EPA-600/2-76-158
September 1976
Environmental Protection Technology Series
NITROGEN AND IRRIGATION MANAGEMENT TO
REDUCE RETURN-FLOW POLLUTION IN
THE COLUMBIA BASIN
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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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 five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards
the Nationai
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EPA-600/2-76-158
September 1976
NITROGEN AND IRRIGATION MANAGEMENT TO REDUCE
RETURN-FLOW POLLUTION IN THE COLUMBIA BASIN
by
Brian L. McNeal
and
Bobby L. Carlile
Department of Agronomy and Soils
Washington State University
Pullman, Washington 99163
Grant No. S-801187
Project Officer
C. E. Veirs
U.S. Environmental Protection Agency
Region X
Seattle, Washington 98101
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
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
Cooperative field studies have evaluated dissolved-N levels and leach-
ing, and corresponding crop yields, for potato production practices in
the Columbia Basin area of Washington. High dissolved-N levels
(with resultant high potential for return-flow pollution) were found
throughout the growing season in well-managed potato fields, with
levels decreased by decreasing fertilization rate, use of slow-re-
lease N fertilizers or nitrification inhibitors, or sprinkler ap-
plication of N fertilizers.
Careful water management with solid-set sprinklers proved capable
of maintaining dissolved-N within the root zone of subsequent crops
by season's end, even on very sandy sites. Alternate -furrow irri-
gation proved effective in "trapping" banded fertilizer N within the
plant root zone on heavier-textured furrow-irrigated soils. Periodic
"mining" of residual N by other crops in the rotation would still be
necessary to prevent eventual return-flow contamination, however.
Site-to^site sampling variability necessitates the use of composited
soil samples, rather than fixed-position soil solution extraction
cups, for adequate monitoring of N in soils of this area. Neither
dissolved soil N nor plant petiole nitrate-N proved to be reliable
predictors of crop N needs at the high residual soil N levels com-
monly found.
This report was submitted in fulfillment of Grants Number 13030-FST
andS-801187, by Washington State University, Pullman, under the
(partial) sponsorship of the Environmental Protection Agency. Work
was completed as of October, 1974.
iii
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CONTENTS
Sections Page
I Conclusions 1
II Recommendations 6
III Introduction 8
IV Experimental Procedure 11
1971 Season 11
1972 Season 15
1973 Season 17
1974 Season 19
V Results and Discussion 21
1971 Season 21
1972 Season 40
1973 Season 52
1974 Season 84
VI References 103
VII Publications 104
VIII Appendix 105
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TABLES
No. Page
1 Summarized Climatological Data, 1971-1969, 22
Block 21 Site
2 Monthly Water Applications, Block 21 Site 23
3 Summarized Furrow Runoff Data, Block 21 Site 24
4 Total Yield Data, Block 21 Site 26
5 Tuber Quality Data, Block 21 Site 27
6 Average Dissolved Inorganic N, Soil Solution, 29
Block 21 Site
7 Dissolved Inorganic N, Paired Locations, 30
Block 21 Site
8 Soil Nitrate N, Sprinkler-irrigated Plots, 31
Block 21 Site
9 Soil Nitrate N, Furrow-irrigated Plots, 32
Block 21 Site
10 Dissolved Inorganic N, Nitrification Retardant 34
Plots, Block 21 Site
11 Irrigation Water and Runoff Water Analyses, 35
Block 21 Site
12 Averaged Values for Dissolved Inorganic N, 37
Block 21 Site
13 Average Soil Parameters as a Function of Depth, 38
Block 21 Site
14 Comparison of Extraction Cup and Soil Sample 41
N Values, Block 21 Site
15 Dissolved Inorganic N, Furrow-rate Experiment, 42
1972
16 Dissolved Inorganic N, Suspension Fertilizer 43
Experiment, 1972
17 Dissolved Inorganic N, Suspension Fertilizer 44
Experiment, Fall of 1972
18 Dissolved Inorganic N, 1971 Suspension Fertilizer 45
Experiment, 1972
vi
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TABLES (continued)
No. Page
19 Dissolved Inorganic N, Fertilizer Factorial 47
Experiment, Fall of 1972
20 Available P and K, Fertilizer Factorial 47
Experiment, Fall of 1972
21 Dissolved Inorganic N, Slow-Release N 49
Experiment, 1972
22 Variations in Soil Silt Content, Experimental 51
Plots, Othello Station
23 Summarized Comparison of Extraction Cup and 53
Soil Sample N Values, Othello Station
24 Dissolved Inorganic N, Suspension Fertilizer 55
Experiments, Tri-Cities Area, 1973
25 Dissolved Inorganic N and Yield Data, Suspension 56
Fertilizer Experiments, Horse Heaven Hills
Area, 1973
26 Dissolved Inorganic N and Yield Data, Suspension 58
Fertilizer Experiments, Moses Lake Area, 1973
27 Dissolved Inorganic N and Yield Data, Suspension 61
Fertilizer Experiments, Othello Area, 1973
28 Dissolved Inorganic N, Slow-release N Experiments, 63
Tri-Cities Area, 1973
29 Dissolved Inorganic N and Yield Data, Slow-release 65
N Experiments, Horse Heaven Hills Area, 1973
30 Dissolved Inorganic N and Yield Data, Slow-release 67
N Experiments, Moses Lake Area, 1973
31 Dissolved Inorganic N and Yield Data, Slow-release N 69
Experiments, Othello Area, 1973
32 Dissolved Inorganic N and Yield Data, Slow-release 72
N Experiments, Othello Station, 1973
33 Additional Dissolved Inorganic N Data, Slow-release 73
N Experiments, Othello Station, 1973
34 Petiole Nitrate-N Levels, Suspension Fertilizer and 76
Slow-release N Experiments, 1973
35 Correlation of Soil Dissolved Inorganic N and 78
Petiole Nitrate-N with Potato Yield and
Quality, 1973
vii
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TABLES (continued)
No.
36 Dissolved Inorganic N and Yield Data, Nitrogation 80
Experiment, Othello Station, 1973
37 Dissolved Inorganic N and Yield Data, Sprinkler 82
Irrigation Rate Experiment, Othello Station,
1973
38 Dissolved Inorganic N, Extraction Cup Values, 83
Othello Station, 1973
39 Summarized Petiole Analyses, By Fertilization 85
Rate, Petiole N Experiment, Othello Station,
1974
40 Summarized Petiole Analyses, By Variety, 86
Petiole N Experiment, Othello Station, 1974
41 Yield Data, Petiole N Experiment, Othello Station, 88
1974
42 Yield Data Correlated with Petiole Nitrate Levels 89
for Entire Season, Petiole N Experiment,
Othello Station, 1974
43 Yield Data Correlated with Petiole Nitrate Levels 90
Prior to August 15, Petiole N Experiment,
Othello Station, 1974
44 Di-Syston Analyses, Di-Syston Experiment, 92
Othello Station, 1974
45 Yield Data, Di-Syston Experiments, 93
Othello Station, 1974
46 Soil Analyses, Sprinkler-irrigated Di-Syston 94
Plots, Othello Station, 1974
47 Soil Analyses, Furrow-irrigated Di-Syston 96
Plots, Othello Station, 1974
48 Properties of Runoff Samples, Furrow-irrigated 99
Plots,, Othello Station, 1974 and 1973
49 Dissolved Inorganic N and Rainfall Data, 101
Minimum Tillage Plots, Othello Station,
1974
Vlll
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ACKNOWLEDGEMENTS
The authors gratefully acknowledge the helpful support, field plot
supervision and maintenance, and yield data provided for the Block 21
site by personnel from the Irrigated Agriculture Research and Exten-
sion Center, Prosser, including J. E. Middleton, S. Roberts, and
T. A. Cline. Similarly, the cooperation, field plot supervision and
maintenance, and yield data provided by R. Kunkel and N. M. Holstad
of the Department of Horticulture, Washington State University,
Pullman, was invaluable and essential to the remaining studies.
Field sampling was conducted by numerous students in addition to the
authors, including C. P. Diaz, T. Dechert, J. T. Leifer, W. E.
Goode, Li. S. Peterson, T. Waszielewski, and K. L. Drecksel.
Petiole sampling and analyses were performed by Horticulture De-
partment personnel, under the supervision of R. Kunkel.
Laboratory analyses were performed under the capable supervision of
N. M. Ellsworth, with analysts including C. T. Hatch, D. Harston,
C. P. Diaz; T. Dechert, T. H. Chaudhary, W. E. Goode, J. T.
Leifer, T. Waszielewski, and S. Johnson.
The support of the project by the Environmental Protection Agency
and the help provided by Mr. C. E. Veirs, the Grant Project Officer,
is acknowledged with sincere thanks. Additional support for the
studies was provided by the College of Agriculture Research Center,
Washington State University, Pullman.
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SECTION I
CONCLUSIONS
High levels of dissolved inorganic nitrogen (primarily nitrate-N) exist
in soil solutions from within and beneath potato fields of the Columbia
Basin during the cropping season. Such values frequently exceed
several hundred mg N/liter early in the season, with minimum values
of 20-60 mg N/liter commonly persisting in the fields even at season's
end. When compared to the recommended drinking water maximum
of 10 mg N/liter, this indicates a considerable potential for ground
water and drainage water contamination by soil solutions displaced
whenever excessive irrigation water usage occurs in this area.
Normal furrow irrigation of potatoes on sandy soils of the Basin pro-
duced extensive leaching of N and required from 5 to 15 times the
quantity of water required for efficient sprinkler irrigation at the
same location. Alternate-fur row irrigation (where two adjacent
irrigation furrows are never wet concurrently) "trapped" much of the
fertilizer N in the plant root zone and produced considerably less
leaching of N.
Careful irrigation with solid-set sprinkler systems, at quantities
dictated by micrometeorological or pan evaporation data, produced
near-maximum yields of high-quality tubers even on extremely sandy
soils, while still maintaining any high levels of dissolved-N from the
current crop season in the top 60 to 120 cm of soil, where it could be
removed by subsequent crops in the rotation. However, there was a
common tendency to over-irrigate late in the season, when plants had
matured and crop water needs had diminished. Center-pivot irriga-
tion appeared to produce excessive leaching of N in some portions of
the irrigated field.
Increases in dissolved-N consistently were observed with increased
fertilization rate, so that greater leaching and subsoil contamination
by N occured at the higher fertilization rates. Increases in N con-
centration were not strictly proportional to fertilization rate, with a
6-fold increase in fertilization rate commonly producing only a 2- to
3-fold increase in dissolved-N levels of the soil solution.
High residual levels of N in the soil solution persisted from fall until
spring, unless leached by over-winter rains. High residual-N levels
were reduced to a more-nearly acceptable range during a subsequent
fallow period or following subsequent growth of a deep-rooted crop.
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An increase in dissolved-N levels was observed at mid-season,
which may be due to release of N from residues of the preceeding
crop.
Deep-leached N appeared to be neither assimilated nor denitrified to
an appreciable extent, with long-term application of 450 kg N/hectare
leading to subsoil dissolved-N concentrations of 150 mg/liter at a silt
loam site. Subsoil dissolved-N concentrations of 20-50 mg/liter per-
sisted even in N-stressed fields, unless such solutions were diluted
or leached subsequently by additional drainage waters. Once beneath
the plant root zone, the dissolved-N thus would constitute a continual
hazard for ground water contamination in the area.
Use of microbial nitrification inhibitors {such as N-Serve) lowered
soil dissolved-N concentrations and reduced the leaching of N from
the plant root zone. Lower leaching losses were obtained for urea +
N-Serve than for NH^NO, + N-Serve, with N apparently not accumu-
lating in the former case because plant uptake occurred as rapidly as
N was converted to the nitrate form.
Use of slow-release N fertilizers (such as sulfur-coated urea or urea-
formaldehyde) substantially lowered dissolved-N levels. The lowered
dissolved-N values (commonly 1/2 or less of those obtained from
comparable rates of traditional fertilizers) led to lowered leaching
losses at sandy or over-irrigated sites. However, higher residual-N
levels often remained at the season's end in plots fertilized with slow-
release fertilizers, due to lowered uptake and leaching losses.
"Nitrogation" (sprinkler application of nitrogen during normal irriga-
tion operations) produced little evidence of substantial N leaching
even at high fertilization rates and infrequent application intervals.
However, dissolved-N levels of 10-50 mg/liter persisted in the
nitrogation plots, with substantially higher values near the season's
end if nitrogation was prolonged into the late-season period of de-
creased plant water uptake.
Sprinkler irrigation at 1.5 times the rate predicted from pan evapora-
tion data produced the highest total yields at a sandy site, despite
some late-season leaching of N. Higher sprinkler rates decreased
potato yields due to excessive leaching of N, and lower rates led to
lowered yields because of uneven water distribution under the windy
Columbia Basin conditions (although the latter was less critical at
less sandy sites). Tuber quality increased slightly at the higher
sprinkler application rates. Early excess sprinkler irrigation for
wind erosion control produced N leaching and gave lowered yields if
N was applied only at planting time, but side-dressed or sprinkler-
applied N later in the season completely offset this effect. Lowered
overall yields on furrow-irrigated sandy soils were lowered even
more for the extreme head (heavily-leached) and tail (water-stressed)
portions of the field. The high water needs of the potato crop make
proper water and N management essential in the prevention of return-
flow contamination in this area.
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Fertilization rates of 220 to 450 kg N/hectare generally were suf-
ficient for maximum yield of high-level tubers at the several ex-
perimental locations sampled throughout the Columbia Basin area.
Yields of U.S. No. 1 tubers throughout the Columbia Basin were
depressed by high nitrogen application rates. This may have been
due to insufficient growing season length for the amount of N applied,
to excessive vegetative growth, or to early-season salt effects re-
sulting from high concentrations of salt in the fertilizer band. In any
event, over-fertilization thus can be argued against on both environ-
mental and economic grounds. Slow-release N fertilizers gave as
good or better yields than traditional fertilizers, and particularly at
the higher fertilization rates. Lower yields from the slow-release
forms on some of the more N-stressed plots might have been over-
come with small amounts of starter N applied at the time of planting.
The less-soluble forms of slow-release fertilizers generally gave
higher yields than the more-soluble forms, unless N stress was
present.
Fumigation of recropped potato lands may have retarded nitrification
and N leaching, although fumigated plots often required more fertilizer
N, due to the higher overall yields produced. Tailoring N application
rates to actual plant populations (which are difficult to predict in ad-
vance) appeared to produce higher yields without correspondingly
higher residual dissolved-N levels.
Petiole NOo-N levels decreased as the season progressed, and gen-
erally increased with increasing N-fertilization rate. However, no
evidence of a "critical" plant petiole nitrate-N level was found for
petiole levels above 5,000 ppm nitrate-N. As a critical level of
10,000 ppm petiole nitrate-N is commonly recommended in the area,
this may account for some of the apparent excessive usage of N on
many potato crops in the Basin. Petiole nitrate-N and rootzone
dissolved-N were not well correlated for plots having fertilizer
banded at moderate to high rates, due to restricted N uptake until the
band became more diffuse later in the growing season. Total yield
or tuber quality could be predicted from dissolved soil N or petiole
nitrate-N only for N-stressed (e.g..highly leached) plots. In general,
neither of these parameters were adequate yield predictors through-
out much of the Columbia Basin area.
Runoff waters from furrow-irrigated plots generally contained less
than 1 to 2 mg/liter dissolved inorganic N, with turbidity values
ranging from 300 to 600 Jackson turbidity units (JTU) for both sandy
and silt-loam sites early in the season, and decreasing to 20 to 40
JTU as furrows stabilized by mid-sea son. Runoff from a furrow-
irrigated sandy site averaged 6 to 9 percent of the water applied to
400-foot runs.
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Soil-test phosphorus (P) and potassium (K) levels increased 5-fold
and 2-fold, respectively, in the top 30 cm of soil for 450 kg/hectare
(oxide form) fertilization rates on long-term fertility plots. Values
for soil-test P also were increased 3-fold for the 30-60 cm depth of
soil in these same plots, with neither P nor K increased at subsequent
plot depths. Fertilization at a rate of 450 kg P-CX/hectare increased
soil-test P to the highest soil-test category in only 2 years. Only
small increases in the P and K levels of adjacent experimental plots
resulted from wind or water transport of heavily-fertilized surface
soil particles. The relatively small increases in soil-test K levels
in the long-term fertility plots may reflect both high levels of plant
uptake of this element, and a tendency towards its fixation in un-
available forms by soils of the area .
The systemic pesticide Di-syston disappeared from fertilizer bands
by season's end when used at recommended rates. However, Di-
syston persisted in the fertilizer bands at higher application rates.
Di-syston appeared to be lost most rapidly from sprinkler-irrigated
plots. No effects of high residual Di-syston levels on crop yields
were evident.
Soil textural variations within both a sandy and a silt loam experi-
mental site were not large, despite the fact that each site had been
leveled to accomodate surface irrigation. However, surface soil
soil-test P and K values varied much more, and were highly cor-
related. Such variations probably arose both from the initial level-
ing operations and from, subsequent fertilization and/or crop utiliz-
ation patterns. Soil sampling variability for dissolved-N levels was
extremely large. Variability in reported N levels was nearly as
large for sprinkler-irrigated plots as for furrow-irrigated plots, for
the lower profile as for the upper profile, for broadcast fertilizer
applications as for banded applications {especially late in the growing
season), and for soil samples as for samples from soil solution
extraction cups. Despite wide variations at any point in space or
time, seasonal average dissolved-N values for extraction cups and
soil samples were essentially identical. Hence the sampling, storage,
and data extrapolation procedures used for the study appear to have
been satisfactory.
Ceramic extraction cups constituted a poor sampling procedure for
dissolved-N, due to extremes in concentration encountered at lateral
soil distances of only a few meters. The cups also failed to con-
sistently extract from all depths at all times in non-flooded fields
(producing variable sampling populations from one period to the next),
had a large probability that solute peaks would occur between extrac-
tion cup depths on any given sampling date, and often were at vari-
able lateral positions with respect to the fertilizer band. Reliance
on even continuous sampling would not circumvent such problems,
because of the widely different rates and patterns of water movement
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at points only a few meters apart in the field. Extrapolation from a
few extraction cup sites to an entire irrigated field appears to be a
completely unacceptable approach for monitoring or verification of
fertilizer leaching patterns in the area.
Water flux values (estimated from tensiometer and water content data)
ranged from 0.02 to 2 cm/day during the growing season at a well-
irrigated silt loam site typical of older potato lands in the Columbia
Basin. Water movement may have been restricted by a compacted
layer which forms at depths of 20 to 30 cm in fields of the area. Al-
though nitrogen flux values vary continuously throughout the growing
season, an average downward water flux of 0.1 cm/day for 120 days
would leach 59 kg N/hectare at an average dissolved-N level of 50
mg/ liter.
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SECTION II
RECOMMENDATIONS
Because of the high dissolved-N levels present even in well-managed
potato fields, good water management is essential to the prevention of
local ground water and drainage water contamination. Carefully reg-
ulated solid-set sprinkler systems appear most capable of restricting
N leaching under the windy Columbia Basin conditions, with water ap-
plication rates estimated (as has been recommended previously) from
evaporation pan or micrometeorological values during mid-season
and from soil sampling during the early-season and late-season
periods of decreased water needs. Center-pivot sprinkler systems
also can be used effectively in this area, although water distribution
patterns and N application practices should be carefully investigated
if deep percolation and surface runoff losses are to be minimized.
Some leaching losses of fertilizer N must be accepted for furrow
irrigati9n systems in the area, because of their higher water re-
quirements for most soils of the Columbia Basin. However, use
of band-applied fertilizers coupled with alternate-furrow irrigation
techniques can substantially lower N leaching losses at many furrow-
irrigated locations.
As economics permits, management practices which minimize the
levels of dissolved-N present in the soil during the growing season
should be selected. These include the use of slow-release N fer-
tilizers or nitrification inhibitors, of sprinkler-applied N ("nitroga-
tion") techniques, of lower rates of fertilizer N than currently
employed in many situations, and of deep-rooted cover crops or
of periodic alternate crops to utilize residual N prior to potato re-
cropping. Over-winter cover crops should be grown with only min-
imum levels of starter N applied at the time of planting, to enhance
utilization of residual dissolved N. Fall application of fertilizer N
for subsequent potato crops should be employed only under conditions
where essentially no nitrification of this N will occur prior to the
over-winter period (because of moisture-temperature relations or
because of nitrification inhibition due to fall fumigation practices).
Recommended minimum petiole nitrate-N levels for high-level
potato production should be lowered to 5,000 ppm for many portions
of the Basin, because of demonstrated high-level production even at
this petiole nitrate-N level.
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Replicated and composited soil samples taken across row-furrow sets
should be used to characterize dissolved-N levels in soils of the area.
Reliance should not be placed upon a few soil solution extraction cups
placed in a "typical" field, for behavior at a single site is rarely
indicative of average behavior throughout an entire irrigated field.
Domestic water supplies from shallow ground water sources in potato-
producing areas should be tested regularly for dissolved-N contam-
ination, with alternate supplies (such as bottled water) seriously con-
sidered for nursing mothers and young infants in such areas.
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SECTION III
INTRODUCTION
High-level potato production normally requires large quantities of
both water and nutrients. Such conditions maximize the potential for
ground water and drainage water return-flow contamination during
crop growth. Hence, the crop makes an excellent indicator of man-
agement techniques required to minimize return-flow contamination
from intensively-cultivated row crops in the irrigated Columbia
Basin area of Washington. The fact that the state of Washington is
second in the nation in total potato production, and leads the nation in
potato production per acre, further adds to the acceptability of the
potato as an indicator crop for this area.
Field studies of a research and demonstration nature normally require
large expenditures of time and money for the collection of even
minimal amounts of data. The current study was proposed as an
extension of a cooperative effort between Washington State University
(WSU) and the U.S. Bureau of Reclamation (USER), with the original
study being designed to demonstrate water requirements and crop
yields on extremely sandy sites proposed for irrigation development
in the Columbia Basin. It was a logical extension to monitor return
flow contamination associated with the various management practices
under examination. Such monitoring was conducted during the initial
year of EPA funding, in cooperation with I.E. Middleton, S. Roberts,
and T. A. Cline of the WSU Irrigated Agriculture Research and Ex-
tension Center, at Prosser. Because of funding delays, however,
the original WSU-USBR cooperative study was completed before sub-
sequent crop seasons could be studied. Thus,an additional cooper-
ator was sought.
The project leaders were fortunate to find a willing cooperator in
Dr. Robert Kunkel of the Department of Horticulture at WSU, whose
large-scale field operations provided numerous opportunities to
monitor return-flow contamination associated with a wide variety of
potato management practices. Although some small-scale coopera-
tive field plots were established as well, most work during the re-
mainder of the project period centered around the monitoring of soil
solutions within and beneath many of Dr. Kunkel's potato management
plots in the Columbia Basin area. The small loss of individual
freedom associated with this approach was offset many-fold by the
large number of plots available for monitoring during this period.
Original objectives of the project were:
0
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"To determine the quantities of nutrients, sediments,
pesticides, and total salts carried by seepage waters under
varied irrigation methods and fertility treatments.
"To demonstrate that the contamination of surface water
and local ground water is significantly influenced by the
method and efficiency of irrigation. The advantages of
proper irrigation practices and fertilizer management in
the control of pollutants will be a prime objective in this
study.
"To develop and promote good water management practices
as a means of reducing water quality degradation and to
demonstrate the economics of these practices under intensive
irrigation agriculture."
Of these objectives, the goals dealing with pesticides and economics
obviously have been short-changed. Pesticide analyses were sup-
planted in many cases by the larger-than-anticipated numbers of
nutrient and total solute (salt) analyses available from the actual
cooperative studies. The goal dealing with economics soon became
regarded as overly-naive, in light of the many management choices
associated with the actual study. Economic considerations logically
should constitute a separate , additional study once adequate sedi-
ment data for the Northwest are available. Such a study would per-
mit a valid comparison to be made of trade-offs between drainage
water and runoff water contamination under various management
conditions.
The original plan of operation for the project was as follows:
"Field research and demonstration studies are proposed to
evaluate irrigation techniques and fertilization management
practices for minimization of water quality impairment in
irrigation waste water. Water and nutrient movements will
be measured under both furrow and sprinkler systems at
various water application rates and fertility treatments .
Suspended sediment in surface waste water will be monitored
and the distribution of nutrients between the aqueous and
solid phases will be examined. Total salt removal under
various treatments will also be studied.
"Urea and ammonium fertilizers in combination with a
nitrification retardant and slow-release formulas will be
studied in an attempt to reduce leaching losses of nitrogen
during early season irrigation.
"Porous cups will be utilized to collect samples of soil solution
for analyses. These cups will be buried at varied depths in
the soil and at sufficient locations in and around each plot to
measure the quality of water moving through the profile.
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"Techniques for the "in situ" measurements of soil moisture
flux will be further developed and tested in field plots in an
attempt to obtain more accurate water mass balance equations
under field conditions."
Of these plans, only the nutrient distributions between sediments and
associated runoff waters, and the "in situ" flux measurements, were
short-changed. Once again, the nutrient distribution studies were
supplanted by the larger-than-anticipated numbers of nutrient and
total salt analyses available from the actual cooperative studies.
Field moisture fluxes proved to be estimated with sufficient accuracy
from tensiometer readings and field water content data, so that in-
situ flux measurements were no longer essential to the study.
The remaining objectives and experimental plans were fulfilled to a
greater extent than had been anticipated, due to the excellent coopera-
tive relationships which existed during the study period.
10
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SECTION IV
EXPERIMENTAL PROCEDURE
1971 SEASON
The 1971 cropping season (the initial year of project funding) was the
third and final year of field research at the Block 21 experimental
site. This location had been selected for a cooperative study by
personnel from Washington State University (primarily from the
Irrigated Agriculture Research and Extension Center, at Prosser)
and the U.S. Bureau of Reclamation (at Ephrata). Soils at the site
were extremely sandy, and hence typified many of the new lands being
developed or proposed for development in the Columbia Basin area.
