
1.77
1.67
2.19
2.70
2.84
4. 19
7.3?.
5.17
7.45
4.40
4.03
1.36
4.73
5.67
4.74
1.81
2.12
4.23
5.23
6.65
4.06
5.08
3.84
3.58
5.15
«> .eo
7.21
3.59
5.28
5.25
6.66
7.73
7.46
9.29
7.33
6.67
6.15
7.72
3.24
6.91
6.89
5.82
3.05
3.01
3. 83
7.03
6.83
6.82
8.54
6.42
5.91
6. S7
8.21
S. 36
3. 12
4.95-
5.50
9.40
8.56
8.63
11 .37
7.ei
£.65
6.60
6.78
7.10
8.72
8.82
7.38
2.67
3.46
4.27
6. 19
5.25
8.02
8.32
8.23
6.65
4.63
t.ll
3. 76
1 . 77
1.42
2.00
f=. 86
8.08
3. ft
3.87
3.1?
4.28
2.48
2.99
3. 16
3.68
3.46
4.04
2.50
3.86
3.52
6.96
£.52
6.57
5.78
8.48
6.78
2.24
6.51
2.61
0.83
2.27
2.50
3.96
5.70
3.06
3.30
2.64
3.01
1.84
2.50
1.55
2.53
2.24
2.46
2.64
2.86
3.04
t.74
4.92
7.68
7.18
6.40
3.96
1 .74
3.12
2 .30
0 .02
1.29
2.17
3.40
3 .08
4.00
4.01
2.03
2.35
5.72
2.29
1.36
2.82
1 .97
3,.33
1.85
1 .39
2 .64
4.91
7.25
5.79
6.60
7.01
2.73
MEAN" 1.89 2.13 4.07 6.17 7.11 4.57 3.60 3.26
STO. DEV.s 0.47 0.95 1.66 1.66 2.09 2.06 1.88 1.83
GENERAL MEAN, ALL DEPTHS AND TREATMENTS* 4.10 MMHOS/CM
TRICKLE-IRRIGATED PLOTS
T
T
T
T
T
T
T
T
T
T
T
IR
2^
fft
I*
4C
5R
ft
6C
1.22
1.37
1.05
2.15
1. 40
3.25
1.26
2.45
1.58
3.53
1.19
2.44
1.17
2.14
1.23
1.69
1.54
2.91
1.44
1.65
2.21
2.34
1.28
2.06
1.45
1.71
1.74
1.65
2.58
3.22
1.82
1.94
1.67
1.88
1.37
2.30
2.00
2.29
1.40
2.35
1.91
3.58
5.14
3.77
1.73
2.19
1.97
2.01
2.03
2.52
2.38
2.47
2.20
2.67
5.C7
4.28
3.15
2.53
2.62
3.26
2.28
2.56
2.69
2.74
3.56
2.95
5.55
4.62
5.14
4.11
3.00
3.39
1.56
2.02
2.17
2.26
3.53
2.96
5.17
3,09
4.84
2.71
2.23
3.78
1.81
1.45
3.03
3.72
2.79
3.00
1.91
1.90
3.39
2.5B
2.52
2.28
ME4N- 1.91 1.80 1.94 2.53 2.93 3.55
STO. D6V.= 0.85 0.53 0.52 1.08 0.90 1.07
GENERAL MEAN, ALL DEPTHS AND TREATMENTS* 2.53 MMHOS/CM
3.03
1.13
2.53
3.69
110
-------
Appendix Table 4. ECe VALUES (mmhos/cm) FOR SATURATION EXTRACTS OF
SOIL SAMPLES FROM SURFACE AND TRICKLE-IRRIGATED PLOTS CDEC. 1973)
"R" AND "C" FOLLOWING TRICKLE PLOT NUMBERS DESIGNATE "ON THE
ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PLOT MO.
p I
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
PI 2
PI 3
P15
P16
P17
Pie
P20
P21
P22
P23
P24
P25
P2A
P27
P29
P30
(CM)
0-20 20-40 40-60 60-80 80-1CO 100-120
SURFACE-IRPIG/.TEO PLOTS
120-140 140-160
1.20
1.78
2.92
1.75
1.08
1.06
1. 70
1.88
2.12
3. 04
1-98
2.44
C.81
1.86
1.72
2.C2
2.30
2.58
1,96
1.46
1.40
2.00
3.52
3. 70
2.46
1.66
2.20
1.88
2.22
2.46
1.00
1.68
2.58
2.24
2.06
3.45
3.12
2.56
3.00
2.-+0
2.20
1.74
2.88
4.84
3.80
1.88
1.74
1.50
2.16
4.50
4.44
3.18
1.54
2.80
3.98
6.64
5.86
5.12
2.08
3.68
4.06
4.50
5.92
7.30
7.94
6.91
4.31
3.54
5.76
5.52
5.70
6.56
3.40
1.84
2.36
3.80
4.78
4.88
5.96
3.72
3.48
6.5?
£.92
6.32
5.8P
5.88
5.48
6.76
6.78
6.54
6.">e
7.76
7.26
4.72
5.00
6.C4
7.20
6.56
7.26
4.12
2.96
2.32
8.48
5.64
5.08
6.38
7.02
5.92
6.20
3.52
5.56
2.16
2.58
5.80
8.40
7.80
5.90
6.26
5.72
6.48
4.78
5.20
3.82
6. =6
4.52
7.50
3.52
2.12
3.14
2.02
5.64
4.70
5.50
8.30
E.64
2.56
2.22
2.66
1.28
1.06
2.08
2.78
3.80
3.20
4.44
2.34
3.72
1.22
2.C8
2.02
3.24
2.42
3176
3.44
2.26
2.24
3.08
5.54
4.90
6.26
8.47
6.56
1.50
2.62
2.32
1.16
0.98
2.00
2.16
2.36
4.26
3.24
2.25
3.52
1.14
1.96
1.42
2.C8
2.22
1.68
3.42
1.68
1.82
1.92
5.80
4.68
2.08
6.54
3.64
2.32
2.56
2.22
1 .30
0.90
1 .60
2.58
1.88
3.74
1 -98
6.43
3.16
1 .82
1.96
1.12
1.78
1.92
1 .68
1.40
1.10
0.84
1 .50
6.88
3.50
1.22
6.98
2.62
MEAN- 2.06 2.63 4.81 6.05 5.30 3.33 2.62 2.48
STO. OEV.* 0.73 0.57 1.58 1.31 1.95 1.78 1.38 1.71
GENERAL KE/N, ALL DEPTHS AND TREATMENTS' 3.66 MMHCS/CM
TRICKLE-IRRIGATED PLOTS
T
T
T
T
T
T
T
T
T
T
1R
1C
2ft
2C
3R
3C
4 R
4C
5R
5C
6R
6C
2.42
1.80
2.G8
C.62
1.42
2.20
1.56
2.26
1.38
1.62
1.80
1.62
1.44
1.94
2.10
1.56
1.76
2.42
1.96
2.36
1.70
1,70
2.44
2.0C
2.00
2.62
1.86
1.76
1.46
2.38
2.40
3.14
1.94
2.58
5.66
2.90
3.58
3.60
2.80
2.86
2.42
2.44
3.04
3.72
2.80
2.66
5.00
3.02
2.66
4.24
2.78
2.36
2.34
3.04
3.10
2.42
3.38
2.38
6.18
6.84
2.84
3.78
2.84
3. 16
1.74
1.70
4.08
3.02
2.24
2.24
6.32
5.64
3.08
1.22
1.64
1.92
1.00
0.84
1.34
1.70
2.26
2.18
3.82
3.96
1.36
1.76
0.42
0.46
1.60
2.42
0.76
1.58
1.06
0.72
2.54
3.56
MEAN= 1.73 1.95 2.56 3.16 3.48 3.30 2.08 1.52
STO. DEV.= 0.49 0.33 1.09 0.72 1.52 1.45 1.04 0.95
GENERAL KE/Nt ALL CEPTHS AND TREATMENTS* 2.47 MHHCS/CM
111
-------
Appendix Table 5. ECe VALUES (mmtios/cm) FOR SATURATION EXTRACTS OF
SOIL SAMPLES FROM SURFACE AND TRICKLE-IRRIGATED PLOTS (DEC. 1974)
"R" AND "C" FOLLOWING TRICKLE PLOT NUMBERS DESIGNATE "ON THE
ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PLOT MO,
0 I
P 2
0 3
P 5
0 6
P 7
8
9
P10
PI I
P12
PI 3
P15
P16
on
PI 8
P20
P2l
P22
P23
P24
P25
P26
P27
02?
P30
DEPTH
0-20 20-40 40-60 60-80 80-100 100-120
SUPPACF-IPRIGATED PLOTS
120-140 140-160
1.51
2.60
1.71
2.15
1.96
1.61
1.52
1.J2
2.24
2.S7
3.14
3.54
1.S6
3.61
2.62
1.^6
3.21
1.77
5.33
1.59
1.7L
1.9?
3.51
4.71
2.44
1.61
2.09
2.75
4.31
3.73
3.30
3.30
2.99
3.71
2.78
4.30
4.53
4.23
5.08
2.84
4. 1 5
5.30 -
4.31
4.9?
4.11
3.14
2.39
3.03
4.57
4.95
6.63
5.39
3.61
4.90
4.74
5.79
7.52
5.61
6.08
4.54
6.3fr
4.51
5.76
5.50
5.67
7.54
4.45
^.38
4.55
6.04
6.45
5.45
4.87
4.27
4.95
4.P2
5.82
6.64
6.46
3.84
5.94
6.69
7.64
7.96
8.82
6.46
5.16
9.10
6.10
7.08
6. SO
6.93
7.79
6.19
5.97
6.76
7.55
7.68
6.95
5.50
3.85
3. HP
5.16
6.57
6.17
7.37
6.36
7.25
7.93
2.11
5.79
4.33
2.61
7.24
7.33
6.85
6.C8
7.32
5.48
6.96
5.50
ft. 68
4.54
6.56
5.25
6.30
4. 10
3.54
3.21
4.64
6.34
5.61
8.06
7.0C
7.64
2.38
1.90
2. P.I
1.43
1.15
4.70
2.33
7.00
3.03
5.41
2.76
3.71
1.32
6.98
2.65
4.41
2.27
2:72
3.28
3.02
2.53
2.73
6. 61
5.39
fc.76
7.09
3.55
1.30
1.66
1.51
1,58
1.10
1.73
1.S5
2.52
2.34
1.87
2.00
5.04
1.21
8.90
1.52
3.65
2. 42
1.75
2.76
2.81
2.81
1.8^
6.48
5.«6
2.C8
3.77
1.61
1.19
1.43
2 .83
2.10
1 .03
1.59
2.34
2.19
2.10
1 .44
2.24
4.28
1 .21
2.49
1.42
2,15
1 .88
1,36
1 .5.4
2.68
0.91
0.68
6.34
3 .86
1.41
2 -92
1.45
2.47 4.05 5.50 6.65 5.74 3.70 2.74 2.11
STD. 0(=V.= 1.03 1.01 0.97 1.25 1.64 1.88 1.8* 1.20
GENERAL MEAN, ALL DEPTHS AND TREATMENTS" 4.12 MMHOS/CM
TRICKLE-IRRIGATED PLOTS
T
T
T
T
T
T
T
T
T
T
Iff
1C
2R
§CR
3C
4R
&
65CR
60
1.23
2.08
1.54
2.57
1.38
2.03
1.80
3.56
0.88
1.82
1.23
2.67
1.49
2.58
2.21
2.87
1.62
2.84
I. 10
4.51
1.14
3.02
2.21
3.29
2.13
2.98
3.10
2.82
1.88
2.64
2.30
4.65
1.31
3.58
3.05
5.80
3.83
7.80
4.46
2.58
2.99
2.54
3.R5
5.19
2.2G
3.48
4. 69
5.17
6.00
5.82
5.38
4.35
2.62
3.55
4.97
5.87
3.61
4.64
6.23
8.86
5.95
5. 13
5.46
4.89
3.67
4. 12
4.92
5.16
4. 24
5.27
7.04
7.39
5.55
4.46
5.46
3.73
2.90
2.12
5.68
4.03
3.41
3.59
6.17
6.50
I'.ll
2 3fl
f. • JO
1.77
1.14
fc • JL *T
Io -i
* o y
2.75
1.65
2 .37
2.87
5 1 96
MEAN- 1.90 2.41 3.02 4.06 5.16 5.27
STD. 06V.« C.75 0.99 1.22 1.55 1.62 1.10
GENERAL MEAN. ALL DEPTHS AND TREATMENTS* 3.63 WMHOS/CM
4.47
1.39
2.77
1.47
112
-------
Appendix Table 6. ECe VALUES (pmtlos/cm) FOR SATURATION EXTRACTS OF SOIL
SAMPLES TAKEN OUTSIDE OF SURFACE AND TRICKLE-IRRIGATED PLOTS (DEC.
1974). "E" AND "W" FOLLOWING PLOT NUMBERS DESIGNATE "EAST OF
PLOT" AND "WEST OF PLOT," RESPECTIVELY
DEPTH
-------
Appendix Table 7. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 0-20 cm (MAY 1973). "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PL* TK
° 1 1 '2
f 2 III
P 3 132
P 5 121
P 6 L31
P 7 U3
P 8 123
P 9 113
P10 112
Pll 232
P12 213
0 13 233
Pit ill
P15 22?
Plfc 231
P17 223
P18 ?12
P20 221
P21 331
P22 333
P23 332
P24 312
P2"5 321
P26 313
P27 323
P 29 311
P30 322
T 1 K 121
TIC 1?2
T 2 R 221
T 2 C 222
T 3 R 311
T 3 C 312
T 4 ft. Ill
T 4 C 112
T 5 R 211
T 5 C 212
T 6 R 321
T 6 C 322
h£i<.\' =
DEPTH
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-2C
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
0-20
D«TE
5/73
5/73
5/73
5/73
!>/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
3/73
5/73
•5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/T3
5/73
b/73
STANDARD DEVIATION'
ECX103
1.24
1.57
1.81
1.01
1.54
1.06
1.64
2.05
1 .68
2.08
2.42
2.66
1.63
1.73
1.68
2.29
1.98
1.67
1.96
1.77
1.76
3.13
2.26
2.61
1.53
1.79
2.21
1.22
1.37
1 .05
2.15
1.40
3.25
1.26
2.45
1.5S
3.53
I. 19
2.44
1.90
0.60
PH
6.2
6,2
6.0
6.8
6.4
6.3
6.2
6.3
6.4
6.2
6.3
6.2
6.6
6.4
6.3
6.4
6.2
6.0
6.8
6.8
6.3
6.2
6.2
6.3
6.2
6.2
6.4
6.2
6.5
6.4
6.2
6.6
6.1
t.6
6.1
6.4
6.*
6.1
5.6
6.3
0.2
TOTL CAT
17.44
21.96
20.65
12.60
20.79
13.63
21.66
28.00
22.08
24.41
32.48
37.8*
21.59
21.55
23.55
30.8*
23.68
20 .64
28.65
23.22
22.99
36.09
2P.35
34.60
23.15
23.64
30.00
18.29
20.71
15.72
29.15
20.52
40.53
18.25
32.60
21.75
41.94
15.46
33.13
24. 9P
7.22
TOTL AM
17.60
24.06
20.65
13.84
18.85
13.76
21.71
29.19
19.45
25.24
35.73
36.47
18.89
23. 18
23.99
30.63
23.99
21.23
28.01
25.01
24.43
37.63
25.70
33.23
23.40
22.94
27.33
18.86
1 8. 88
13.76
27.9?
17. 89
37.31
16.75
2S. 57
20.34
39.24
14.02
31.49
24.39
7.02
AVG CAT
17.52
23.01
20.65
13.22
19.82
13.69
21.68
28.59
20.76
24.82
34.1 0
37.15
20.24
22.36
23.77
30.73
23.83
20.93
28.33
24.1 1
23.71
36.86
27.02
33.91
23.27
23.29
26.69
IB. 5 7
19.79
14.74
28.53
19.20
38.92
17.50
30.53
21. Qt
40.59
14.74
32.31
2*. 6 8
7.07
AN CA
6.26
8.51
8.34
4.28
8.98
4.43
8.87
12.89
7.58
9.57
14.92
15.83
8.55
S.03
9.33
14.46
H.77
7.62
13.76
11.11
8.76
12.30
10.39
14.29
8.33
9,77
12.46
5.5?
6.31
5.76
11.31
7.19
19.60
6.62
13.15
7. SO
18.82
4.85
13.15
9.96
3.75
"
-------
Appendix Table 8. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 20-40 cm (MAY 1973). "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PI#
Tft.
DEPTH D-TF ECX103 PH
TOTL CAT TOIL AN AVG CAT «N CA
NA
CL
Ct>3 HC03 S04
NO 3
Ul
P I
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P14
P15
P16
P17
P13
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
TIC
T 2R
T 2 C
T 3 R
T 3 C
T 4ft
T 4t
T 5R
T 5 C.