The project was designed to demonstrate that carefully controlled
sprinkler irrigation of such soils was feasible, whereas furrow (rill)
irrigation was impractical; and to conduct research into proper ir-
rigation, fertilization, and management practices for such soils.
Site and Crop
The experimental site was on Farm Unit 30, Block 21, of the Columbia
Basin Irrigation Project. The land was the property of the U.S.
Bureau of Reclamation and had been leveled for the study. Sprinkler
and furrow irrigation systems were installed prior to the first year
of operation in 1969. The total experimental area was 13.6 hectares
(33.5 acres), with 3.9 ha. used for sprinkler irrigation, 2.3 ha, for
furrow irrigation, and the balance as border area. The latter was
cropped to alfalfa in order to minimize boundary effects at the site.
Russet Burbank potatoes were used as the indicator crop. The ex-
perimental plot area was doubled in order to avoid potatoes follow-
ing potatoes in successive years. Thus , part of the area could be
maintained in fallow or an alternate crop while the remainder was in
potatoes. This procedure helped minimize problems with Verticillium
wilt and similar crop-specific diseases.
Experimental Design
Both furrow and sprinkler irrigation methods were investigated, using
three irrigation rates, each replicated three times. Sprinkler plots
were 24.4 x 24.4 meters, with furrow-irrigated plots being 10.4 x
122 meters (34 x 400 feet). Each of the latter generally was treated
as two 10.4 x 61-meter sub-plots representing the head and tail
11
-------
portions of the field, respectively. A third set of plots was establish-
ed in 1969 and 1971 to measure the effects of early-season sprinkler
irrigation for wind erosion control on such sandy soils. The latter
plots were 12.2 x 12.2 meters. Experimental variables were built
around a split plot design, with fertilizer rates constituting the split
plot and irrigation treatment constituting the whole plot. Internal
borders separated the split plots.
The three sprinkler irrigation treatments used during the study period
were based on the estimated minimum quantity of water (designated
as the Ql treatment) needed to just meet the evapotranspiration needs
of the crop. This quantity was determined by the evaporation pan
method (Jensen et al. , 1961) as approximately 35% of the available
moisture in the top 60 cm. (2 feet) of soil plus estimated application
losses for the sprinkler system used. Additional sprinkler-irrigation
rates included 1.25 x Ql and 1.50 x Ql (designated respectively as the
Q2 and Q3 rates) in 1969 and 1970, and 1.50 x Ql and 1.80 x Ql {des-
ignated respectively as the Q3 and Q4 rates) in 1971. The Q4 rate
was added in 1971 to determine if the Q3 rate was approaching the
maximum application rate for optimal potato production under the
conditions of these experiments. Water was applied every other day
in 1969 and daily in 1970 and 1971 at the indicated rates. Soil moisture
levels were checked by gravimetric sampling. Treatments Q2 , Q3,
and Q4 were controlled by nozzle size-pressure relationships for the
system so that a single length of time could be used for each ir-
rigation application.
Fertilizer treatment sub-plots were four rows wide and 12.2 meters
(40 feet) long, with fertilizer banded at planting time. Levels of
nitrogen were varied in 112 kg/ha. (100 Ib/a) increments between 112
and 560 kg N/ha., at 0, 110 or 560 kg P/ha. , and at 0, 220 or 560 kg
K/ha. Zinc was applied uniformly to all plots at a rate of 17 kg/ha.
The 5 nitrogen application rates, plus supplementary P and K treat-
ments, gave a total of 12 fertilizer treatments for this experiment.
The three furrow irrigation treatments used during the study period
were based on the quantity of water (designated as the Wl treatment)
required to wet the rows to mid-bed at mid-run for each irrigation.
This was considered the minimum quantity of water that could be
used for furrow irrigation at the site. This judgement was con-
firmed by the moisture stress that existed for many plots in the tail
portion of the field at this water application rate. Additional furrow-
irrigation rates each season included 2.0 x Wl and 3.0 x Wl (des-
ignated respectively as the W2 and W3 rates) on a time basis. Despite
the water stress at the tail end of the field for the Wl treatment,
excessive deep percolation occurred even with this treatment for plots
at the head end of the field. Irrigation interval was four days in 1969,
three days in 1970, and two days (on an alternate-furrow basis) in
12
-------
1971. Fertilizer treatments were similar to those for the sprinkler
experiments, except that only 4 nitrogen application rates were
employed. Separate yield data were maintained, in order to permit
measurement of fertility-moisture interactions related to differential
leaching between the head and tail of the furrow-irrigated field.
In a third experiment at this location for the 1969 and 1971 seasons ,
the effect of early season sprinkler irrigation for wind erosion con-
trol was evaluated. Two irrigations of approximately 8 surface cm.
(3 surface in.) of water each (8.6 cm on May 20 and 8.1 cm on May
28) were applied between planting and plant emergence for these
plots. Normal irrigation rates (comparable to the Ql rates described
above) then were applied during the regular crop season. In addition
to assessing the degree of N leaching accompanying this practice, the
use of urea and of nitrification retardants (e.g., N-Serve) was
evaluated in an attempt to reduce nitrate formation during the early
season period, and thereby reduce the potential for deep leaching of
N.
General
A weather station was maintained at the site, monitoring wind speed
and direction, pan evaporation, rainfall, and minimum and maximum
daily temperatures. A winter wheat or sorghum cover crop was
maintained on those plots not in use during a given season or portion
thereof. Standard recommended applications of herbicides, fungicides,
and insecticides were made throughout the growing season for control
of plant pests. In a cooperative study, plant petioles were collected
and analyzed throughout the growing season in order to assist fertiliza-
tion recommendations for such sandy soils in the Columbia Basin.
Crop yield data for the various treatments were collected as part of
the cooperative study.
Soil and Water Sampling and Analyses
Porous ceramic extraction cups were used to collect samples of the
soil solution for analysis throughout the growing season. The cups
were standard (2.2 cm OD x 7.0 cm) tensiometer cups from Soil
Moisture Equipment Co. , Santa Barbara, California. They were
connected to the soil surface with 0.5 cm nylon tubing, with Silastic
bathtub calk used to produce a vacuum tight seal between tubing and
extraction cup. The cups were buried at 30 cm depth intervals in
the soils of 3 replicates each of the Ql, Q3, Wl and W3 irrigation
treatments, at the 560 kg N/ha. fertilization rate. These data pro-
vided a measure of the quality of water percolating through the profile
and/or moving laterally from the plots. Cups were placed to a
13
-------
maximum depth of 2.4 to 3.1 meters (8 to 10 ft.), depending upon the
depth of underlying basalt bedrock in each plot. A portable vacuum
pump was used to produce a vacuum of approximately 0.4 bar at
each location, with a small butane tank used as a vacuum buffer
volume on the manifold system for each set of cups . Soil solution
extraction was terminated for each depth after 50-100 ml of solution
had been obtained from the appropriate extraction cup or after 24
hours had elapsed since irrigation. Samples were stored in a
refrigerator at ca. 4° C until analysis.
All extraction cups were prewashed with 1 !N HC1 prior to installation,
as recommended by Grover and Lamborn (1970). Dissolved inorganic
N in the samples was measured -with a steam distillation method
employing MgO and Devarda's alloy (Bremner, 1965). Most of this
nitrogen was in the nitrate form, as identified by combining the
above steam distillation procedure with one employing MgO alone
(Bremner, 1965) during the initial phase of the study. In addition,
sample pH and electrical conductivity (EC) were measured with a
standard laboratory pH meter and conductivity cell, respectively.
Chloride was measured potentiometrically with a commercial
chloridimeter (Cotlove, 1964).
Soil samples were collected at 30 cm (1 ft) depth increments on April
13, July 19, and September 24 from beneath those plots in which the
extraction cups had been placed, as a check on soil solution measure-
ments. Samples were collected with a King tube sampler during the
season and either with a King tube or a hydraulic Giddings sampler
at season's end. Samples were placed in 250 or 500 ml plastic
cartons for transport the same day to the laboratory in Pullman. The
samples then were frozen until they could be dried and analyzed.
Drying was in a convective drying oven at 60° C for 24 hours, with
samples then ground to pass a 2 mm sieve and stored until analysis.
Analyses were performed on 2:1 water:soil extracts, which were
clarified by centrifugation after a 10-minute extraction period on a
reciprocating shaker. Mechanical analysis (particle-size distribution)
was run for some samples by the hydrometer procedure of Day (1965),
using sodium hexametaphosphate (Calgon) as the dispersing agent.
Samples of input irrigation water and of surface runoff water from
the furrow-irrigated plots were obtained periodically throughout the
growing season. Additional analyses performed on these samples
included turbidity in Jackson turbidity units (J.T.U.) with a Hach
turbidimeter, soluble orthophosphate by an ascorbic acid modification
of the Murphy and Riley (1962) method, and soluble polyphosphate by
hydrolysis with H^SO^-HNO, in an autoclave for 30 minutes (American
14
-------
Public Health Association, 1965), followed by analysis as for
orthophosphate.
In addition to porous cup collection of soil solutions, piezometers
(hollow pipes) were drivaito ground water (2.4 to 3.1 meter depth)
at several locations around the periphery of the study area, in
order to monitor changes in ground water elevation and quality during
the study period. Ground water sampling was not designed to reflect
individual treatment effects, but rather to show major differences in
ground water response between the sprinkler- and furrow-irrigated
areas.
1972 SEASON
Work during the second year of the study was moved to the Othello
Experimental Station, which is owned by Washington State University.
The silt loam soils at this site are more typical of the older, develop-
ed areas of the Columbia Basin. Such soils have lower permeabilities
and higher water-holding capacities than do the sandy soils studied
during the first year of the project. Studies at this location were in
cooperation with R. Kunkel and N. M. Holstad of the Department of
Horticulture at Washington State University. A combination of
ceramic soil solution extraction cups, and replicated soil samplings,
was used to characterize the distribution and movement of fertilizer
elements under various management regimes . Most experimental
plots on the Othello station were either 2 or 4 rows wide, and ap-
proximately 9.2 meters (30 feet) long. Six replicates of most treat-
ments were sampled, with results composited to produce the data
tabulated in this report.
Furrow-irrigation Rate Experiment
In a replicated irrigation-rate, fertilization-rate experiment con-
ducted during the 1972 growing season, a standardized, furrow-
irrigation setting was employed to wet alternate sides of a given
crop row every 2, 4, or 6 days (normal irrigation practice at the
station involves an alternate-row interval of 2.5 days). Nitrogen
fertilization rates of 220 and 460 kg N/ha. were applied to the plots
in a banded application at the time of planting. Extraction cups were
placed in all the experimental plots, with samples of extracted soil
solution, as well as soil samples, taken at regular intervals through-
out the growing season.
15
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Tensiometers were used in the plot area of these and other experi-
ments to provide estimates of the downward flux of water (quantity
moving per unit of soil cross-sectional area) during the growing
season. Portable tensiorneters were used for similar measurements
at off-station locations during the 1973 season. Sufficient data were
collected from these sources to permit fairly reliable estimates of
downward water flux from soil water contents alone at the Othello
site.
Suspension Fertilizer Experiment
In fertilizer-rate experiments at Othello, suspension fertilizers (high-
analysis mixtures of liquid and solid forms) were used as a concen-
trated source of nutrients, with treatments including banded, broad-
cast, sidedressed, and mixed applications at six rates ranging from
110 to 670 kg/ha, for each fertilizer element. Selected treatments
from this experiment were monitored, using both soil samples and
soil solution extraction cups, in replicated plots throughout the 1972
growing season. In addition, selected plots from the 1971 suspension
fertilizer experiments at the Othello station were monitored to assess
dissolved-N levels after the over-winter period and throughout the
following summer and fall. The latter plots were seeded to ryegrass
in August of 1972, with the ryegrass clumps covering about 25% of the
soil surface at the time of the fall sampling.
Long-term Fertilizer Factorial
A key set of experiments at the Othello station was the long-term
fertilizer plots , which had been maintained in differential fertilizer
treatments ranging from 110 to 450 kg/ha, of each nutrient element
annually since 1965, until 480 kg N/ha. was applied uniformly to the
plot area in 1972. Both soil sampling and ceramic soil solution
extraction cups were used to monitor these plots. The plots had been
furrow-irrigated prior to the 1972 season, but were sprinkler-ir-
rigated during the sampling period. Downward water flux estimates
were made from tensiometers placed in the plots.
Slow-release Nitrogen Sources
In a final set of experiments monitored at the Othello station during
the 1972 season, traditional N sources were compared with slow-
release N formulations by replacing one-third of the traditional N
source with one of three slow-release sources and monitoring soil
solution dissolved-N levels and corresponding crop yields. Soil
sampling was used exclusively for monitoring of these plots.
16
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1973 SEASON
During the 1973 cropping season, soil sampling was expanded to assess
fertilizer utilization and leaching in several growers' fields. These
fields were arrayed in a 150 km (100 mile) arc extending from a loca-
tion in the Horse Heaven Hills area south of Pasco and Kennewick to
a location east of Moses Lake in the northern portion of the Columbia
Basin. All locations were managed by the growers themselves, and
thus provided an estimate of potential contamination of ground waters
and drainage waters under "real-world" operating conditions. In
addition, experiments were continued at the Othello Experimental
Station of Washington State University.
Sampling of Growers' Fields
Two of the locations which were sampled used center-pivot sprinkler
systems, and thus provided valuable data on the leaching occurring
at different locations along the quarter-mile-long, moving booms of
such systems. A replicated plot design laid out across the entire
diameter of the circle provided data comparing fertilizer utilization
and leaching as a function of relative boom location, fertilization rate,
dry versus liquid fertilizer formulation, banded versus broadcast
fertilizer application, and fumigated versus non-fumigated (chiseled
only) potato seedbeds. In addition, a study of relative N leaching as
a function of fertilization rate, using both standard and slow-release
N fertilizer sources, was included at each location. As an aid to
evaluating the feasibility and benefits of each treatment, yield data
were obtained for all treatments at each location.
The two remaining growers' fields consisted of one furrow-irrigated
location and one solid-set sprinkler-irrigated site. Treatments
evaluated at these locations included fertilization rate, dry versus
liquid fertilizer formulation, fumigated versus non-fumigated potato
seedbed, banded versus broadcast fertilizer applications, and
standard versus slow-release nitrogen sources. The locations pro-
vided additional data on fertilizer utilization and leaching under
cropping conditions typical of those encountered in the central
Washington area.
All locations were sampled extensively at the start of the growing
season, approximately monthly during the growing season for
selected plots, and again extensively at the conclusion of the growing
season. Soil sampling was used exclusively to monitor these loca-
tions. Yield data were obtained from all plots to permit evaluation
17
-------
of the feasibility of various management practices. Data from these
locations also supplemented data from the two extensively-studied
sites (Block 21 and the Othello station) in a comparison of plot-to-plot
soil variability under a wide variety of experimental conditions.
Sampling at the Othello Station
In addition to the above experiments, further experiments were con-
ducted in 1973 on the Othello Experimental Station. One experiment
involved a detailed comparison of yields and of utilization and leach-
ing of N for three standard and three slow-release N fertilizer
sources. A second experiment evaluated fertilizer utilization at dif-
ferent fertilization rates for sprinkler-irrigated potatoes harvested
after variable growing periods, to simulate potato production for dif-
ferent portions of the fresh and processing markets. Still another
experiment involved evaluation of yields and fertilizer leaching for
differentially-fertilized plots irrigated at three different sprinkler-
irrigation rates (estimated optimum, 0.75 x optimum, and 1.50 x
optimum) and fertilized at rates ranging from 110 to 670 kg N/ha.
Irrigation scheduling was based upon a combination of micro-
climatological measurements and weighing lysimeters maintained by
G. S. Campbell, W. H. Gardner, and C. Calissendorff of WSU. A
final experiment at this location involved assessment of yields and of
N leaching in plots where a majority of the fertilizer N was applied in
soluble form through the sprinkler line at two rates, and at intervals
of either two, four, or six weeks, during the final 2/3 of the growing
season. This was done to see if lowered soil solution N values could
be maintained through "nitrogation" (sprinkler application of fertilizer
N), while still giving high-level production of high-quality tubers.
The 1973 cropping season also was used to collect supplemental data
on water quality effects from irrigation agriculture, including addi-
tional monitoring of typical irrigation waters and tailwaters for
furrow-irrigated plots at the Othello station, and evaluation of sedi-
ment yield from these same plots. An extensive comparison of
petiole N values and of corresponding soil N levels was initiated by a
Peruvian student (C. P. Diaz) who assisted with much of the field
program for 1973. This study was designed to aid in establishing
necessary plant and soil N values which permit both economical
potato production and minimal leaching of fertilizer N. Yearly soil
test analyses of surface soils from the long-term fertilizer factorial
experiment (described above) were also evaluated in 1973, to deter-
mine the extent of lateral surface transport of P and K during furrow
irrigation of these plots.
18
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1974 SEASON
Much of the research effort during the final year of study revolved
around completion of accumulated analyses from samplings of pre-
vious seasons, and summarization and evaluation of accumulated
experimental data. Hence, the field program for 1974 was returned
to the Othello station and reduced considerably in scope. Most
experimental work was concentrated on two small-scale experiments
at this location.
Potato Yields at Constant Petiole Nitrate-N Levels
A standard approach to nitrogen management in the Columbia Basin
and elsewhere has been the monitoring of plant petiole nutrient levels,
with application of nitrogen through the sprinkler line whenever the
petiole N or nitrate-N values approach a specified "critical" level.
In order to obtain data on the reliability of this approach, three
varieties of potatoes were grown in sprinkler-irrigated plots on the
Othello station, with N applied through the sprinkler line in an
attempt to maintain petiole nitrate-N levels of 2,500, 5,000, 10,000,
or 20,000 ppm throughout the growing season. Fertilization through
the lines was begun on June 13, after 90 kg N/ha. which was banded
at the time of planting was largely depleted. Fertilization was with
liquid ammonium nitrate (20% N). Petiole samples were taken weekly
from June 12 to September 18, or until suitable petioles were no
longer being produced by the vines. All plots were replicated 6 times,
Effects of Di-systoh Rates on Potato Yields
In another 1974 experiment at the Othello station, two potato varieties
were treated with 4.5, 9, 18, or 36 kg/ha. (actual) Di-syaton (a
systemic insecticide), with the dual goal of monitoring decreases in
Di-syston levels throughout the growing season and of determining the
yields from potato plots exposed to various Di-syston rates. One
portion of the experiment consisted of a sprinkler-irrigated field
having superimposed N fertilization rates of 220 or 450 kg N/ha. A
second portion consisted of a furrow-irrigated field fertilized at a
rate of 450 kg N/ha., but with superimposed plant populations of
37,000 or 57,000 plants per hectare. Soil sampling was conducted
monthly and consisted of a constant volume of soil (including each of
the two fertilizer bands for a single potato row) from each sampled
plot. Di-Syston analyses were carried out by gas chromatography
following hexane extraction, using a modification of the procedure of
Clapp (1975). Samples of soil from the fertilizer bands also were
used to follow changes in EC, pH, chlorides, and dissolved inorganic
N within the band during the growing season.
19
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Nitrogen Movement Associated with Minimum Tillage Potato Pro-
duction (Preliminary)
In a final sampling program for the 1974 season, soil samples were
collected in early spring from plots where potatoes were being planted
directly in the stubble of a previously-fertilized winter wheat or rye-
grass cover crop. This management approach, designed to minimize
both wind erosion and traffic compaction in potato fields of the
Columbia Basin area, is being tested extensively on the Othello station
at the present time. Samples were taken with a King tube by 30 cm-
or 60 cm-increments to the depth of the underlying caliche layer.
The samples were placed in plastic cartons, transported to Pullman,
and then handled and analyzed as described above for other soil
samples collected during the study period.
20
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SECTION V
RESULTS AND DISCUSSION
1971 SEASON
Experiments for the 1971 season were conducted at the sandy Block 21
experimental site. As for previous years of the Block 21 study (1969
and 1970), the data demonstrated that extensive leaching of N
from the soil profile occurred when such soils were furrow-irrigated,
or when they were sprinkler-irrigated at excessive rates. However,
carefully managed sprinkler-irrigation generally maintained fertilizer
N in the upper part of the soil profile, where it could be taken up by a
deep-rooted cover crop or by subsequent crops in the rotation.
Climatological and Water Application Data
Climatological data for the Block 21 experimental site are summarized
by month and growing season in Table 1. Typical features of growing
seasons in the area are steady winds (of greater intensity during the
late spring and early fall portions of the growing season), generally-
cool late springs and early summers, and hot, dry mid-summer
months. Distinctive for the 1971 season was the prolonged (28 day)
period of greater-than 32° C (90° F) temperatures in late July and
early August, which began just 2 days after the daily minimum temper-
ature had dropped to 4° C (39° F). Wind during this season ranged
from a high of 870 km/day on April 12 to a low of 18 km/day on August
20. The 1970 and 1969 seasons exhibited hotter and drier Junes than
did the 1971 season, as reflected by both the temperature and evapora-
tion data. Another distinctive feature of the Climatological data was
the low evaporative demand in September of 1970, reflecting the early
killing frost of this season.
Water application data for the Block 21 experimental site are sum-
marized by month and growing season in Table 2, with correspond-
ing runoff data from the furrow-irrigated plots summarized in Table
3. An average of only 67 to 76 surface cm (2.2 to 2.5 surface feet)
of irrigation water was required for potato production at this site
under the conditions of most efficient irrigation management (Ql
sprinkler treatment), whereas an average of 290 to 445 surface cm
of water was required for the lowest rate of furrow irrigation. The
enhanced potential for nutrient leaching from such soils during fur-
21
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Table 1. SUMMARIZED CLJMATOLOGICAL DATA, 1971-1969, BLOCK 21 SITE
ro
Parameter
1971 Season
(April 6-Sept. ZO)
Total precipitation (cm)
Total evaporation (cm)
Average minimum
temperature (° C)
Average maximum
temperature (° C)
Average wind (km/day)
1970 Season
(April 7 -Sept. 11)
Total precipitation (cm)
Total evaporation (cm)
Average minimum
temperature (° C)
Average maximum
temperature (° C)
Average wind (km/day)
1969 Season
(May 5 -Sept. 16)
Total precipitation (cm)
Total evaporation (cm)
Average minimum
temperature (° C)
Average maximum
temperature (° C)
Average wind (km/day)
April
0.43
13.9
2
18
245
2.11
12.8
2
16
285
-
-
_
-
May
1.68
22.6
7
24
253
0.23
21.0
6
22
190
1.35
7
26
174
June
3.53
22.1
7
23
182
0.76
29.3
12
29
193
1.22
11
29
237
July
0.64
31.1
13
31
148
0.33
28.1
12
30
127
0.00
13. 9a
1 f\
10
31
116
Aug.
0.28
25.0
12
32
93
0.00
28.8
12
31
148
0.00
22.9
28
146
Sept.
2.16
14.1
5
23
249
0.41
6.0
7
23
163
0.00
12.3
7
i
28
219
Total or
Wtd. Avg.
8.71
128.8
8
26
190
3.84
125.9
9
26
182
2.57
49.1
Q
7
29
174
Measurements begun July 19.
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Table 2. MONTHLY WATER APPLICATIONS, BLOCK 21 SITE
(surface cm of water)
Experixnenta
1971 Season
(April 6-Sept. 20)
Early excess
Ql
Q3
Q4
Wl
W2
W3
1970 Season
(April 7 -Sept. 11)
Ql
Q2
Q3
Wl
W2
W3
1969 Season
(May 5 -Sept. 16)
Early excess
Ql
Q2
Q3
Wl
W2
W3
April
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.6
2.0
2.4
8.2
10.1
8.6
0.0
0.0
0.0
0.0
0.0
0.0
May
20.2
3.3
5.1
6.0
34.1
36.6
38.2
2.9
3.7
4.4
19.3
22.2
21.1
9.9
3.5
_
3.5
0.0
0.0
0.0
June
12.7
11.5
17.5
20.9
71.2
94.1
119.7
16.9
21.2
25.5
97.4
166.0
251.4
21.5
14.7
-
21.6
62.9
140.7
157.4
July
26.4
26.6
40.7
48.5
96.4
193.0
296.9
26.3
32.9
39.5
139.1
227.2
371.2
27.2
26.2
-
38.2
94.5
192.9
253.5
Aug.
23.1
23.0
35.6
42.5
107.3
210.0
330.6
22.9
28.7
34.5
140.5
253.1
393.1
24.9
24.8
-
36.9
95.5
170.5
237.8
Sept.
3.2
3.3
5.0
6.0
29.0
45.4
70.1
4.6
5.7
6.9
40.3
69.4
39.7
6.4
5.8
-
8.6
35.1
58.2
82.2
Total
85.5
67.7
104.0
124.0
338.0
579.0
855.6
75.1
94.2
113.2
444.9
748.1
1161.3
89.9
75.1
-
108.9
288.0
562.4
730.8
^Early excess = Ql + two early-season applications for wind erosion control; Ql, Q2, Q3 , and
Q4 = sprinkler application rates of optimum, 1.25 x optimum, 1.50 x optimum and 1.80 x
optimum, respectively; Wl, W2, and W3 = furrow application rates of minimum, 2.0 x mini-
mum, and 3. Ox minimum, respectively.
K>
-------
Table 3. SUMMARIZED FURROW RUNOFF DATA, BLOCK 21 SITE
a. Expressed as surface centimeters of water
a
Experiment
Wl (1971)
W2 (1971)
W3 (1971)
Wl (1970)
W2 (1970)
W3 (1970)
Wl (1969)
W2 (1969)
W3 (1969)
April
0.0
0.0
0.0
0.3
0.2
0.1
0.0
0.0
0.0
May
1.0
0.8
1.4
2.6
2.0
2.2
0.0
0.0
0.0
June
4.2
5.9
8.4
11.9
42.8
45.7
4.5
7.5
9.7
July
5.9
16.9
24.4
14.9
50.2
68.4
5.8
16.8
19.1
Aug.
6.8
23.1
36.9
9.7
30.4
38.2
5.8
15.9
18.0
Sept.
2.1
4.3
7.2
2.5
7.1
10.7
1.9
3.4
5.1
Total or
Wtd. Avg.
19.9
51.1
78.3
41.9
132.7
165.3
18.0
43.6
51.8
b. Expressed as a percentage of the applied water
Experiment
Wl (1971)
W2 (1971)
W3 (1971)
Wl (1970)
W2 (1970)
W3 (1970)
Wl (1969)
W2 (1969)
W3 (1969)
April
0.0
0.0
0.0
3.1
1.8
1.2
0.0
0.0
0.0
May
2.9
2.3
3.6
13.3
9.2
10.3
0.0
0.0
0.0
June
5.9
6.3
7.0
12.2
25.8
18.2
7.1
5.4
6.1
July
6.1
8.8
8.2
10.7
22.1
18.4
6.2
8.7
7.5
Aug.
6.3
11.0
11.2
6.9
12.0
9.7
6.0
9.3
7.6
Sept.
7.3
9.5
10.2
6.3
10.2
9.2
5.3
5.8
6.1
Total or
Wtd. Avg.
5.9
8.8
9.2
9.4
17.7
14.2
6.2
7.8
7.1
, W2, and W3 = furrow application rates of minimum, 2.0 x minimum, and 3.0 x mini-
mum, respectively.
-------
row irrigation or poorly managed sprinkler irrigation is evident from
this comparison. Because of the high infiltration rates of soils at the
site, runoff generally was less than 6 to 9 percent of the total water
applied to furrow-irrigated plots, even after irrigation furrows had
been carefully shaped and packed to minimize early-season percola-
tion losses during the 122 meter (400 ft) irrigation run. The marked
increase in water application and runoff in 1970 is ascribed to the
increased frequency of irrigation compared to the 1969 season.
Adoption of the alternate-furrow irrigation approach substantially
lowered water application and runoff values for the 1971 season.
Yield Data
Data on total yield of potatoes at the Block 21 site are summarized in
Table 4. Corresponding values for percent U.S. No. 1 tubers are
given in Table 5. Yield data for the 1970 season are considered un-
reliable, because of a severe infestation of leafroll at the site. The
infestation had a particularly marked effect on potato quality for the
furrow-irrigated plots.
Highest total yields generally were obtained for the high-rate Q3
sprinkler irrigation treatment, despite substantial leaching of
fertilizer N. The low-rate Ql and Q2 sprinkler treatments ap-
parently produced moisture stress in some plots under the windy
Columbia Basin conditions , and the high-rate Q4 treatment pro-
duced excessive leaching of N. The latter effect was evident for the
lower N-fertilization rates in 1971. Application of early excess
sprinkler irrigation reduced yields at the lowest N-fertilization rate,
but sidedressed and sprinkler-applied N added later in the growing
season restored high yields for this treatment. Because all N was
not banded at the time of planting in the early-excess experiment,
results are not strictly comparable with those for standard sprinkler-
irrigated plots.
Total yields were substantially lower for the fur row-irrigated plots.
Average yields generally were somewhat higher for the tail portion
of the field (61-122 meters of run), although differences in yield be-
tween the two portions of the field were not large. Yields of furrow-
irrigated plots generally were lowest in the head portion of the field
for the W3 (high-rate furrow) treatment, due to the high leaching
produced. However, the same treatment generally produced the
highest yields in the tail portion of the field, due to decreased mois-
ture stress.
Yields of U.S. No. 1 tubers (Table 5) were substantially higher for
the sprinkler-irrigated plots than for their furrow-irrigated counter-
parts. Values commonly were highest at intermediate nitrogen ap-
plication rates, with the depressing effect of high levels of N on
tuber quality particularly evident at the lower water application rates
and in the tail portion of the furrow-irrigated field.
25
-------
Table 4. TOTAL YIELD DATA, BLOCK 21 SITE
(quintal/hectare)3
Treatment
1971 Season
Early excess
Ql
Q3
Q4
Wl (0-6lm)
W2 (0-61m)
W3 (0-6lm)
Wl (6l-122m)
W2 (6l-122m)
W3 (6l-122m)
1970 Season
Ql
Q2
Q3
Wl (0-6lm)
W2 (0-61m)
W3 (0-61m)
Wl (6l-122m)
W2 (6l-122m)
W3 (6l-122m)
1969 Season
Early excess
Ql
Q2
Q3
Wl (0-61m)
W2 (0-61m)
W3 (0-61m)
Wl (61- 122m)
W2 (6l-122m)
W3 (61- 122m)
Nitrogen application rate (kg N/hectare)
110 220 340 450 560
426
516
450
417
-
_
-
-
-
-
452
405
461
-
-
.
-
-
-
412
376
392
450
-
-
-
-
-
551
495
536
493
251
227
231
241
242
246
465
487
536
352
316
245
419
412
448
515
508
515
494
383
321
310
377
379
396
553
587
598
591
329
289
284
347
300
358
529
549
531
363
423
278
448
426
508
586
520
531
508
479
381
345
401
475
484
600
521
603
562
314
253
283
237
228
311
458
514
554
351
358
382
355
420
441
609
560
566
580
411
368
450
372
407
459
-
590
644
626
349
293
314
311
264
278
472
438
516
419
358
233
305
379
376
627
584
587
589
457
414
435
430
417
488
^Divide by 1.12 to convert values to cwt/acre.
"Early excess = Ql + two early-season applications for wind erosion
control; Ql, Q2 , Q3, and Q4 = sprinkler application rates of
optimum, 1.25 x optimum, 1.50 x optimum and 1.80 x optimum,
respectively; Wl, W2, and W3 = furrow application rates of mini-
mum, 2.0 x minimum, and 3.0 x minimum, respectively.
26
-------
Table 5. TUBER QUALITY DATA, BLOCK 21 SITE
(percent U.S. No. 1's)
Treatment
1971 Season
Early excess
Ql
Q3
Q4
Wl (0-61m)
W2 (0-6lm)
W3 (0-6lm)
Wl (6l-122m)
W2 (6l-122m)
W3 (61- 122m)
1970 Season
Ql
Q2
Q3
Wl (0-6lm)
W2 (0-6lm)
W3 (0-6lm)
Wl (6l-122m)
W2 (6l-122m)
W3 (6l-122m)
1969 Season
Early excess
Ql
Q2
Q3
Wl (0-6lm)
W2 (0-6lm)
W3 (0-6lm)
Wl (6l-122m)
W2 (61-122m)
W3 (61- 122m)
Nitrogen application rate (kg N/hectare)
110 220 340 450 560
82.3
84.4
78.7
75.9
*
^
_
-
68.5
67.5
63.6
_
._
_
_
.
.
88.0
85.5
89.5
91.5
_
_
_
-
85.4
84.4
84.5
83.5
65.5
65.0
67.7
57.5
61.9
65.7
67.2
70.1
69.6
33.6
29.3
21.0
26.1
35.1
38.6
80.7
76.4
87.9
89.0
59.0
67.0
65.0
48.3
61.3
55.4
84.6
81.9
83.8
86.3
78.8
61.1
58.1
53,2
56.9
60.3
66.8
65.3
60.9
36.8
19.7
26.2
13.2
37.4
22.1
58.3
67.6
90.0
87.9
55.3
59.1
67.6
37.7
35.9
40.0
81.2
77.0
76.5
81.2
70.9
61.6
68.8
56.0
57.9
55.4
63.9
66.5
64.8
32.7
22.1
31.2
15.8
24.1
31.1
63.1
76.8
83.8
88.5
58.2
50.2
56.2
35.3
38. 6
43.0
-
70.5
71.4
75.1
58,5
55.6
67.0
46.9
47.3
44.8
59.7
59.6
57.3
27.1
14.8
17.2
8.8
31.1
26.3
66.4
70.2
82.9
84.6
35.3
48.5
49.3
17.9
36.0
41.5
aEarly excess = Ql + two early-season applications for wind erosion
control; Ql, Q2, Q3, and Q4 = sprinkler application rates of
optimum, 1.25 x optimum, 1.50 x optimum and 1.80 x optimum,
respectively; Wl, W2, and W3 = furrow application rates of mini-
mum, 2.0 x minimum, and 3.0 x minimum, respectively.
27
-------
Soil Solution Dissolved Inorganic Nitrogen Values
Summarized results of the extraction cup sampling for soil solution
N values in 1971 and 1970 are presented in Table 6. No extraction
cup sampling was carried out at the site in 1969. Complete extrac-
tion cup data for the two seasons, including values for electrical
conductivity (EC) and dissolved chloride (Cl) as well, are presented
in Appendix Tables A-l to A-9. Appendix data for the 1971 season
are the average of 3 replicates, whereas data for the 1970 season
represent individual sites, and thus more clearly demonstrate the
sampling problems encountered.
High dissolved -N concentrations (primarily nitrate-N) were observed
in soil solutions extracted from all plots during the growing season
(Tables 6, A-3, A-6, and A-9). Values in excess of 100 mg/liter
(and over 1,000 mg/liter for individual samples) were not uncommon.
Values of 20-60 mg/liter at the basalt interface underlying the field
were normal when adequate N was present in the soil profile for
potato production.
Good water management at this sandy site minimized leaching of N
(Table 6). Most N was leached from the soil profile by early
August for the high-rate furrow plots. Appreciable N still remained
in the lower profile of the low-rate furrow plots by mid-August of
1971. The high-rate sprinkler plots similarly were depleted of N
throughout much of the soil profile by early September, although
they retained considerable N at the time of the August sampling.
Fertilizer N remained primarily in the 60- to 120-cm soil zone
throughout the crop year for the low-rate sprinkler plots. It should
be remembered when interpreting the data that high concentrations
of solutes may be present in the soil mass between extraction cup
depths on a. given sampling date, although not measured by the ex-
traction cups on that date. Another problem is that all cups may
not extract solution on a given date, so that different sample popula-
tions may exist at different sampling times. This effect was
particularly pronounced for our studies in 1971, when ceramic cups
were purchased from an alternate supplier with poorer quality con-
trol than the Santa Barbara supplier.
The values in Table 6 represent means of three replicates, so exam-
ination of data from individual locations (e.g. Tables A-4 to A-9) is
necessary in some cases to show definite leaching trends at high
water application rates. Such individualized examination also tends
to verify that the solute peaks were relatively static for the low-rate
28
-------
Table 6. AVERAGE DISSOLVED INORGANIC N, SOIL SOLUTION
BLOCK 21 SITE
(mg/ liter)
a. 1971 Season
Treatment
Low rate sprinkler
(Ql)
High rate sprinkler
(Q3 = l.SxQl)
Low rate furrow
(Wl)
High rate furrow
(W3 = 3 x Wl)
Depth
Top 120 cm
Lower Profile
Top 120 cm
Lower Profile
Top 120 cm
Lower Profile
Top 120 cm
Lower Profile
May
5
16
20
16
59
56
206
23
9
June
11
60
26
29
63
195
20
390
5
July
8
122
100
211
52
512
162
77
91
Aug.
12
255
200
153
85
85
123
16
9
Sept.
9
513
93
93
23
26
12
2
3
b. 1970 Season
Treatment
Low rate sprinkler
(Ql)
High rate sprinkler
(Q3 = l.SxQl)
High rate furrow
(W3 = 3 x Wl)
Depth
Top 120 cm
Lower Profile
Top 120 cm
Lower Profile
Top 120 cm
Lower Profile
April
20
64
115
261
30
143
23
June
4
91
39
181
33
229
27
July
3
24
39
381
20
58
5
Aug.
5
213
25
110
235
1
1
Sept.
4
82
62
15
42
1
3
sprinkler plots. A major problem which must be solved before ex-
traction cups can be used to provide valid estimates of solute leach-
ing in non-tiled areas is the between-site variability in leaching
rates. Even email variations in leaching rate cause solute peaks to
arrive at a specif c depth at different times at different sites? Part
of the variability in absolute solute concentrations is also due to
variations in lateral placement of extraction cups with respect to
the fertilizer band.
29
-------
Table 7. DISSOLVED INORGANIC N, PAIRED LOCATIONS, BLOCK
21 SITEa
(mg/liter)
Location
Plot 1, #1
Plot 1 , #2
Plot 2, #1
Plot 2, #2
Plot 3 , # 1
Plot 3, #2
Plot 4 , # 1
Plot 4, #2
Depth,
cm
180
180
180
180
180
180
240
240
June
11
18
83
25
24
9
16
34
July
8
4
14
30
19
30
8
41
42
Aug.
12
3
13
17
17
106
323
70
41
Sept.
9
19
7
13
8
10
56
94
36
Extracted Solutions, high-rate (Q3) sprinkler plots, 1971 season.
An example of sampling variability in our studies is given in Table 7,
where dissolved-N concentrations are reported for cups placed at
the same depth within the same experimental plots (approximately 6
meters apart). Note the extremes encountered, such as the varia-
tions on June 11 for plot 2, on August 12 for plot 3, and on September
9 for plot 4. Such data point out the hazard of indiscriminately
extrapolating from a few extraction cups to an entire irrigated field.
Tables 8 and 9 give the results of a 1971 soil sampling program
designed to reduce the problems associated with extraction cup
sampling of the soil solution. Results are for nitrate-N only, al-
though such results normally differ appreciably from values for
total dissolved-N only for the surface 30 cm of soil. The results
are expressed on a weight basis as ppm of the soil mass, and hence
must be multiplied by a factor of 6 to 8 to produce values more
truly comparable with the soil solution values discussed above.
The values generally were less variable than the extraction cup
data, but were still highly variable (e.g.,Table 8: June 11, high
rate, and July 19, high rate; Table 9: June 11, low rate, July 19,
low rate, and September 24, low rate). Such variability could be
explained partially for the furrow plots as variations in the move-
ment of the wetting front during irrigation (e.g. , Table 9, reversal
of positions of replicates 2 and 3 on July 19 compared to their
30
-------
Table 8. SOIL NITRATE N, SPRINKLER-IRRIGATED PLOTS,
BLOCK 21 SITE3
(ppm, soil basis)
Depth, cm
April 14
0- 60
60-120
120-180
180-240
Average
June 11
0- 60
60-120
120-180
180-240
Average
July 19
0- 60
60-120
120-180
180-240
Average
Sept. 24
0- 60
60-120
120-180
180-240
Average
Ql application rate**
Rep 1 Rep 2 Rep 3
61.2
2.4
13.5
8.7
21.5
100.5
3.3
44.7
17.6
41.5
109.8
6.5
34.8
13.8
41.2
19.1
19.8
11.5
14.8
TE73
66.5
1.9
10.7
3.9
20.8
99.0
3.6
26.7
6.7
34.0
107.6
5.7
28.4
7.3
37.3
14.1
54.1
11.0
15.8
23.8
18.0
3.7
6.1
11.5
9.8
70.6
1.6
.9.6
15.5
24.3
36.2
1.7
9.0
15.4
T576"
34.6
13.7
6.6
12.3
7578
Q3 application rate
Rep 1 Rep 2 Rep 3
7.9
1.2
1.1
1.6
3.0
32.4
1.2
0.8
0.7
T78
0.5
1.6
19.6
1.3
5.8
0.7
1.0
1.1
0.7
0.9
17.3
3.1
1.7
8.6
7.7
114.6
1.8
2.1
7.7
377S
14.3
51.7
8.0
4.0
19.5
1.0
4.2
8.7
30.8
11.2
43.8
3.8
12.6
11.0
17.8
89.3
1.5
2.8
13.8
2o79
256.5
61.8
13.8
5.1
$473
4.1
14.0
15.3
22.1
13.9
High nitrogen (560 kg N/ha.), banded application, 1971 season.
DQ1 = low rate sprinkler application, Q3 = high rate sprinkler ap-
plication (= 1.5 x Ql).
31
-------
Table 9. SOIL NITRATE N, FURROW-IRRIGATED PLOTS, BLOCK
21 SITEa
(ppm, soil basis)
Depth, cm
April 14 , row
0- 60
60-120
120-180
180-240
Average
June 11, row
0- 60
60-120
120-180
180-240
Average
July 19, row
0- 60
60-120
120-180
180-240
Average
Sept. 24, row
0- 60
60-120
120-180
180-240
Average
Sept. 24, furrow
0- 60
60-120
120-180
180-240
Average
Wl application rateb
Rep 1 Rep 2 Rep 3
19.2
1.7
3.7
12.9
9.4
32.3
16.3
1.3
5.8
13.9
1.2
21.8
12.7
3.0
-9TT
7.3
1.9
0.8
3.5
3.4
0.9
0.6
0.8
0.5
0.7
15.7
15.5
12.0
2.4
11.4
136.2
34.7
11.7
8.8
47.9
93.7
24.0
49.7
74.8
7J6T6"
5.1
2.2
4.5
2.3
3.5
5.7
1.0
1.0
0.5
~2TT
35.4
6.4
30.8
10.0
20.7
98.0
124.2
18.9
6.0
ST715
13.4
8.9
8.2
5.8
9.1
51.9
5.7
9.0
7.2
T875
0.9
1.0
0.9
0.4
0.6
W3 application rate
Rep 1 Rep 2 Rej> 3
9.4
5.2
6.8
1.8
5.8
91.2
5.7
6.4
2.3
2~6T4
44.9
12.5
9.0
9.4
T970
16.3
2.9
1.6
1.3
5.5
2.3
0.8
0.4
0.4
1.0
34.7
11.4
6.5
2.9
13.9
98.5
28.8
5.4
26.8
39.9
3.1
1.8
6.2
4.5
3.9
3.2
2.4
1.2
0.8
1.9
2.3
0.5
0.4
0.7
1.0
14.0
2.0
1.1
1.0
4.5
67.1
16.3
2.5
0.7
2T7f
22.7
7.6
7.1
6.0
To79
23.9
3.3
2.5
3.0
~8T2
20.7
4.0
0.9
2.5
7.0
High nitrogen (560 kg/ha.), banded application, 1971 season.
"Wl = low rate furrow application, W3 = high rate furrow application
(= 3 xWl).
32
-------
positions on June 11). However, such an explanation is invalid for
the sprinkler-irrigated plots. An assessment of this effect was
attempted in subsequent years, by comparing values for banded and
broadcast fertilizer applications and different -water application
methods.
Table 10 summarizes data on the N concentrations of solutions ex-
tracted from plots fertilized with the standard N source for this study
(ammonium nitrate) and for plots to which a microbial nitrification
inhibitor (N-Serve) was applied along with either an ammonium
nitrate (NH,NO~) or urea nitrogen source. Dissolved inorganic-N
levels in excess of 200 mg/liter were observed for the NH.NO- plots,
and fertilizer N had been leached to a considerable depth by the 13th
week of the study. Application of N-Serve with the NH.NCL lowered
the maximum N concentrations considerably, and led to the preser-
vation of considerable dissolved-N in the upper part of the profile
even after 13 weeks of leaching. The combination of urea plus N-
Serve lowered the maximum dissolved-N concentrations even more,
and apparently led to release of fertilizer N at a rate less than the
maximum plant uptake rate, so that appreciable quantities of dis-
solved-N never accumulated in the profile during the experiment.
In addition to soil solution extraction, ground water samples were
collected from piezometers located around the perimeter of the study
area. Of the eight piezometer locations, only three accumulated suf-
ficient water for measurement and sampling during the irrigation
season. These locations were in the vicinity of the furrow-irrigation
plots. Free-flowing water was not observed in these piezometers
until the first of July, with dissolved-N values averaging 3.8 mg/1 at
the edge of the furrow plots, and between 20 and 30 mg/1 within the
plot boundaries. This substantiates early indications of a significant
leaching of N from the furrow-irrigated plots.
Sampling of Irrigation and Runoff Waters
Samples of irrigation water and surface runoff water (tailwater) from
the furrow-irrigated plots at the Block 21 experimental site were col-
lected during the 1970 and 1971 seasons. Results of their analyses
are given in Table 11. In addition, complete chemical characterization
of major constituents in the irrigation water was carried out for the
1970 samples. These analyses revealed an average of 32% Na, 3% K,
28% Ca, and 37% Mg (on an equivalent basis) for the major cations,
and 9% CO3> 54% HCO3, 27% SO^, 9% Cl, and 1% NO- for the major
anions. Irrigation water composition did not vary appreciably during
the season. Runoff water quality also was relatively constant, al-
though N levels of the runoff water increased substantially near the
33
-------
Co
Table 10. DISSOLVED INORGANIC N, NITRIFICATION RETARDANT PLOTS,
BLOCK 21 SITEa
(mg/liter)
Fertilizer
Treatment
NH.NO,
4 3
NH4NO3 +
N -Serve
Urea +
N -Serve
Depth, cm
60
120
180
240
60
120
180
240
60
120
180
240
Weeks after fertilizer application
1
10
8
14
40
12
54
68
7
18
21
57
3
40
9
19
20
25
--
40
70
15
14
33
5
220
18
24
*.
12
--
18
34
80
26
13
9
9
4
170
215
48
2
--
17
2
--
13
8
36
13
4
5
33
92
30
130
10
14
--
6
13
12
1971 season, irrigated at the high-rate (Q3) sprinkler-application rate, fertilized at a
rate of 340 kg N/ha. , microbial nitrification retardant = N-Serve.
-------
Table 11. IRRIGATION WATER AND RUNOFF WATER ANALYSES, BLOCK 21 SITE
Co
Ln
Sampling Date
Irrigation waters
4-20-70
5-26-70
8-20-70
7- 1-71
Runoff waters
Wla 4-17-70
6- 4-70
7-21-70
6-11-71
7- 1-71
7- 8-71
W2 4-17-70
6- 4r70
7-21-70
6-11-71
7- 1-71
7- 8-71
W3 4-17-70
6- 4-70
7-21-70
6-11-71
7- 1-71
7- 8-71
PH
_
-
_
8.6
8.4
8.1
8.2
8.5
8.4
8.3
8.5
8.0
_
8.6
-
-
8.5
8.2
8.3
8.6
8.4
8.2
EC,
umho/cm
531
482
435
465
286
504
443
479
468
486
434
509
-
467
-
-
448
496
440
480
468
486
Cl,
mg/liter
19
18
16
18
11
17
18
16
17
18
18
17
-
17
-
-
19
17
18
17
18
18
Inorganic
N,
mg/liter
1.4
0.0
1.0
4.1
0.9
1.3
0.7
0.8
4.2
2.7
0.9
0.5
-
0.8
-
-
1.4
1.6
0.5
1.9
4.3
2.5
Turbidity,
JTU
-
-
-
-
501
406
-
119
-
37
430
180
-
89
~
595
104
-
103
-
20
»W1 = low-rate furrow plots, W2 = 2 x Wl, W3 = 3 x Wl.
-------
end of the 1971 season, and water turbidity decreased markedly within
each season and between 1970 and 1971. The latter effect may be at-
tributed to the greater water application and runoff rates for the 1970
season (Tables 2 and 3). Turbidity values generally were high enough
to suggest major problems in reducing suspended solids or turbidity
values to commonly-proposed return flow standards. Values for
suspended solids (in mg/liter) averaged about 3 times the turbidity
values (in JTU). This high relation probably reflects the relatively
coarse nature of the suspended materials in runoff waters from this
site.
Soil Solution Sampling Variability
Summarized means and standard deviations for soil solutions collected
at three specified times during the 1971 season at the Block 21 ex-
perimental site are given in Table 12. Mean concentration values
between the upper and lower profile substantiate the leaching trends
for low and high irrigation rates, as inferred previously. The soil
sampling values permitted an additional comparison, in which the
dissolved-N from the surface 30 cm of soil could be deleted to pro-
duce values for the 30- to 120-cm. depth only. These values demon-
strated the high levels of N that remained in the 0 to 30-cm depth
throughout the irrigation season for many of the treatments. Ex-
traction cups had been placed at the 30-cm depth in all plots for the
1970 season, but they rarely produced soil solution samples because
of the rapid drainage from, this portion of the root zone. The in-
crease in dissolved-N for samples from the surface 120 cm of soil
between early season and mid-season probably reflected the conver-
sion of additional ammonium to the soluble nitrate form during the
intervening period.
Standard deviation values for the 1971 season averaged 74% of the
mean values for the extraction cup data, and 78% of the mean values
for the soil sampling data. Thus, there appeared to be little to
choose between the two sampling approaches. This was surprising,
for the soil sampling data included the entire soil profile, rather than
the relatively-few points in the soil profile which were sampled by
the extraction cup approach. Thus, solute peaks between extraction
cup depths should not have been detected. It may be that the rela-
tively large sample volumes extracted from this coarse-textured soil
represented a rather sizable volume of soil, and thus provided an
integrating effect not unlike the soil sampling approach.
Variability was only slightly less for the sprinkler-irrigated plots
than for the furrow-irrigated plots (74% of the mean vs 79%) and
was only slightly higher for the upper profile than for the lower
36
-------
Table 12. AVERAGED VALUES FOR DISSOLVED INORGANIC N, BLOCK 21 SITE
(mg/liter)
Treatment
a. Extraction cup data
Ql (Low rate
sprinkler)
Q3 (High rate
sprinkler)
W 1 (Low rate
furrow)
W3 (High rate
furrow)
b. Soil sampling data
Ql (Low rate
sprinkler)
Q3 (High rate
sprinkler)
W 1 (Low rate
furrow)
W3 (High rate
furrow)
Depth,
cm
0-120
120+
0-120
120+
0-120
120+
0-120
120 +
0-120
30-120
120+
0-120
30-120
120+
0-120
30-120
120+
0-120
30-120
120+
5-1 to 6-30
Std.
Mean Dev.
47
28
62
65
174
51
330
31
379
33
67
398
29
44
549
328
60
439
180
29
20
16
8
19
141
27
95
36
179
15
41
239
16
36
410
312
52
181
100
27
7-1 to 8-15
Std.