T 6 R
T 6 C
*«»•-
STAKO-
122
111
132
121
131
133
123
113
112
232
213
233
211
222
231
223
212
221
331
333
332
312
321
313
323
311
322
121
122
221
222
311
312
111
112
211
212
321
322
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-40
20-4C
20-40
20-40
VI AT UN =
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/T3
5/73
5/73
5/73
5/73
5/73
1.29
2.32
2.54
1.26
1.30
1.32
1.53
1.92
1.96
2.85
1.65
2.36
1.39
2.08
1.60
2.44
2.77
1.60
1.44
1.38
2.01
5.80
2.78
3.50
1.63
1.98
2.91
1.17
2.14
1.23
1.69
1.54
2.91
1.44
1.65
2.21
2.34
1.28
2.06
2,03
0.85
6.2
6.3
6.1
6.7
6.3
6.4
6.4
6.2
6.0
6.1
6.3
6.8
6.4
6.3
6.2
6.4
6.1
6.0
6.6
6.5
6.3
6.1
6.0
6.2
6,2
6.2
' t.4
6.6
6.6
6.0
6.5
6.0
6.1
6.2
6.2
6.0
6.2
6.3
6.2
6.3
0.2
18. 2
-------
Appendix Table 9. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 40-60 cm (MAY 1973). "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
OcPTH OATF EC X103
PH
TOTL CAT TOTL AN AVG CAT «N CA
CL
CP3 HC03
SO*
NO 3
P 1 122
P 2 111
P 3 132
P ^ 121
P 6 131
P 7 133
P8 123
P 9 113
P 10 112
Pll 232
P12 213
P13 233
P14 211
P15 222
P16 231
P17 223
Pia 212
P20 221
P21 331
P22 333
P23 332
P24 312
P25 321
P26 313
P2T 321
P 2° 311
P30 322
T 1R 121
T 1C 122
T 2fl 221
T 2 C 222
T 3 R 311
T 3C 312
T 4 fi 111
T 4C 112
T 5 R 211
T 5 C 212
T 6R 321
T 6 C 322
MEAN*
+0-60
40-60
40-60
+0-60
iO-f.0
40-60
40-60
40-60
40-60
40-60
40-60
40-60
40-60
40-6C
40-60
40-60
40-60
40-60
40-60
40-60
40-60
+0-60
40-60
40-60
+ 0-6 C
40-60
40-60
40-60
40-60
+ 0-60
40-60
40-60
+0-0 0
40-60
40-60
40-60
40-60
+0-60
40-60
5/73
5/7i
5/73
5/73
5/73
5/73
?/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
f/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
STANDARD DFV!ATI0N=
3.95
4.34
4.12
1.77
1.67
2.19
2.70
2.84
4.19
7.33
5.17
7.45
4.40
4.03
1.36
4.73
5.87
4.74
1.81
2.12
4.23
5.23
6.65
4.06
5.08
3.34
3.58
1.45
1.71
1.74
1.65
2.58
3.22
1.82
1.94
1.67
1.88
1.37
2.30
3.4?
1.72
5.9
6.0
5.9
6.2
6.4
5.9
6.2
6.1
5.9
6.0
6.2
6. t>
6.2
6.0
6.2
6.2
6.0
6.1
6.2
6.3
6.2
6.1
6.2
6.3
t. 1
6.1
6.4
6.1
6.4
6.6
6.3
6.3
6.1
6.2
5.8
6.1
(>.2
6.0
fc.2
6.2
0.2
5a.2h
74.63
57.47
23.75
18.98
24.35
35.18
38.05
59.49
110.16
34.36
103.57
66.23
58.85
14.51
69.73
86.74
69.42
22.89
26.48
59.87
76.13
96.33
48.35
77.56
55.17
48.09
21.27
23.93
22.82
21.71
35.47
45.58
2B.1P
28.56
18.93
23.56
17. 1A
30.25
48.26
26.71
57.96
67.45
50.63
ZO. 74
17.28
24.48
34.15
33.12
57.36
106. 89
77.08
= 6.63
67.07
53.54
15.73
69.68
90.97
78.50
22. It
29.78
55.74
76.75
95.0"}
51.59
79.95
48.61
49.3X
19.98
20.98
22.27
19.94
34.45
40.34
26.27
25.24
20.05
23.22
15.9*
28. 8fi
46.88
2C-.61
58.11
71.04
54.05
22.24
18.13
24.41
34.66
35.58
58.67
109.52
80.72
100.10
66.65
56.19
15.12
69.70
88.85
73.96
22.51
28.13
57.80
76. 4<*
95.70
49.97
78.75
51.89
48.70
20.62
22.45
22.54
20.82
34.96
42.96
27.22
26.90
19.49
23.39
16.55
29.56
47.57
26.61
26.19
34.36
24.89
8.46
6.42
B.'tb
14.51
13.91
25.78
48.86
+0.17
31.78
29.70
24.28
2.33
35.70
45.14
34.49
9.03
12.18
29.34
40.45
40.67
20.57
40.67
22.41
18. 7-+
6.12
9.30
8.26
6.88
13.69
21.65
10.38
9.21
7.53
9.59
4.22
11.80
20.72
13.27
7.93
10.70
6.77
2.65
1.64
2.35
3.54
3.55
6.21
13.68
13.90
21.63
8.96
8.04
1.46
9.41
11.21
8.80
2.71
3.12
7.26
9.72
13.71
6.39
9.51
6.38
5.31
3.26
2.91
3.37
3.09
4.77
5.74
3.48
3.93
1.84
2.94
2.55
3.54
6.33
4.34
23.15
28.28
24.69
11.96
10.23
12.95
16.36
19.68
26.37
46.28
29.04
48.51
26.52
25.37
10.26
24.20
29.01
24,38
10.35
10.11
22.17
24.26
40.18
20.24
25.93
25.21
22.t>7
11.09
10.87
10.49
10.90
16.26
17.19
13.76
14.76
B.
-------
Appendix Table 10. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 60-80 cm (MAY 1973). "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PLM
TR
OSPTH
?•: XI03
PH
TQTL CAT TOTL *N AVG CAT AN CA
CL
C03
HC03 SC4
NOB
F 1 122
P 2 111
P 3 1 32
P 5 121
P 6 131
P 7 133
P 8 123
P 9 113
P10 112
Pll 212
P12 213
F-13 233
"14 211
P15 222
P16 231
P17 223
P18 212
P20 221
P21 331
c^2 333
»23 3?2
P24 312
P25 321
P26 313
P27 323
P29 311
P30 3^2
T 1R 121
T 1C. 122
T 2R 221
T 2 C 222
T 3 R 311
T 3C 112
T 4 R 111
T t C i 12
T 5 R 211
T 5 C 212
T 6 R 321
T 6 C 322
M£"*ii =
S TAN DAR D
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
60-80
50-80
60-80
60-80
50-80
60-80
60-8U
60-80
60-80
60-80
60-80
60-80
60-80
'.0-80
60-80
60-80
60-80
60-80
60-80
60-80
60-PO
60-80
60-60
60-80
60-80
r.o-qo
DEVIATION^
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
E/73
5/73
5/73
5/73
•V73
5/73
5/73
5'/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5.15
6.30
7.21
3.59
5.28
5.25
6.66
7.73
7.=,«
9.29
7.33
6.67
6.15
7.72
3.24
6.91
6.89
5.82
3.05
3.01
3.83
7.03
6.83
6,8?
8.54
6.42
5.51
2,00
2.29
1.40
2.35
1.91
3.58
5.14
3.77
1.73
2.19
1,97
2.01
5.05
2.26
5.8
6.1
5.8
6.0
6.1
6.0
6.0
6.1
5.3
6.0
6.2
6.. I
6.0
6.0
6.4
6.0
6,1
6.2
6.4
6.6
6.2
6.0
6.2
6.4
6.0
6.1
6.2
6.1
5.c
6.1
6.2
6.2
6.1
5.9
6.1
6.0
6.0
6.2
6.0
6.1
0.2
70.92
103.12
108.03
50.87
88.1fc
83.59
<35.79
136.61
96.06
124.05
101.44
96.24
93.37
104.18
41.34
109.15
106.60
86.72
37.62
39.12
47.91
105.68
107.24
108.72
109. IP
100.94
91.64
26.11
34.72
21.51
32.28
25.76
43.40
34.95
48.21
24.30
29.71
25.27
29.95
73.60
34.88
64.57
98.54
108.91
47.97
81.42
79.3*
111.41
125.51
99.44
127.88
112.74
99.63
86.47
9fl.70
38.33
106.15
106.57
84.67
38.72
37.15
47.63
108.24
110.09
105.56
109.00
95.20
84.96
24.99
34.42
21.39
28.43
22.85
37.85
79.31
46.57
25.71
2«.26
24.01
28.33
72.21
35.40
67.74
100.83
108.47
49.42
84. 79
80.96
103.60
131.06
97.75
125.96
107.09
97.96
89.9?
101.44
39.83
107.65
106.58
85.69
38.17
38.13
47.77
106.96
108.66
107.14
109.09
98.07
88.30
25.55
34.57
21.45
30.38
24.30
40.62
82.13
47.39
25.00
28.98
24.64
29.14
72.90
35.06
26.38
45.47
51.97
25.10
50.13
40.37
47.55
75.39
35.45
40.12
34.89
34.08
32.43
41,10
17.10
58.19
52.37
39.81
17.24
19.28
19.07
41.93
50.80
52.39
35.35
45.85
41.53
10.00
13.81
7.96
13.10
7.71
20.55
44.82
21.07
8.79
10.38
9.42
9. 43
32.02
17.19
9.35
15.41
13.31
6.82
11.60
10. 33
H . 9 7
16.97
1+.15
19.05
17.30
14.35
15.77
17.66
5.17
14.85
14.07
11.06
4.18
4.56
6.09
18.46
13.20
1+.9*
20.34
13.00
11.01
3.24
5.20
2.59
4.41
4.15
5.07
11.06
5.37
2.30
3.33
2.67
4. 17
10.28
5.55
34.45
40.70
+ 1.45
18.18
25.35
31.01
33.17
42.57
45.06
63.44
47.87
46.66
44. GO
43. PI
18.37
34.65
38.87
34.64
15. IB
13.96
21.67
43.34
41.74
40.15
51.75
40.82
37.79
12.18
14.95
10.25
14.01
13.20
16.78
28.22
2C.?9
12.69
15.42
12.61
15. t?
30.20
14.09
0.74
1.54
1.30
0.77
i.oe
0.88
1.10
1.6B
1.40
1.44
1.38
1.15
1.17
1.61
0.70
1.26
1.29
1.21
1.02
1.32
1.08
l.?5
1.50
1.24
1.74
1.27
1 .31
0.69
0.76
0.71
0.76
0.70
I. 00
0.85
0.78
0.52
0.58
0.57
0.62
I. OS
0.37
7.54
9.92
6.17
2.01
2.05
5.47
3.12
3.82
4.11
16.70
2.92
13.32
4.32
6.43
2.04
5.83
7.43
2.54
5.58
6.93
7.22
10.00
11.31
9.58
3.20
5.59
4.91
3.84
6.57
3.00
5.97
3.27
8.50
7.73
9.64
3.46
5.09
3.92
5.00
6.18
3.23
0.0
0.0
0.0
0.0
0.0
0,0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0'
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
5.00
6. SO
5.80
5.40
b.OO
4.20
8.80
13.00
7.20
7.40
9.20
9.20
5.20
8.00
8.60
7.80
6.20
a. 60
1C. 00
8.20
10.20
16.80
8.20
8.60
11.00
10.80
11.00
8.40
7.80
10.20
5.80
8.20
5.80
5.60
7.40
9.00
6.40
6.20
6.00
8.05
2.44
50.70
81.00
95.75
40.45
73.37
68.14
99.46
108.69
88.04
101.62
100.62
75.95
76.95
83.74
27.69
90.32
91.80
73.53
19.64
20.73
29.64
81.44
89.37
87.38
89.72
78.81
69.05
12.40
14.02
7.24
15.20
10.42
20.00
63.37
25.80
10.90
11.98
12.89
15.20
56.75
34.49
1.33
0.82
1.19
0.11
0.0
0.53
0.03
0.0
0.09
2.16
0.0
1.21
0.0
0.53
0.0
2.20
1.14
0.0
3.50
1.24
0.57
0.0
1.21
0.0
0.08
0.0
0.0
0.35
6.03
0.95
1.51
0.96
3.55
2.6 1
3.73
2.35
+ .79
1.00
2.13
1.23
1.46
-------
Appendix Table 11. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 80-100 cm (MAY 1973). "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
fin
TR
DEPTH DATE ECX103
00
TOIL CAT TOTL AM AVC CAT AN C*
MG
N*,
CL
003
HC03 S04
N03
P 1
p 2
r n
P 5
9 6
P 7
f 8
P 9
PK>
Pll
P12
P13
P1A
P15
F16
P17
PIS
P20
»21
P22
P23
P24
P25
P26
r?7
p?9
P30
T 1R
TIC.
T 2«
T 2C
T 3fi
T 3C
T 4R
T 4C
T 5 R
T 5 C
T A S
T ft C
f*EAN =
S TAN- C -
122
111
l'<2
121
131
1 33
123
113
112
232
213
233
211
22?
211
221
21?
221
m
333
i?2
312
321
313
323
311
i22
121
122
221
222
311
312
111
112
211
212
321
322
S3Q OcV
flC-100
80-100
SC-100
ac-100
8C-100
80-100
BC- 100
80-100
80-1CO
BC-100
80-100
8C-100
to- loo
0-100
8C-100
80-100
80-100
33-100
dC-100
3C-1;>0
6C-100
80-100
80-100
80-100
80-i no
80-100
fiO-100
HC-100
30-100
8C-100
80- 100
80-100
80-10C
80-100
SC-100
80-100
80-^100
flfl-100
a o-i uo
I A T I v*C.'=
= /7H
S/73
5/73
5/73
•5/73
5/73
5/73
5/73
5/73
5/71
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/M
c/73
5/73
5/73
5/73
5/7''
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
=7/73
5/73
6.97
a, 21
3.36
.1.12
4.95
5,50
9.40
8.56
S.63
11.37
7.31
6.65
6.60
6.73
7.10
8.72
8.82
7.38
2.07
3.46
4.27
6.19
5.25
O.C2
S.32
3.23
3.65
2.03
2.52
2.38
2.47
2.23
2.67
5.07
4.28
3.15
2.53
2.62
3.26
5.82
2.66
6.0
5.8
5.7
6.0
f.2
t.O
6.0
6.0
5.?
5.6
6.6
6.0
6.J
6.2
6.1
6.0
K,a
6.2
6.6
6.6
6.2
6. I
6.1
6.0
6.0
6.2
6.2
6.3
fe. I
fr.4
6.8
6.0
6.2
5.8
5.9
6.0
6.0
6.1
6.1
6.1
0.3
93.<33
129.89
113.36
39.70
7o.8C
7B.64
122. 93
122. "5
115.12
155.42
122.19
131.52
98.75
96.09
109.26
116.96
123.10
113.11
33.70
44.95
56.28
95.23
75.79
126.19
109.87
135,42
133.77
30.37
36.02
30.80
33.11
28.02
32.16
81.07
65.21
45.56
30.84
35.44
45.76
83.46
39.65
83.93
114.48
113.58
39.36
6°. 33
76.91
123.60
127.64
113.02
175.73
119.99
126.46
98.83
89.74
105.53
114.69
138.07
117.34
31.39
41.4*
52. 80
R4.ll
66. 33
130.72
109.88
130. 81
127.70
28.52
33.54
34.61
32.94
24.43
29.99
73.50
5S.63
40.91
2fi. 28
34.10
43.33
81.70
41.50
91.43
122. la
113.4?
39.53
73.06
77.81
125.71
125.24
114.07
165.60
121.09
128.99
93.79
92.91
107.39
115.82
130.58
115.22
32.54
+3.19
54.54
84.67
71,06
128.45
109 .,17
133.11
130.73
29.44
34.78
32.70
33.32
26.22
31.07
77.28
61.92
43.23
29.56
34.77
44.57
82.58
+0.+6
35. 7S
67.56
43.29
13.95
36.11
35.14
41.36
42.89
35.84
49.63
54.12
25.66
33.83
39.11
56.06
36.64
53.56
48.72
13.49
23.49
25.61
30.71
31.03
59.76
40.67
63.53
39.21
11.62
16.21
11.81
12.69
10.03
11.53
37.14
27.28
17.28
11.44
11.53
17,58
32.64
16. +0
11.46
17.98
17.67
4.59
10.51
10.02
16. OS
13.20
15.10
20.96
17.42
23.91
14.18
10.52
17.01
20.68
17.05
14.35
3.94
5.06
6.51
9.51
= .84
16.84
13.37
17.45
22.93
4.04
3.76
3.98
3.83
2.«l
2.99
10. E7
8.25
5.92
3.01
+ .43
5.78
11.35
6.39
45.72
43. 10
51.09
20.59
2P.94
32. SO
63,
-------
Appendix Table 12. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 100-120 cm (MAY 1973) . "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PL"
P 1
P 2
P 3
P 5
P 6
P 7
P 8
(• 9
PIO
Pll
PI?