Mean Dev.
192
119
177
98
241
154
69
45
666
51
86
821
663
49
337
97
157
206
43
43
182
120
196
109
238
60
52
23
332
27
49
1208
873
29
437
70
203
182
32
16
8-16 to 9-16
Std.
Mean Dev.
438
101
81
23
35
11
2
3
274
257
68
36
38
87
188
64
26
121
28
10
420
38
120
15
38
12
1
2
170
180
21
37
39
99
198
69
21
83
8
7
oo
-------
Table 13 . AVERAGE SOIL PARAMETERS AS A FUNCTION OF
DEPTH, BLOCK 21 SITE
Depth,
cm
a . Mea
0-30
30-60
60-90
90-120
120-150
b. Stan
0-30
30-60
60-90
90-120
120-150
Hydraulic con-
ductivity, cm/hr
24 hr 24 hr/2 hr
ns
7.8
5.6
2.6
1.4
1.4
dard dev:
2.4
2.4
2.0
1.4
1.2
1.02
1.05
1.02
1.02
1.06
ations
.07
.07
.09
.07
.08
ECe,
Particle size
distribution, %
mmho/cm Sand Silt Clay
0.67
0.59
0.64
0.66
0.85
.32
.18
.20
.26
.58
76
74
57
44
44
4
6
14
14
17
20
23
37
48
49
4
6
12
13
15
4
4
6
7
6
1
1
2
2
3
Expressed as the 58-sample mean, and the respective standard
deviation.
profile (80% of the mean vs 72%). Hence, the arguments that sam-
pling variability would be reduced markedly by restricting studies to
sprinkler-irrigated fields, or to the lower soil profile (where root-
zone variability in solute peaks should be smoothed out somewhat),
were not valid at this experimental site.
Variations in Soil Properties at the Block 21 Site
Prior to development of the Block 21 experimental site, personnel
from the U.S. Bureau of Reclamation conducted an extensive soil
sampling program at the locations Samples were collected on a
31- or 46-meter (100- or 150-foot) grid interval, with a total of 58
soil cores taken from the site area. Data included hydraulic con-
ductivity, settling volume, pH of 1:5 soihwater extracts, electrical
conductivity (EC) of saturation extracts, particle-size distribution,
and textural classification. A summary of typical data is presented
in Table 13. The soils tended to have decreasing sand contents and
increasing silt contents with increasing soil depth. Slightly greater
amounts of clay also were found with increasing soil depth, but such
38
-------
variations were less marked than for sand or silt values. The re-
placement of a significant portion of the sand in surface soil samples
by silt at greater depths led to substantial reductions in soil hydraulic
conductivity. The ratio of 24-hour hydraulic conductivity to 2-hour
hydraulic conductivity was nearly unity in all cases, indicating that
the samples were quite stable during the passage of water.
Total salt concentrations of the samples, as reflected by EC values,
tended to increase slightly with increasing soil depth, However, all
soluble salt levels for soils at the site were quite low. Although not
provided in the table, pH values increased with depth from an
average of 8.4 for surface soils to an average of 9.3 for the greatest
soil depths. The pH increase tended to be gradual, rather than being
associated with any common zone of major textural change. Settling
volumes similarly increased with depth, averaging 15.2 ml for sur-
face soil samples and 16.7 ml for the greatest soil depths. Average
percentages of particles in the various sand-size classes were:
very coarse sand, 0.2%; coarse sand, 0.7%; medium sand, 2.5%;
fine sand, 26.7%; and very fine sand, 46.1%.
Soil characterization data also were grouped and compared for the
different experimental areas used each year at the Block 21 site.
There was approximately a two-fold variation in 24-hour hydraulic
conductivity values of the 0-30 cm depth increments between the
areas for the 1969 and 1971 furrow plots and those for the 1969 and
1971 sprinkler plots. Such variations paralleled variations in per-
cent sand, although variations in sand contents were consideraly
smaller. The site actually would be ruled fairly uniform with re-
gard to its textural variations at any given soil depth. However,
lenses of silty material were inter stratified with the sands at
many sampling locations, and relatively minor variations in sand
and silt contents produced substantial variations in soil hydraulic
conductivity. Therefore, variations in the hydraulic properties of
the soil could account for much of the lateral sampling variability
encountered at this site.
Comparison of Extraction Cup and Soil Sample Values
A disconcerting feature of the extraction cup approach was the large
variation in dissolved-N values which existed from one extraction
cup to another under supposedly similar experimental conditions.
Because of this variation, and in an effort to collect samples from
various points on the landscape in order to obtain a better picture
of overall trends , the extraction cup program was eventually phased
39
-------
out, with increasing reliance being placed each year on an extensive
soil sampling program. A comparison of extraction cup and soil
sampling data for comparable treatments and depths at the Block 21
site, and for approximately comparable times, is given in Table 14.
Overall average values for soil solution N were virtually identical
for both the extraction cup and soil sampling programs. This pro-
vides an important independent check of the reliability of each pro-
gram, and verifies that the method of extrapolating dissolved-N
values from 2:1 waterrsoil extracts to field water contents on the
basis of the ratio in water contents is acceptable. It also indicates
that relatively minor changes in soil dissolved-N values occurred
during the periods of sampling and transporting samples over the
190 km (120 mile) distance from the Columbia Basin to the laboratory
in Pullman. However, despite the good agreement in overall
averages, large differences between values for extraction cups and
adjacent soil samples were the rule rather than the exception for
any given sampling date and depth. Standard deviation values in all
cases were nearly as large as the respective averages, because of
the wide variations in dissolved-N levels between points only a few
meters apart. As indicated above, this is probably due to variations
in water movement patterns. An average of a 3.65-fold variation
occurred between extraction cup and soil sample values at corres-
ponding times and locations for non-zero levels of nitrogen. When
compared to the average concentration level of approximately 105 mg
N/liter, and to the recommended drinking water standard of 10 mg
N/liter, such variation renders almost meaningless any reliance on
detailed data obtained from extraction cups at only a few sites in an
irrigated field. Average ratios in extraction cup and soil solution
values for the 0- to 120-cm and greater than 120-cm depths were
4.26 and 3.04, respectively, so point-to-point variations in reported
concentration for the lower profile were nearly as large as variations
for the upper profile .
1972 SEASON
Experiments for the 1972 season were moved to the Othello Research
Station of Washington State University, in cooperation with Dr.
Robert Kunkel of the Department of Horticulture at WSU. Soils at
this location are typical of the older irrigated lands of the Columbia
Basin Project, as opposed to the more sandy newer lands typified
by the Block 21 experimental site.
40
-------
Table 14. COMPARISON OF EXTRACTION CUP AND SOIL SAMPLE
N VALUES, BLOCK 21 SITEa
(mg/liter)
Depth,
cm
May 5 (ci
90
180
240
basalt
Qlb Q3
Cup Soil Cup
ip) and
16
_
16
22
June 11 (cup) and
60
90
120
180
240
basalt
27
71
_
40
16
24
July 15 (cup) and
60
90
120
180
240
basalt
262
16
119
226
35
38
Sept. 9 (cup) and
60
90
120
180
240
basalt
653
549
123
129
132
31
April 14
26
_
28
12
(soil)
17
_
102
32
June 11 (soil)
78
16
_
199
56
21
26
37
32
99
43
July 19 (soil)
86
43
25
166
64
19
Soil
22
_
53
43
_
14
8
15
63
66
346 1400
238
16
19
56
66
Sept. 24 (soil)
348
258
165
55
88
41
21
181
63
8
20
36
502
88
22
23
34
29
29
57
66
127
14
Wl
Cup
56
206
_
-
_
283
107
18
_
22
15
385
132
150
_
63
84
9
3
19
2
W3
Soil Cup Soil
34
97
-
.
742
151
84
_
37
51
52
188
147
_
131
143
36
13
28
_
17
23
_
_
9
1330
77
_
-
_
5
81
70
49
21
H
69
1
4
1
0
.
1
26
_
-
8
639
159
_
_
_
68
28
42
59
51
34
41
30
13
12
_
7
May 5 /April 14
June 11
July 15/July 19
Sept. 9 /Sept. 24
Overall
Averages
Cup Soil
50 35
133 136
112 148
94 74
103 106
Paired standard deviations
20
106
126
52
91
a!971 season, soil values = means of three replicates from within the
crop row. Extraction cup values = means of 1 to 3 samples from
replicate plots corresponding to the soil samples.
Ql = low-rate sprinkler, Q3 = 1.5 x Ql. Wl = low-rate furrow,
W3 = 3 x Wl.
41
-------
Furrow-Irrigation Rate Experiment
Summarized average values for dissolved-N in the soil solutions
of the furrow-irrigation rate plots at the conclusion of the 1972
growing season are given in Table 15. More detailed data on dis-
solved-N and dissolved salt levels in samples from this experiment
are given in Tables A-10 and A-ll of the Appendix. As is evident
from Table 15, concentrations of N in the soil solution varied with
location in the field, and with irrigation and fertilization rate.
Values at all depths and for all treatments at the tail (outflow) end
of the field were several-fold higher than recommended drinking
water standards. Lowest dissolved-N levels consistently were
found at the head (inflow) end of the field, due to the greater leach-
ing in this area. In general, high dissolved-N values remained in
the soil solution whenever an actively-growing potato crop was
maintained until the first killing frost of the fall (e.g. , in mid-
September of 1972).
The data of Tables A-10 and A-ll provide more detailed information
on nitrogen and salt distributions as a function of field location,
fertilization rate, irrigation rate, sampling depth, and position with
respect to existing rows and furrows. Much of the applied N had
disappeared from the soil at the head of the field by the end of the
season. Although either leaching or nitrogen uptake by plants might
explain such data, comparison of the N data with corresponding
values for dissolved salts suggests leaching as the main nitrogen
loss mechanism. The low N values corresponded almost invariably
to low dissolved-salt values and to the higher water application rates
(e.g., at the tail of the field). Accumulations at the soil surface
may have represented upward flow of soil solution, and evaporation,
during the month between frost-kill of the crop and soil sampling.
Little difference in N or salt concentrations was observed between
row and furrow samples, and variation was nearly as great for
Table 15. DISSOLVED INORGANIC N, FURROW-RATE EXPERI-
MENT, 197 2a
(mg/liter)
Location
Head of
field
Tail of
field
Depth,
cm
0-60
60+
0-60
60+
High
water
30
6
49
31
Low
water
38
13
104
93
High
N
47
10
88
88
Low
N
21
9
64
36
a-Conclusion of growing season; high water and low water = wetting of
alternate sides of a given crop row every 2 and 6 days, respective-
ly; 122 meter irrigation run; high N and low N = 450 and 220 kg
N/ha., respectively.
42
-------
sprinkler-irrigated as for furrow-irrigated plots. Such data sup-
port the claim that alternate-furrow irrigation, as commonly
practiced in the Columbia Basin, does not lead to the pronounced
contrasts between samples from rows versus furrows that are
observed commonly for adjacent-furrow irrigation. The data also
emphasize the pronounced variations in solute concentrations which
can exist from point to point even in "uniformly" treated fields,
and support the belief that extensive soil sampling offers the best
possibility for obtaining reliable soil solution data in actual growers'
fields.
Water flux estimates fell in the range of 0.02 to 0.2 cm/day for this
experimental site during the 1972 season. These values are quite
low in relation to soil texture and existing irrigation practices ,
and probably reflect the presence of a compacted layer at the 20- to
30-cm depth in the soil. Such "pans" commonly are observed even
during the first year of potato'production on these high-silt soils,
and limit both root penetration and water flow in many potato fields
of the Columbia Basin. The water flux estimates can be combined
with values for dissolved nutrient concentrations to provide esti-
mates of the quantities of nutrients being leached under various
farm management regimes. For example, a flux of 0.1 cm/day for
a 120-day growing season corresponds to 11.9 surface cm of water,
or to 59 kg N/ha. at an average dissolved-N level of 50 mg/liter.
Suspension Fertilizer Experiments
Typical trends in dissolved-N values for the soil solution as a
function of time are given in Table 16 for replicated samples from
the 1972 suspension fertilizer experiment at the Othello Station.
Table 16. DISSOLVED INORGANIC N, SUSPENSION FERTILIZER
EXPERIMENT, 1972a
(mg/liter)
Treatment
670 kg N/ha.
broadcast
670 kg N/ha.
banded
Depth,
cm
0-60
60+
0-60
60+
June
22
138
190
475
118
Aug.
3
48
29
245
115
Sept.
1
54
127
40
54
Nov.
1
89
43
54
42
Othello Station.
43
-------
Similar trends were observed for both the banded and the broad-
cast applications, with dissolved-N values decreasing during the
growing season, but still several-fold higher than the recommended
drinking water standard at the time of the first killing frost. More
detailed data from three of the suspension fertilizer plots are pre-
sented in the first section of Table A-12 of the Appendix. Standard
deviations expressed as a percentage of average concentration values
showed similar amounts of variation for each type of placement.
Samplings from these experiments provided a partial basis for
separation of sampling variability due to fertilizer placement from
variability due to variations in soil properties from point to point
throughout the experimental area.
Average values for dissolved-N in the soil solution of selected plots
from the suspension fertilizer experiment at the end of the 1972
growing season are presented in Table 17. The values increased
regularly with increase in fertilizer application rate, and were
several-fold higher than the recommended drinking water standard
even at the 110 kg N/ha. fertilization rate. The increase in dis-
solved-N levels at the greater profile depths indicates that some
leaching of nutrients beyond the plant root zone occurred even
during this single growing season, despite the low water fluxes at
the Othello location.
Detailed results of sampling for dissolved-N and dissolved salts in
the suspension fertilizer experiment at the end of the 197Z growing
season are presented in Tables A-13 to A-15 of the Appendix. The
values in Tables A-13 and A-14 permit a comparison of between-plot
and within-plot variations in solute concentrations. Although within-
plot variations were less than between-plot variations, the latter
Table 17. DISSOLVED INORGANIC N, SUSPENSION FERTILIZER
EXPERIMENT, FALL OF 197Za
(mg/liter)
Treatment
Broadcast
Banded
Depth, cm
0-60
60+
0-60
60 +
110 kg /ha.
37
21
38
23
4$0 kg /ha.
49
31
45
17
670 kg/ha.
89
43
54
42
Othello Station; conclusion of growing season.
44
-------
variations averaged only 1.8 times the former for the broadcast
treatments. Thus, there is a large amount of variation even be-
tween values from within the same experimental plot. The method
of fertilizer placement does not appear to be a major factor con-
tributing to sample variability by the end of the growing season
under conditions similar to those at this experimental site. As
evidenced from Table A-15, little difference in either level or varia-
tion of dissolved-N values was found between samples from the rows
and from the furrows of this experiment. This probably can be
attributed to the use of the alternate-furrow irrigation method, with
subsequent failure of solutes to accumulate in the crop row as is
normal for adjacent-furrow irrigation methods.
Results of continued monitoring throughout the 1972 season of
replicates from the 1971 suspension fertilizer experiment are pre-
sented in Table 18. As anticipated, dissolved-N levels remained
high following the over-winter period, and were related to the
fertilizer levels previously applied to the respective plots. Average
values in the top 60 cm of the soil profile ranged from 8 to 20 times
the recommended drinking water standard, despite the passage of a
year since fertilization. A summer fallow period, followed by the
planting of a fall ryegrass crop, resulted in much lower dissolved-N
levels, with resultant values for the root zone nearly meeting drink-
ing water standards. Most changes probably resulted from N
assimilation during the fallow period, as the ryegrass provided only
partial surface cover at the time of the fall sampling. No substantial
change in subsoil dissolved-N levels was evident by the fall of 1972,
although levels for the 670 kg N/ha. N-fertilization rate had de-
creased by approximately 40 mg/liter. These data suggest the value
of a suitable crop rotation following high-level potato production,
because of the high dissolved-N concentrations normally remaining
in the soil solution following the potato growing season.
Table 18. DISSOLVED INORGANIC N, 1971 SUSPENSION FERTI-
LIZER EXPERIMENT, 1972a
Treatment
Broadcast
Banded
Depth,
cm
0-60
60+
0-60
60 +
Spring of '72
110 kg /ha.
78
24
81
39
670 kg /ha.
199
83
148
127
Fall of 72
110 kg /ha.
12
31
17
47
670 kg/ha.
17
47
31
87
Othello Station.
-------
Detailed results from the sampling of the 1971 suspension fertilizer
experiment are included in Tables A-16 and A-17 of the Appendix.
Between-plot variability averaged 1.5 and 1.6 times within-plot
variability for the broadcast and banded treatments, respectively,
and variability for the banded plots averaged 1.4 times the variability
for the broadcast plots. Overall conclusions are similar to those for
the 1972 suspension fertilizer experiment.
Summarized yield data from the plots sampled in the 1971 and 1972
suspension fertilizer experiments are presented in Table A-18 of the
Appendix. "Yields in most cases were substantially higher than those
reported for the Block 21 site, and represent yields 50% to 75% higher
than the average for commercial fields in the Columbia Basin, though
such levels were being approached by a few of the best growers in the
area. Substantial increases in total yield and yield of U.S. No. 1
tubers were observed as the rate of fertilizer application was in-
creased from 110 to 450 kg N/ha. However, only minor increases
or even decreases in total yield were obtained with further increase in
the N-fertilization rate to 670 kg N/ha. , and substantial reductions in
the yield of U.S. No. 1 tubers were observed at the higher fertilization
rates. Part of this latter decrease may be attributed to the early
frost, which prevented the crop from filling out many of the tubers
formed at the higher rates. Part also may be due to a slowing of
early-season growth because of salt effects. In any event, the data
suggest that excessively high fertilization rates may have detrimental
effects on crop yield as well as on water quality. Hence, careful
selection of N-application rates and addition of some supplemental N
as crop needs became established during the growing season (instead
of attempting to estimate and satisfy all crop needs at the start of the
season) should be considered wise management decisions.
Long-term Fertilizer Factorial Experiment
Typical results of the fall 1972 sampling for the long-term fertilizer
factorial experiment are presented in Tables 19 and 20. Average
values for dissolved-N are presented in Table 19 . Levels of 40-60
mg/liter were present in the root zone of all plots, following a uniform
application of 480 kg N/ha. in the spring of 1972. The N,, P,, and K
treatments refer to plots receiving essentially no N, P^O,- and K2O,
respectively, since 1965, whereas the N . , P., and K4 Treatments
refer to plots receiving approximately 450 kg/ha, of the respective
nutrients annually during the same period (except for 1968 and 1969,
when wheat was grown to "mine" residual N from the soil). The most
noteworthy trend is the high level of dissolved-N which accumulated
46
-------
Table 19. DISSOLVED INORGANIC N, FERTILIZER FACTORIAL
EXPERIMENT, FALL OF 1972a
(mg/liter)
Depth, cm
0-60
60+
N,"
63
49
N4
44
147
Pl
44
102
P4
62
105
Kl
44
108
K4
63
99
Othello Station.
*N, and N4, P. and P , and K, and K. = 0 and 450 kg/ha. of the re-
spective nutrients (as N, T-O., or K2O) annually for 1965-1967
and 1970-1971. 480 kg N/ha. applied fo all plots in 1972.
beneath the N, plots. The level is 3 times that beneath the N, plots,
and nearly 15 times the recommended drinking water standard. Thus,
continual growth of potatoes at high N-fertilization levels results in
substantial accumulations of N below the root zone, where it con-
stitutes a hazard with respect to ground water contamination. Even
the average dissolved-N level below the N, plots is several-fold
higher than the recommended drinking water standard, and is in the
range of minimum dissolved-N levels found during first year cropping
to potatoes for other experiments at the Othello Station. This sub-
stantiates the assertion that relatively high dissolved-N values are re-
quired for high-yield potato production, and that high levels of
Table 20. AVAILABLE P AND K, FERTILIZER FACTORIAL
EXPERIMENT, FALL OF 1972a
(mg/1000 g soil)
Depth,
cm
0-30
30-60
60-120
p b p
P
11
4
5
K
194
94
86
P
51
11
7
K
156
84
85
K,
1
P
33
8
7
K.
4
K
115
81
84
P
29
7
6
K
235
97
87
Othello Station.
and P., and K, and K. = 0 and 450 kg/ha, of the respective nutrient
as P?O, or K~b) annually for 1965-1967 and 1970-1971.
47
-------
dissolved-N can remain in the soil solution even for N-stressed fields.
There was no significant influence of fertilizer phosphorus (P) or of
fertilizer potassium (K) on dissolved-N values. As is evident in
Table 20, high levels of P fertilization since 1965 have resulted in sub-
stantial accumulations of "available" P in the 0-30 cm soil depth,
minor accumulations in the 30-60 cm depth, and essentially no
changes at greater depths. Levels of available K were lower for the
surface layers of the high P plots, which probably reflects the in-
creased plant growth and subsequent nutrient uptake accompanying
high soil P levels . Similar trends were observed for available K and
P levels as a function of K fertilization rate.
Detailed results from the long-term fertilizer factorial experiment are
presented in Tables A-19 to A-21 of the Appendix. As is evident from
Table A-19, the greatest increases in residual N beneath the N4 plots
began with the 60 to 90 cm soil depth, and extended through the 180
cm depth. No consistent trends were evident in the data for the top
60 cm of soil profile, which reflects uniform plot fertilization in 1972.
Hence, the influence of root activity from a current potato crop
appears restricted to the top 60 cm of soil in this area. This results
both from the shallow-rooted nature of the potato crop, and from the
compacted layer that tends to develop at shallow depths during potato
production on these high-silt soils. The data also suggest that N
once it has leached beyond the effective root zone, is neither assim-
ilated nor denitrified to an appreciable extent. This emphasizes the
importance of proper water management during potato production to
prevent deep percolation whenever possible. It also suggests the
merit of including deep-rooted crops in the rotation on a regular basis,
to "mine" residual N from the soil profile.
Table A-20 presents average results of soil tests for "available" P and
K in the top 30 cm of soil from each plot at selected intervals during
the long-term fertility experiments. Some buildup of P levels
occurred during the 7 years of analysis even for the low P plots, due
to lateral transport by tillage, wind and water. However, the high
P fertilization rate increased soil test P values to the upper range
of the standard soil test procedure for the area during the first two
years of fertilization, with this high level then being maintained
throughout the remaining experimental period. Increases in soil K
levels were less dramatic, and probably reflect both the high K re-
quirement of the potato crop and the presence of significant amounts
of K- "fixing" minerals in soils of the area. An unexplained zone of
relatively high soil-test P and K values occurred at the 120 to 180 cm
depth for many profiles (Table A-21), but these elements generally
were accumulated only in the top 30 cm of soil when applied to the
high-fertility plots . Little difference between the high-fertility and
low-fertility plots generally was evident for the 60 to 120 cm soil
-------
depth and below. The zone high in P and K deep in some of the pro-
files probably reflects former surface soil buried during the land
leveling operations carried out prior to surface irrigation at this site.
In Table A-22, average yield data each year for plots selected for
study from the long-term fertility experiment are presented. The
problem of delining total yields on lands cropped continually to
potatoes is clearly evident from these data, and was only partially
rectified by fumigation or by two intervening years of wheat pro-
duction. Small quantities of residual soil N were being removed by
the intervening wheat crop even in its second year of its growth (as
evidenced by the 1969 yield data), but the major residual effects
were demonstrated in the first year of wheat production. The
dramatic increases in potato yields on the N, plots in 1971 can be
attributed to the application of 110 kg N/ha. to these plots after
several years with no N application. Little evidence of residual N
effects was detected for the N. plots in 1972, when a uniform N ap-
plication was made to all plots. However, the uniform application
was high enough to provide adequate N for most potato production
without requiring the utilization of residual soil N.
Slow-Release Nitrogen Experiment
Results of the 1972 slow-release N experiments are summarized in
Tables 21, A-12, A-23, and A-24. As is evident in Tables 21 and
A-12, partial replacement of the traditional N source with one of
the slow-release N sources commonly led to substantial reductions in
dissolved-N levels during the growing season. This in turn should
lead to less leaching of N whenever excess irrigation water is applied
to the crop.
Table 21. DISSOLVED INORGANIC N, SLOW-RELEASE N
EXPERIMENT, 1972a
(mg/liter)
b
Treatment
510 kg N/ha.
340 kg N/ha.+ 170 kg
N/ha. as UF
340 kg N/ha.+ 170 kg
N/ha. as SC 20
340 kg N/ha.+ 170 kg
N/ha. as SC 30
NH^NO^
Aug. 10
470
136
404
139
Aug. 29
76
24
59
33
(NHJ-SO,
x 42 4
Aug. 10
106
74
40
160
Aug. 29
49
14
36
36
^Othello Station.
bRate listed first = traditional source (NH,NO, or (NHJ,SOJ; rate
listed second = slow-release N source (urea formaldehyde, or
fur-coated urea releasing 20% or 30% of its N in 7 days under
standardized conditions).
sul-
49
-------
Substantial leaching of N appeared to have occurred by August 10 for
some of the sulfur-coated urea plots. However, such leaching may
have been due to the traditional N sources which comprized the bulk
of the applied N, rather than to the slow-release N formulations. By
August 29, use of the slow-release N sources had led to substantially
lower soil solution N values in virtually all cases. With the exception
of one urea-formaldehyde treatment, little change in dissolved-N
values below the first 30 cm of the soil profile was evident from the
slow-release N sources (Table A-23). However, high N concentrations
were evident in the surface soil at the end of the season for all N
sources. This probably reflects N release and/or accumulation from
the deeper soil depths between the time of the killing frost in mid-
September and the sampling in late October. Plant uptake of released
N would no longer occur during this period.