Fli
014
P15
P IA
PIT
P18
P20
P21
P22
023
P24
£ 2*"
P27
•••30
T IR
T 2C
T 3fi
T 3C
T 4R
T 4C
T 5R
T 5 C
T 6C
MEAN*
TR
122
111
132
121
131
133
123
113
112
232
233
211
222
223
212
221
333
332
312
321
313
323
311
322
in
122
221
222
311
312
111
112
211
212
322
STANDARD
DEPTH
loa-izo
1CO-12C
100-120
100-120
100-120
1C 0-120
1CO-120
1C d- 120
100-120
1CC-120
100-120
100-120
ioa-120
100-120
10C-12C
100-120
100-12 C
100-120
100-120
100-120
IOC-120
100-120
1CC-120
100-120
100-120
100-120
100-120
100-120
100-120
100-120
100-120
ICO- 120
100-120
100-120
100-120
100-120
100-120
100-120
DEVIATION*
DATE
5/73
5/73
5/73
5/73
5/T3
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/7J
5/73
5/"73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
ECX103
4.63
6.11
3.76
1.77
2*SO
3.06
8.08
3.B6
3.87
3.19
4.28
2.48
2.99
3.16
3.68
3.46
4.04
2.50
3.86
3.52
6.S6
6.52
6.57
5.78
8.49
6.78
2.28
2.56
2.69
2.74
3.56
2.95
5.55
4.62
5.14
1139
4.29
1.97
PH
6.3
5.9
6.0
6.2
6.0
t.l
6.0
5.9
5.9
6.0
6.4
6.2
6.2
6.3
6.1
6.2
6.1
6.3
6.2
6.6
6.1
5.8
6.2
6.0
6.0
6.1
6.2
6.4
6.3
6.2
6.0
6.1
6.0
5.8
6.0
6.0
6.0
6.2
6.1
0.2
TOIL CAT
62.92
97.86
43.19
20.89
18.69
34.31
i J3.91
117.33
51.31
50.75
39.56
58.36
30.95
37.72
37.51
44.77
42.71
52.05
30. 9C
51.93
44.90
96.93
89.47
96.61
83.73
113.99
90.95
31.95
38.43
39.53
39.21
45.62
35.70
78.77
63.07
77.20
54.58
47.53
58.57
28.57
TOIL AN
60.00
88.46
43.07
23,77
17.93
37.54
130.68
116.61
49.29
54.50
42. 18
52.31
30.04
40.51
3S.56
42.42
43.76
51.64
28.53
50.70
40.47
93.04
87.62
96.73
79.51
123.94
87.39
30.07
35.17
35.06
38.09
41.63
32.61
75.34
58.85
68.43
51.44
48.44
57.01
28.26
AVG C4T
61.46
93.17
43.13
22.33
18.31
35.92
132.29
116.97
50.30
52.62
40.87
55.33
30.49
39.11
38.03
43.59
43.23
51.84
29.71
51.31
42.68
94.98
88.54
96.67
81.62
118.96
89.17
31.01
36.80
38^65
43.62
34.15
77.05
60.96
72.81
53.01
47.98
57.79
28.36
AN CA
23.62
52.4/3
12,73
5 »29
12.50
57.17
38.86
18.51
15.61
12.85
17.37
7.54
9.69
14.46
18.06
13.68
19.38
12.07
28.99
19.73
37.04
30.94
40.67
30.54
39.21
35.48
13.85
16.40
16.44
16.64
17.97
13.42
38.03
28.11
34.56
25.57
19.96
22.94
12.59
MG
8.07
13.78
4.22
2.16
2.64
3.75
14.25
13.54
5.18
4.89
4.29
5.75
3.66
3.94
4.78
5.51
4.34
5.42
4.10
6.04
5.19
11.61
9.29
12.02
11.00
18.56
9.90
4.11
5.18
4.42
4.65
5.16
3.62
11.71
8.69
10.60
7.13
6.45
7.09
3.R8
UA
30.32
30.48
25.55
12.21
10.30
17.50
61.04
63.51
26.92
29.56
21.71
34.51
19.26
23.22
17.66
20.51
23.94
26.51
13.85
15.54
19.03
46.72
47.75
42.72
40. BO
54.55
44.33
13.33
16.10
17.95
17.29
21.78
17.66
28.23
25.53
30.99
21.12
20.24
27.64
13.53
K
0.91
1.12
0.69
0.33
0.46
0.56
1.45
1.42
0.70
0.69
0,71
0,73
0.49
0.87
0.61
0.69
0.75
0.74
0.88
1.36
0.95
1.56
1.49
1.20
1.39
1.67
1.24
0.66
0.75
0.72
0.63
0.71
1.00
0.80
0.74
1.05
0.76
0.88
0.90
0.33
CL
5.67
4.87
9.10
2.16
1.23
5.51
21.32
20.27
6.01
8.25
3.40
11.27
2.44
5.75
3.17
5.63
6.46
3.10
4.71
9.44
8.78
12.32
20.35
13.92
13.71
9.96
11.34
6.19
7.29
7.49
8.84
9.61
7.39
15.90
13.61
18.55
9.68
6.71
8.98
5.21
C03
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
HC03
6.60
6.00
6.20
7.00
5.40
5.40
8.20
7.15
5.52
10.60
7.80
5.60
3.80
6.20
6.40
5.20
5.60
6.20
6.60
12.80
8.80
15.80
10.40
10.80
8.40
13.40
7.00
8.40
8.40
7.00
7.40
5.80
5.40
5.80
4.80
5.40
5.40
8.00
7.39
2.55
S04
44.80
75.66
26.17
14.30
11.21
25.12
98.14
86.50
37.00
34.76
30.98
35.00
23.80
27.00
28.15
30.19
30.40
42.03
11.90
25.60
19.67
64.92
56.32
71.98
57.19
99.02
69.05
I8ll3
19.93
20.08
24,80
15ll2
50.11
36.45
39.87
3O.56
30.80
38.88
23.59
N03
2.93
1.95
1.60
0.31
0.09
1.51
3.02
2.69
0.76
0.89
0.0
0.44
0.0
1.56
0.84
1.40
1,30
0.3 1
5.32
§. 86
.22
0.0
0.55
oral
0.21
U56
0.0
0.71
1.35
0.64
1.77
1.42
4.70
3.53
3.99
4.61
5.80
2.93
1.76
1.61
-------
to
o
Appendix Table 13. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 120-140 cm (MAY 1973) . "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
Pl.lt
o 1
F ?
f 3
P 5
P 6
F 7
F R
F >
F10
Pll
PI?
F 13
?14
P15
P16
P17
P18
P20
P2I
P?>
P23
P24
P25
P26
P27
P29
P30
T 1«
T 1C
T 2R
T 2C
T 3R
T 3C
T tR
T 4C
T Sfl
T 5C
T 6R
T 6C
M&W.
TR
122
111
132
121
131
131
123
1 13
112
232
?I3
2'3
211
222
231
223
212
221
331
313
332
312
321
313
323
311
322
121
122
221
222
311
312
111
112
211
212
321
322
DEPTH
120-140
120-140
120-140
120-14C
120-140
120-140
120-1+C
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-ltO
120-140
12C-140
120-140
12C-140
12C-14)
12C-140
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-140
120-14C
120-140
120-140
120-140
120-140
120-140
120-140
DATE
5/73
5/73
b/73
5/73
5/73
•5/7 3
ii/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
b/73
5/73
5/73
5/73
5/73
*/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
S/73
5/73
5/73
5/73
5/73
STAN04RO OfV!ATICt* =
ECX103
2.24
6.51
2.61
0.83
2.27
2.50
3.S6
5.70
3.06
3.30
2.64
3.01
1.84
2.50
1.55
2.53
2,24
2.46
2.64
2.86
3.04
6.74
•*• ^2
7.68
7.18
6.40
3.96
1.56
2.02
2.17
2.26
3.53
2.56
5.17
3.09
4.84
2.71
2.23
3.76
3.42
1.69
PH
6.2
5.8
6.2
6.3
6.2
6.4
6.1
5.3
5.7
6.0
fc.O
6.4
fc. 3
6.2
6.0
b. 8
6.2
6. 1
6.2
6. V
6.1
5.8
6.0
6.1
fc.l
6.2
6.3
6.0
6.0
6.2
6.0
6.1
6.2
6.3
6.2
5.9
t.2
6.1
6.3
6.1
0.2
TQTL CAT
26.07
102.85
35.50
9.28
27.02
29.40
V9.16
78.15
35.98
40.03
26.40
36.36
22.37
29.42
18.34
31.03
26.31
27.64
32.62
34.68
37.16
93.07
65.84
122.68
114.98
S5.15
49.74
21.90
26.58
31.74
34.64
47.30
40.69
71.66
46.59
64.92
39.87
31.74
49.77
46.27
27.42
TCTL AN
27.39
92.38
37.17
9.62
29.26
26.00
50.55
S1.08
38.56
42.63
28.55
37.05
22.53
30.60
1S.+0
27,74
23.36
28.51
28.59
35.95
35.27
85.00
64.92
120.32
107.57
89.14
55.90
19.82
24.12
32.67
31.02
44.86
40.37
65.23
41.62
63.28
37.20
28.86
47.09
44.91
25.30
AVG CAT
26.73
97.61
36.33
9.45
28.14
27.70
49.85
79.61
37.27
41.33
27.47
36.70
22.45
30.01
18.87
29.39
24.83
28.07
30.60
35.31
36.21
89.03
65.3S
121.75
111.27
92.14
52.82
20.86
25.35
32.20
32.83
46.08
40.53
68.44
44.10
64.10
38.53
30.30
48.43
45.59
26.57
AN CA
7.05
55.00
8.77
2.20
11.00
7.89
14.98
28.36
9.61
11.78
6.75
8.11
5.16
6.78
4.94
10.06
6.36
6.78
13.16
1*.77
15. S4
35.43
25.07
57.91
51.98
32.68
17.95
7.43
9.60
12.28
11.41
20.41
14.86
35.25
18.70
28.48
17.24
13.07
22.35
17.63
13.85
MG
2.46
16.86
5.11
0.74
3.03
2.75
4.37
8.27
2.65
3.44
2.40
3.21
1.43
2.72
1.89
3.74
2.39
2.22
4.06
4.40
4.35
10.11
6.97
16.34
15.10
9.71
4.92
2.89
3.22
3.99
5.49
5.92
5.88
9.26
6.38
9.07
4.72
4.29
6.52
5.47
3.88
Hf
15.98
29.74
20.67
6.14
il:!7
29.04
40.38
23.03
24.10
16.54
24.45
15.36
19.26
11.08
16.56
16.99
18.14
14.46
13.68
15.93
46.03
32.63
46.71
46.02
51.38
26.07
11.07
13.20
14.95
17.16
20.11
19.08
26.15
20.74
26.30
17.13
13.63
19.95
22.32
10.83
K
0.58
1.25
0.95
0.20
0.48
0.49
0.77
1.14
0.69
0.71
0.71
0.59
0.42
0.66
0.43
0.67
0.57
0.50
0.94
1.83
0.94
1.50
1.17
1.72
1.86
1.38
O.RO
0.51
0.56
0.52
0.58
0.86
0.87
1.00
0.77
1.07
0.78
0.75
0.95
0.85
0.39
CL
3.12
6.92
6.12
I. 00
1.46
7.68
7.84
10.58
5.25
6.40
3.66
7.84
1.58
5.49
1.44
4.36
4.49
2.70
4.66
7.01
8.43
14.17
13.48
7.97
14.06
8.85
6.41
4.01
4.78
6.25
8.01
11.00
9.66
17.11
11.12
23.64
9.39
5.35
9.19
7.50
4.59
CJ3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
HCD3
5.60
6.60
3.80
3.60
5.60
3.60
7.40
7.60
7.00
7.80
7.00
6.00
6.20
5.00
5.40
5.80
5.20
4.40
4.60
15.00
7.80
9.40
fi.60
10.40
9.00
10.00
9.20
7.40
7.90
6.00
6.40
5.40
6.00
4.20
7.80
8.80
8.00
8.80
5.50
6.92
2.24
SD4
15.94
77.71
27.14
4.90
22.00
13.30
31.76
62.19
25.72
28.13
17.87
22.60
14.72
19.20
11.80
15.81
12.14
20.74
14.40
13.94
17.98
60.22
42.28
102.34
84.33
70.29
40.26
8. 16
10.80
IT.70
16.40
25.00
20.19
41.31
21.10
30.40
18.85
14.46
30.80
29.36
22.65
NO 3
2.73
1.15
5.11
0.12
0.20
1.22
3.55
0.71
0.59
0.30
0.02
0.41
0.03
0.91
0.76
1.77
1.53
0.67
4.93
0.0
1.06
1.21
0.56
0. 11
0.1B
0.0
0.03
0.25
0.64
2.72
0.21
3.46
4.52
2.61
1.60
0.44
0.96
0.25
1.60
1.13
1.28
-------
Appendix Table 14. COMPOSITION (meq/1) OF SATURATION EXTRACTS OF SOIL SAMPLES TAKEN FROM SURFACE
AND TRICKLE-IRRIGATED PLOTS AT A DEPTH OF 140-160 cm (MAY 1973) . "R" AND "C" FOLLOWING
TRICKLE PLOT NUMBERS DESIGNATE "ON THE ROW" AND "BETWEEN TWO ROWS," RESPECTIVELY
PL*
TR
DEPTH
DATE ECX103
PH
ts9
TOTL CAT TOTL AN AVG CAT AM CA
NA
CL
C03
HC03 SC4
NO 3
p 1
P 2
P 3
P 5
P 6
P 7
P 8
P 9
P10
Pll
P12
P13
P 14
P15
P16
P17
P1R
P20
P21
P22
P23
P24
P25
P26
P27
P29
P30
n?
T 2R
T 2C
T 3R
T 3C
T 4ft
T 5R
T 6R
T 6C
MF«N-
ST*.* n
122
111
132
121
131
133
123
113
112
232
213
233
211
222
231
223
212
221
331
333
332
312
321
313
323
311
322
Hi
221
222
311
312
111
211
321
322
A3D
140— loO
140-16C
14C-160
140-160
lHO-160
140-160
14C-i6C
140-160
140-160
14C-160
140-ltO
14C-160
1 40- 16 C
140-160
14C-160
140-160
140-160
140-160
140-160
14C-160
140-160
14C-160
140-160
140-160
140-160
140-160
140-160
140-160
140-160
140-160
140-160
14C-160
140-160
140-160
140-160
140-160
140-160
DEVIATION*
5/7'
5/73
r> / 7 3
5/73
5/7 3
5/73
r-/73
5/73
5/73
5/73
5/73
r./73
5/73
5/73
5/71
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
5/73
1.74
3-12
2.30
O.B2
1 .29
2.17
3.40
3.08
4.00
4.01
2.03
2.35
5.72
2.29
1.36
2.82
1.S7
3.33
1.85
1.39
2.64
4.91
7.25
5.79
6.60
7.01
2.73
1.81
1.45
3.03
3* 72
2« 79
3.00
1.91
3.39
2.52
2.2*
3.08
1.62
6.0
5.8
6.2
6.3
6.3
fr.2
6.0
6.0
5.8
6.0
fc.2
6.2
5. S
6.1
e.2
6. 1
6.0
5.8
6.1
6.'
6.2
6.2
6.1
6.1
6.2
6.0
6.4
6.2
6.3
6.0
6.4
6.0
6.1
6.2
6.2
6.0
6.1
6.1
0.2
19.94
42.50
20.65
9.39
15.02
25.18
42.89
35.69
51.65
55.55
24.21
2P.35
82.81
26.33
15.53
34. 7C
23.56
45.74
20.47
16.22
33.31
64,99
117.55
85.98
98.01
104.48
33.07
25.47
21.51
45.32
57.68
42.7-6
35.21
28,68
45.57
32.15
30.47
41.58
26.23
21.26
39.37
21.99
9.68
14.75
26.22
38.89
40.88
52.38
57.87
24.69
25.75
79.48
28.08
15.93
31.83
26.02
**3 • 4-1
23.39
14.97
34.02
60. 16
107.93
82.32
97.35
95.41
31.78
23.98
19.45
42.14
51.71
40.66
35.97
25.13
40.55
31.66
27.82
40.13
24.35
20.60
40.93
21.32
9.53
14.68
25.70
40.89
38.28
52.01
56.71
24.45
27.05
81.14
27.20
15.73
33.29
24.79
44.57
21.93
15.59
33.66
62.57
112.76
84.15
97.68
99.94
32.42
24.72
20.48
43.73
54.69
41.71
35.59
26.90
43.06
31.90
29.14
40.86
25.26
4 9C-
IB. 53
6.58
2.15
4.23
6.40
16.75
10.58
2 5»TO
5.04
5.71
40.86
5.54
3.75
12.71
6.45
16.64
7.03
7.00
13.43
20.55
57.78
39.02
41.94
36.99
10.07
10.60
7.61
18.77
23.88
13.89
15.70
9.48
16.25
14.28
11.44
15.86
12.72
7 0 I
5.97
2.39
0.35
1.49
2.20
4.29
2.85
4.00
5.77
2.10
1.90
9.23
1.93
1.39
3.61
2.56
4.45
2.35
1.68
3.97
6.34
13.89
10.34
12.49
10.79
3.01
2.93
2.66
6.47
7.75
5.50
4.44
4.33
5.79
4.00
3.86
4.64
3.20
12.40
17.19
11.15
6.18
8.92
16.12
2C.99
21.57
28.44
23.16
16.54
20.15
31.60
18,23
10.01
17.51
13.91
23.90
10.41
6.96
14.?8
36.85
+4.33
35.25
41.73
55.00
19,33
11.33
10.72
19.37
25.17
22.65
14.09
14.26
22.71
12.98
14.46
20.29
10.94
0.54
0.81
0.53
0.21
0.38
0.46
0.86
0.69
0.86
0.92
0.53
0.59
1.12
0.63
0.38
0.87
0.64
0.75
0.68
0.58
0.93
1.25
1.55
1.37
1.85
1.70
0.66
0.61
0.52
0.71
0.88
0.72
0.98
0.61
0.82
0.89
0.71
0.81
0.36
2.75
3.97
5.60
1.08
2.02
6.03
5.84
5.91
6.52
5.66
3.51
6.05
4.01
5.35
1.39
4.49
3.52
3.47
3.03
2.47
6.81
14.17
17.08
8.72
15.18
9.47
4.49
4.15
3.20
12.10
12.43
9.47
8.86
4.76
12.18
5.98
5.37
6.41
3.96
0.0
0.0
0.0
0.0
0.0
0.0
O.'O
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
o.o
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
8.0
lo
0.0
0.0
0.0
0.0
0.0
6.10
5.60
4.00
4.80
4.00
5.40
7.60
8.00
3.40
7.80
6.80
4.60
3.60
7.00
5.40
9.40
4.40
7.80
5.40
9.20
10.00
8.00
9.20
10.00
12.60
5.00
6.00
10.00
7.40
7.40
6.20
5.60
5. 2O
7.00
5.60
6.40
6.70
2.10
11.76
27.02
11.79
3.62
8.51
13.99
25.17
26.81
41.69
44.00
14.34
14.38
71.61
14.86
9.00
16.27
17.60
31.25
8.40
3.30
17.21
37.99
81.36
63.02
69.46
SO. 60
21.26
8.93
6.64
21.40
31.84
23.20
20.OO
13.05
21.77
17.60
13.66
26.12
21.33
0.65
2.78
0.60
0.18
0.22
0.80
0.28
0.16
0.77
0.41
0.04
0.52
8.26
.87
0.14
1.72
0.50
0.89
6.56
0.0
0.0
0.0
0.34
0.58
0.11
0.14
0.03
0.90
0.21
1.24
1.24
2.39
1.91
0.32
0.80
2.48
2.39
0.90
1.23
-------
Appendix Table 15. ELECTRICAL CONDUCTIVITIES (mmhos/cm) OF SOIL
SOLUTION WITHDRAWN FROM SURFACE AND TRICKLE-
IRRIGATED PLOTS IN 1972
Plot No.
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Tl
T2
T3
T4
T5
T6
June July
11.76
7.98
4.97
3.14 5.00
6.26
9.30 11.88
10.09
6.53
7.93
8.36
14.23
3.01
2.03 2.00
2.40
4.34 5.16
6.84 9.74
9.40
11.38
3.62
6.10
Aug.
8.82
10.03
6.56
5.79
13.36
9.24
9.12
6.30
9.04
6.16
8.25
8.66
11.64
2.88
1.90
6.63
6.42
7.56
9.44
12.82
3.82
5.76
Sept.
7.86
7.96
6.86
3.96
12.72
13.88
6.46
13.42
8.14
6.56
11.12
11.06
2.88
2.08
2.88
7.12
7.68
10.66
9.86
4.38
4.18
6.96
122
-------
Appendix Table 16. ELECTRICAL CONDUCTIVITIES Cmmhos/cm) OF SOIL
SOLUTION WITHDRAWN FROM SURFACE AND TRICKLE-IRRIGATED PLOTS IN 1973
Plot No. Jan.
1 9.18
2 11.12
3
5 6.90
6 6.60
7 7.51
8
9 9.92
10 13.54
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Tl
T2
T3
T4
T5
T6
Feb . Mar . Apr .
4.73
10.48 10.00
9.74 13.90
10.10
5.15 5.72
6.96 7.96
9.74 9.38
9.66 10.02
8.94 9.36
8.50 8.82
5.46
2.40
5.52
3.28
5.90
7.70
5.30
9.74
8.64
May July
7.62
10.92
7.60
5.64
7.98
12.12
8.46
10.00
16.30
10.22
5.42
8.22
9.50
8.72
7.68
4.84
2.83
4.00
2.27
5.48
2.72
8.80
6.96
4.92 4.50
5.84 4.35
4.70 4.68
14.50 7.11
Aug.
7.05
7.60
4.82
9.00
9.42
9.40
2.66
10.42
7.68
8.00
3.00
9.60
4.98
6.90
8.65
20.14
5.46
4.55
7.28
Sept.
15.10
10.48
6.92
4.38
8.14
7.94
10.02
10.14
24.60
9.96
1.56
7.48
7.26
7.48
6.12
4.80
2.86
5.26
1.82
7.40
4.90
4.24
8.35
9.25
7.54
123
-------
Appendix Table 17. ELECTRICAL CONDUCTIVITIES (mmhos/cm) OF SOIL
SOLUTION WITHDRAWN FROM SURFACE AND TRICKLE-
IRRIGATED PLOTS IN 1974
Plot No.
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
Tl
T2
T3
T4
T5
T6
June
9.82
5.63
5.97
7.42
11.21
2.97
1.62
2.25
2.35
2.64
2.49
2.19
3.50
6.50
2.17
8.37
5.13
1.87
4.90
6.39
3.78
2.36
2.39
July Aug. Sept.
10.63 6.66
10.50 5.93
9.71 8.93
4.48 4.35
10.90 10.22 8.12
10.03
8.42 8.87
8.42
10.54
8.85 7.43
10.75
6.26 4.33
7.77
8.55 7.53
11.01
9.84
7.65
4.47 4.27
3.57 3.50
4.76 4.18
3.00
7.38
10.15
6.44
7.50
20.76
4.74
5.20
6.07
3.78
5.33
7.36
Oct.
7.89
6.07
2.88
7.30
8.42
6.18
6.24
9.40
8.28
9.90
4.13
7.34
7.98
9.27
6.99
4.46
3.46
4.84
3.29
7.40
8.00
6.52
7.32
4.28
4.55
7.34
124
-------
to
Cn
Appendix Table 18. CHEMICAL COMPOSITION (meq/1 EXCEPT N03 IN ppm) OF SAMPLES TAKEN
FROM TEST WELL #1 DURING THE YEARS 1972, 1973 AND 1974
WELL DATE ECX103 PH CATIONS ANIONS CA MG NA K CL C03 KC03 S04 N03,PPM
1
1
1
1
1
1
1
i
1
1
1
1
I
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
I
1
1
1
^
^
1
tN -
). 0
4/20/72
6/26/72
11 7/72
«/ 3/72
9/ 1/72
10/ 7/72
11/10/72
U/ 6/72
I/ 5/73
21 2/73
3/ 9/73
4/ 6/73
5/ 4/73
6/ 8/73
6/15/73
7/ f/73
9/14/73
10/12/73
ll/ 9/73
12/21/73
2/15/74
4/16/74
5/14/74
5/2P/74
6/11/74
6/25/74
7/ 9/74
7/23/74
8/ 6/74
<>/20/74
9/ 3/74
9/17/74
10/ 1/74
10/15/74
11/12/74
11/26/74
12/10/74
6V. =
1.07
1.22
i.ie
1.14
1.14
1.13
1.16
1.10
0.98
1.14
1.18
1.18
1.17
1.04
1.12
1.14
1.1?
0.97
0.97
0.90
0.95
0.88
0.99
1.03
1.03
1.04
1.07
1.79
1.01
1.34
0.94
1.01
0.97
1.00
1.04
0.92
0.90
0.93
I .08
O.lfi
7.20
7.75
7.74
7.67
7.64
7.48
7.70
7.65
7.35
7.16
7.10
7.16
6. ^0
7.00
6.90
7.00
7.54
7.89
P. 25
8.43
8.04
7.93
7.97
7.84
7.91
7.80
8.13
7.44
3.29
7.68
»., 13
H,C5
5
10.21
11.21
12,29
12,41
10.01
1C. 19
9.74
8.71
10.17
12.54
10.05
10.65
11.54
10.68
19.56
10.60
13.41
11.21
11.47
10.98
10.67
11.15
Q.20
11.21
10.47
1 1 . 34
1.75
11.04
13.94
12.59
11.5?
12.47
11.76
10.25
10.03
10.11
11.60
11.79
11.04
13.05
12.43
11.63
13.10
11.28
11.50
9.87
10.05
9.26
10.44
12.46
10.38
11.01
10.69
10.94
18.64
11. C7
14. 16
10.31
11.06
10.21
10.36
10.79
9.30
11.27
10.42
11.43
1.67
5.53
6.3P
4.96
3.P7
5.65
5.62
4.21
4.8C
5.36
5.94
4.36
5.8P
6.18
3.73
4.83
5.80
6.09
5.45
5.43
4.64
5.14
5.56
6.56
5.59
5.02
6.26
5.61
10.59
5.63
5.69
6.04
6.22
6.23
5.81
6.14
4.67
5.86
5.86
5,61
i .ce
1.69
1.77
1.5?
1.56
1.66
1.50
1.57
1.53
1.58
1.60
1.58
1.60
1.56
1.56
1.56
1.51
1.60
1.36
1.43
1.62
1.49
1.44
1.7P
1.54
U65
1.54
2.17
1.52
2.33
1.68
1.76
1.64
1.60
1.68
1.52
1.59
1.5?
1.62
c.ia
3.44
4.97
4,44
4.78
•t.79
4.66
4.5H
4. 1 M
3.51
4.46
5.G5
4.98
4.92
ft. 72
4.63
4.78
4.52
3.C5
3.13
3.31
1.91
3.02
4.00
2.72
3.66
3.48
3.30
6.55
3.30
5.17
3.33
3.33
2.97
3.12
3.17
2.37
3.62
2.95
3.93
0.94
0.14
0.22
0.19
0. 18
0. 18
0.19
0. IP
0.17
0. 16
0,17
0.20
0.21
0.19
0.20
0.19
0.20
0.20
0.15
0.15
0. 17
0.17
0. 15
0.20
0.20
0.16
0,15
0.23
0.25
0.15
0.22
0.16
0.16
0.14
0.14
0.16
0.14
0.1*
0.14
0.18
0.03
2.54
2.94
2.79
2.74
2.72
2.75
2.75
2.73
2.71
2.77
2.80
2.75
2.92
2.76
2.74
2.82
2.56
2.65
2.62
2.64
2.57
2.76
3.21
2.72
2.87
2.77
2.80
4.49
2.78
3.58
2.73
2.92
2.71
2.63
2.78
2.70
2.93
2.72
2.83
0.33
0.0
0.0
0.94
0.0
0.54
0.0
0.62
0.0
0.0
0,88
0.52
0.0
0.44
0.0
0.0
0.0
0.38
0.25
0.0
0.0
0.10
0.0
0.20
0.0
0.0
0.0
0.12
0.0
0.04
0.0
0.0
0.0
0.10
0.40
0.0
0.0
0.0
0.0
0.15
0.26
3.66
4.79
3.42
3.96
'+.00
4.54
2.03
3.36
3.66
3.72
3.95
4.88
4,00
4.70
4.15
5.50
-5.50
2.95
3^06
2.78
3.75
4.00
3^70
3.60
3.50
5.26
3.40
4.72
3.68
3.64
3.00
3.04
3,48
2.48
3.53
3.50
3.74
0.72
4.83
6.21
5.44
4.87
5.21
4.47
4.P5
3.44
3.74
4.23
4.50
3.38
5.67
4.95
4.72
4.77
4.78
5.63
4.11
4.33
3.80
3,
0.0
0.0
0.0
0.0
0.02
0.15
O.O5
0.19
0.20
1.34
0.14
0.1 1
0.32
0.14
0.43
O.2.*
0.56
0.73
-------
Appendix Table 19. CHEMICAL COMPOSITION (meq/1 EXCEPT NOa IN ppm) OF SAMPLES TAKEN
FROM TEST WELL #2 DURING THE YEARS 1972, 1973 AND 1974
WELL
DATE PCX103 PH CATICNS UNIONS CA
MG
NA
CL
C03 HC03
SO* N03.PPH
to
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
p
2
2
2
2
2
N =
.
4/2C/72
6/17/72
6/26/72
7/ 7/72
8/ 3/72
9/ 1/72
10/ 7/72
11/10/72
12/ 8/72
I/ 5/73
2/ 2/73
3/ 9/73
4/ 6/73
5/ 4/73
6/ 8/73
6/15/73
7/ 6/73
8/17/73
9/14/73
10/12/73
ll/ 9/73
12/21/73
2/19/74
4/16/74
5/14/74
5/28/74
6/11/74
6/25/74
7/ 9/74
7/23/74
8/ 6/74
8/20/74
9/ 3/74
9/17/74
10/ 1/74
10/15/74
11/12/74
11/26/74
12/10/74
:
DEV.=
1.36
1.68
1.78
1.80
1.46
1.44
1.40
1.26
1.44
1.40
1.44
1.47
1.50
1.46
1.26
1.44
1.42
1.47
1.45
1.46
1.48
1.66
1.62
1.38
1.64
1.98
1.38
1.32
1.40
1.32
1.52
1.21
1.28
1.30
1.26
1.25
1.20
1.03
1.28
1.43
0.18
7.25
7.58
7.61
7.55
7.62
7.48
7.47
7.54
7.55
7.27
7.16
7.11
7.00
6.98
7.00
7.10
7.00
7.38
7.73
8.09
8.17
7.88
8.06
7.90
7.83
7.82
7.97
8.48
7.46
3.15
7.98
8.26
8.33
8.31
8» 0*5
7.98
8.10
8.33
8. 16
7.71
0.44
14.55
19.64
21.31
13^36
16.03
15.50
13.73
14.18
15.65
15.74
12.82
16.13
16.93
13.63
16.25
15.71
16.99
16.50
16.82
16.78
17.58
17.47
16.07
17.43
19.72
15.62
16.31
15.12
15.21
15.27
15.46
15.24
13.25
13.41
11.57
13.09
14.02
10.79
15.6fc
2.22
13.81
19.12
20.39
?0.42
16.37
15.69
15.47
14.45
14.54
15.11
15.12
15.38
16.31
16.81
16.57
16.37
16.85
15.35
15.69
15.78
16,79
18.06
18.07
16.55
17.20
20.13
15.23
16,87
14.86
14.64
16.11
14.97
15.22
13.44
13.50
14.09
14.43
14.63
10.84
15.93
1.95
6.82
10.75
11.72
11. OS
5.35
8.01
7.78
6.20
6.6
-------
Appendix Table 20. CHEMICAL COMPOSITION (meq/1 EXCEPT JK>3 IN ppm) OF SAMPLES TAKEN
FROM TEST WELL #3 DURING THE YEARS 1972, 1973 AND 1974
WPLL
FCX103 PH CATICNS ANICNS
CA
NG
NA
CL
C03
HC03 SQ4 N03.PPH
to
3
3
3
3
3
3
3
3
3
3
3
3
3
3
•*
3
3
3
3
3
•»
^
3
3
3
3
•^
3
3
•<
3
^
3
3
3
3
•a
3
MEAN
STO.
4/20/72 1.60
6/17/72 1.60
6/26/72 1.62
7/ 7/72 1.60
8/ 3/72 1.62
9/ 1/72 l.Sfc
10/ 7/?2 1.56
U/10/72 1.60
12/ 8/72 1.64
I/ 5/73 1.58
2/ 2/73 1.58
3/ S/73 1.56
4/ 6/73 1.50
5/ 4/73 1.50
6/ fi/73 1.32
6/15/73 1.52
7/ 6/73 1.5?
8/17/73 1.52
c/l4/73 1. te
10/12/73 1.53
ll/ c/73 1.3R
12/21/73 1.37
2/19/74 1.40
4/16/7* 1.4-9
5/14/74 I.R8
5/26/74 2.27
A/ll/74 1.81
6/25/74 1.35
7/ 9/74 1.89
7/23/74 1.36
fl/ 6/74 1.82
8/20/74 1.74
9/17/74 1.91
10/ 1/74 1.86
10/15/74 1.6?
11/12/74 1.60
11/26/74 1.34
12/10/74 1.43
= 1.62
D?V.= O.lr-
7.37
7.63
7.60
7.57
7.57
7.44
7.26
7.45
7.47
7.25
7.16
7.05
7.01
t.95
7.00
7.10
7.00
7.2S
7.61
7.S4
8.33
8.02
a. 17
7.79
7.H5
7.87
7. "7
e.?o
7.42
8.22
7.95
8.20
8.25
7.93
P. 20
8.15
*.o?