Average yield data for the plots sampled from the slow-release N
experiment are presented in Table A-24. Total yields were similar
for both the 340 and 500 kg N/ha. rates of each standard N source,
but yields of U.S. No. 1 tubers were consistently lower at the 500
kg/ha, rate. Those treatments employing slow-release nitrogen
sources generally averaged both higher total yields and higher yields
of U.S. No. 1 tubers than did the corresponding 500 kg/ha, standard
treatments, although they averaged lower yields of U.S. No. 1 tubers
than did the 340 kg/ha, standard treatments. Thus, use of slow-re-
lease N sources eventually may become competitive with conventional
fertilizer treatments wherever environmental concerns are a signifi-
cant factor in the selection of a crop fertilization program.
Plant Population Experiment
Still another experiment at the Othello station in 1972 involved the
sampling of residual N from a 1971 experiment in which both the plant
population per acre and the N fertilization rate were varied, in order
to assess the feasibility of tailoring fertilization programs to the
actual number of plants growing in a given field. This addresses a
significant problem in potato production, because of the difficulty in
predicting plant populations prior to crop emergence. Results of
soil sampling in the spring of 1972 are given in Table A-25, and yield
data for the corresponding plots are provided in Table A-26. Little
difference in residual N was evident for the various treatments follow-
ing the over-winter period. Differences in residual N had persisted
for a similar sampling program on the 1971 suspension fertilizer
experiment (Table A-16), and hence major differences in residual N
from the various treatments probably never really materialized. As
would be expected, higher total yields were obtained from high plant
populations per acre than from low plant populations. Differences
were greater for 1971 than for 1972, which may result from the early
50
-------
killing frost in 1972. Yields of U.S. No. 1 tubers also were increased
substantially by increasing plant population at the low N-fertilization
rate, but not at the highN-rate. This substantiates results dis-
cussed previously, where higher N-fertilization rates often resulted
in reduced yields of U.S. No. 1 tubers, despite increases in total
yield with increased fertilization rate.
Variations in Soil Properties on the Othello Station
Sampling for soil variability at the Othello Field Station was less ex-
tensive than conducted by the Bureau of Reclamation for the Block 21
site. However, mechanical analyses were performed for a large
number of samples from this site, with the results summarized in
Table 22. The main textural variation at the site was in sample silt
content, with a corresponding opposite variation in sample sand con-
tent. The majority of the sand was in the very fine sand fraction, so
distinctions between sand and silt contents often were rather arbitrary.
Table 22. VARIATIONS IN SOIL SILT CONTENT, EXPERIMENTAL
PLOTS, OTHELLO STATIONa
Experiment
Overall
Fertilizer Factorial
Suspension Fertilizer
Irrigation Rate
Sprinkler Plots
Paired Row-Furrow Sets
0-30
54+5
53+3
51+1
55+6
51+2
54+1
30-60
58+5
59+2
55+1
60+4
55+1
58+2
Depth, ci
60-120
59+6
56+10
63+2
59+5
62+2
59+2
11
120-180
59+11
46+7
55+1
63+11
59+5
60+2
180-240
56+13
38+5
68+8
55+3
58+4
1972 experiments; clay contents = 2-4% (average = 2.5+0.6%);
average sand fractions: very coarse sand = 0.5+1.0^ coarse
sand = 1.4+1.6%, medium sand = 1.5+0.9%, find sand = 15.2+6.2%,
and very fine sand = 81.5+7.1%.
51
-------
Trends were less consistent at this site than for the Block 21 site,
and overall average variations in texture with depth were small. Sets
of samples from rows and adjacent furrows exhibited only small dif-
ferences, so variations generally were on a rather large lateral scale.
Soil test values for "available" P and K (not given) suggested con-
siderably more variation in field soil properties than did mechanical
analysis data. Such differences probably reflect both differences in
location of the original surface soil with respect to the present soil
surface and variations in fertility applications during the subsequent
ten years of farm operation.
In summary, variations in soil texture were relatively slight through-
out both the Block 21 and Othello Station experimental areas. From
this standpoint, the areas represented good units for experimental
measurements. However, variations in hydraulic conductivity and
soil fertility were more pronounced, and probably relate more mean-
ingfully to the variations in soluble salt and dissolved-N levels which
were observed. Both fields had been leveled previously to permit
surface irrigation operations, as is typical for many of the older
lands of the Columbia Basin Project. Many of the more recently-
developed lands in the Basin area have been left unleveled and ir-
rigated with sprinkler-irrigation systems. Variations in surface
hydraulic conductivity and surface fertility levels should be less
pronounced at such sites than at the two sites characterized for this
report.
Comparison of Extraction Cup and Soil Sampling Values
A comparison of extraction cup and soil sampling values for dissolved-
N in soil solutions at the Block 21 site was given previously. Similar
data are summarized in Table 23 for the 1972 and 1973 growing seasons
at the Othello station. As for the Block 21 site, overall values of
average extraction cup and soil sampling estimates agreed quite
closely, but values for individual depths and sampling times (as
reflected by the standard deviations) varied widely. Once again,
the data dramatize the difficulty of using values from a few extraction
cup sites to predict behavior on a field-wide basis.
1973 SEASON
Although some experiments for the 1973 season were maintained on
the Othello research station, the main portion of the season's pro-
gram involved extensive sampling of the soil solution in actual
growers' fields. Dr. Robert Kunkel had negotiated with several
growers to install several standardized experiments in their fields,
52
-------
Table 23. SUMMARIZED COMPARISON OF EXTRACTION CUP AND
SOIL SAMPLE N VALUES, OTHELLO STATION3
(mg/liter)
Date
1972 season
7-21 or 7-28
8-18 or 8-25
9-8 or 9-15
Overall
1973 season
5-29 or 6-11
7-6
8-28 or 8-29
Overall
Average (cup)
71
54
42
56
404
242
98
225
Average (soil)
74
50
48
57
283
336
94
209
Standard
deviation
51
38
30
40
335
400
106
274
aSoil and extraction cup samples from within the crop row, at the
depths and dates specified, within a few meters of one another.
Averages for 10 furrow-irrigated sites (averaging 3.6 depths each)
and 5 sprinkler-irrigated sites (averaging 2.6 depths each).
°Averages for 14 sprinkler-irrigated sites (averaging 3.1 depths each),
in order to obtain an appraisal of yield changes to be expected from
several management variables under commercial conditions. The
main experiments monitored as part of our program during this
season were the suspension fertilizer experiment and the slow re-
lease N experiment. Each of these experiments was discussed
previously in the section describing the 1972 growing season.
Suspension Fertilizer Experiments
Tri-cities area -
One set of suspension fertilizer experiments was placed in a field
irrigated by a center-pivot irrigation system and located approxi-
mately 65 km east and north of the Tri-cities (Richland, Pasco, and
53
-------
Kennewick) area. The soil at this site was a silt loam, and proved
to be so fine-textured that considerable runoff and surface ponding of
water invalidated many of the yield data. As a result, it was decided
mid-way through the season not to harvest the plots at this location.
However, soil samples were obtained from the field on June 12 and
August 20, and summarized results are presented in Table 24. High
levels of dissolved inorganic N in the surface 0-60 cm of soil were
observed in all cases for the early sampling date. Values in the root
zone on this date averaged 2.3-fold higher for the high fertilization
rate than for the low rate. However, no differential leaching of N
below the 60 cm depth for the more heavily fertilized plots was ap-
parent at this time. Subsoil N concentrations in all cases were in
the range of 35-70 mg N/liter, reaffirming that concentrations of
this magnitude commonly are left in the soil from proceeding potato
crops. Standard deviations as a percentage of the respective means
were essentially identical for both subsoil and root zone samples.
By August 20, increases in dissolved inorganic N were apparent for
subsoil samples from all of the more heavily-fertilized treatments.
Average values for dissolved inorganic N in the root zone also re-
mained generally higher for the higher fertilization rate, except
where sampling variability obscured the trend. Dissolved-N levels
below the plant root zone averaged 39 mg/liter for the low fertilization
rate and 68 mg/liter for the high fertilization rate, or 4 and 7 times
the recommended drinking water standard, respectively. Standard
deviations for dissolved-N in the root zone and beneath the root zone
averaged 100% and 83% of the respective means, so lateral variations
in dissolved-N levels were maintained to considerable depths at this
site.
Average dissolved-N levels in the plant root zone were lower for the
fumigated plots. This may reflect either higher yields or inhibition
of the nitrification process, with subsequent maintenance of larger
amounts of ammonium N, in the fumigated soils.
Horse Heaven Hills area -
Cooperative experiments during 1973 in the Horse Heaven Hills area
also included a field irrigated by center-pivot irrigation on a con-
siderably more sandy site. Ponding during the irrigation season
was not a problem at this location. Dissolved-N in the root zone of
the field on May 23 was higher in six of eight cases for the higher
fertilization rate, with values averaging 177 and 204 mg/1, respective-
ly, for the two rates (Table 25). No consistent change in root zone
dissolved-N levels was evident for the fumigated samples.
54
-------
Table 24. DISSOLVED INORGANIC N, SUSPENSION FERTILIZER EXPERIMENTS,
TRI-CITIES AREA, 1973a
Treatment
Fumigated
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FlBrD
F4BrD
Chiseled Only
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FlBrD
F4BrD
June 12
Dissolved N, mg/1
0-60 cm 60+ cm
163 58
352 54
216 69
782 56
205 53
358 43
108 47
92 55
289 47
418 54
230 54
984 51
190 38
413 35
144 51
287 39
Std. deviation, %
0-60 cm 60+ cm
23 46
90 70
60 69
86 42
37 103
94 72
53 74
78 59
120 87
67 84
56 51
74 69
71 82
125 60
53 41
46 63
August 20
Dissolved N, mg/1
0-60 cm 60+ cm
239 38
113 51
185 51
311 64
39 34
224 100
20 31
63 55
. _
-
mm
-
_
-
_ ,_
-
Std. deviation, %
0-60 cm 60+ cm
86 47
102 128
80 37
96 64
119 100
118 148
106 81
95 62
m* »
-
_
-
_
-
_ _
-
01
Oi
aCenter-pivot irrigation, silt loam site
and F4 = 110 and 450 kg/ha. N, P?*"^' an<* ^2^' resPectively- Ba = banded, Br = broadcast,
L = suspension fertilizer, D = dry fertilizer. Fumigation with Telone C at a rate of 230
liter/ha. (25 g/a). Planted May 7-8, plots not harvested, due to ponded conditions in much
of the experimental area.
-------
Table 25. DISSOLVED INORGANIC N AND YIELD DATA, SUSPENSION FERTILIZER
EXPERIMENTS, HORSE HEAVEN HILLS AREA, 1973a
b
Treatment
Fumigated
FIBaL
F4BaL
FIBaD
F4BaD
FlBrL
F4BrL
FIBrD
F4BrD
Chiseled Only
FIBaL
F4BaL
FIBaD
FiBaD
FIBrL
F4BrL
FIBrD
F4BrD
May 23 June 27
Dissolved N, nag/1
0-60 cm 60+ cm
83 60
141 46
74 35
152 65
239 39
268 53
319 66
250 48
41 60
115 36
56 62
188 61
159 56
190 127
446 73
331 106
Std. deviation, %
0-60 cm 60+ cm
46 71
86 69
86 93
83 96
111 50
64 27
86 33
68 20
61 44
82 74
75 49
69 42
113 103
84 26
97 57
78 110
Dissolved N, mg/1
0-60 cm 60+ cm
_ _
30 49
121 112
66 73
187 141
_
_
_
~
Std. deviation, %
0-60 cm 60+ cm
_
-
.
-
50 66
117 22
80 77
104 60
_
-
_
-
-
-
-
Yield0
Total, U.S. No.
quintal/ha. 1's, %
452 95
525 93
458 94
506 94
5!6 93
493 93
504 94
495 95
463 87
409 91
390 |7
357 88
427 84
463 86
400 11
383 82
Ln
Center-pivot irrigation, sandy site.
bAll plots received 50 kg
slots received 50 kg P?O, /ha. and 200 kg K?O/ha. (both preplant broadcast) and 250 kg N/ha. (50 kg/ha, preplant
iprinkler-applied) from tfie grower in addition to the experimental treatments. Fl and F4 = 0 and 270 kg/ha. N, P
pectively. Ba = banded, Br = broadcast. L = suspension fertilizer, D = dry fertilizer. Fumigation with Telone C
(25 gal/a.). Planted March 16-19, harvested August 1.
cQuintal/ha. = cwt/acre x 1.12.
: dry
Kennebec potatoes.
broadcast, 200 kg/ha.
,O,, and K7O, re-
"atS230 liters/ha.
-------
Greater leaching of N occurred at this sandy site, as was already
evident by May 23. Average values for dissolved-N below the plant
root zone for the two fertilization rates on this date were 56 and 68
rng/1, respectively. The trend was even more evident by June 27,
when average values for dissolved-N below the root zone for the
two fertilization rates were 61 and 127 mg/1, respectively. Higher
root zone dissolved-N levels also persisted for the higher rate on
the latter date, with average values for the two fertilization rates of
48 and 154 mg/1, respectively.
Values for standard deviation as a percentage of the mean were
lower for the subsoil than for the root zone, with respective values
for the two zones on May 23 of 81% and 60%, and on June 27 of 88%
and 56%.
Overall response to increased N fertilization at this site was neg-
ligible, with average yields of 451 and 455 quintals/ha, for the two
fertilization rates. Potato quality was also independent of ferti-
lization rate, with an average of 91 percent U.S. No. 1 tubers pro-
duced at each rate. A slightly greater amount of N appeared to be
required for the higher yields obtained from the fumigated plots.
Average values for percent U.S. No. 1 tubers were 94% for the
fumigated treatment and 87% for the chiseled-only treatment.
It appears that the 245 kg N/ha. applied to the Fl fertilization plots
was adequate for optimum potato growth at this site. A question
which cannot be answered from these data alone is the question of
how much this relatively-low N fertilization rate would need to be
increased if the site were in its first year of potato production,
rather than being a site recropped to potatoes.
Moses Lake area -
Results of the 1973 suspension fertilizer experiment in the Moses
Lake area are provided in Tables 26 and A-27. Surface soil dis-
solved-N values are subdivided by sampling location with respect to
the plant row in the latter table.
Values for dissolved-N in the root zone generally were higher for
the higher fertilization rate, and tended to decrease considerably
during the growing season for both rates. An apparent leveling off
of dissolved-N levels between August and October may have resulted
from some upward movement of water, and subsequent evaporation
at the soil surface, following the irrigation season.
57
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Table Z6. DISSOLVED INORGANIC N AND YIELD DATA, SUSPENSION FERTILIZER
EXPERIMENTS, MOSES LAKE AREA, 1973a
Treat roe nt1*
June 7 and 11
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FlBrD
F4BrD
August 14
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FlBrD
F4BrD
Dis solved N,
mg/1
0-60 cm 60+ cm
217 12
453 29
312 24
660 17
66 17
206 51
39 12
209 45
44 2
221 25
104 1
94 0
57 10
110 2
20 0
35 4
Std. deviation;,
%
0-60 cm 60-f cm
60 114
86 102
79 88
100 69
92 43
1Z4 135
93 113
68 32
84 200
115 136
US 100
136
78 80
82 150
166
167 175
Dissolved N,
mg/1
0-60 cm- 60+ cm
October 2
67 9
236 19
67 16
124 28
38 7
109 7
25 11
22 6
Std. deviation,
%
0-60 cm 60+ cm
114 108
99 97
56 68
58 124
75 152
102 148
120 100
100 210
Yield0
Total, U.S. No.
quintal/ha. I'a , %
513 70
608 53
586 61
628 56
385 60
483 59
380 43
438 52
Ln
00
. Rill irrigation, sandy site.
Fl and F4 = 110 and 450 kg/ha. N, PaOc, aad K2O. respectively. Ba = banded, Br = broadcast. L = suspension fertilizer.
D = dry fertilizer. Planted May 1-2, harvested October 4-5. Russet Burbank potatoes.
c Quintal/ha. = cwt/acre x 1.12.
-------
Values for dissolved-N levels below the plant root zone at this loca-
tion also tended to reflect differences in fertilization rate, although
such concentrations were considerably lower for this furrow-irri-
gated site than for any of the sprinkler-irrigated sites. This
partially reflects greater leaching of the furrow-irrigated plots.
However, root zone dissolved-N levels remained relatively high
throughout the growing season at the Moses Lake site, suggesting
that considerable "entrapment" of nitrogen in the ridge area re-
sulted from the alternate-furrow irrigation practice carried out at
this location. Much of the root zone N is moved back and forth in the
ridge during the irrigation season, but dissolved-N deeper in the soil
profile is leached out of the profile by the excess water applied when
furrow irrigation is practiced on such sandy sites. Subsoil dissolved-
N levels at both fertilization rates were of the same order of magni-
tude as the maximum drinking water standard throughout most of the
growing season at this site, so dilution by the leaching waters con-
siderably lessened the ground water contamination hazard.
Standard deviations as a percentage of the means were as high or
higher in the area below the root zone as within the root zone at this
site. However, this is misleading because of the low values for dis-
solved-N in the lower soil profile. Average percentage standard
deviation values varied from 88% to 118% of the respective means.
A significant response to N was obtained at this location, which re-
flects the leaching (and particularly early-season leaching) which
occurred. Total yields for the two fertilization rates were 466 a"nd
540 quintal/ha. > respectively. A combination of periodic N-stress
and water stress resulted in relatively poor tuber quality, with
average figures for percentage of U.S. No. 1 tubers for the two
fertilization rates being 59% and 55%, respectively.
Data for the sampling of surface soils at this site as a function of
position with respect to the plant row are included in Table A-27.
On August 1, average levels for dissolved-N in the surface 30 cm
of soil for the row, the furrow, and halfway between the two were
102, 11, and 23 mg/1, respectively. Thus, the highest concentration
of dissolved-N was beneath the fertilizer row, as would be expected
from normal water movement patterns in furrow-irrigated soils.
On August 14, the concentrations of dissolved-N beneath the furrow
were actually higher than beneath the row, because a recent ir-
rigation had moved much of the N laterally to this location.
Standard deviations as a function of time and of position with respect
to the potato row were high in all cases. They averaged 90% and 68%
of the respective means for the sampling position study on August
1 and August 14, compared to corresponding standard
deviations for the entire replicates on these dates of 115% and 107%,
59
-------
respectively. The higher overall values reflect the variations which
occurred in dissolved-N with sampling location, but the exact loca-
tions of high N and low N zones could not be predicted without a prior
knowledge of recent wetting patterns under the alternate-furrow ir-
rigation regime.
Othello area -
A final set of 1973 suspension fertilizer experiments was conducted
on a silt loam site in the Othello area, where irrigation was carried
out using a solid-set sprinkler system. Appropriate data for the soil
sampling program at this location are included in Tables 27 and A-28.
Average levels of dissolved-N in the plant root zone reflected fertili-
zation rates, with high-rate values averaging 2 to 5 times the low-
rate values throughout the growing season. Values had decreased to
only 2 to 6 times the recommended drinking water standard by late
August. A subsequent increase in concentration by October 16 prob-
ably reflected upward movement of solutes and surface evaporation
of water following the irrigation season.
Values for dissolved-N in subsoil samples at this site also reflected
differences in fertilization rate. Values were considerably higher
than those observed for the other grower's fields, reflecting a higher
initial level of fertility due to prior management practices. Sub-
stantial downward movement during the current irrigation season
was also evident. The higher soil N levels were also reflected by
the yield data (Table 27), with average total yields for the two
fertilization rates of 730 and 743 quintal/ha. , respectively. Average
percentages of U .S. No. 1 tubers were 59% and 52%, so weight of
U.S. No. 1 tubers actually declined by nearly 12% at the higher
fertilization rate.
Average standard deviation values, expressed as a percentage of the
mean, were approximately 100% for both the root zone (0-60 cm) and
subsoil (greater than 60 cm) zones. These values are of the same
magnitude as those obtained at the furrow-irrigated site near Moses
Lake, so mere sampling of sprinkler-irrigated fields, as opposed to
furrow-irrigated fields, does not eliminate most of the inherent soil
solution sampling variability.
Results of dissolved-N sampling in relation to location near the plant
row are given in Table A-28. For the lower fertilization rate, N
concentrations decreased gradually during the growing season and
were close to the drinking water maximum during most of August.
However, minimum values averaged 3 to 4 times the drinking water
60
-------
Table Z7. DISSOLVED INORGANIC N AND YIELD DATA, SUSPENSION FERTILIZER
EXPERIMENTS, OTHELLO AREA, 1973a
Treatment
May Z9
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FIBrD
F4BrD
July 17
FIBaL
F4BaL
FIBaD
F4BaD
FIBrL
F4BrL
FIBrD
F4BrD
Dissolved N,
mg/1
0-60 cm 60+ cm
689 44
1045 75
154 37
575 99
139 119
240 79
90 60
184 92
4 1Z7
290 111
8 79
141 358
148 211
413 113
5 80
46 44
Std. deviation,
0-60 cm 60+ cm
101
88
72
no
65
104
40
79
57
137
142
124
168
146
142
104
"Solid-set sprinkler, irrigation, silt loam site.
bFl and F4 = 110 and 450 kg/ha. N, P2Oc and K2O
fertilizer. Fumigation with Telone t at 230 ]
75
87
49
54
163
66
93
72
80
86
75
18
162
35
156
59
Dissolved N,
mg/1
0-60 cm 60+ cm
August 22
6 28
93 145
Z2 144
66 114
56 155
66 182
8 5
7 1
October 16
/I 70
295 133
74 37
77 139
73 77
153 100
35 37
47 72
Std . deviation,
0-60 cm 60+ cm
113
147
124
94
141
130
125
95
48
83
62
59
102
97
52
52
86
91
166
122
117
125
100
200
92
119
104
138
116
70
109
129
Yiel
Total,
quintal/ha.
716
740
754
808
713
584
739
840
U.S. No.
1's, %
68
59
60
55
60
51
49
41
respectively. Ba = banded, Br = broadcast. L = suspension fertilizer, D = dry
iters/ha. (25 gal/acre). Planted April 20-24, harvested October 17-19. Russet
cQuinta.l/ha. = cwt/acre x 1.12.
-------
standard at the higher fertilization rate. No consistent trend with
relation to sampling position was evident on any of the sampling dates.
Values tended to be somewhat higher beneath the crop row, perhaps
because of greater upward movement and evaporation at this location
between irrigations, but differences were relatively minor after the
first sampling date. Values for standard deviation as a percentage
of the mean also appeared unrelated to sample location. However,
the standard deviation values were substantially lower than values
for the furrow-irrigated site near Moses Lake, indicating consider-
ably more uniformity with respect to sampling position (because of
the lack of lateral flushing of salts and accumulation in the zone of
most recent wetting front advance) for the sprinkler-irrigated field.
Slow-Release Nitrogen Experiments
A series of experiments in which several slow-release N sources
were compared to traditional N sources was also placed in grower's
fields during the 1973 season. Results of the experiments are
summarized below.
Tri-Cities area -
Results of the slow-release N experiment for the silt loam site in the
Tri-Cities area are given in Table 28. This was the site at which
serious ponding resulted from inadequate water filtration when center-
pivot irrigation was employed for a fine-textured soil, so no yield data
were obtained for the experiments. Increasing N application rates
resulted in higher root zone dissolved-N values, with correspond-
ingly greater potential for N leaching during the growing season.
Use of slow-release N fertilizers substantially decreased average
dissolved-N values in most cases. The more readily-soluble slow-
release N source (SCU 100) tended to produce higher dissolved-N
levels early in the season than did the more insoluble, slow-release
N sources (e.g., SCU 25). The effect was less pronounced later in
the season, which may reflect a longer preservation of soluble N in
the root zone for forms releasing their N more slowly.
Values for dissolved-N in soil solutions below the root zone were not
related to N fertilization rate or to fertilizer form early in the season.
Slightly higher values for some of the slow-release N plots on August
20 may or may not reflect effects from the formulations themselves,
for initial soil N levels were higher in this case for the slow-re-
lease N plots as well. Values for subsoil dissolved-N ranged from
2 to 11 times the maximum drinking water standard, necessitating
good water management if deep percolation and contamination of
local ground water supplies were to be avoided in this case.
62
-------
U>
Table 28. DISSOLVED INORGANIC N, SLOW-RELEASE N EXPERIMENTS, TRI-CITIES
AREA, 1973a
b
Treatment
170 kg /ha. NH4NO3
170 kg/ha. (NH4)SO4
170 kg/ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU 45
170 kg/ha. SCU 25
390 kg/ha. NH4NO3
390 kg/ha. (NH4)2SO4
390 kg/ha. Urea
390 kg/ha. SCU 100
390 kg/ha. SCU 45
390 kg/ha. SCU 25
Dissolved
0-60 cm
521
347
233
345
147
106
592
320
431
403
506
312
June
N, mg/1
60+ cm
82
67
40
41
166
12 S
42
44
51
90
46
74
12
Std.
0-60
41
46
45
25
38
35
34
90
30
91
109
55
deviation, %
cm 60+ cm
73
74
37
79
85
96
38
52
55
91
39
72
August 20
Dissolved
0-60 cm
120
71
37
-
48
329
446
195
-
181
N, mg/1
60+ cm
7
27
11
-
32
31
25
57
-
63
Std.
0-60
160
91
115
-
128
116
123
68
-
92
deviation, %
cm 60+ cm
114
100
82
-
106
61
48
58
-
70
aCenter-pivot irrigation, silt loam site.
bSCU 100, 45 and 25 = sulfur-coated ureas releasing 100%, 45%, and 25% of their N, respectively, during the standard
7-day leaching test. Planted May 7-8, plots not harvested, due to ponded conditions in much of the experimental
-------
Values for average standard deviations as a percentage of the means
were actually greater for the deeper soil depths on June 12, though
this trend was reversed by August 20. Once again, the early-season
values more probably reflected prior N accumulations. No consistent
difference with fertilizer source was evident.
Horse Heaven Hills area-
Similar data for the 1973 slow-release N experiments in the Horse
Heaven Hills area are given in Table 29. Traditional N sources
tended to produce higher root zone dissolved-N levels early in the
season than did slow-release N sources, but the trend was reversed
by mid-season. The slow-release N sources produced lower subsoil
dissolved-N levels on both sampling dates. This suggests that slow-
release N provides a feasible means for controlling N losses on
sandy sites, particularly during early-season growth. However, the
higher resultant soil dissolved-N levels in mid- to late-season pro-
duce an off-setting tendency for leaching of N by that time, if water
management is not carefully regulated.
Values for average standard deviations as a percentage of the re-
spective means were higher on both sampling dates for root zone
samples than for those from the subsoil. No consistent differences
in these values for the slow-release N and traditional N sources
were evident on the two sampling dates.
Total yields were higher for slow-release N sources at this site than
for traditional N sources , with average values of 412 and 385
quintal/ha., respectively. Total yields also increased steadily with
decreasing solubility of the slow-release sources (in other words,
in going from highly soluble SCU 70 to fairly insoluble SCU 30). This
suggests that-rate of N release is an important factor in preventing
leaching and insuring N availability throughout the growing season
at sandy sites. However, tuber quality decreased with decreasing
solubility of the slow release N sources as well, so the rate of N
release in this case may have been marginal for high quality tuber
production. Average values of greater than 90% U.S. No. 1 tubers
were obtained for the suspension fertilizer experiments at the same
site. A slight increase in yield also was observed at this site in
going from 220 to 280 kg/ha, of traditional N, with respective average
yields of 379 and 391 quintal/ha. No difference was observed in per-
centage of U.S. No. 1 tubers between the two rates of traditional N.
Because of the slightly higher percentage of U.S. No. 1 tubers pro-
duced by traditional sources, there was virtually no difference in
total yield of U.S. No. 1 tubers between the various N sources.
64
-------
Table 29. DISSOLVED INORGANIC N AND YIELD DATA, SLOW-RELEASE N
EXPERIMENTS, HORSE HEAVEN HILLS AREA, 1973a
b
Treatment
220 kg/ha. SCU 70
220 kg /ha. SCU 47
220 kg/ha. SCU 30
220 kg /ha. NH4NO3
280 kg/ha. NH4NO3
220 kg /ha. 2SO4
280 kg/ha. (NH4)2SO4
280 kg/ha. Urea
280 kg/ha. Urea
Ma
Dissolved N, mg/1
0-60 cm 60+ cm
477 47
253 42
327 64
361 129
-
491 60
-
555 61
-.
? 23-24 f
Std. deviation, %
0-60 cm 60+ cm
99 90
97 42
90 57
66 141
-
77 59
-
55 75
-
T June
Dissolved N, mg/1
0-60 cm 60+ cm
153 46
189 51
337 94
-
223 101
-
133 93
-
95 120
79
Std . deviation , %
0-60 cm 60+ cm
145 57
80 46
198 97
-
130 58
-
84 26
-
155 105
Yield0
Total. U.S. No.
quintal/ha. 1's, To
388 83
396 77
452 77
388 83
360 79
388 82
422 82
362 85
390 85
n. releasing 70%. 47%, and 30% of their N. respectively, daring the standard 7-day leaching
test. Planted March 15. harvested August 6. Kennebec potatoes.
cQuintal/ha. = cwt/acre x 1.12.
-------
Moses Lake area -
Summarized results for the 1973 slow-release N experiments in the
Moses Lake area are given in Tables 30 and A-27. Average values
for dissolved inorganic N in the root zone were consistently higher for
the higher fertilizer rate at this site. Mid-season values for dis-
solved-N in the root zone at a given fertilization rate were decreased
substantially for the slow-release N sources compared to the tra-
ditional N sources. However, by October 2, nearly identical or even
higher average concentrations of dis solved -N remained in the root
zone soils of the slow-release N plots. The data substantiate a
tendency for relatively high levels of N to remain in the root zone at
season's end when slow-release N sources are employed, although
values for dissolved-N during the growing season are substantially
lower when using such sources.
As with the suspension fertilizer experiments, relatively low values
for subsoil dissolved-N were observed at this site. Values were
slightly higher for the higher fertilization rates when using traditional
N sources, but none of the differences were large. Average values
ranged from about 1/2 to 2 times the maximum recommended drinking
water standard. As for the suspension fertilizer experiment, the low
values apparently resulted from the movement of much of the soil N
laterally when the alternate-fur row irrigation technique was employed,
with a concurrent rather rapid flushing of any N from the soil below
the plant root zone during furrow irrigation at this sandy site.
Higher yields actually were obtained for traditional N sources than for
slow-release N sources at this particular site, with yields for the two
sources averaging 409 vs. 389 quintal/ha, at the 170 kg/ha, fertiliza-
tion rate and 559 vs. 479 quintal/ha, at the 390 kg/ha, rate. Average
percentages of U.S. No. 1 tubers were in the range 50-55% for all
fertilizer sources and rates. Thus, there was a significant response
to N at the site, which probably reflects the accentuated tendency for
N leaching whenever furrow irrigation is practiced on a sandy soil.
The slow-release N sources did not produce the anticipated increase
in yield under furrow-irrigated conditions, but this may be because
the rate of N release was inadequate to meet the N demands of the
crop in this situation.
A comparison of dissolved-N values in the surface 30-cm of soil for
various sampling locations with respect to the crop row are presented
in Table A-29. Higher values were observed in all cases for the
higher fertilization rates. Highest dissolved-N values were obtained
for the crop row on August 1, but the trend was actually reversed on
August 14, because of average wetting front movement to the position
66
-------
Table 30. DISSOLVED INORGANIC N AND YIELD DATA, SLOW-RELEASE N EXPERIMENTS,
MOSES LAKE AREA, 19?3a
ON
-J
Treatment
170 kg /ha. NH. NO,
170 kg/ha. Urea
170 -kg /ha. SCU 100
170 kg/ha. SCU 45
170 kg/ha. SCU 25
390 kg/ha. NH.NO,
390 kg/ha. Urea
390 kg /ha. SCU 100
390 kg/ha. SCU 45
390 kg/ha. SCU 25
170 kg/ha. NH.NO,
170 kg/ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU 45
170 kg/ha. SCU 25
390 kg/ha. NH.NO,
390 kg/ha. Urea
390 kg /ha. SCU 100
390 kg/ha. SCU 45
390 kg/ha. SCU 25
Dissolved N, mg/1
0-60 cm 60+ cm
June 7
74 3
217 12
144 8
75 12
89 15
706 32
334 32
190 7
368 7
60 11
August 14
147 3
38 2
68 12
23 0
93 12
127 4
79 4
23 1
Std. deviation, %
0-60 cm 60+ cm
79 133
58 83
45 56
86 78
75 60
60 41
55 109
71 107
29 55
105 55
138 100
96 200
86 83
167
171 167
83 100
57 100
128 100
Dissolved N, mg/1
0-60 cm 60+ cm
October 2
51 15
65 7
48 9
87 12
29 0
146 26
108 24
121 21
274 24
95 22
Std. deviation, %
0-60 cm 60+ cm
81 86
134 188
40 94
83 105
90
80 17
44 31
38 65
113 178
78 107
Yield0
Total, U.S. No.
quintal/ha. 1's, %
436 S3
382 54
364 51
476 53
325 42
530 54
588 56
526 60
440 57
473 51
aRill irrigation, sandy site.
b3CU 100, 45 and 25 = sulfur-coated ureas releasing 100%, 45%, and 25% of their N, respectively, during the standard 7-day leaching
test. Planted May 1, harvested October 8. Russet Burbank potatoes.
cQuintal/ha. =. cwt/acre x 1.12.
-------
of the adjacent furrow during the most recent alternate-fur row ir-
rigation at the site. Average dissolved-N levels were higher in all
cases for traditional N sources than for slow-release N sources.
No consistent variation in standard deviations as a percentage of the
respective means was evident as a function of either fertilizer source
or fertilization rate. Respective values by sampling position averaged
65% on both August 1 and August 14, with overall values for the
replications approximating 100% for each date. As indicated previous-
ly, this reflects the tendency of the dissolved-N to be concentrated in
the zone of most recent wetting-front advance whenever sampling is
conducted.
Othello area -
Results of experiments on the use of slow-release N at the silt loam
site in the Othello area are presented in Tables 31 and A-30. Values
for dissolved inorganic-N in the root zone generally increased with in-
creasing fertilization rate, except for situations where high sampling
variability was encountered near the localized fertilizer band early in
the growing season. The slow-release N sources produced lower
dissolved-N values during early- and mid-season sampling, but pro-
duced higher dissolved-N values in the plant root zone late in the
year. This indicates a decrease in potential for N leaching early in
the season, but substantial N carryover to subsequent seasons at high
fertilization rates. Thus, it is important that the slow-release N
application be tailored as closely as possible to actual crop needs, so
that significant N leaching does not occur during over-winter periods.
Values for dissolved-N in the root zone for this experiment dropped
to acceptable drinking water standards by late season, even though
they increased again by the end of the season because of upward move-
ment of solution and/or because of continued release of N after plant
uptake of the element had essentially ceased.
Values for dissolved-N below the plant root zone generally reflected
increases in fertilization rate and in the proportion of traditional (vs.
slow-release) N sources. The relatively large amounts of water
passing through the plant root zone at this location are reflected by
the relatively rapid movement of dissolved-N out of the soil beneath
the root zone by late summer at the low fertilization rate, and by the
rapid accumulation of N in the soil beneath the root zone at the high
fertilization rate (particularly when using traditional N fertilizer
sources). Values for dissolved-N beneath the plant root zone aver-
aged less than three times the drinking water standard for the low
fertilization rate (25 mg/1), but averaged nearly 11 times the drinking
68
-------
\o
Table 31. DISSOLVED INORGANIC N AND YIELD DATA, SLOW-RELEASE N EXPERIMENTS,
OTHELLO AREA, 1973a
Treatment
70 kg /ha. NH.NO,
TO kg /ha. Urea
70 kg/ha. SCU 100
70 kg/ha. SCU 45
70 kg/ha. SCU 25
500 kg/ha. NH.NO,
500 kg /ha. Urea
300 kg /ha. SCU 100
500 kg /'ha. SCU 45
500 kg/ha. SCU 25
170 kg /ha. NH.NO,
170 kg /ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU 45
170 kg/ha. SCU 25
SCO kg/ha. NH.NO,
500 kg /ha. Urea
500 kg /ha. SCU 100
500 ke/ha. SCU 45
500 kg/ha. SCU 25
Dissolved N, mg/1
0-60 cm 60+ cm
May 28 & 39
607 36
416 48
108 47
144 16
101 38
562 50
326 66
427 97
381 40
Z73 104
July 19
13 28
16 44
29 29
16 34
393 77
34 324
107 54
3Z 37
Std. deviation, "
0-60 cm 60+ cm
102 33
50 46
42 104
60 81
28 0
26 54
80 79
31 81
65 62
55 114
79 86
72 86
83 28
96 82
70 103
6 115
49 80
128 78
Dissolved N, mgA
0-60 cm 60+ cm
August 22
11 5
10 5
6 0
10 4
123 161
13 111
132 291
60 13
October 16
58 22
121 36
171 17
138 22
209 25
240 91
107 140
224 114
393 47
115 38
Std. deviation. %
0-60 cm 60+ cm
155 120
93 80
168
150 200
136 71
131 132
91 35
127 177
69 117
64 96
66 89
78 47
29 55
77 71
77 94
84 32
108 76
49 57
Yield0
Total, U.S. No.
quintal/ha. 1's, %
758 73
706 71
706 72
706 72
643 69
735 68
675 68
719 75
731 68
765 67
a3ohd-set sprinkle? system, silt loam site.
bSCU 100, 45 and 25 = sulfur-coated ureas releasing 100%, 45%, and 25% of their N, respectively, during the standard 7-day leaching
test. Planted April 19, harvested October 17. Russet Burbank potatoes.
cQuintal/hectare = cwt/acre x 1.12.
-------
water standard (107 mg/1) for the high fertilization rate. Even the
slow-release N fertilizer produced an average subsoil dissolved-N
value nearly 9 times the drinking water standard (86 mg/1) at this
site, indicating the importance of sound water management as well
as proper fertilizer management if leaching of N is to be controlled.
Little growth response to N fertilization was observed for this site.
Total yield values for the two fertilization rates when using
traditional N sources averaged 732 and 706 quintal/ha., respectively,
with corresponding percentages of U.S. No. 1 tubers of 72 and 68%.
Thus, reductions in both total yield and tuber quality occurred with
increasing application rates of traditional N fertilizers. However,
total yields for the same fertilization rates when using slow-release
N fertilizers averaged 684 and 738 quintal/ha. , with corresponding
percentages of U.S. No. 1 tubers of 71 and 70%. Furthermore, total
yield was increased substantially at the higher fertilization rate as
the N was more slowly released, with values ranging from 719
quintal/ha, for SCU 100 (the most soluble of the slow-release sources)
through 731 quintal/ha, for SCU 45 ( a material of intermediate sol-
ubility), to 765 quintal/ha, for SCU 25 (the least soluble of the slow-
release sources employed). However, the percentage of U.S. No. 1
tubers decreased at the higher fertilization rate as the N was more
slowly released. Thus, although a substantial increase in total yield
could be obtained from the highest fertilization rate and the most
slowly-released form of N, this treatment resulted only in a relatively
minor increase in the actual weight of U.S. No. 1 tubers over that
produced at lower fertilization rates with traditional N sources.
Average standard deviations expressed as a percentage of the respec-
tive means were virtually identical for root zone and subsoil dis-
solved-N values at this site. Furthermore, no consistent trends with
either time, rate, or fertilizer source were observable.
Trends in dissolved-N levels for the surface 30 cm of soil with respect
to positioning near the crop row are given in Table A-30. For a given
fertilizer source on a given sampling date, average dissolved-N
values increased with increasing fertilization rate. Average minimum
values for the traditional N sources -were in the 10-20 mg/1 range,
whereas minimum values for the slow-release N sources were in the
20-40 mg/1 range (because no uncommonly low values were obtained
near season's end in this case). Dissolved-N values for samples
taken from the crop row tended to be higher than for samples taken
from the irrigation furrow on all sampling dates, which probably re-
flects both greater evaporation from the crop row between irrigations
and a tendency for water to drip off foliage and produce additional
leaching in the furrow during irrigation.
70
-------
Values for standard deviations as a percentage of the means exhibited
no consistent trends with position, time, or N source, although
slightly higher standard deviations generally occurred for the slow-
release N sources than for the traditional sources. Standard de-
viations for higher rates of fertilization were higher than for lower
rates of fertilization early in the season, until the fertilizer band
became dissipated by repeated water movement. The standard de-
viation values were lower than obtained for the furrow-irrigated site
near Moses Lake, reflecting the lack of lateral variability associated
with the most recent advance of the wetting front on sprinkler-ir-
rigated fields.
Othello station -
Data for slow-release N experiments conducted on the Othello re-
search station in 1973 are given in Tables 32, 33, and A-31. No
suspension fertilizer experiments were conducted at this location in
1973. Increasing the N fertilization rate increased the levels of dis-
solved-N in the root zone for all sampling times and all fertilizer
sources. Use of slow-release sources decreased average root zone
dissolved-N values in most cases. As stated earlier, an apparent
increase in dissolved-N values between the August and October
samplings may reflect either upward movement and evaporation of
solution at the soil surface after irrigation had ceased, or release
of N from crop residues and slow-release fertilizer granules at a
rate exceeding the plant uptake rate late in the growing season.
Use of slow-release N fertilizer sources produced dissolved-N values
only one to two times the maximum permissible drinking water
standards for the mid-season samplings at the lowest fertilization
rate. Dissolved-N values in the root zone were less than two times
the drinking water standard by August 23 for traditional N sources
as well, but substantially higher values existed for such sources
{15-16 times the drinking water standard) during July.
Average values for dissolved-N below the plant root zone generally
were higher for the higher fertilization rate and for the traditional
N sources. Use of the lower rate of fertilization produced 3- to 4-
fold lower values for dissolved-N below the root zone late in the
growing season, and use of slow-release N sources produced an
average of a 4-fold lower accumulation of N below the root zone at
the higher fertilization rate than did the use of traditional N sources.
Yields were poorly related to N fertilization rate. Average yields for
traditional N sources were 616 and 597 quintal/ha., respectively, for
the low and high fertilization rates, with comparable values for the
71
-------
Table 32. DISSOLVED INORGANIC N AND YIELD DATA, SLOW-RELEASE N
EXPERIMENTS, OTHELLO STATION, 1973a
b
Treatment
170 kg/ha. NH.NO,
170 kg /ha. Urea 3
170 kg /ha. SCU 100
170 kg/ha. SCU 25
500 kg /ha. NH^NOj
500 kg /ha. Urea
500 kg/ha. SCU 100
500 kg/ha. SCU 25
170 kg/ha. NH.NO,
170 kg/ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU 25
500 ke/ha. NH.NO
500 kg /ha. Urea
500 kg /ha. SCU 100
500 kg /ha. SCU 25
170 kg /ha. NH.NO^
170 kg/ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU Z5
500 kg/ha. NH.NO
500 kg/ha. Urea
500 kg/ha. SCU 100
500 kg/ha. SCU 25
Dissolved N, mg/1
0-60 cm 60+ cm
May 24
112 11
156 20
182 26
345 20
191 5
562 34
294 49
219 27
July 10
210 25
89 115
27 15
23 23
578 655
766 36
778 18
148 20
July 24
167 16
151 78
27 17
21 12
565 25
761 22
592 47
270 52
Std. deviation, %
0-60 cm 60+ cm
87 91
86 15
63 85
119 75
111
121 27
65 122
104 85
99 76
106 119
69 80
58 61
84 170
68 108
81 83
117 120
141 81
99 97
61 100
51 8
75 40
45 14
105 123
97 75
Dissolved N, mg/1
0-60 cm 60+ cm
August 23
24 29
11 21
18 21
11 13
394 415
510 52
214 38
182 68
October 18
40 7
26 8
65 17
71 10
191 171
340 229
278 82
224 21
Std. deviation, %
0-60 cm 60+ cm
97 83
107 57
62 52
94 92
78 149
84 44
74 74
144 122
67 100
57 163
79 77
52 106
135 111
120 106
118 96
133 43
Yield0
Total, U.S. No.
quintal/ha. I's. ft,
600 56
631 61
592 60
719 55
526 61
668 60
577 62
731 63
aRill irrigation, silt loam site.
bSCU 100 and SCU 25 = Sulfur-coated ureas releasing 100% and 25% of their N, respectively, during the standard 7-day leaching
test. Planted May 1, harvested October 30 and November 2. Russet Burbank potatoes.
cQuintal/hectare = cwt/acre x 1.12.
-------
u>
Table 33. ADDITIONAL DISSOLVED INORGANIC N DATA, SLOW-RELEASE N
EXPERIMENTS, OTHELLO STATION, 1973a
Treatment
170 kg /ha. NH.NO,
170 kg/ha. (NH,)-SO
170 kg/ha. Urea * *
170 kg/ha. SCU 100
170 kg/ha. SCU 45
170 kg/lu. SCU 25
340 kg/ha. NH.NO,
340 kg/ha. tNK.1,50.
340 kg/ha. Urea
340 kg/ha. SCU 100
340 kg /ha. SCU 45
340 kg/ha. SCU 25
500 kg /ha. NH.NO,
SCO kg/ha. (XK,I2SO4
500 kg /ha. Urea
300 kg/ha. SCU 100
500 kg/ha. SCU 45
500 kg/ha. SCU 25
dissolved N, mg/1
0-60 cm 60+ cm
May 24
112 11
217 22
156 20
182 26
134 16
345 20
567 38
122 17
312 34
291 6
443 20
256 30
191 5
120 49
562 34
294 49
335 47
219 27
Std. deviation,
-------
slow-release N sources of 656 and 654 quintal/ha. Thus, slightly
higher yields were obtained with slow-release N fertilizers at this
location, and the lower rate of N fertilization was adequate for max-
imum crop yields. The greatest total yields and actual (not per-
centage) yields of U.S. No. 1 tubers were obtained for the slowest
of the two slow-release fertilizers tested.
Additional data on the distribution of dissolved-N for the various
fertilizer sources and soil depths are provided in Table 33. This
table includes results for three traditional N sources and three slow-
release sources, compared to the data on only two sources of each
type as listed in Table 32. Little change in dissolved-N levels on
May 24 was observed between the 340 and 500 kg N/ha. fertilization
rates, and no leaching of N to greater than the 60 cm depth had oc-
curred by this sampling date. By July 10, substantial differences
in dissolved-N values were apparent with respect to fertilization
rate, N source, and sampling position (crop row vs. irrigation
furrow). Markedly lower dissolved-N values for the root zone were
obtained for the leached portion beneath the irrigation furrow com-
pared to the zone of solute accumulation in the crop row. However,
relatively little difference between the row and furrow sampling
locations was evident for soil depths greater than 60 cm. This
was particularly true where the rate of N release had been controlled
by using slow-release N fertilizer.
By October 18, values for dissolved inorganic N in the plant root zone
were only 3 to 6 times the recommended drinking water standard for
the lowest N fertilization rate, but were still 26 to 27 times the drink-
ing water standard for the highest fertilization rate. Root zone dis-
solved-N values were as high or higher for the slow-release N
sources by this sampling date, although lower dissolved-N values at
the deeper soil depths beneath the slow-release N plots verified that
less leaching of N had occurred in this case during the preceeding
crop growth period.
No consistent differences in standard deviations (expressed as per-
centages of the respective means) were evident between values for
the plant root zone and those for the lower soil profile, with
averages for the two depths of 91% and 85% of the mean, respectively.
Slightly more variation occurred for the higher fertilization rate and
for the traditional N sources in most cases. Standard deviations of
90% to 94% of the mean concentrations were observed for the tradi-
tional N sources, compared to values of 82% to 88% of the respective
means for the slow-release N sources.
74
-------
Table A-31 summarizes variations in dissolved-N levels in the sur-
face 30 cm of soil at this location for various N sources, sampling
periods, and sampling positions with respect to the crop row. In all
cases, higher dissolved-N levels were observed for the higher
fertilization rate. Dissolved-N values were highest for the crop row
and lowest for the irrigation furrow on three of the four sampling
dates for this furrow-irrigated field. On the fourth date (August 10),
highest values actually were observed for the irrigation furrows.
This reflects the alternate-furrow irrigation employed, with much of
the sampling on this date apparently associated with crop rows which
had recently been flushed free of salt by the lateral flow of the ir-
rigation wetting front. There was a definite tendency for the percent
standard deviation for the irrigation furrow (40%) to be lower than
that for the crop row (70%) or for the region half-way between the
row and the furrow (65%).
Petiole Nitrate-N vs. Soil Test Nitrogen as Yield Predictors
Soil samples from the 0 to 30-cm soil depth in the crop row, the
furrow, and half-way between at the Moses Lake, Othello area, and
Othello Station locations were tested as predictors of crop yields for
the 1973 season. Petiole nitrate-N levels from the same experimental
plots also were tested as yield predictors for the same period. Re-
sults of the petiole analyses are presented in Table 34.
Petiole nitrate-N levels generally increased with increasing N
fertilization rate, and decreased with time, at all experimental lo-
cations. Lower petiole nitrate-N levels generally accompanied the
use of slow-release N fertilizers (compared to traditional N sources).
This is consistent with results of the soil analyses reported previously.
An exception to the trend with increasing fertilization rate occurred
for the 340 kg N/ha. treatment of the suspension fertilizer experiments
at the Moses Lake location. Many of the plots from this particular
treatment were located near the head of the furrow-irrigated field,
and hence were subject to excessive leaching. Thus, the "effective"
fertilization rate for this treatment was less than the "anticipated"
fertilization rate.
An exception to the normal time trend occurred as well at the Moses
Lake location, for the banded application of the suspension fertilizer
experiment. This may reflect decreased availability to the plant of
N in the concentrated fertilizer band, due to osmotic effects, until the
band became more diffuse later in the growing season. Petiole nitrate-
N levels for the Moses Lake location were well below the normally-
accepted minimum safe tissue level of 5,000 to 10,000 ppm throughout
most of the sampling period. Vines died by mid-August at this loca-
tion, probably from N stress resulting from excessive leaching of
nitrate even during alternate-furrow irrigation at this extremely sandy
site.
75
-------
Table 34. PETIOLE NITRATE-N LEVELS, SUSPENSION FERTILIZER AND SLOW-RELEASE
N EXPERIMENTS, 1973
(ppm, dry-weight basis)
Location
Moses Lake area
Othello area
Othello station
Days
Since
Planting
90
104
90
108
115
125
132
134
85
98
111
133
Suspension feVtilizer experiments
Broadcast
110 220 340 450
kg /ha.
640 1840 840 3740
660 1170 740 2130
110 220 340 450
kg /ha.
-
5140 7190 4110 4360
-
-
....
3650 5040 2760 2240
Banded
110 220 340 450
___ ____ __ kg/ha.
140 250 240 390
360 500 520 460
110 220 340 450
kg/ha^
-
5220 5410 6020 3580
-
...
-
3240 4290 3180 2060
"
Maturity study
Check
220 340 450 560
kg/ha. __ _____
12400 13200 14000 13500
12200 15700 16900 18700
7230 11700 13700 14500
5140 8720 11400 13400
Vine Kill
220 340 450 560
.._ ._ ___ kg/ha^
13300 13000 14500 14100
13000 16500 16700 18300
8380 12000 13700 14600
6100 9640 11400 12800
Slow- release nitrogen experiments
Traditional
170 280 390
kg/ha.
620 2120 5170
620 1230 2020
170 340 500
kg /ha.
7550 15000 16900
.
5290 11800 14200
4870 6780 5140
2600 4950 7940
_
Slow -Release
170 280 390
kg/ha.
730 1120 1550
630 960 1380
170 340 500
kg /ha.