8.30
7.67
0.44
17.49
18.73
13.85
16. G2
15.50
18.25
18.05
14.67
15.67
16.63
16.78
13.85
15.32
17.85
14.70
17.52
17.24
17.64
lfi.30
17.66
ie.63
14.30
14.18
17.15
19.84
22.20
?C.76
19.53
20.49
21.86
?2.4l
21.11
20.60
20.72
16.57
19.43
18.32
14.39
17.78
2.40
16.10
18.44
18.30
17.97
18.13
17.67
17.50
14.73
15.97
17.49
15.35
15.94
15.84
17.76
15.67
17.66
17.64
15.69
15.22
16.55
17.25
14.52
14.80
16.29
1J».88
22.50
19. +4
19.63
15-52
??.06
21.25
20.65
19.45
19.97
i«.fc i
19.74
18.43
13.28
17.71
2. 13
8.45
9.63
9.86
7.50
5.89
9.18
9.21
6.19
6.90
7.46
8.09
4.96
6.73
9.03
5.86
8.79
8.73
8.67
7.82
8.72
7.12
5.14
5.23
7.31
10.60
in. 29
10. P2
c.Ol
11.32
10.77
11.58
10.56
10.02
10.23
6.<32
9.23
9.16
5.45
8.38
1.86
2.29
2.41
2.41
2.32
2.35
2.39
2.30
2.38
2.57
2.57
2.39
2.25
2.13
2.30
2.21
2.27
2.26
2.26
2.25
2.35
2.37
2.30
2.26
2.67
2.76
3.91
2.77
2.80
?.12
3.09
2.97
2.95
3.21
3.06
2.71
2.46
2.39
2.28
2.52
0.37
6.53
6.43
6.33
5.95
7.00
6.45
6.29
5.87
5.97
6.36
6.08
6.39
6.21
6.23
6.37
6.23
6.01
6.46
5.99
6.37
6.89
6.65
6.45
6.95
6.16
7.73
6.94
7.78
6.80
7.73
7.61
7.37
7.13
7.20
6.83
7.52
6.57
6.44
6.64
0.55
0.22
0.26
0.25
0.25
0.26
0.23
0.25
0.23
0.23
0.24
0.22
0.25
0.25
0.29
0.26
0.23
0.24
0.23
0.24
0.22
0.25
0.21
0.24
0.22
0.32
0.27
0.23
0.34
0.25
0.27
0.25
0.23
0.24
0.23
0.21
0,22
0.20
0.22
0.24
0.03
3.31
3.44
3.42
3.40
3.49
3.42'
3.56
3.45
3.52
3.50
3.44
3.33
3.23
3.22
3.18
3.22
3.27
3.07
3.22
3.12
3.09
2.92
3.04
*.13
4.42
5.76
4.48
4.45
4.68
5.01
5.6*
4.93
5.C8
4.62
4.05
4.03
3.89
3.08
3.79
0.76
0.0
0.0
0.0
0.0
0.0
0.08
0.0
0.0
0.0
0.0
0.80
0.10
0.0
0.20
0.0
0.0
0.0
1.60
0.75
0.75
0.0
0.10
0. 15
J.O
0.0
0.0
0.0
0.16
0.0
0.0
0.0
0.0
0.24
0.0
0.52
0.0
0.0
0.0
0.14
O..V3
5.66
7.08
6.69
6.98
6.68
6.46
6.54
4.45
6.63
7.17
5.61
5.95
6.20
6.78
5.30
7.40
7.40
4,30
5.00
5.92
7.0?
4.28
4.28
6.35
6.54
6.44
6.ti4
6.66
6.20
6.65
6.48
6.50
4.68
6.38
5.94
6.44
6.56
2.52
6.C8
1.05
7.11
7.92
8.19
7.59
7.96
7.71
7.40
6.83
5.82
6.P2
5.50
6.52
6.41
7.53
7.16
7.00
6.96
6.69
6.20
6.71
7.12
7.19
7,31
7.76
7.92
10.30
8.12
8.36
8.64
10.40
9.13
9.21
9.45
8.97
8.12
?.24
7. =56
7.68
7.68
1.11
1.24
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
2.35
0.0
1 . 62
1.80
2.55
0.32
2.0fi
3.32
2.98
1.55
1.58
1.30
0.06
0.0
0.0
0.0
0,04
0.11
0.16
0.22
0.45
0.14
0.14
0.09
1.7?
0.21
0.31
0.69
0.9«
-------
Appendix Table 21. CHEMICAL COMPOSITION (meq/1 EXCEPT N03 IN ppm) OF SAMPLES TAKEN
FROM TEST WELL #4 DURING THE YEARS 1972, 1973 AND 1974
V:FL
cure
CATIONS
CA
HG
NA
CL
co3
nco3
so4
to
CO
4
4
4
4
4
4
•+
4
4
*
4
4
4
4
4
4
4
^s
4
4
4
A
•V
A
4
4
4
*
4
4
t
4
4
4
4
<*
4
4
4
MEAN
STD.
4/20/72
6/17/72
6/26/72
7/ 7/72
8/ 3/72
9/ t/72
10/ 7/72
11/10/72
12/ 8/72
I/ 5/73
2/ 2/7?
3/
5.59
5.S4
5.25
5.49
5. 58
5.52
5.42
5.90
5.73
5. S3
6.62
7.07
6.01
5. HP
6.10
6.C7
6.46
6.29
6.73
6.77
6.7>3
7.01
7.63
6.59
6.94
7.75
3.5P
8.25
9.10
8.40
8.84
9.57
8.03
7.29
E.53
8.51
fi.53
*.SJ
6.93
1.20
0.22
0.25
0.24
0.22
0.23
0.22
0.25
0.23
0.24
0.25
0.23
0.27
0,25
G.?9
0.26
0.25
0.25
0.23
0.27
0.2*
0.27
0.?3
0.2ft
0.26
0.37
0.24
0.27
0.39
0.27
0. 3?
0.29
0.27
0.20
0.26
0.25
0.23
0.22
0.21
0.73
0.26
0.04
3.66
3.15
3.08
3.07
3.01
3.04
3.01
2.97
2.95
3.01
2.95
2.93
2.91
2.96
2.93
2.93
2.96
2.78
3.19
3.76
3.62
3.77
5.2t,
5.93
5.69
4.47
5.6ft
5.77
5.27
6.06
5.10
5.18
4.8-t
4.12
3.76
3.16
3.00
3.16
3.66
3,82
1.07
0.0
0.0
0.0
0.0
0.0
0.10
^. 12
0.0
0.0
0 .0
0.0
0.10
o.o
0.16
o.o
0. J
0.0
1.70
0.25
0.15
0.0
O./'O
0.15
O.'J
0.0
0.0
0.0
0.12
0.0
0.0
0.0
0.0
0.0
0.12
0.0
0.0
0.0
0.0
0.0
O.C8
0.27
5.97
5.P4
5.95
5.75
5.74
4. 39
6.42
3.94
7.57
S.37
7.82
7.84
a. 54
5.78
6.50
8.50
6.+0
5. 15
6.87
6.52
6.28
3. 75
4.98
6.57
6.20
6.74
6.48
6.72
5.88
7. 12
7. 12
7.72
6.20
5.62
7.52
6.92
6.88
7.0?
3 . °2
6.40
1. 19
7. «6
7.48
7.48
7.31
6.62
6.90
6.17
5.34
T.03
6.16
4.56
*.28
4.72
6.48
e.69
*.<-<-•
6 . 3 c
6.27
6.96
7.24
7.40
".56
9.33
".32
10.62
9.44
11.19
11.23
11.11
It. 2^
12.68
12.56
10.0 1
10.30
9.13
7.71
6.99
6.68
6.64
7.95
2.41
O.u
O.f
0.0
0.0
0.0
0 . 0
o.y
0.0
O.U
0.0
0.0
0.c'5
0.0
2.55
1.62
2.55
O.oO
I .10
2.6"
2.75
1.10
0. 7f>
l.V-S
O.Of
0.0
0.0
G.O
0.0'
0.08
G.O?
0.14
0.37
5.03
0.14
0.09
0.0
1.12
0.10
0.15
0.67
1.12
-------
Appendix Table 22. CHEMICAL COMPOSITION (meq/1 EXCEPT N03 IN ppm) OF SAMPLES TAKEN
FROM TEST WELL #5 DURING THE YEARS 1972, 1973 AND 1974
WELL
DATE ECX103 PH CATIONS ANIONS CA
CL
CQ3 HCG3 SO* NOStPPK
to
5
5
5
5
5
5
5
5
5
5
5
5
5
S
5
5
5
5
5
5
5
5
5
5
5
c;
5
5
5
5
5
5
c
5
5
M =
>. D
4/20/72
6/17/72
6/26/72
7/ 7/72
8/ 3/72
9/ 1/72
10/ 7/72
11/10/72
12/ 8/72
I/ 5/73
2/ 2/73
3/ 9/73
4/ 6/73
5/ 4/73
6/ 8/73
6/15/73
7/ 6/73
6/17/73
9/14/73
10/12/73
ll/ 9/73
12/21/73
2/19/74
4/16/74
5/14/74
5/28/74
6/11/74
6/25/74
7/ 9/74
7/23/74
8/ 6/74
8/20/74
9/ 3/74
9/17/74
10/ 1/74
10/15/74
11/12/74
11/26/74
12/10/74
EV.=
1.67
1.58
1.60
1.60
1.52
1.44
1.38
1.36
1.35
1.32
1*32
1.31
1.33
1.30
1.32
1.26
1.36
1.39
1.52
1.66
1.47
1.60
1.50
1.42
1.97
1.56
1.93
2.02
2.09
2.18
2.09
1.95
2.23
2.54
2.60
2.50
2.07
1.64
1.69
1.66
0.3R
7.48
7.69
7.49
7.45
7.60
7.49
6.57
7.31
6.35
7.31
7.05
7.13
7.20
7.26
7.20
7.10
6.80
7.58
7.70
7.fl3
6.24
7.97
8.22
7.74
7.71
7.83
7.66
8.25
7.25
e.14
7.85
8.24
7.95
7.97
7,91
7.95
8.00
8.14
8.18
-.61
0.47
18.70
18.35
18.45
16.53
13.86
14.51
15.37
10.85
14.10
14.90
14.59
11.71
12.73
14.04
14.84
14,32
15.11
16.80
18.36
19.17
18.72
16.71
17.38
17.06
19.77
16.62
22.17
22.15
22.25
22.53
24.61
23.74
24.92
28.09
29.75
27. 2S
24.70
20.32
16.40
16.52
4.64
18.52
18.14
18.39
18.11
16.75
15.05
15.47
10.94
14. 17
14.75
12.73
13.01
13.63
12.40
14.88
14.59
14.51
13. 10
17.17
17.02
17. "0
16.71
17.39
17.65
20.13
16.14
20.94
22.13
21.76
23.11
23.53
23.31
26.00
26.96
28.65
27.25
24.98
22.61
16.58
18.41
+ .53
8.71
8.78
8.93
7.31
4.80
5.65
7.06
2.95
6.19
6.91
6.33
3.61
4.81
5.98
6.97
6.26
6.84
7.34
9.11
9.05
8.02
6.71
8.41
6. PI
10,04
8.37
11.20
10.16
11.92
9.68
12.66
11.06
10,94
13.52
14.80
12.34
11.27
10.13
5.27
8. 39
2.74
3.46
3.26
3.21
3.16
2.81
2.73
2.60
2.57
2. £3
2.57
2.44
2.27
2.27
2.32
2.37
2.36
2.37
2.74
2.84
3.10
3.26
3.33
2.66
2.95
3,25
2.12
3.40
3.43
2.73
4.24
3.94
4.19
5.2B
5.47
5.63
5.18
4.1?
3.F7
2.98
3.23
O.S3
6.25
5.98
5.98
5.75
5.93
5,83
5.40
5.05
5.00
5.14
5.05
5.55
5.36
5.44
5.21
5.39
5.54
6.42
6.08
6.71
7.10
6.39
5.98
7.01
6.06
5.93
7.24
8.13
7.26
8.26
7.65
3.15
8.41
8.71
8.93
9.38
8.96
6.03
7.83
6.58
1.27
0.28
0.33
0.33
0.31
0.32
0.30
0.31
0.28
0.28
0.28
0.27
0.23
0.29
0.30
0.29
0.31
0.36
0.30
0.33
0.31
0.34
0.28
0.33
0.29
0.42
0.20
0.33
0.43
0.34
0.35
0.36
0.34
0.29
0.39
0,39
0.38
0.34
0.29
0.32
0.32
0.04
3.61
3.64
3.58
3.49
3.31
3.16
3.08
2.97
2.95
2.94
2.97
2.90
2.87
2.82
2.85
2.81
2.98
2.88
3.40
4.11
4.16
4.46
4.29
4.22
4.96
2.87
5.34
5.33
5.50
5.46
5.10
5.48
6.B3
7.57
7.16
6,95
5.24
4.53
4.10
4.18
1.36
0.0
0.72
0.0
0.0
0.0
0.06
O.C
0.84
0.0
0.0
0.0
1.08
0.0
0.40
0.0
0.0
0.0
1.20
0.75
0.35
0.0
0.0
0.13
0.0
0.0
0.0
0.0
0.24
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.15
0.32
6.54
6.58
7.33
7.14
6.77
4.87
6.28
3.02
5.30
6.97
6.41
•5.22
6.94
4.00
7.40
6.70
6. 30
3.80
5.97
6.45
6.32
4.00
4.70
5.75
5.76
6.68
5.90
6. 18
5.60
6.10
6.92
6.64
6.70
5.86
6.34
6.28
7.16
7.60
2.98
5.99
1.16
8.37
7.20
7.48
7.48
6.67
6.96
6.11
4.11
5.92
4.64
3.35
3.80
3. SI
5.17
4.61
5.06
5.22
5.22
7.00
6.P7
7.40
a. 24
8.20
7.68
9.41
6.59
9.70
10.38
10.66
11.55
11.51
11.19
12.32
13.53
15.15
14.02
12.56
10.48
9.49
8.08
3.08
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.62
0.62
0.87
1.15
1.47
0.70
0.25
2.96
?.42
1.33
0.91
l.ll
0.17
0.0
0,01
0.02
0.0
0.15
0.02
0. 1"
0.26
9.21
0.14
0.14
0.0
1.23
0.21
0.50
0.68
1.56
-------
Appendix Table 23. CHEMICAL COMPOSITION (meq/1 EXCEPT N03 IN ppm) OF SAMPLES TAKEN
FROM THE IRRIGATION WELL DURING THE YEARS 1972, 1973 AND 1974
co
o
WEI
I
I
I
I
T
f
T
t
T
x
T
T
I
f
I
!
I
T
I
J
T
I
T
T
T
A
I
I
T
t
T
i
i
i
!
I
I
T
i
i
i
i
i
MEA^
sin.
L DATE
3/ 3/72
3/ 3/72
10/13/72
11/10/72
12/ 8/72
5/18/73
5/25/73
6/ 1/73
6/ 8/73
6/15/73
6/22/73
6/29/73
7/ 6/73
7/20/73
8/17/73
9/14/73
10/19/73
10/26/73
ll/ 9/73
11/26/73
12/10/73
12/21/73
I/ 4/74
1/18/74
2/ 5/74
2/19/74
3/ 5/74
3/19/74
4/ 2/74
4/16/74
4/30/74
5/14/74
5/28/74
6/11/74
6/25/74
7/ 9/74
7/23/74
8/ 6/74
S/20/74
9/ 3/74
9/17/74
10/ 1/74
10/15/74
10/29/74
11/12/74
11/26/74
12/10/74
-
OEV.=
ECX103 PH CATIONS AMHNS
1.45
1.46
1.34
1.36
1.34
1.38
1.28
1.18
1.14
1.32
1.35
1.37
1.34
1.30
1.38
1.28
1.32
1.28
1.24
1.18
1.21
1.16
1.2P
1.22
1.08
1.14
1.32
1.26
1.27
1.04
1.08
1.07
1.27
1.23
1.17
1.15
1.18
1.13
1.11
1.1?
1,16
1.22
1.15
1.03
1.07
0.98
1.10
1.22
0.11
8.07
8.03
7.36
7.38
7.92
6.80
6.80
7.00
6.ao
6.80
6.80
7.00
7.00
6.80
6.57
7.39
8.21
8.04
8.29
8.42
8.1?
8. 11
8.01
7.55
7.96
7.93
7.95
7.66
7.60
7.55
7.59
7.74
7.80
7.58
8.27
7.76
8.30
7.91
8.C8
7.92
7.95
8. 16
7.87
7.93
8.26
S.30
8.04
7.70
0.51
10.68
10.74
14.93
10.84
12.91
12.21
11.31
12.46
11.74
14.72
15.38
15.51
14.82
14.75
15.56
14.81
14.78
14.76
11.04
9.80
10.92
11.04
12,98
13.92
12.08
12.71
13.35
15.47
14.03
12.04
13.60
13.34
13.84
13.98
13.50
12.69
13.12
13.22
13.60
13.12
13.26
14.05
12.80
11.12
12.51
12.63
10. 85
13.07
1.51
12.02
12.27
15.74
10.27
12.26
14.18
13.61
14.52
13.77
15.60
15.79
16.73
16.05
15.74
13.78
14.05
14.37
14,38
11.44
10.02
11.52
11.80
13.53
13.12
12.95
12.93
12.^7
12.70
13.48
13. 17
13.00
13.13
13.23
13,64
13.08
12.57
12.54
12.98
13.13
13.38
13.35
13. R«
12.94
11.46
12.32
12.56
11.53
13.26
1.41
CA
3,62
3.83
7.44
3.50
5.35
4.56
3.53
4.91
4.30
7.13
7.71
7.76
7.21
7.22
7.51
7.60
7.02
6.85
3.16
3.64
3.36
4.34
5.80
6.48
5.07
5.51
6.08
7.35
6.56
5.88
6.42
5.95
6.46
6.50
6.03
5.91
5.98
6.04
6.24
5.9P
5.97
6.65
5.77
4. 11
5.55
5.48
4.06
5.73
1.32
HG
1.80
1.70
1.88
1.87
2.10
1.85
1.88
1,89
1.82
1.87
1.90
1.90
1.83
1.78
1.89
1.75
1.81
1.76
1.82
1.72
1.72
1,67
1.68
1.72
1.53
1.60
1.57
1.85
1,68
1.55
1.59
1.52
1.64
1.58
1. = 1
1.12
1.49
1.52
1.50
1.57
1.57
1.64
1.52
1.34
1.43
1.53
1.52
l.t<5
0.1?
NA
5.10
5.02
5.40
5.27
5.27
5.57
5.68
5.44
5.40
5.44
5.55
5.63
5.56
5.56
5.92
5.28
5.67
5.95
5.84
4.25
5.67
4.84
5.31
5.51
5.29
5.41
5.52
6.08
5.60
5.3*
5.42
5.63
5.55
5.71
5.70
5.48
5.46
5.47
5.68
5.38
5.54
5.58
5.35
5.49
5.36
5.45
•5/08
5.-V6
0.2S
K
0.16
0.19
0.21
0.20
0.19
0.23
0.22
0.22
0.22
0.28
0.22
0.22
0.22
0.19
0.24
0.18
0.2?
0.20
0.22
0.19
0.17
0.19
0.19
0.21
0.19
0,19
0. 18
0.19
0.19
0. 17
0.17
0.24
0.19
0.19
0.26
0.18
O.i9
0.19
0.18
0.19
0.18
0.18
0.16
0.18
0.17
0.17
0.19
0.20
0.03
CL
2.76
2.76
2.84
2.31
2.83
2.82
2.73
2.76
2.73
2.69
2.73
2.71
2.72
2.56
2.58
2.61
2.77
2.62
2.50
2.52
2.47
2.57
2.43
2.58
2.55
2.52
2.43
2.46
2.49
2.49
2.46
2.38
2.28
2.33
2.41
2.38
2.41
2.43
2.40
2.36
2.28
2.26
2.31
2.28
2.27
2.30
2.26
2.53
0.13
CO 3
0.46
0.40
0.60
0.42
0.16
0.0
0.0
0.0
0.0
0.20
0.20
0.0
0.0
0.0
0.50
0.65
0.65
0.70
0.0
0.10
0.20
0.25
0.10
0.0
0.21
0.09
0.40
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.24
0.0
0.04
0.0
0.0
0.0
0.0
0.60
0.0
0.0
0.0
0.0
0.0
0.15
0.22
H--.03
2.96
3.21
5.60
2.53
3.93
4,00
'-t. 80
5.90
4.90
6.90
6.90
8.00
7.20
7.80
2.40
4.62
4.23
5.4.8
3.26
2.70
3.05
3.62
5.45
5.04
4.65
4.95
4.60
5.14
5.58
5.35
5.45
5.7*
5.70
5.82
5.46
5.46
5.20
5.34
5.48
5.72
5.66
5.08
5.54
4.20
5.42
5.58
4.14
T.OL
1.27
S04 MO3,»PH
5.84
5.90
6.70
4.51
5.34
7.33
6.05
5.83
fc.il
5.78
5.<=4
6.00
6.11
5.37
3.30
6.12
6.6?
5.63
5.66
4.68
5.78
5.33
5.53
5.49
5.53
5.37
5.33
5.09
5.41
5.33
5.0?
5.01
5.25
5.49
4.97
4.73
4.P^
5.21
5.25
5.2S
5.41
5.94
5.09
4.96
4.tl
4.68
5.13
5.56
0.70
0.0
0,0
0.0
0.0
0.0
1.95
1.72
1.85
1.6*
1.75
1.45
1.12
l.-»5
0.85
0.0
2.82
2.5°
2.91
1.40
1.43
1.24
2.10
1.05
0.38
0.67
0.22
0.70
0.92
0.12
0.03
0.06
0. 10
0.0
0.0
0.0
0.15
0.0
0. 1H
0. 10
0. 30
0.26
0.14
C.2 1
1.05
O.S4
0.2°.
0.23
0.73
0.84
-------
Appendix Table 24. COTTON YIELDS IN kg/ha FOR FIRST, SECOND AND TOTAL
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS (1972, 1973 AND 1974)
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
1st
538
538
549
554
616
593
498
370
252
504
347
448
431
717
532
476
342
297
521
426
448
510
403
442
599
465
521
16.9
1972
2nd
146
324
470
711
610
370
532
375
409
420
554
347
582
515
515
510
426
241
403
482
538
319
319
319
386
448
448
36.9
Surface-irrigated plots
1973
Total
683
862
1020
1270
1230
963
1030
745
661
924
902
795
1010
1230
1050
986
767
538
924
907
986
829
722
761
986
913
970
-
1st
666
918
767
706
818
795
834
610
879
655
722
868
823
773
745
963
666
1070
554
650
661
655
554
661
678
756
997
17.7
2nd
728
761
594
728
627
627
610
550
560
571
538
381
655
605
538
504
577
560
728
594
599
470
538
448
582
543
448
14.0
Trickle-Irrigated
Tl
T2
T3
T4
T5
T6
c.v.
1130
840
566
543
504
739
20.5
269
235
666
767
711
140
3.8
1400
1070
1230
1310
1210
880
-
1200
1220
633
840
1060
857
7.7
202
224
610
358
224
426
20.7
Total
1390
1680
1360
1430
1440
1420
1440
1160
1440
1230
1260
1250
1480
1380
1280
1470
1240
1630
1280
1240
1260
1130
1090
1010
1260
1300
1440
-
plots
1400
1440
643
1200
1280
1280
-
1st
885
958
857
890
930
879
884
778
969
773
801
610
868
851
784
773
851
1010
857
762
756
745
907
711
857
812
969
8.5
986
997
834
997
1080
941
6.8
1974
2nd
162
190
174
257
291
207
196
230
168
118
140
174
157
342
179
235
207
224
207
151
146
112
134
129
140
174
185
26.0
112
112
95
78
112
73
20.5
Total
1050
1150
1030
1150
1220
1090
1080
1010
1140
890
941
784
1020
1190
963
1010
1060
1240
1060
924
902
857
1040
840
997
986
1150
—
1100
1110
930
1070
1190
1010
-
131
-------
Appendix Table 25. PERCENT LINT OF COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS
(1972, 1973 AND 1974)
Surface-irrigated plots
1972 1973
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
1st
35.9
37.0
34.9
36.9
34.7
35.8
35.8
35.3
35.4
36.1
35.0
34.4
36.0
35.4
35.5
35.1
34.2
38.0
34.8
34.5
34.7
36.0
37.3
35.7
36.4
35.1
34.8
2.01
2nd
37.6
37.9
37.4
37.8
36.5
35.3
38.2
36.8
35.5
36.7
36.9
37.2
38.8
36.3
37.4
37.2
35.6
39.8
37.3
36.7
37.4
38.3
38.8
36.6
37.2
36.3
36.8
2.52
1st
37.9
38.3
36.0
38.1
37.9
36.9
36.3
37.1
38.8
34.9
37.3
38.5
37.4
38.0
35.1
36.7
36.7
36.9
36.8
36.2
35.6
36.4
35.6
36.5
36.2
35.9
38.5
2.38
Trickle-irrigated
Tl
T2
T3
T4
T5
T6
c.v.
36.8
37.7
34.3
34.5
35.2
36.3
0.49
38.2
38.1
38.3
37.3
37.3
38.7
0.49
37.7
36.6
38.0
37.1
37.9
37.1
1.89
2nd
35.3
38.1
36.5
38.6
39.0
36.4
36.3
35.5
36.7
36.8
36.3
37.8
37.2
37.6
32.9
37.0
35.7
41.1
36.4
41.3
37.1
37.3
38.6
34.1
35.6
35.5
35.3
4.67
plots
35.9
37.2
38.7
37.2
36.4
38.9
2.05
1974
1st
36.5
39.0
38.1
36.6
37.0
37.6
37.2
35.8
37.9
38.0
38.3
37.9
38.5
38.4
37.2
36.5
35.9
36.1
36.8
37.6
37.5
37.4
38.4
37.6
36.4
37.6
38.0
2.32
36.8
36.7
35.2
37.6
36.0
37.9
3.38
2nd
38.7
39.9
38.1
38.9
37.9
39.5
36.6
37.9
38.1
37.6
39.2
38.7
39.2
39.4
38.0
37.1
38.1
39.2
37.9
37.5
38.4
39.7
37.6
38.6
37.9
38.6
37.4
2.02
38.6
39.5
39.3
40.7
39.6
40.6
3.04
132
-------
Appendix Table 26. 2.5 PERCENT SPAN OF COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS
(1972, 1973 AND 1974)
Surface-irrigated plots
1972 1973
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
1st
1.29
1.23
1.26
1.22
1.26
1.19
1.20
1.26
1.19
1.20
1.26
1.21
1.22
1.23
1.23
1.21
1.21
1.13
1.15
1.21
1.25
1.19
1.22
1.25
1.16
1.27
1.24
2.66
2nd
1.22
1.18
1.14
1.22
1.21
1.13
1.16
1.20
1.18
1.19
1.14
1.20
1.17
1.19
1.18
1.17
1.20
1.05
1.17
1.19
1.14
1.20
1.17
1.20
1.17
1.18
1.21
3.18
1st
1.15
1.21
1.15
1.19
1.14
1.15
1.16
1.13
1.13
1.17
1.15
1.12
1.16
1.15
1.19
1.17
1.14
1.15
1.14
1.11
1.19
1.13
1.15
1.17
1.18
1.17
1.17
1.82
Trickle-irrigated
Tl
T2
T3
T4
T5
T6
c.v.
1.18
1.18
1.26
1.26
1.25
1.13
1.88
1.17
1.10
1.19
1.17
1.19
1.15
2.74
1.19
1.20
1.19
1.16
1.17
1.20
0.69
2nd
1.16
1.17
1.22
1.19
1.26
1.13
1.16
1.16
1.19
1.21
1.15
1.15
1.17
1.16
1.14
1.16
1.16
1.17
1.15
1.16
1.19
1.14
1.13
1.21
1.17
1.15
1.17
2.46
plots
1.19
1.21
1.14
1.13
1.13
1.16
1.86
1974
1st
1.23
1.19
1.15
1.19
1.20
1.20
1.19
1.17
1.15
1.15
1.20
1.17
1.18
1.18
1.22
1.21
1.20
1.16
1.20
1.19
1.20
1.14
1.17
1.17
1.14
1.17
1.13
2.27
1.20
1.18
1.23
1.18
1.20
1.14
3.31
2nd
1.19
1.16
1.15
1.16
1.25
1.21
1.19
1.20
1.16
1.20
1.14
1.17
1.19
1.17
1.20
1.18
1.17
1.17
1.20
1.17
1.22
1.17
1.15
1.14
1.17
1.17
1.16
1.93
1.16
1.18
1.15
1.17
1.16
1.08
2.81
133
-------
Appendix Table 27. UNIFORMITY RATIO OF COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS (1972,
1973 AND 1974)
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
1st
48.8
49.6
46.0
49.2
47.6
43.7
42.5
45.8
45.4
44.2
46.0
43.8
46.7
44.7
45.5
43.0
43.0
49.6
46.1
46.3
46.4
48.7
45.9
45.6
44.8
45.7
48.4
3.65
Surface-
1972
2nd
45.1
45.8
42.1
42.6
43.0
40.7
41.4
45.0
42.*4
40.3
41.2
42.5
46.1
42.0
42.4
41.9
45.0
43.8
40.2
43.7
43.0
41.7
46.1
42.5
44.4
42.4
42.1
4.19
-irrigated
1973
1st
44.3
47.1
46.1
44.5
43.0
44.3
44.8
44.2
46.0
44.4
44.3
45.5
46.6
44.3
46.2
43.6
44.7
45.2
43.9
44.1
46.2
45.1
43.5
45.3
44.9
48.7
47.0
2.40
Trickle-irrigated
Tl
T2
T3
T4
T5
T6
c.v.
44.9
46.6
47.6
46.8
44.0
44.2
4.83
42.7
40.9
41.2
44.4
44.5
45.2
6.48
44.5
45.0
45.4
42.2
43.6
42.5
4.48
plots
2nd
44.0
46.2
45.1
45.4
42.1
44.2
44.0
45.7
47.9
43.8
46.1
.43.5
46.2
44.0
43.0
45.7
43.1
43.6
46.1
45.7
44.5
46.5
46.9
47.1
43.6
41.7
44.4
3.68
plots
44.5
45.5
44.7
46.0
43.4
44.8
1.28
1st
48.0
47.1
47.8
45.4
48.3
47.5
47.1
43.6
47.8
47.8
46.7
45.3
46.6
48.3
46.7
47.1
46.7
46.6
46.7
46.2
46.7
46.5
47.9
49.6
46.5
46.2
46.0
2.96
45.8
48.3
43.9
46.6
46.7
44.7
1.88
1974
2nd
46.2
47.4
45.2
47.4
46.4
47.9
45.4
45.0
47.4
47.5
46.5
47.9
45.4
45.3
45.0
44.9
47.9
46.2
45.8
44.4
46.7
47.0
44.3
47.4
45.3
47.9
47.4
2.73
44.8
44.9
49.6
44.4
48.3
45.4
3.76
134
-------
Appendix Table 28. MICRONAIRE OF COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS
(1972, 1973 AND 1974)
1972
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
Tl
T2
T3
T4
T5
T6
c.v.
1st
4.1
3.9
4.2
4.9
4.0
2.9
3.3
3.6
0.4
4.3
4.1
3.6
3.9
4.3
3.6
3.9
3.5
3.7
3.6
3.5
4.3
3.0
4.2
3.1
3.7
3.8
4.1
10.5
3.6
4.5
3.7
3.4
3.8
4.3
4,82
2nd
3.7
4.3
3.5
3.3
3.7
3.6
3.9
4.3
3.2
3.7
3.0
3.5
4.2
3.3
3.8
3.8
3.8
4.2
2.9
3.9
3.8
3.4
4.9
3.5
3.7
3.2
3.6
13.2
3.9
4.0
2.9
3.9
3.5
4.4
14.3
Surface-irrigated
1973
1st
3.6
4.2
3.9
3.8
3.3
4.4
4.0
3.7
4.2
3.8
3.9
4.2
4.0
3.9
4.0
4.0
4.2
3.7
3.8
4.2
3.9
3.8
3.5
4.1
3.8
3.7
3.7
5.15
Trickle- irrigated
4.0
3.9
3.6
3.2
3.0
3.8
7.47
plots
2nd
3.4
3.9
4.0
3.7
3.8
3.6
3.7
3.9
3.7
4.4
3.5
4.0
4.1
3.9
3.6
3.5
3.0
3.6
3.9
3.9
4.3
3.6
4.0
3.9
3.6
3.1
3.0
8.69
plots
2.9
3.0
3.4
3.3
2.7
3.1
8.73
1974
1st
3.3
3.4
4.1
3.8
4.7
4.3
4.0
3.1
4.0
4.3
3.5
4.1
3.7
3.7
4.0
4.2
3.5
4.0
4.0
3.8
4.0
3.6
4.3
4.0
3.8
4.0
4.1
8.37
3.1
3.6
3.5
3.1
3.3
3.1
7.56
2nd
3.4
3.5
3.8
3.5
3.8
4.1
3.5
3.6
3.3
4.3
3.6
4.2
3.5
3.2
4.2
3.5
4.1
4.0
3.3
3.0
3.4
3.8
3.4
3.8
4.0
3.8
3.9
10.5
3.2
3.1
3.7
3.3
2.9
2.9
11.4
135
-------
Appendix Table 29. STRENGTH OP COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS
C1972, 1973 AND 1974)
Surface-irrigated plots
1972 1973
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
1st
25.3
24.4
28.2
24.8
24.8
25.5
25.0
26.2
24.4
26.2
26.2
25.9
25.6
25.2
25.2
26.9
26.5
25.0
24.9
25.4
26.9
25.1
23.6
26.3
26.4
25.3
23.4
2.93
2nd
21.8
20.5
19. Q
21.7
21.0
21.8
19.2
20.5
20.3
19.9
20.6
21.0
19.4
21.3
19.7
20.4
21.2
20.0
20.3
20.5
19.5
20.2
19.3
19.7
19.8
19.6
21.5
3.05
1st
25.0
25.0
24.8
22.4
26.0
25.7
24.9
23.2
22.8
25.8
24.8
24.9
25.1
26.0
25.7
24.0
26.2
22.9
24.7
24.8
26.4
24.1
22.5
24.7
26.1
25.8
26.2
3.41
Trickle-irrigated
Tl
T2
T3
T4
T5
T6
c.v.
24.8
24.8
24.2
26.7
26.9
26.6
7.00
22.9
21.7
20.8
20.9
19.3
22.6
1.01
24.1
22.7
24.2
25.6
25.2
25.3
5.36
2nd
23.1
23.1
24.9
21.6
23.3
22.8
24.4
21.1
22.6
24.2
23.0
22.0
22.2
20.0
23.7
23.8
24.4
22.3
23.1
23.4
24.2
21.8
22.9
23.0
24.3
23.4
23.5
4.30
plots
22.5
22.0
22.6
21.1
19.7
20.9
6.91
1974
1st
22.2
21.0
21.0
22.6
22.8
22.4
19.9
21.4
22.6
21.9
21.7
21.6
20.5
20.7
23.1
22.0
21.9
22.2
21.7
21.2
21.4
20.3
22.6
21.6
22.2
22.9
23.3
4.42
20.8
22.2
21.5
20.1
20.6
21.2
3.19
2nd
22.4
21.1
22.3
20.0
23.3
22.7
22.2
21.9
21.3
21.2
20.0
21.6
21.6
20.1
23.0
20.2
22.3
20.7
19.6
21.9
20.0
20.4
20.6
21.2
21.9
21.2
22.9
5.08
19.7
23.2
20.9
19.3
20.7
18.9
7.79
136
-------
Appendix Tafcle 30. ELONGATION OF COTTON FROM FIRST AND SECOND
HARVESTS FOR SURFACE AND TRICKLE-IRRIGATED PLOTS
(1972, 1973 AND 1974)
1972
1
2
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
20
21
22
23
24
25
26
27
29
30
c.v.
Tl
T2
T3
T4
T5
T6
c.v.