3120 11300 16200
-
3890 8800 13300
6750 5220 6470
1970 4500 6530
-
Slow-release nitrogen experiments
Traditional
170 340 500
kg/ha.
7350 13000 14700
8810 13300 17400
5990 9690 13200
2850 6160 9450
Slow-Release
170 340 500
kg/ha.
7070 10400 13400
7550 11500 14500
4740 9110 11600
3110 5280 8620
-------
Although sampling of the suspension fertilizer experiment in the
Othello area was limited, a decrease in petiole nitrate-N levels at
the higher N fertilization rates consistently appeared. This could
also be explained as the result of limited N uptake from highly con-
centrated suspension fertilizer zones, although greater differences
between broadcast and banded treatments, and similar effects for
higher application rates of traditional (dry) fertilizers to the slow-
release N experiments, would be expected as well.
As the "check" and "vine kill" plots of the Othello Station maturity
study were treated identically until the end of the growing season,
differences between the two illustrate the cumulative results of
sampling and analytical errors. As can be seen from the data, such
errors generally were small, averaging only 5.0 percent of the mean
petiole nitrate-N levels in this case.
Results from the correlation of petiole nitrate-N or surface soil
dissolved inorganic N levels with crop yield and quality are given in
Table 35. Petiole nitrate-N and surface soil (e.g., root zone) dis-
solved-N were well correlated for the slow-rlease N experiments
(with the exception of one sampling date for the Othello area location)
and for the maturity study at the Othello station. The two para-
meters were poorly correlated for the suspension fertilizer experi-
ments. As indicated above, this may have resulted from low uptake
of N from banded fertilizer plots at the higher fertilization rates,
despite high soil dissolved-N levels, due to osmotic effects on roots
near the highly concentrated fertilizer band.
Total yield and yield of U.S. No. 1 tubers were well correlated with
soil dissolved-N levels for both sets of experiments at the Moses
Lake location in 1973, reflecting the N stress at this location due to
excessive leaching of nitrate. Positive correlations between total
yield, tuber quality, and petiole nitrate-N levels also were obtained
for the slow-release N experiments at this location, although negative
correlations were obtained between petiole nitrate-N, total yield and
tuber quality for the suspension fertilizer experiments. This reflects
higher yields at the higher fertilization rates in these experiments,
despite lower petiole nitrate-N levels on both sampling dates. The
lower petiole nitrate-N values may reflect early season inhibited
root activity near the fertilizer band (as discussed previously), with
the higher fertilization rates leading to more nearly adequate late-
season soil N levels at this heavily-leached location.
Poor correlations between total yield, tuber quality, and either
petiole nitrate-N or surface-soil dissolved-N were obtained for each
of the other experimental locations. This reflects the abundance of
77
-------
Table 35. CORRELATION OF SOIL DISSOLVED INORGANIC N AND PETIOLE NITRATE -
N WITH POTATO YIELD AND QUALITY, 1973
Location
Moses Lake
Othello area
Othello station
Bays after
planting
90
104
89
109
1Z3
132
86
100
113
128
Petiole NO,-N
vs soil N
Susp. Slow N
.183 .902
-.150 .753
.863
-.648 .8Z3
.089
-.672 .71Z
.72Z .88Z
.982 .990
.913 .898
.996 .944
Total yield
vs soil N
Susp. Slow N
.671 .694
.784 .760
Susp. Slow N
-.356 -.090
-.088 -.053
-.059 .345
-.070 .184
Matur Slow N
-.734 -.590
-.732 -.330
-.710 -.326
-.743 -.319
Total yield
vs petiole NO, -N
Susp. Slow N
-.48Z .504
-.477 .365
Susp. Slow N
.Z81
.06Z .256
-.156
.054 .259
Matur Slow N
-.432 -.504
-.575 -.461
-.528 -.395
-.577 -.369
Yield U.S. No. 1's
vs soil N
Susp. Slow N
.458 .604
.625 .659
Susp. Slow N
-.Z44 -.253
.061 -.165
.046 .016
.073 .135
Matur Slow N
-.722 -.402
-.732 -.124
-.733 -.043
-.734 -.073
Yield U.S. No. 1's
vs petiole NO,-N
Susp. Slow N
-.531 .492
-.508 .461
Susp. Slow N
.105
-.185 .044
-.072
-.198 .028
Matur Slow N
-.442 -.369
-.594 -.326
-.537 -.237
-.602 -.243
co
Linear correlation coefficients.
-------
available N present at these locations, so that crop yield frequently
was depressed at the higher fertilization rates. In fact, strong
negative correlations between crop yield or quality and soil or plant
N levels were obtained in several cases at these sites.
From these studies it appears that petiole nitrate-N or surface soil
dissolved-N levels have only limited values as predictors of crop
yield or tuber quality on recropped potato lands (or other lands of
high residual soil N levels) in the Columbia Basin. They are of value
as predictors primarily on N-stressed areas (such as the furrow-
irrigated, sandy Moses Lake location). They certainly do not
answer the whole question of predicting crop N needs (and hence
minimizing N leaching losses) for this area.
Nitrogation Experiment, Othello Station
Another set of experiments at the Othello Station during the 1973 season
involved application of fertilizer through the sprinkler line ("nitroga-
tion") at various fertilization rates and application intervals. Results
of these experiments are given in Table 36.
Mid-season (July 6) values for dissolved inorganic N in the root zone
and subsoil did not vary consistently. Root zone N values were
highest for the least heavily-fertilized plots, which probably reflects
high early-season variability remaining from the low levels of N
banded to all plots at planting time. Subsoil N values appear to re-
flect accumulations from prior cropping of the experimental area.
Root zone dissolved-N levels by late season (August Z8) and season's
end (October 18) generally were higher for the higher fertilization
rates and for the less-frequent fertilization intervals. Yield levels
were highest for the lower fertilization rate ( consistent with other
results suggesting an excess of N in many fields of the Columbia
Basin area) and the most frequent application interval. The merit of
continuously "feeding" the potato crop with adequate, although not
excessive, quantities of fertilizer N through the sprinkler system
appears obvious from these data. Levels of dissolved inorganic N
in the root zone and subsoil from such fields appear to be relatively
insensitive to fertilization rate or application interval. However,
little evidence of substantial leaching of N was apparent, even at
high fertilization rates and for long application intervals.
79
-------
Table 36. DISSOLVED INORGANIC N AND YIELD DATA, NITROGATION EXPERIMENT,
OTHELLO STATION, 1973a
Treatment
340 kg N/ha. , 2 week interval
340 kg N/ha. , 4 week interval
340 kg N/ha. , 6 week interval
670 kg N/ha. , 2 week interval
670 kg N/ha., 4 week interval
670 kg N/ha. , 6 week interval
340 kg N/ha. . 2 week interval
340 kg N/ha.. 4 week interval
340 kg N/ha. , 6 week interval
670 kg N/ha. , 2 week interval
670 kg N/ha.. 4 week interval
670 kg N/ha., 6 week interval
Dissolved N, mg/1
0-60 cm 60+ cm
July 6
98 67
234 179
60 22
17 20
9 17
27 2
August 28
18 34
39 25
73 44
46 24
42 28
105 26
Std. deviation, %
0-60 cm 60+ cm
124 66
89 60
83 59
88 50
75 112
86 150
47 124
55 44
60 64
56 104
59 82
48 92
Dissolved N, mg/1
0-60 cm 60+ cm
October 18
75 24
87 50
115 53
115 34
61 14
129 12
Std . deviation , %
0-60 cm 60+ cm
47 50
71 69
49 32
60 102
58 83
69 95
"Solid-set sprinkler system, silt loam site.
Quintal/hectare = cwt/acre x 1.12.
Yield5
Total, U.S. No.
quintal/ha. 1's, %
775 69
643 71
709 77
644 70
704 76
582 68
-------
Sprinkler Irrigation Rate Experiment, Othello Station
In a final experiment at the Othello Station for 1973, dissolved in-
organic soil N, crop yield, and tuber quality were assessed as a
combined function of N fertilization and sprinkler irrigation rates.
Irrigation was based on micrometeorological measurements at levels
of 75%, 100% (assumed optimum), and 150% of estimated crop
evapotranspiration needs. Results are given in Table 37.
Soil solution dissolved-N levels generally increased with increasing
N fertilization rate. Early season (May 29) subsoil N values in-
creased with increasing irrigation rate, suggesting some early-
season leaching of N at the higher rates. By midseason (July 6),
however, N had leached below the root zone even at the lowest ir-
rigation rate, and by late season (August 28) and season's end
(September 27), N had been leached from the entire soil profile
at the highest irrigation rates, completely reversing the early-season
trends. Subsoil dissolved-N concentrations by season's end were
decreased by leaching even at the lowest irrigation rate, reflecting
a common tendency to over-irrigate late in the season, when plant
evaporative needs begin to decrease. Crop yield generally was
higher at the higher fertilization and water application rates. Tuber
quality increased slightly with increasing irrigation rate, but ap-
peared to be unaffected by fertilization rate.
Good water management appears essential in the prevention of N
leaching on silt loam soils of the Columbia Basin, even as it was for
the sandy site studied in 1970jand 1971. However, actual potato pro-
duction on the finer-textured sites appears to be slightly less depend-
ent on water application rates. This may be due to the greater water
storage capacities of such soils, and to a tendency for additional
water to substitute for leached N to a limited extent during potato
tuber production.
Soil Solution Extraction Cup Values , Othello Station
Extraction cup data for the Othello Station in 1973 were limited to a
few sites in the nitrogation and sprinkler irrigation rate experiments.
Results of these measurements are given in Table 38. The data gen-
erally confirmed the soil sampling information, but results were
more variable, because of the failure to obtain samples from all sites
on all sampling dates. The extraction cup program had, in general,
been phased out by this time, so no attempt was made to provide the
cups with the extensive attention needed to keep all of them operative
throughout the entire season.
31
-------
Table 37. DISSOLVED INORGANIC N AND YIELD DATA, SPRINKLER IRRIGATION RATE
EXPERIMENT, OTHELLO STATION, 19?3a
Treatment
c
75%ET,
TSToET.
100% ET,
100ro ET ,
150T? ET,
150% ET ,
75r ET,
75T ET,
75*" ET,
~sr ET,
100T ET,
100T ET,
100T ET,
100r ET,
150r ET,
150r ET,
150T ET,
150T ET,
220 kg N/ha.
670 kg N/ha.
220 kg N/ha.
670 kg N/ha.
220 kg N/ha.
670 kg N/ha.
110 kg N/ha.
220 kg N/ha.
450 kg N/ha.
670 kg N/ha.
110 kg N/ha.
220 kg N/ha.
450 kg N/ha.
670 kg N/ha.
110 kg N/ha.
220 kg N/ha.
450 kg N/ha.
670 kg N/ha.
Dissolved N, mg/1
0-60 cm 60+ cm
May 29
292
296
594
1317
443
1222
July 6
.
135
-
436
.
52
_
369
.
161
_
733
3
9
26
22
35
62
.
21
.
352
.
30
.
77
-
66
-
249
Std.
0-60
128
141
91
87
74
58
.
43
-
106
-
102
-
113
-
158
-
70
deviation, %
cm 60+ cm
133
89
69
64
57
118
_
105
-
121
-
100
-
97
-
155
-
221
Dissolved
0-60 cm
August 28
33
164
9
53
14
24
September
33
55
284
347
18
12
16
23
28
29
27
31
N. mg/1
60+ cm
51
356
12
287
9
90
27
8
18
75
162
8
6
86
146
13
13
29
24
Std.
0-60
46
157
104
168
62
77
101
55
92
139
71
58
90
101
22
83
55
78
deviation, %
cm 60+ cm
73
105
92
119
67
174
128
93
186
129
160
100
121
177
24
39
70
46
Yieldb
Total,
quintal/ha.
638
610
740
666
631
652
657
672
711
635
706
640
U.S. No.
1's, «i
75
74
74
74
74
76
79
77
76
81
76
75
aSolid-set sprinkler irrigation, silt loam site.
bQuintal/hectare = cwt/acre-x 1.12.
CZT = evapotranspiration by the crop, as estimated from micrometeorological measurements.
-------
Table 38. DISSOLVED INORGANIC N, EXTRACTION CUP VALUES, OTHELLO STATION,
1973a
Exoeriment an
Nitrogatlon
340 kg N/ha.
340 kg N/ha.
340 kg N/ha.
340 kg N/ha.
670 kg N/ha.
670 kg N/ha.
670 kg N/ha.
670 kg N/ha.
Sprinkler rate
ZZO kg N/ha.
2ZO kg N/ha.
670 kg N/ha.
670 kg N/ha.
450 kg N/ha.
450 kg N/ha.
220 kg N/ha.
220 kg N/ha.
670 kg N/ha.
670 kg N/ha.
d treatment
2 week Interval
2 week interval
6 week interval
6 week interval
2 week interval
2 week interval
6 week interval
6 week interval
75% ETb
75*. ET
75*. ET
757, ET
100% ET
100% ET
150% ET
150". ET
150?, ET
ISO?, ET
Depth
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
Top 60
Lower
cm
Profile
cm
Profile
cm
Profile
cm
Profile
cm
Profile
cm
Profile
cm
Profile
cm
Profile
cm
Profile
June 11
510
91
72
0
140
34
304
83
457
63
133
14
64S
11
1217
53
June 21
-
.
-
290
45
35
18
189
IS
586
112
50
968
94
July 6
-
.
-
4
41
670
1
7
118
29
53
1387
12
July 14.
-
13
4
0
18
1
150
26
24
509
292
4
48
394
20
July 18
13
13
7
0
24
0
6
167
0
55
391
311
18
66
289
24
July 25
8
23
8
12
0
178
3
181
902
328
31
28
110
39
Aug. 10
9
15
16
11
3
61
8
J54
21
34
83
Z6
AUE. 29
26T
125
225
90
12
163
2
35
0
8Z
31
248
3
45
108
14
(JL>
aSolid-set sprinkler system, tilt loam site.
= crop evapotranspiration, as estimated from microclimatological measurements.
-------
Soil solution samples from the nitrogation experiments supplemented
the soil sampling program nicely and demonstrated the low dissolved-
N levels possible with this approach. Values tended to increase
markedly by late season, as plant N needs diminished. Limited soil
solution sampling should prove useful in "nitrogated" fields to per-
mit better cutoff of fertilization as plant needs decrease.
Results from the sprinkler-irrigation rate plots were less definitive.
Higher soil solution N values were obtained, in general, from the
more heavily-fertilized plots, but this trend was marked, in many
cases, by failure of the extraction cups to accurately sample the
highest concentrations of dissolved-N in the profile, because of
"peaks" of dissolved-N between extraction cup depths. Considerable
N from the 670 kg/ha, plots was evident for the deepest extraction
cups in the low water application rate plots, but similar high con-
centrations of N were never observed for the deepest cups in the
high water application rate plots. The greater amount of leaching
in the latter plots could have kept the N flushed from the lower sub-
soil region if most of the deeper cups were placed immediately
above a soil layer limiting water movement, but such flushing should
also have been evident from the soil sampling data for the same
plots. The results can only be regarded as an unexplained anomaly
at present.
1974 SEASON
Because of a large backlog of accumulated analyses, only two small
experiments and two supplemental samplings for additional data on
the Othello Station were conducted in 1974. Results from these
studies are presented below.
Petiole Nitrogen Experiment
In one small experiment conducted on the Othello Station, total yield
and tuber quality were determined for plots maintained at approx-
imately constant petiole nitrate-N levels throughout the growing
season. Results of petiole analyses for samples from these plots
are given in Tables 39 and 40.
The range in petiole N values over the selected fertilization rates
was not as great as had been expected (Table 39). The experimental
field had been maintained in alfalfa for 3 years prior to the 1973
season, and N released from soil organic matter and crop residues,
84
-------
Table 39. SUMMARIZED PETIOLE ANALYSES, BY FERTILIZATION RATE, PETIOLE N
EXPERIMENT, OTHELLO STATION, 1974a
Date
6-12
6-26
7- I
7- 9
7-15
7-23
7-29
8- 5
8-11
8-18
8-30
9- 4
9- 9
9-18
Days
since
planting
70
84
90
98
104
112
118
125
131
138
150
155
160
169
NITROGEN
Nlb N2 N3 N4
3.2 3.3 3.2 3.4
2.7 2.8 Z.7 3.1
2.4 2.5 2.5 2.8
2.1 2.2 2.6 2.7
1.9 2.0 2.2 2.6
1.9 2.0 2.2 2.8
1.8 2.1 2.1 2.7
1.6 1.9 2.0 2.5
1.5 1.7 1.7 2.4
0.7C 0.6c 1.2C 2.8c
0.5c 0.4c 0.9c 1.6c
l.Oc 1.3c U7c 3.1c
l.lc 1.4c 2.7C
1.6c 2.9c
POTASSIUM
Nl NZ N3 N4
10.2 10.1 9.8 9.9
9.0 9.5 9.4 9.6
-
8.0 8.1 8.Z 8.3
7.5 7.9 7.5 8.3
7.6 7.4 7.Z 7.7
7.1 6.8 6.Z 7.3
6.2 6.7 6.5 7.3
7.0 6.4 6.0 7.4
6.4 6.2 6.2 7.6
6.8 7.2 6.4 8.8
7.2 7.2 6.7 8.5
7.6 6.2 8.1
6.3 8.5
CALCIUM
Nl NZ N3 N4
2.1 2.0 2.2 2.1
2.3 2.Z 2.2 2.1
2.1 2.0 2.2 2.0
2.2 2.3 2.1 2.0
2.3 2.3 2.2 2.1
2.0 2.1 2.1 1.9
3.0 2.8 2.7 .Z.4
Z.4 2.1 Z.3 1.8
2.4 2.1 2.2 1.7
2.9 2.5 2.5 1.9
Z.8 2.4 2.3 1.7
2.8 2.5 Z.4 1.8
2.3 2.4 1.7
2.4 1.9
PHOSPHORUS
Nl NZ N3 N4
.43 .41 .38 .43
.51 .49 .46 .48
.41 .45 .40 .44
.43 .44 .41 .43
.35 .35 .34 .39
.30 .3Z ..Z7 .31
.Z7 .30 .28 .33
.26 .27 .23 .26
.21 .23 .21 .26
.20 .21 .20 .26
.20 .21 .18 .Z6
.19 .Zl .17 .Z6
.19 .16 .Z3
.18 .ZO
3
Solid-set sprinkler irrigation, silt loam site.
bNl, NZ. N3, and N4 = constant petiole nitrate-N levels, maintained by adding 90, 170, 410, and 540 kg N/ha.
c= estimated from corresponding nitrate-N values.
-------
O3
Table 40. SUMMARIZED PETIOLE ANALYSES, BY VARIETY, PETIOLE N
EXPERIMENT, OTHELLO STATION, 1974a
(% dry weight)
Treatment
Sprinkler-irrigated plots
NIDI
N1D2
N1D3
N1D4
N2D1
N2D2
N2D3
K2D4
Furrow-irrigated plots
P1D1
P1D2
P1D3
P1D4
P2D1
P2D2
P2D3
P2D4
May 16
76.8
93.8
210.7
720. Z
125.5
146.1
279.9
168.5
Norgold
June 26 July 23
Norgold
9.4 2.9
31.0 31.3
172.3 138.5
215.2 144.7
22.1 11.5
97.9 386.8
237.4 113.4
607.8 403.0
Aug. 30
0.0
7.4
94.0
301.2
0.0
11.8
85.7
397.8
Kennebeck
--
34.3
208.2
194.7
466.7
36.0
175.2
226.9
977.6
45.0
301.3
87.8
351. 1
79.6
53.7
83.5
427.9
19.4
202.3
253.0
785.2
0.0
54.5
212.9
361.6
May 16
30.2
179.1
131.1
567.3
138.9
165.0
114.6
192.8
--
Russet Burbank
June 26 July 23
Russet Burbank
21.2 0.0
20.7 62.4
138.9 410.0
331.3 195.0
19.9 36.0
64.6 21.9
184.4 152.3
155.7 126.3
Russet Burbank
228.3 107.8
137.7 174.0
376.4 244.8
445.0 286.2
55.5 71.9
198.5 272.2
189.3 213.2
718.6 356.9
Aug. 30
0.0
26.8
208.4
684.7
0.0
7.2
270.7
272.0
82.2
112.9
83.9
1203.1
329.9
54.3
326.6
438.3
aSilt loam site.
bNl = 220 kg N/ha.. N2 = 450 kg N/ha.. PI = 38,000 plants, ha., P2 = 55,500 plants/ha., Dl = 4.5 kg Di-syston
(actuaU/ha. , D2 = 9 kg Di-Syston/ha. , D3 = 18 kg Di-Syston/ha. , D4 = 36 kg Di-Syston/ha.
-------
coupled with the 90 kg N/ha. banded at the time of planting, was
sufficient to maintain fairly high nitrate-N and total N levels in the
petioles throughout the growing season even at the lowest fertiliza-
tion rate. Similarly, maintenance of the highest specified nitrate-
N level throughout the season proved difficult, even with the addition
of nearly 560 kg N/ha. to each experimental plot. However, the
spread in average petiole total N levels during the period from
July 1 to September 1 was reasonably good, with average values for
the four N levels of 1.6%, 1.7%, 1.9%, and 2.5%,respectively.
Average petiole calcium values tended to decrease with increasing
N fertilization rate for the same period (possibly due to enhanced
growth accompanied by a nutrient dilution effect), but neither the
average phosphorus nor the average potassium values varied con-
sistently with N fertilization rate. Average levels of petiole N
did not vary consistently between varieties (Table 40), although
Russet Burbank petioles maintained higher N levels late in the
season-than did either Kennebeck or Norgold Russet petioles.
Kennebeck petioles maintained higher average levels of potassium
and phosphorus, but lower levels of calcium, than did petioles from
the other varieties. The relative trends with respect to these
nutrients were reversed for Norgold Russet petioles, with Russet
Burbank petioles exhibiting intermediate average levels of all
three nutrients.
Yield data for the 1974 petiole N experiments are summarized in
Tables 41-43. Total yields generally were highest for the Kennebeck
variety and considerably lower for the Norgold Russet variety (Table
41). Russet Burbank yields generally were similar to, but slightly
lower than, those of the Kennebeck variety. Percentages of U.S.
No. 1 tubers consistently were similar for the Kennebeck and Norgold
Russet varieties, but substantially lower for the Russet Burbank
variety. Yields of U.S. No. 1 tubers followed the same relative
order as observed for total yields, although levels for Russet Bur-
bank were more similar to those of Norgold Russet than of Kennebeck
in this case.
Total yields in all cases remained constant or even decreased as a
function of N fertilization rate except for the highest fertilization
rate, where a substantial increase in total yield was obtained
(Table 41). Percentage of U.S. No. 1 tubers remained essentially
invariant with increasing N fertilization rate. Total yield of Russet
Burbank tubers tended to increase, and percentage of U.S. No. 1
tubers tended to decrease, with increasing petiole nitrate-N levels
as determined 90 days after planting. However, the trend was less
37
-------
Table 41. YIELD DATA, PETIOLE N EXPERIMENT, OTHELLO STATION, 1974C
C3
CO
Variety
Based on plot f<
Norgold
Kennebeck
R. Burbank
Based on petio]
Norgold
Kennebeck
R. Burbank
Total
Nl
ertilization
538
777
735
yield,
N2
rates
520
719
731
quintal/ha.
N3
520
750
744
N4
557
837
800
LI
e nitrate -M
507
-
661
L2
levels
547
805
734
L3
at 90 days
536
823
796
L4
535
748
-
Based on petiole NO,-N levels at 120 days:
Norgold
Kennebeck
R . Burbank
531
836
732
536
756
753
Based on petiole NO0-N levels at
Norgold
Kennebeck
R . Burbank
774
776
_
811
710
535
731
700
150 days:
_
849
836
539
827
809
_
875
718
Nl
77
75
63
U.S. No.
N2
77
79
67
1's, %
N3
81
77
65
N4
76
78
58
LI
81
-
66
74
80
61
_
77
65
L2
80
78
63
76
72
65
_
63
67
L3
78
76
60
80
81
67
_
80
65
L4
77
72
-
79
77
60
-
68
51
^Solid-set sprinkler irrigation, silt loam site.
bN1_4 = 90, 170, 410, and 540 kg N/ha. , respectively; Ll-4 =<8,000, 8,000-11,000, 11,000-
14,000, and>14,000 ppm nitrate-N, respectively, at 90 days; Ll-4 =<4,000, 4,000-8,000,
8,000-12,000 and>12,000 ppm nitrate-N, respectively, at 120 days; Ll-4 =<2,000, 2,000-
4,000, 4,000-6,000, and >6,000 ppm, respectively, at 150 days.
-------
Table 42. YIELD DATA CORRELATED WITH PETIOLE NITRATE LEVELS FOR ENTIRE
SEASON, PETIOLE N EXPERIMENT, OTHELLO STATION, 1974a
Variety
Total yield, quintal/ha. b
0 1-20 21-40 41-60 61-80 81+
days
Based on days petiole nitrate-N below 10,000
Norgold
Kennebeck
R . Burbank
547 512 534
875 - 781 848 768
759 827 721 745
Based on days petiole nitrate-N below 7,500
Norgold
Kennebeck
R. Burbank
505 547 544 536
875 781 986 730 829
861 764 724 748 752
Based on days petiole nitrate-N below 5,000
Norgold
Kennebeck
R. Burbank
511 563 506
768 943 689 811 978
757 767 738 731 819
days
ppm
-
978
780
ppm
ppm
0
days
-
68
-
77
68
52
78
74
56
U.
1-20
79
-
50
80
79
58
81
80
70
S. No.
21-40
82
79
60
77
81
64
72
73
67
1's, %
41-60
77
77
59
76
71
70
-
76
65
61-80
-
74
67
-
79
65
-
82
64
81+
days
-
82
64
Total yield, quintal /ha.