1st
7.0
7.0
7.0
7.3
6.8
6.8
7.0
6.4
6.8
6.0
6.8
7.3
7.3
6.8
6.8
6.5
7.0
6.3
6.8
6.5
6.5
6.5
6.0
6.0
6.5
6.8
5.5
5.72
6.0
6.0
7.3
6.3
6.5
5.8
7.20
2nd
7.5
7.0
6.5
7.0
7.8
6.3
6.5
6.0
7.3
6.8
6.3
6.8
6.0
6.5
6.3
6.8
7.5
6.8
7.0
7.5
7.0
8.0
6.0
6.3
6.3
6.3
7.0
7.13
9.0
8.0
7.8
7.8
7.0
,7.0
10.0
Surface-irrigated
1973
1st
7.0
6.5
5.8
5.5
7.0
6.8
6.8
6.5
6.8
6.3
6.0
6.0
6.8
6.8
6.8
5.8
6.3
6.3
5.8
6.3
6.8
6.0
6.0
5.8
6.0
6.3
6.3
6.68
Trickle-irrigated
7.3
6.0
5.8
6.3
6.0
6.5
5.74
plots
2nd
5.0
5.3
5.5
5.0
5.8
6.0
5.5
5.0
5.5
5.8
5.8
5.5
5.5
5.3
6.0
5.5
5.5
5.3
5.8
5.8
5.3
5.5
6.8
5.3
6.0
5.8
5.5
6.82
plots
6.3
5.8
5.3
6.0
5.3
6\0
2.45
1974
1st
6.5
6.0
6.3
6.3
6.0
6.3
7.0
7.0
5.8
5.8
5.5
5.8
7.0
6.8
6.8
5.5
6.0
6.0
6.8
6.5
6.0
6.0
5.8
5.5
6.3
6.3
5.8
8.38
6.5
6.5
6.3
6.3
6.3
5.8
4.55
2nd
7.0
6.8
6.8
6.5
7.3
6.0
7.5
7.0
7.0
6.0
6.0
6.5
7.0
7.3
6.8
6.5
6.8
6.5
6.8
6.8
6.3
6.5
6.3
6.3
6.5
7.0
6.8
5.06
6.0
7.3
6.8
6.0
6.0
6.0
11.8
137
-------
Appendix Table 31. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE A (1972)
oo
oo
SITE
DATE ECXIQ3 PH CATIONS AMTONS CA
NA
CL COS HC03 S04 N03,PPM
A
A
A
A
A
A
A
A
ft
A
&
A
1/72
2/72
3/72
4/7H
5/72
6/72
7/72
ft/72
0/72
10/72
11/72
12/72
1.43
1.45
1.26
1.33
1.32
1.26
1.26
1.20
1.26
1.35
1.38
1.40
7.32
7.84
7.99
7.21
7.32
7.52
7.62
7.53
7.83
7.54
7.61
7.49
13.40
13.37
12.03
13.76
12.16
13.17
12.48
12.47
13.53
13.32
13.06
14.41
14.60
14.53
12.32
13.02
13.09
13.62
12.97
11.78
13.32
14.00
13.05
14.38
4.96
5.11
4.85
6.12
4.30
5.24
4.73
4.82
5.52
5.01
4.81
6.10
1.83
1.83
1.66
1.75
1.74
1.72
1.66
1.63
1.69
1.85
U91
6.43
6.23
5.34
5.71
5.89
5.95
5.87
5.80
6.09
6.23
6.20
6.18
0.18
0.20
0.18
0.18
0.23
0.26
0.22
0.22
0.23
0.23
0.22
0.22
3.59
3.76
3.36
3.41
3.40
3.47
3.30
3.20
3.44
3.72
3.76
3.75
0.45
0.65
0.30
0.35
1.00
0,29
0.30
0.0
0.29
0.35
0.31
0.29
3.87
3.61
3.93
2.78
2.70
3.96
3.88
3.39
3.66
3.08
2.41
3.64
6.66
6.51
5.23
6.47
5.99
5.90
5.49
5.19
5.93
6.85
6.57
6.70
1.61
0.31
0.31
0.62
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
STD.
1.32 7.57 13.10 13.43 5.13 1.76 5.99 0.21 3.51 0.38
0.08 0.23 0.70 0.83 0.54 0.09 0.30 0.02 0.20 0.24
3.41
0.54
6.12 0.24
0.59 0.49
-------
Appendix Table 32. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE B Q-972)
CO
to
SITS
P
e
8
F
P
e
P
p
p
R
fl
««,.
TO. nEV
DATF
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
.=
ECX103
1.48
1.51
1.30
1.35
1.37
1.30
1.27
1.24
1.30
1.40
1.46
1.46
1.37
0.09
PH
7.49
7.81
7.98
7.04
7.38
7.44
7.72
7.68
7.85
7.73
7.64
7.57
7.61
0.25
CATIONS
13.87
13.86
12.19
14.09
12.45
13.74
12.50
11.68
13.88
14.93
14.00
14.58
13.48
1.02
ANTONS
15.33
15.60
13.21
14.16
14.38
13.99
13.13
11.51
13.71
15.03
13.56
14.88
14.04
1.1A
CA
5.20
5.30
4.90
6.31
4.23
5.45
4.79
3.72
5.73
6.16
5.27
5.82
5.24
0.75
MG
1.86
1.88
1.67
1.78
1.84
1.78
1.67
1.66
1.71
1.88
1.9R
2.11
1.82
0.14
NA
6.62
6.44
5.44
5.82
6.14
6.28
5.81
6.07
6.21
6.65
6.52
6.43
6.20
0.37
K
0.19
0.24
0.18
0.18
0.24
0.23
0.23
0.23
0.23
0.24
0.23
0.22
0.22
0.02
CL
3.62
3.85
3.39
3.46
3.49
3.49
3.36
3.31
3.49
3.75
3.84
3.81
3.57
0.20
C03
0.49
0.14
0.31
0.0
1.04
0.24
0.95
0.32
0.45
0.63
0.37
0.71
0.47
0.31
HC03
4.05
4.30
4.01
4.32
3.47
4.00
3.18
2.08
3.46
3.37
2.34
3.44
3.50
0.71
S04
7.12
7.30
5.50
6.37
6.38
6.26
5.64
5.80
6.31
7.28
7.01
6.92
6.49
0.63
N03.PPM
3.35
0.93
0.0
0.62
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.41
0.98
-------
SITE
Appendix Table 33. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE A (1973)
OATE ECX103 PH CATIONS AN10NS CA
MG
NA
CL C03 HC03 S04 N03.PPM
A
A
A
A
A
A
A
A
A
A
A
A
1/73
2/73
3/73
4/73
5/73
6/73
7/73
R/73
9/73
10/73
11/73
12/73
1.34
1.36
1.25
1.23
1.21
1.17
1.22
1.19
1.19
1.29
1.29
1.26
6.75
7.07
7.42
6.68
6.92
6.84
7.10
7.67
8.22
8.05
8.54
8.27
13.78
13.39
13.46
12.72
12.36
12.53
12.94
13.19
12.72
14.63
12.58
12.42
13.95
13.75
12.20
12.93
13.31
13.40
12.59
12.10
12.42
14.59
12.98
12.98
5.64
5.03
5.47
4.98
4.80
5.26
5.41
5.43
4.79
6.28
4.69
5.30
1.85
1.79
1.62
1.58
1.58
1.55
1.57
1.56
1.57
1.66
1.74
1.75
6.07
6.35
6.12
5.90
5.71
5.47
5.72
5.98
6.14
6.46
5.91
5*16
0.22
0.22
0.25
0.26
0.27
0.25
0.24
0.22
0.22
0.23
0.24
0.21
3.70
3.70
3.56
3.49
3.41
3.20
3.25
3.05
3.03
3.47
3.39
3.45
0.43
0.0
0.54
0.30
0.43
0.04
0.61
0.51
0.42
0.55
0.17
0.52
3.77
4.23
3.41
3.24
3.92
4.94
3.28
3.46
3.53
3.63
2.99
3.01
6.05
5.82
4.64
5.83
5.51
5.21
5.43
5.05
5.40
6.88
6.41
5.97
0.0
0.13
3.39
4.40
2.57
0.68
1.01
1.60
2.42
3.55
1.54
1.63
MEAN =
STD.
1.25 7.46 13.06 13.10 5.26 1.65 5.92 0.24 3.39 0.38 3.62 5.68 1.91
0.06 0.66 0.67 0.74 0.44 0.10 0.36 0.02 0*22 0.20 0.55 0.61 1.39
-------
Appendix Table 34. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE B (1973)
SITF
DATE EC X10 3 PH CSTIONS ANT ON S CA
MG
NA
CL C03 HC03 S04 N03tPPM
B
B
B
B
B
B
8
B
B
8
e
e
MEtM.
STD.
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
c/73
10/73
11/73
12/73
DEV.=
1.41
1 .41
1.29
1.23
1.26
1.24
1.29
1.26
1.28
1.37
1.33
1.34
1.31
0.06
6.92
7.19
7.39
7.25
6.80
6.94
6.90
7.74
8.41
8.23
8.43
8.33
7.54
0.65
14.56
13.04
13.79
12.80
12.52
13.36
14.28
14.00
13.52
15.84
13.19
12.70
13.63
0.94
14.54
14.42
12.67
12.12
14.01
14.36
13.43
12.48
13.47
15. 69
13.68
13.14
13.67
1.01
6.02
4.36
5.66
5.02
4.70
5.70
5.94
5.70
5.26
6.87
4.55
5.40
5.43
0.71
1.95
1.85
1.65
1.60
1.65
1.64
1.68
1.67
1.63
1.77
1.90
1.81
1.74
0.11
6.38
6.62
6.22
5.94
5.92
5.77
6.40
6,41
6.34
6.98
6.48
5.27
6.23
0.45
0.21
0.21
0.26
0.24
0.25
0.25
0.26
0.22
0.24
0.22
0.26
0.22
0.24
0.02
3.75
3.73
3.59
3.46
3.42
3.31
3.34
3.20
3.25
3.88
3.61
3.30
3.49
0.22
0.17
1.14
0.42
0.44
0.0
0.20
0.11
0.42
0.60
0.45
0.27
0.25
0.37
0.30
4.09
3.59
3.67
3.55
4.70
5.14
4.14
3.14
3.48
3.91
3.39
2.82
3.80
0.65
6.53
5.94
4.94
4.66
5.88
5.68
5.81
5.69
6.09
7.40
6.36
6.73
5.98
0.74
0.0
1.30
2.81
0.60
0.91
1.72
1.63
1.93
2.89
3.33
3.00
2.33
1.87
1.04
-------
Appendix Table 35. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE A (1974)
to
SITE
DATE FCX103 PH C^TIfNS ANIONS CA
NA
CL C03 HC03 SO* N03,t»PM
A
A
A
1
A
A
A
A
A
A
A
1/74
2/74
3/74
4/74
5/74
6/74
7/74
fi/74
9/74
10/74
11/74
12/74
1.27
1.30
1.27
1.14
1.15
1.14
1.20
1.17
1.24
1.21
1.25
1.23
7.45
8.07
7.99
7.83
7.85
8.10
7.98
8.14
8. 15
8.10
fi.18
8.10
13.09
15.23
14.22
13.50
12.61
12.26
12.96
13.46
14.14
13.32
13.66
13.72
12.93
14.85
13.73
12.75
12.00
12.22
12.33
12.87
13.78
13.20
13.77
13.55
5.44
5.82
5.89
5.50
5.47
5.04
5.25
5.53
5.81
5.26
5.74
5.32
1.76
1.76
1.66
1.64
1.61
1.42
1.42
1.59
1.70
1.65
1.51
1.72
5.65
7.37
6.41
6.15
5.28
5.55
6.06
6.10
6.40
6.20
6.20
6.46
0.24
0.28
0.26
0.21
0.25
0.25
0.23
0.24
0.23
0.21
0.21
0.22
3.46
4.26
3.79
3.46
3.19
3.05
3.15
3.37
3.21
3.22
3.44
3.48
0.0
0.32
0.31
0.28
0.20
0.10
0.02
0.20
0.14
0.05
0.0
0.0
3.66
3.94
3.94
3.48
3.40
3.98
4.06
4.03
4.10
3.81
4.39
4.00
5.70
6.30
5.67
5.53
5.21
5.09
5.09
5.25
6.32
6.10
5.92
6.06
0.42
1.65
0.97
0.10
0.31
0.27
0.42
1.10
0.60
1.11
1.21
0.50
STO. 0?V.*
1.21 7.99 13.51 13.16 5.51 1.62 6.15 0.24 3.42 0.13 3.90 5.69 0.72
0.05 0.21 0.79 0.82 0.27 0.12 0.53 0.02 0.33 0.12 0.28 0.46 0.47
-------
Appendix Table 36. MEAN MONTHLY COMPOSITION (meq/1 EXCEPT N03 IN ppm)
OF DEL RIO DRAIN WATER AT SITE B (1974)
CO
SITE
B
B
B
B
B
B
B
B
B
B
B
B
ME*N =
STO.
DATE ECX103 PH CATIONS ANIONS CA
MG
NA
CL C03 HC03 S04 N03.PPM
1/74
?/74
3/74
4/74
5/74
6/74
7/74
8/7'*
'/74
10/74
11/74
12/74
.=
1.36
1.30
1.31
1.18
1.21
1.21
1.25
1.21
1.27
1.32
1.27
1.28
1.26
0.05
7.91
8.02
7.95
7.84
7.97
8.06
7.95
8.14
8.19
8.09
P. 21
8.08
8.03
0.11
13.71
15.40
14.90
14.11
13.56
13.73
13.85
14.19
14.74
14.31
14.24
14.03
14.23
0.54
14.45
15.33
14.22
13.55
13.05
13.13
13.20
13.66
14.62
14.52
14.62
14.35
14.06
0.72
5.78
5.82
6.35
5.82
5.76
5.58
5.70
5.90
6.19
6.07
5.85
5.81
5.89
0.22
1.85
1.80
1.75
1.73
1.69
1.55
1.41
1.62
1.75
1.65
1.54
1.71
1.67
0.12
5.84
7.50
6.54
6.34
5.86
6.35
6.51
6.43
6.58
6.38
6.64
6.29
6.44
0.42
0.24
0.28
0.26
0.22
0.25
0.25
0.23
0.24
0.22
0.21
0.21
0.22
0.24
0.02
3.56
4.26
3.83
3.51
3.24
3.27
3.26
3.47
3.30
3.35
3.54
3.53
3.51
0.29
0.10
0.46
0.45
0.05
0.23
0.04
0.03
0.14
0.16
0.13
0.0
0.0
0.15
0.16
4.31
4.08
3.95
4.16
3.97
4.24
4.21
4.23
4.36
4.47
4.62
4.18
4.23
0.19
6.46
6.50
5.97
5.83
5.61
5.57
5.69
5.80
6.78
6.55
6.42
6.63
6.15
0.44
1.37
1.81
1.55
0.03
0.31
0.43
0.64
1.49
1.13
1.27
2.22
0.78
1.09
0.66
-------
Appendix Table 37. ESTIMATED EC (mmhos/cm) OF RETURN FLOW BETWEEN DEL RIO DRAIN SAMPLING
SITES A AND B FOR 1972 AS CALCULATED BY THE EQUATION:
EC_ x flow_ - EC x flow.
rL.uw j.o J.IN m /sec
Date
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
Flow at
Site A
0.330
0.303
0.609
0.649
0.517
0.417
0.585
0.671
0.507
0.163
0.126
0.169
Flow at
Site B
0.434
0.407
0.668
0.737
0.608
0.471
0.653
0.787
0.660
0.383
0/368
0.311
Increase
in flow
0.104
1.104
0.059
0.087
0.090
0.054
0.069
0.117
0.153
0.220
0.242
0.142
EC at
Site A
1.43
1.44
1.31
1.29
1.32
1.27
1.26
1.22
1.26
1.36
1.36
1.39
(flown - flow.)
t* J\.
EC at
Site B
1.48
1.49
1.35
1.33
1.39
1.30
1.26
1.25
1.30
1.41
1.43
1.45
Increase
in EC
0.05
0.05
0.04
0.04
0.07
0.03
0.0
0.03
0.04
0.05
0.07
0.06
EC of re-
turn flow
(mmhos/cm)
1.64
1.63
1.76
1.63
1.79
1.53
1.26
1.42
1.43
1.45
1.47
1.52
Mean =1.54
-------
Appendix Table 38. ESTIMATED Ca CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN DEL RIO DRAIN
SAMPLING SITES A AND B FOR 1972 AS CALCULATED BY THE EQUATION: [Ca..] x flow.. - [Ca.] x flow.
-m r\ri -rr. -r»-t _"3/ •" DA A
rijuw j
LO UN nr"/sec
(flowB - flow.)
Ca Cone, of
Date
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
Flow at
Site A
0.330
0.303
0.609
0.649
0.517
0.417
0.585
0.671
0.507
0.163
0.126
0.169
Flow at
Site B
0.434
0.407
0.668
0.737
0.608
0.471
0.653
0.787
0.660
0.383
0.368
0.311
Increase
in flow
0.104
0.104
0.059
0.087
0.090
0.054
0.069
0.117
0.153
0.220
0.242
0.142
Ca at
Site A
4.96
5.11
4.85
6.12
4.30
5.24
4.73
4.82
5.52
5.01
4.81
6.10
Ca at
Site B
5.20
5.30
4.90
6.31
4.23
5.45
4.79
3.72
5.73
6.16
5.27
5.82
Increase return flow
in Ca
0.24
0.19
0.05
0.19
-0.07
0.21
0.06
-1.10
0.21
1.15
0.46
-0.28
Mean
(meq/1)
5.97
5.85
5.42
7.72
3.83
7.06
5.30
-2.60
6.43
7.01
5.51
5.49
= 5.25
-------
Appendix Table 39. ESTIMATED Mg CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN DEL RIO DRAIN
SAMPLING
FLOW IS
Date
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
SITES A AND B
IN m3/sec
Flow at
Site A
0.330
0.303
0.609
0.649
0.517
0.417
0.585
0.671
0.507
0.163
0.126
0.169
FOR 1972 AS
Flow at
Site B
0.434
0.407
0.668
0.737
0.608
0.471
0.653
0.787
0.660
0.383
0.368
0.311
CALCULATED BY
Increase
in flow
0.104
0.104
0.059
0.087
0.090
0.054
0.069
0.117
0.153
0.220
0.242
0.142
THE EQUATION:
Mg at
Site A
1.83
1.83
1.66
1.75
1.74
1.72
1.66
1.63
1.69
1.85
1.83
1.91
[Mg ] x flow
JD 15
(flOWg
Mg at
Site *
1.86
1.88
1.67
1.78
1.84
1.78
1.67
1.66
1.71
1.88
1.98
2.11
- [MgJ x
A
- flow.)
A
Increase
in Mg
0.03
0.05
0.01
0.03
0.10
0.06
0.01
0.03
0.02
0.03
0.15
0.20
flow
A
Mg cone, of
return flow
(meq/1)
1.96
2.02
1.77
2.00
2.41
2.24
1.76
1.83
1..78
1.90
2.06
2.35
Mean = 2.01
-------
Appendix Table 40. ESTIMATED Na CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN DEL RIO DRAIN
SAMPLING SITES A AND B FOR 1972 AS CALCULATED BY THE EQUATION: [NaJ
TIT f\r.f TO TUT —^ / &
x flowB - [Na.] x flow.
ciAJVi J-o i» m-'/sec 7-rr r-: r
(flowB - flowA)
Date
1/72
2/72
3/72
4/72
5/72
6/72
7/72
8/72
9/72
10/72
11/72
12/72
Flow at
Site A
0.330
0.303
0.609
0.649
0.517
0.417
0.585
0.671
0.507
0.163
0.126
0.169
Flow at
Site B
0.434
0.407
0.668
0.737
0.608
0.471
0.653
0.787
0.660
0.383
0.368
0.311
Increase
in flow
0.104
0.104
0.059
0.087
0.090
0.054
0.069
0.117
0.153
0.220
0.242
0.142
Na at
Site A
6.43
6.23
5.34
5.71
5.89
5.95
5.87
5.80
6.09
6.23
6.20
6.18
Na at
Site B
6.62
6.44
5.44
5.82
6.14
6.28
5.81
6.07
6.21
6.65
6.52
6.43
Increase
in Na
0.19
0.21
0.10
0.11
0.25
0.33
-0.06
0.27
0.12
0.42
0.32
0.25
Na cone, of
return flow
(meq/1)
7.23
7.05
6.47
6.64
7.57
8.81
5.30
7.62
6.61
6.96
6.69
6.73
Mean =6.97
-------
Appendix Table 41.
ESTIMATED EC (mmhos/cm) OF RETURN FLOW BETWEEN DEL RIO DRAIN SAMPLING SITES
A AND B FOR 1973 FLOW IS IN m3/sec
oo
Date
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Flow at
Site A
0.097
0.275
0.464
0.943
0.759
0.829
1.012
1.074
0.916
0.604
0.478
0.338
Flow at
Site B
0.245
0.352
0.499
1.100
0.715
0.910
1.147
1.309
1.051
0.952
0.601
0.501
Increase
in flow
0.149
0.076
0.035
0.157
-0.044
0.081
0.135
0.234
0.134
0.348
0.123
0.162
EC at
Site A
1.35
1.37
1.30
1.23
1.21
1.17
1.20
1.18
1.20
1.28
1.26
1.31
EC at
Site B
1.41
1.40
1.34
1.23
1.26
1.24
1.28
1.25
1.28
1.36
1.35
1.36
EC of re-
Increase turn flow
in EC (nunhos/cm)
0.06
0.03
0.04
0.0
0.05
0.07
0.08
0.07
0.08
0.08
0.09
0.05
Mean
1.45
1.51
1.86
1.23
0.40
1.96
1.88
1.57
1.83
1.50
1.70
1.46
= 1.53
-------
Appendix Table 42. ESTIMATED Ca CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1973 FLOW IS IN m /sec
Date
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Flow at
Site A
0.097
0.275
0.464
0.943
0.759
0.829
1.012
1.074
0.916
0.604
0.478
0.338
Flow at
Site B
0.245
0.352
0.499
1.100
0.715
0.910
1.147
1.309
1.051
0.952
0.601
0.501
Increase
in flow
0.149
0.076
0.035
0.157
-0.044
0.081
0.135
0.234
0.134
0.348
0.123
0.162
Ca at
Site A
5.64
5.03
5.47
4.98
4.80
5.26
5.41
5.43
4.79
6.28
4.69
5.30
Ca at
Site B
6.02
4.36
5.66
5.02
4.70
5.70
5.94
5.70
5.26
6.87
4.55
5.40
Increase
in Ca
0.38
-0.67
0.19
0.04
-0.10
0.44
0.53
0.27
0.47
0.59
-0.14
0.10
Mean
Ca cone, of
return flow
(meq/1)
6.27
1.95
8.15
5.26
6.42
10.22
9.92
6.94
8.47
7.89
4.01
5.61
- 6.76
-------
Appendix Table 43. ESTIMATED Hg CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1973 FLOW IS IN m3/sec
en
o
Date
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Flow at
Site A
0.097
0.275
0.464
0.943
0.759
0.829
1.012
1.074
0.916
0.604
0.478
0.338
Flow at
Site B
0.245
0.352
0.499
1.100
0.715
0.910
1.147
1.309
1.051
0.952
0.601
0.501
Increase
in flow
0.149
0.076
0.035
0.157
-0.044
0.081
0.135
0.234
0.134
0.348
0.123
0.162
Mg at
Site A
1.85
1.79
1.62
1.58
1.58
1.55
1.57
1.56
1.57
1.66
1.74
1.75
Mg at
Site B
1.95
1.85
1.65
1.60
1.65
1.64
1.68
1.67
1.68
1.77
1.90
1.81
Mg cone, of
Increase return flow
in Mg (meq/1)
0.10
0.06
0.03
0.02
0.07
0.09
0.11
0.11
0.11
0.11
0.16
0.06
Mean =
2.01
2.07
2.04
1.72
0.45
2.56
2.51
2.17
2.43
1.96
2.52
1.94
2.03
-------
Appendix Table 44. ESTIMATED Na CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1973 FLOW IS IN m3/sec
Ul
Date
1/73
2/73
3/73
4/73
5/73
6/73
7/73
8/73
9/73
10/73
11/73
12/73
Flow at
Site A
0.097
0.275
0.464
0.943
0.759
0.829
1.012
1.074
0.916
0.604
0.478
0.338
Flow at
Site B
0.245
0.352
0.499
1.100
0.715
0.910
1.147
1.309
1.051
0.952
0.601
0.501
Increase
in flow
0.149
0.076
0.035
0.157
-0.044
0.081
0.135
0.234
0.134
0.348
0.123
0.162
Na at
Site A
6.07
6.35
6.12
5.90
5.71
5.47
5.72
5.98
6.14
6.46
5.91
5.16
Na at
Site B
6.38
6.62
6.22
5.94
5.92
5.77
6.40
6.41
6.34
6.98
6.48
5.27
Increase
in Na
0.31
0.27
0.10
0.04
0.21
0.30
0.68
0.43
0.20
0.52
0.57
0.11
Na cone, of
return flow
Cmeq/1)
6.58
7.59
7.53
6.18
2.31
8.85
11.50
8.38
7.71
7.88
8.69
5.50
Mean =7.39
-------
Appendix Table 45.
Ol
IS3
ESTIMATED EC (mmhos/cm) OF RETURN FLOW BETWEEN DEL RIO DRAIN SAMPLING
SITES A AND B FOR 1974 FLOW IS IN m3/sec
Date
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Flow at
Site A
0.380
0.505
0.561
0.857
0.841
0.979
1.095
1.255
1.151
0.826
0.628
0.536
Flow at
Site B
0.500
0.639
0.729
1.039
1.053
1.156
1.387
1.522
1.427
1.030
0.836
0.670
Increase
in flow
0.119
0.133
0.168
0.181 '
0.212
0.176
0.292
0.267
0.276
0.204
0.208
0.133
EC at
Site A
1.26
1.31
1.26
1.14
1.14
1.18
1.20
1.20
1.23
1.26
1.22
1.16
EC at
Site B
1.33
1.33
1.32
1.19
1.22
1.25
1.30
1.24
1.26
1.36
1.28
1.21
Increase
in EC
0.07
0.02
0.06
0.05
0.08
0.07
0.10
0.04
0.03
0.10
0.06
0.05
EC of re-
turn flow
(imnhos/cm)
1.55
1.41
1.52
1.43
1.54
1.64
1.68
1.43
1.39
1.77
1.46
1.41
Mean =1.52
-------
01
co
Appendix Table 46. ESTIMATED Ca CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1974 FLOW IS IN m3/sec
Date
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Flow at
Site A
0.380
0.505
0.561
0.857
0.841
0.979
1.095
1.255
1.151
0.826
0.628
0.536
Flow at
Site B
0.500
0.639
0.729
1.039
1.053
1.156
1.387
1.522
1.427
1.030
0.836
0.670
Increase
in flow
0.119
0.133
0.168
0.181
0.212
0.176
0.292
0.267
0.276
0.204
0.208
0.133
Ca at
Site A
5.44
5.82
5.89
5.50
5.47
5.04
5.25
5.53
5.81
5.26
5.74
5.32
Ca at
Site B
5.78
5.82
6.35
5.82
5.76
5.58
5.70
5.90
6.19
6.07
5.85
5.81
Increase
in Ca
0.34
0.0
0.46
0.32
0.29
0.54
0.45
0.37
0.38
0.81
0.11
0.49
Mean
Ca cone, of
return flow
(meq/1)
6.86
5.82
7.89
7.33
6.91
8.58
7.39
7.64
7.78
9.35
6.18
7.78
= 7.46
-------
Appendix Table 47. ESTIMATED Mg CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1974 FLOW IS IN m3/sec
Date
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Flow at
Site A
0.380
0.505
0.561
0.857
0.841
0.979
1.095
1.255
1.151
0.826
0.628
0.536
Flow at
Site B
0.500
0.639
0.729
1.039
1.053
1.156
1.387
1.522
1.427
1.030
0.836
0.670
Increase
in flow
0.119
0.133
0.168
0.181
0.212
0.176
0.292
0.267
0.276
0.204
0.208
0.133
Mg at
Site A
1.76
1.76
1.66
1.64
1.61
1.42
1.42
1.59
1.70
1.65
1.51
1.72
Mg at
Site B
1.85
1.80
1.75
1.73
1.69
1.55
1.41
1.62
1.75
1.65
1.54
1.71
Mg cone, of
Increase return flow
in Mg (meq/1)
0.09
0.04
0.09
0.09
0.08
0.13
-0.01
0.03
0.05
0.0
0.03
-0.01
Mean =
2.14
1.95
2.05
2.16
2.01
2.27
1.37
1.76
1.96
1.65
1.63
1.67
1.88
-------
Appendix Table 48. ESTIMATED Na CONCENTRATIONS (meq/1) OF RETURN FLOW BETWEEN
DEL RIO DRAIN SAMPLING SITES A AND B FOR 1974 FLOW IS IN m3/sec
01
01
Date
1/74
2/74
3/74
4/74
5/74
6/74
7/74
8/74
9/74
10/74
11/74
12/74
Flow at
Site A
0.380
0.505
0.561
0.857
0.841
0.979
1.095
1.255
1.151
0.826
0.628
0.536
Flow at
Site B
0.500
0.639
0.729
1.039
1.053
1.156
1.387
1.522
1.427
1.030
0.836
0.670
Increase
in flow
0.119
0.133
0.168
0.181
0.212
0.176
0.292
0.267
0.276
0.204
0.208
0.133
Na at
Site A
5.65
7.37
6.41
6.15
5.28
5.55
6.06
6.10
6.40
6.20
6.20
6.46
Na at
Site B
5.84
7.50
6.54
6.34
5.86
6.35
6.51
6.43
6.58
6.38
6.64
6.29
Increase
in Na
0.19
0.13
0.13
0.19
0.58
0.80
0.45
0.33
0.18
0.18
0.44
-0.17
Mean
Na cone, of
return flow
Oneq/1)
6.44
7.99
6.97
7.24
8.16
10.79
8.20
7.98
7.33
7.11
7.97
5.61
- 7.65
-------
SECTION X
GLOSSARY
The definitions pertaining to cotton quality were taken from 1972
Regional Cotton Variety Tests. ARS-5-62. May 1975. Agricultural
Research Service, USDA.
Available water - The portion of water in a soil that can be readily
absorbed by plant roots. Considered by most workers to be that water
held in the soil against a pressure of up to approximately 15 bars.
Drawing sliver - Cotton fiber length measured on the servo fibrograph
from samples taken from the second-drawing sliver. The mean is the
average length, in inches, of all fibers longer than one-fourth inch.
The UHM (upper-half mean) is the length, in inches, of the half of the
fibers by weight that contains the longer fibers.
Elongation - The percentage elongation at break of the center one-eighth
inch of a cotton fiber bundle measured for strength on the stelometer.
Evapotranspiration - The combined loss of water from a given area, and
during a specified period of time, by evaporation from the soil surface
and by transpiration from plants.
Hydraulic conductivity - The proportionality factor in Darcy's law as
applied to the viscous flow of water in soil. Darcy's law states that
the flux of fluid is proportional to the driving force (hydraulic gradient).
Lint percent - The weight of lint ginned from a sample of seed cotton,
expressed as a percentage of the weight of seed cotton.
Micronaire - The fineness of the cotton fiber sample taken from the
ginned lint measured on the micronaire and expressed in standard
(curvilinear scale) micronaire units.
Neutron probe - A device, that relies on fast neutron thermal ejection
in the presence of hydrogen nuclei, to estimate the concentration of
hydrogen (and hence water) in a system. Used to determine soil moisture.
Salinity sensor - As used in this study - A porous plate whose electrical
resistance is governed by the salts present in the plate (after equili-
bration with the soil solution) and used to estimate the electrical con-
ductivity of the soil solution.
Span length - Cotton fiber length measured on the digital fibrograph.
The distance spanned by a specified percentage of the fibers in the
test specimen, where the initial starting point of the scanning in the
test is considered 100 percent. The 2.5-percent span length is the
156
-------
length* tn inches, on. the te§t specimen spanned by 2.5 percent of the
fibers scanned at the Initial starting point.
Strength. - The fiber strength, of a bundle of cotton fibers measured on
the stelometer with the two jaws holding the fiber bundle separated by
a 1/8 inch spacer, expressed in centinewtons per tex.
Tensjometer - A device for measuring the negative pressure Cor tension)
of water in soil "in situ"; a porous permeable ceramic cup connected
through a tube to a manometer or vacuum gauge.
Uniformity ratio - For cotton; the ratio of mean length to upper-half
mean QJHM) length, expressed as a percentage.
Water application efficiency - The percentage of the water applied that
is actually stored in the root zone for use by the crops.
157
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-77-093
3. RECIPIENT'S ACCESSION-NO.
. TITLE AND SUBTITLE
NFLUENCE OF TRICKLE AND SURFACE IRRIGATION ON
IETURN FLOW QUALITY
5. REPORT DATE
May 1977 issuing date
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT
Peter J. Wierenga
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Agronomy
ew Mexico State University
as Cruces, New Mexico 88003
10. PROGRAM ELEMEN-
1HB617
' NO.
11. CONTRACT/GRANT NO.
S-803156
(Formerly 13030GLM)
12. SPONSORING AGENCY NAME AND ADDRESS
lobert S. Kerr Environmental Research Laboratory-Ada,
Office of Research and Development
J.S. Environmental Protection Agency
Ma, Oklahoma 74820
OK
13. TYPE OF REPORT AND PERIOD COVERED
Final-July 1971 to Feb. 1975
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A field plot study was conducted to determine the effects of controlled surface irri-
gation and trickle irrigation on the quality and quantity of irrigation return flow.
The surface-irrigated plots showed an increase in salt concentration with depth to
the clay-sand interface. Below the clay-sand interface at 80-100 cm, a sharp decrease
in salt concentration was observed. It appeared that a larger change in soil salinity
was produced by altering irrigation frequency than by changing irrigation efficiency.
Irrigating when 50 percent of the soil water had been depleted was the irrigation fre-
quency most conducive to salt retention by the soils. Trickle irrigation was effec-
tive in controlling the volume of return flow, while maintaining relatively low sali-
nity levels in the soil around the trickle emitters. Accumulated salts were readily
moved away from trickle lines by preplant irrigation or rainfall. The mean salt con-
centration of the irrigation return flow, as estimated from deep soil solution samples
agreed well with the average salt concentration of the groundwater to a depth of 11
meters. Below 11 meters the salt content of the groundwater decreased.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Irrigation, leaching, salinity
Water quality
Irrigation return flow,
Rio Grande basin,
Mesilla valley,
Irrigation efficiency
02C
8. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
!0. SECURITY CLASS (Thispage)
Unclassified
21. NO. OF PAGES
176
22. PRICE
EPA Form 2220-1 (9-73)
158 #U.S. GOVERNMENT PRINTING OFFICE: 1977-757-056/61! 18 Region No. 5-1 |
------- |