Greater than 10 days
10,000 ppm 7,500 ppm 5,000
ppm
Less
10,000 ppm
than 10
7,500
days
ppm 5
,000 ppm
93
vO
Based on recovery period after falling below a specified petiole nitrate-N level
Norgold
Kennebeck
R. Burbank
595 (81)c
859 (81)
780 (61)
607 (82)
765 (80)
749 (63)
570 (81)
837 (79)
776 (69)
552 (82)
707 (68)
747 (70)
560 (79)
814 (79)
819 (64)
568 (77)
781 (79)
672 (60)
aSolid-set sprinkler irrigation, silt loam site.
^Quintal/hectare = cwt/acre x 1.12.
cValues in parentheses denote U.S. No, 1 tubers, %.
-------
Table 43. YIELD DATA CORRELATED WITH PETIOLE NITRATE LEVELS PRIOR TO
AUGUST 15, PETIOLE N EXPERIMENT, OTHELLO STATION, 1974a
Variety
Total yield, quintal/ha.
0 days 1-20 21-40 41-60
Based on days petiole nitrate-N below 10,000 ppm
Norgold 469 560 - 534
Kennebeck
R. Burbank
812 848 759 802
759 - 787 738
Based on days petiole nitrate-N below 7,500 ppm
Norgold
Kennebeck
R . Burbank
493 588 522
856 730 829
787 738 - 748
Based on days petiole nitrate-N below 5,000 ppm
Norgold
Kennebeck
R. Burbank
511 563 528
856 752 883
758 736 775 732
0
76
75
50
78
77
53
79
77
61
Total yield, quintal/ha
Greater than 10 days
10, 000 ppm 7, 500 ppm 5, 000 ppm
10,000
U.S.
1-20
81
80
-
81
71
68
77
74
66
Less
ppm 7
No. 1's, %
21-40
71
66
75
79
79
80
67
than 10 days
,500 ppm 5
41-60
77
77
65
64
61
,000
ppm
Based on recovery period after falling below a specified petiole nitrate-N level
Norgold
Kennebeck
R. Burbank
566 (81)c
859 (81)
787 (66)
607 (82)
731 (81>
773 (70)
570 (81)
729 (78)
767 (67)
552 (82)
729 (62)
747 (70)
519 (77)
529 (78)
722 (60)
514 (73)
697 (59)
Solid-set sprinkler irrigation, silt loam site.
k Quintal/he eta re = cwt/acre x 1.12.
cValues in parentheses denote U.S.
No. 1 tubers, %.
-------
consistent for data from the 120-day and 150-day sampling periods,
except for the effect on tuber quality at high petiole nitrate-N levels.
Total yield of Kennebeck tubers tended to increase with increasing
petiole nitrate-N levels for the 150-day petiole sampling, and per-
centage of U.S. No. 1 tubers tended to decrease at the highest
petiole nitrate-N level in all cases for the Norgold Russet and
Kennebeck varieties. However, no other consistent trends were
evident from, the data.
In an attempt to better isolate "critical" petiole nitrate-N levels for
optimum growth of the potato varieties studied, individual plot yield
data were segregated on the basis of cumulative time for which
petiole nitrate-N analyses fell below predetermined levels. These
results are given in Tables 42 (where petiole analyses for the entire
season were considered) and 43 (where only petiole analyses for
samples taken prior to August 15 were considered). The latter
approach was an attempt to eliminate late-season petiole samplings,
which frequently are regarded as having only limited value in yield
predictions. In neither case did any of the petiole nitrate-N levels
examined (10,000, 7,500, or 5,000 ppm) appear to be "critical" for
high-level production of good-quality tubers. If a "critical" petiole
nitrate-N concentration existed for tuber production at this location
in 1974, it was below the 5,000 ppm level. At the bottom of each
table, total yield and tuber quality are compared for various lengths
of recovery period (i.e.,at higher petiole nitrate-N levels) after
petiole results had fallen below a specified nitrate-N level. Slightly
higher yields generally were obtained for the longer recovery periods,
but no adverse effects on quality (e.g.,knobbiness) was evident for
samples from plots where petiole nitrate-N levels fell below any of
the tested "critical" levels and then returned to higher values for a
sustained period.
No adverse effects on total yield or yield of U.S. No. 1 tubers ap-
peared to be associated with petiole nitrate-N levels of 10,000, 7,500,
or 5,000 ppm at this location in 1974.
Di-Syston Experiments
In a second set of experiments at the Othello Station in 1974, effects
of high application rates of Di-Syston (a systemic insecticide) on yield
and tuber quality were assessed. Results from this experiment are
summarized in Tables 44-47.
To determine the rate of Di-Syston degradation when large quantities
of the insecticide were applied in the fertilizer band at the time of
planting, soil samples of constant volume from the immediate vicinity
of the fertilizer band were taken from selected plots at approximately
91
-------
Table 44. DI-SYSTON ANALYSES, DI-SYSTON EXPERIMENT, OTHELLO
STATION, 197 4a
(ppm, soil basis)
Date
6-12
6-26
7- 1
7- 9
7-15
7-23
7-29
8- 5
8-11
8-18
8-30
9- 4
9- 9
9-18
Days
after
planting
70
84
90
98
104
in
118
125
131
138
150
155
160
169
NITROGEN
Ken Nor Bur
J.3 l.Z i.l
3.0 3.0 2.4
Z.I 2.7 2.2
Z.4 2.4 2.4
2.1 2.2 2.2
2.1 2,1 2.5
2.1 2.1 2.4
1.8 2.0 2.2
1.7 1.8 2.0
l.lc L4c 1.5C
0.7C - l.Oc
1.4C - Z.lc
1.4C - 2.1c
1.8c - 2.7c
POTASSIUM
Ken Nor Bur
10.7 9.4 9.9
10.3 9.2 8.7
-
8.7 8.2 7.5
8.8 6.8 7.9
8.7 6.5 7.2
8.2 5.6 6.6
7.8 5.6 6.6
7.3 5.5 7.4
7.Z 5.4 7.3
7.2 - 7.4
7.4 - 7.4
7.2 - 7.4
7.3 - 7.5
CALCIUM
Ken Nor Bar
1.7 2.2 2.5
1.7 2.5 2.5
1.5 2.2 2.5
1.8 Z.4 2.2
1.8 2.5 2.5
1.6 2.3 2.1
2.2 3.3 2.7
1.8 2.7 2.0
1.6 2.7 2.0
Z.O 3.1 2.2
Z.3 - 2.3
2.2 - 2.5
2.1 - 2.2
2.1 - 2.Z
PHOSPHORUS
Ken Nor Bar
.49 .35 .40
.60 .45 .40
.51 .41 .36
.48 .41 .41
.40 .32 .34
.34 .25 .30
.34 .25 .29
.29 .22 .26
.24 .21/ .24
.23 .20 .22
.21 - .22
.20 - .21
.19 - .19
.20 - .18
VO
ro
aSolid-set sprinkler irrigation, silt loam site.
bKen = Kennebeck, Nor = Norgold, Bur = Russet Burbank.
c= estimated from corresponding nit rate-N values.
-------
Table 45. YIELD DATA, DI-SYSTON EXPERIMENTS, OTHELLO STATION, 1914s
vo
u>
Variety and treatment
Sprinkler -irrigated plots
Norgold
220 kg N/ha.
450 kg N/ha.
Russet Bur bank
220 kg N/ha.
450 kg N/ha.
Furrow-irrigated plots
Kennebeck
38,000 plants /ha.
55,500 plants/ha.
Russet Burbank
38,000 plants/ha.
55,500 plants /ha.
Total
Dlc
615
620
851
900
360
335
360
360
yield,
D2
578
631
787
839
329
349
347
360
quintal /ha.
D3 D4
603
612
923
830
338
317
347
342
631
603
827
833
292
332
360
305
U
Dl
78
78
63
68
65
76
64
68
.S. No.
D2
78
77
61
66
70
78
65
70
1's,
D3
75
75
68
65
66
77
61
63
yo
D4
77
71
65
67
62
75
63
67
Silt loam, site.
Quintal/hectare = cwt/acre x 1.12.
CD1 = 4.5 kg Di-Syston (actual) per ha. , D2 = 9 kg Di-Syston/ha. , D3 = 18 kg Di-Syston/ha.,
D4 = 36 kg Di-Syston/ha.
-------
Table 46. SOIL ANALYSES, SPRINKLER-IRRIGATED DI-SYSTON PLOTS, OTHELLO
STATION, 1974a
vo
b -i
Treatment May 16
NIDI
N1D2
N1D3
N1D4
N2D1
N2D2
N2D3
N2D4
NIDI
N1D2
N1D3
N1D4
N2D1
N2D2
N2D3
N2D4
72.1
78.1
113.3
91.7
113.8
70.7
91.0
84.7
8133
9070
9561
10736
8754
7483
6711
7405
Norgold
June 26
21.7
13.3
28.3
12.9
35.9
20.3
15.2
19.2
1601
390
912
71
231
323
188
325
July 23
8.4
10.6
26.1
7.8
13.4
14.3
8.7
12.4
13
43
164
68
24
27
18
74
Aug. 30
May 16
EC, mmho/cm
4.9
7.4
9.4
4.3
8.0
6.7
3.2
4.5
74.5
66.9
100.9
76.5
80.0
102.6
89.5
66.0
Cl, mg/1
10
25
38
43
25
15
14
134
9717
7902
8981
8729
8764
9293
9594
6746
Russet
June 26
18.2
14.8
20.5
13.1
19.6
17.7
13.7
15.8
1277
277
213
46
151
45
270
390
Burbank
July 23
11.4
16.6
17.0
10.4
9.7
16.8
14.4
12.6
10
69
77
45
81
32
96
157
Aug. 30
7.1
7.3
7.2
7.2
9. 1
x *
6.2
8.5
5.1
11
12
28
49
4
4
70
37
-------
Table 46. (continued) SOIL ANALYSES, SPRINKLER-IRRIGATED DI-SYSTON PLOTS,
OTHELLO STATION, 1974a
Treatment
NIDI
N1D2
N1C3
N1D4
N2D1
N2D2
N2D3
N2D4
Norgold
May 16
5275
165C8
13407
6581
14419
6532
11065
9444
June
26 July 23
Aug. 30
May
Dissolved inorganic N
1588
376
856
345
2156
915
947
1442
27
27
255
54
226
205
43
389
16
20
55
10
57
41
14
43
4346
4807
10411
6697
7099
11620
8053
5594
Russet
16 June 26
» mg/1
731
157
679
378
1376
913
791
1134
Burbank
July 23
15
64
40
55
186
405
179
475
Aug. 30
81
11
22
20
30
27
93
31
VO
Ul
Silt loam site.
bNl = 220 kg N/ha. , N2 = 450 kg N/ha. , Dl = 4.5 kg Di-Syston (actual)/ha. , D2 = 9 kg
Di-Syston/ha., D3 = 18 kg Di-Systo'n/ha., D4 = 36 kg Di-Syston/ha.
-------
Table 47. SOIL ANALYSES, FURROW-IRRIGATED DI-SYSTON PLOTS, OTHELLO
STATION, 1974a
vo
k
Treatment
P1D1
P1D2
P1D3
P1D4
P2D1
P2D2
P2D3
P2D4
P1D1
P1D2
P1D3
P1D4
P2D1
P2D2
P2D3
P2D4
June 26
25.9
21.6
26.3
27.1
16.2
21.3
13.6
28.9
1579
1027
1409
1178
481
936
223
1516
Kennebeck
July 23
17.8
17.4
20.8
19.9
20.7
22.6
8.7
17.2
503
709
612
1038
1285
1426
70
845
Russet Burbank
Aug. 30
June
EC, mmho/cm
8.8
13.6
9.5
12.9
10.8
10.9
5.9
14.0
30.2
31.3
29.0
34.9
21.2
29.9
30.9
39.8
Cl, mg/1
48
123
527
197
1904
733
222
907
1479
2174
2170
1659
829
1972
1685
2120
26 July 23
21.0
16.0
21.3
8.6
39.4
25.4
11.8
27.3
1606
892
1333
435
2597
258
597
1864
Aug. 30
16.3
10.5
8.2
15.9
15.3
10.3
8.3
13.7
858
280
704
767
145
751
123
612
-------
Table 47. (continued) SOIL ANALYSES, FURROW-IRRIGATED DI-SYSTON PLOTS,
OTHELLO STATION, 1974a
vO
-J
Treatment
P1D1
P1D2
P1D3
PID4
P2D1
P2D2
P2D3
P2D4
June 26
2568
2241
2528
3035
1414
2128
1492
2960
Kennebeck
July 23
712
1295
987
1408
771
865
373
1016
Aug. 30
Russet Burbank
June
Dissolved inorganic
69
88
71
255
100
109
58
460
2743
2723
2532
2170
1710
3050
2614
4059
26 July 23
N, mg/1
820
601
983
346
2864
1488
664
2098
Aug. 30
422
53
47
137
337
498
50
370
Silt loam site.
3P1 = 38,000 plants, ha., P2 = 55,500 plants/ha. , Dl = 4.5 kg Di-Syston (actual)/ha. ,
D2 = 9 kg Di-Syston/ha. , D3 = 18 kg Di-Syston/ha. , D4 = 36 kg Di-Syston/ha.
-------
monthly intervals. Di-Syston analyses for these samples are given
in Table 44, with salt (EC), chloride, and dissolved inorganic N
levels for the same soil samples summarized in Tables 46 - 47.
Although sampling variability was large, soil Di-Syston levels
dropped more rapidly for the sprinkler-irrigated plots, and were
negligibly small for the two lowest Di-Syston application rates (4.5
and 9 kg actual material/ha.) by late August. Substantial con-
centrations of Di-Syston remained in the fertilizer band for the
entire season at the higher Di-Syston application rates, however,
and even at the lower rates for many of the furrow-irrigated plots.
No consistent effects of nitrogen fertilization rate ( under sprinkler-
irrigation) or plant population (under furrow-irrigation) on the rate
of Di-Syston breakdown were evident from these data.
Levels of soluble fertilizer constituents such as chloride, dis-
solved inorganic N, and salts (reflected by the EC readings) gen-
erally decreased regularly throughout the growing season, with
results for the highly-mobile chloride exhibiting the greatest
deviations from this trend. No consistent trends with increasing
N fertilization rate or increasing plant population were evident from
the data.
Yield data for the 1974 Di-Syston experiments are given in Table 45.
Increasing N fertilization rate generally increased total yield slightly,
and increasing plant population consistently increased the percentage
of U.S. No. 1 tubers. No definitive effects of increasing Di-Syston
rate on tuber yields or quality were evident from the data. Yields
were consistently and substantially higher for the sprinkler-irrigated
plots, with the relative yields between varieties for a given experi-
mental area remaining the same as for the 1974 petiole N experiment
(discussed previously).
Runoff Samples, Othello Station, 1974
Furrow runoff samples for several of the 1974 experiments at the
Othello Station were collected periodically throughout the season.
Results of these analyses are given in Table 48. Additional runoff
analyses for the 1973 season also are included in the table.
With the exception of one 1973 sampling, EC (dissolved salt) levels
were low and similar to those of irrigation water supplied to the
Othello Station. Again with the exception of one 1973 sample, dis-
solved chloride, N, and phosphorus levels were low. Some
polyphosphate levels were unusually high, but these may have been
experimental artifacts. Turbidity levels in runoff samples from this
silt loam site generally were highest early in the season and de-
clined to relatively low levels as furrows stabilized later in the
season.
90
-------
Table 48. PROPERTIES OF RUNOFF SAMPLES, FURROW-IRRIGATED PLOTS,
OTHELLO STATION, 1974 and 1973a
vo
VO
Plot area
Seed plots
Seed plots
Seed plots
Di-Syston
Di-Syston
Di-Syston
Di-Syston
Di-Syston
Di-Syston
Minimum tillage
Minimum tillage
Minimum tillage
Minimum tillage
Minimum tillage
Variety trials
Variety trials
Variety trails
Variety trails
1973 experiments
1973 experiments
J973 exoeriments
Date
7-10
7-23
7-29
7-10
7-23
7-Z9
8-5
8-11
8-18
7-10
7-29
8-5
8-11
8-18
7-23
8-5
8-11
8-18
8-15
8-23
8-29
Water on Sampling
9:00 AMb 1:30 PM
9:00 AM 5:15 PM
9:30 AM 3:25 PM
9:00 AM 1:30 PM
8:00 AM 5:15 PM
9:30 AM 3:30 PM
3:40 PM
1:15 PM
2:10 PM
8:00 AM 1:30 FM
9:00 AM 3:20 PM
3:30 PM
1:00 PM
2:00 PM
8:00 AM 5:30 FM
3:50 PM
1:20 PM
2:20 PM
_-
_.
--
PH
7.97
7.88
7.80
7.73
7.78
7.90
7.76
7.92
7.77
8.06
7.97
7.87
7.86
7.74
7.90
7.67
7.67
7.86
7.97
7.87
7.83
EC,
jimho/cm
146
131
145
134
139
131
128
125
133
148
141
133
142
133
146
133
132
135
162
228
123
Ortho- Poly-
Cl N P P
all mg/ liter
0.8 0 0.12 0.98
1.0 0 0.01 0
1.0 0 0.04 0.04
1.1 0 0.02 0.04
1.0 0.78 0.02 0.03
1.3 0 0.01 0.78
0.5 0 0.01 0.04
0.4 0.15 0.01 0.02
0.8 0 0.01 0.39
0.9 0 0.07 0.10
0.9 0 0.13 16.6
0.5 0 0.02 0.10
0.4 0 0.05 0.01
0.7 0 0.04 0.11
0.7 0 0.07 0.03
0.8 0 0.01 0.11
0.5 0 0.04 0.10
0.5 0 0.01 0.10
3.0 1.34 0.20 0.22
10.4 2.55 0.31 0.06
0.5 0 0.06 0.01
Turbidity,
JTU
510
19
45
160
110
75
58
28
43
170
110
16
2.5
12
170
16
4.4
3.7
1.6
120
16
aSilt loam site.
All plots at this location watered on a five-day rotation.
-------
Minimum Tillage Experiment (Preliminary Sampling)
A final experiment of considerable environmental impact was
sampled during the 1974 season. Dr. R. Kunkel of Washington State
University has proposed the use of over-winter cover crops or
second crops on potato lands to stabilize the soil against wind and
water erosion and to "scavenge" residual N remaining in the soil
profile following the potato cropping season. He has also proposed
direct planting of potatoes into the chemically-killed stubble of this
cover crop to aid in early-season erosion control and to minimize
the number of tillage operations required on the land (with sub-
sequent compaction and root restriction problems). Plots to
demonstrate the feasibility of this approach were established on the
Othello Station in the fall of 1973, and planted to potatoes in April
of 1974. Fertilizer N had been applied to the plots at a rate of 340
kg/ha, at the same time as fall planting, to see whether fall fer-
tilization of the potato crop could be employed. Results of the soil
samplings are included in Table 49.
Average values for dissolved inorganic N in the top 60 cm of soil
were low in all cases and never more than 2 times the maximum
drinking water standard. This appears to reflect the combined
effects of uptake of soluble N by the cover crop and leaching of
nitrate from the surface soil layer during the over-winter period,
with little conversion of additional N from the ammonium to the
nitrate form because of cool soil temperatures during the early
spring.
Values for soil solution N were markedly higher (averaging 8 to 18
times the maximum drinking water standard) for the 60- to 120-cm
soil depth. These high levels of N had leached well below the normal
rooting zone of potatoes at this location, and foliage of the cover crop
already had been killed at the time of sampling, so such N was
beyond the depth of potential crop uptake and was subject to leaching
during the 1974 crop season. Values at each of the 12 sampling sites
in the field varied somewhat, but the zone of high N concentrations
occurred at between 60 and 150 cm of depth in all cases, with over-
lying and underlying soil exhibiting low N concentrations. Maximum
dissolved-N values at all sites were of the same order of magnitude
(95-272 mg/liter), suggesting that the movement of N resulted from
a uniform field-wide fertilization such as applied to the field in the
fall of 1973 during cover crop establishment. No regular differences
between the wheat and ryegrass crops were evident from the data.
A reasonable explanation for the data is provided by the 1973-74 fall
and winter rainfall data at Othello, as summarized in Table 49.
Precipitation was approximately 50% higher at the site during this
100
-------
Table 49. DISSOLVED INORGANIC N AND RAINFALL DATA, MINIMUM TILLAGE PLOTS,
OTHELLO STATION, 1974a
Depth, cm
0-30
30-60
60-90
90-120
120-150
150-170
Dissolved inorganic N, mg/liter
Wheat
Average
22
10
82
149
58
18
Plots
Range
4-45
2-18
25-183
95-224
5-106
9-38
Ryegrass
Average
14
15
128
184
43
14
Plots
Range
5-35
1-27
24-166
70-272
4-102
2-31
Month
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Total for
period
Precipitation, cm
1.30
3.15
9.17
7.26
3.30
2.21
0.00
26.39
Furrow irrigation, silt loam. site.
-------
period than the long-term average, so the initial year of minimum
tillage experimentation was carried oat under abnormally wet con-
ditions . As the soil at the Othello Station retains an average of
about 0.17 cm of water per cm of depth at "field capacity", there
was enough precipitation to move fertilizer nitrates to the 150-cm
depth at any sampling site which was slightly more coarse-textured
than the average, or at any site where water might tend to accumu-
late briefly in shallow surface depressions. To the rainfall values
of Table 49 should be added the quantities of irrigation water applied
for stand establishment and for early fall irrigation of the cover
crop. Even with surface evaporation during the windy fall season
and evapotranspiration losses by the crop during the entire over-
winter period, there appears to have been adequate water available
at the Othello Station to produce the leaching recorded in Table 49.
The minimum tillage treatments used for this initial study not only
failed to prevent N leaching following cropping to potatoes, but
actually may have contributed additional N (from the heavy fall
fertilization) to be moved through the soil during the wet over-winter
period. The importance of minimum fertilization for cover establish-
ment is thus demonstrated, as well as the importance of adding fall-
applied N in predominantly ammonium (including anhydrous ammonia)
form and at a time when it will be converted only slowly to the nitrate
form during the remaining fall months. Fumigation has been stressed
as an important management practice for fields recropped to potatoes,
so any die-back in the soil population of nitrifying bacteria which ac-
companies fumigation may aid in retarding nitrate formation and sub-
sequent leaching of N. By the time the soil bacterial population has
multiplied again following fumigation, the average soil temperature
may be low enough (less than approximately 10° C (50° F)) to inhibit
conversion of ammonium N to the nitrate form. Fortunately, many
grass cover crops are able to use either ammonium or nitrate N in
satisfying their nutritional needs.
Another method for preventing the nitrification of fall-applied am-
monium fertilizers is their late application, or their application to
dry soils, so that either soil temperature or soil moisture status is
unfavorable for subsequent microbial conversion of N to the nitrate
form. However, such conditions are unsatisfactory for establishment
of the winter cover crop to be used for erosion control. Additional
work must be done to establish proper fertilization timing and as-
sociated management techniques required to maximize early fall
growth of the cover crop while minimizing N leaching during the over-
winter period. Use of only a small quality of "starter" N for the
cover crop, with the main application of N for the next season's
potato crop to be made either during the spring planting operation or
through the sprinkler system during the potato growing season, may
prove to be the most efficient means of N management for such
potato recrop systems.
102
-------
SECTION VI
REFERENCES
1. American Public Health Association. 1965. Standard Methods
for the Examination of Water and Waste-water, 12th Edition.
American Public Health Association, New York. 874 p.
2. Bremner, J. M. 1965. Inorganic forms of nitrogen. In:
C. A. Black, D. D. Evans, J. L. White, L. E. Ensminger,
and F. E. Clark, eds. Methods of Soil Analysis. American
Society of Agronomy, Madison, Wisconsin, pp. 1179-1237.
3. Clapp, D. W. 1975. Di-Syston degradation in soil. Un-
published Ph.D. Dissertation, University of Idaho, Moscow.
52 p.
4. Cotlove, E. 1964. Determination of chloride in biological
materials. In: David Click, ed. Methods of Biochemical
Analysis, Vol. XII. Interscience, New York. pp. 277-391.
5. Day, P. R. 1965. Particle fractionation and particle-size
analysis. In: C. A. Black, D. D. Evans, J. L. White,
L. E. Ensminger, and F. E. Clark, eds. Methods of Soil
Analysis . American Society of Agronomy, Madison,
Wisconsin, pp. 545-567.
6. Grover, B. L. and R. E. Lamborn. 1970. Preparation of
porous ceramic cups to be used for extraction of soil water
having low solute concentrations . Soil Science Society of
America, Proceedings 34; 706-708.
7. Jensen, M. C., J. E. Middleton, and W. O. Pruitt. 1961.
Scheduling irrigation from pan evaporation. Circular 386,
Washington Agricultural Experiment Station, Pullman. 14 p.
8. Murphy, J. and J. P. Riley. 1962. A modified single solution
method for the determination of phosphate in natural waters.
Analytica Chimica Acta 27; 31-36.
103
-------
SECTION VII
PUBLICATIONS
1. Middleton, J. E., S. Roberts, B. L. McNeal, B. L. Carlile,
D. W. James, and T. A. Cline. 1975. Irrigation and
fertilizer management for efficient crop production on a
sandy soil. Bulletin 811, Washington Agricultural Experiment
Station, Pullman. 10 p.
2. McNeal, B. L. , andR. Kunkel. 1973. Nitrate leaching following
potato fertilization. In: Proceedings 12th Washington Potato
Conference, February 6-8, 1973, in Moses Lake. pp. 103-109.
3. Shainberg, I. , and B. L. McNeal. 1976. Evaluation of some
theories of miscible displacement. Soil Science Society of
America, Proceedings (submitted).
4. McNeal, B. L. 1975. Nitrogen, minimum tillage, and the
Columbia Basin. In: Proceedings 14th Washington Potato
Conference, February 4-6, 1975, in Moses Lake. pp. 75-79.
5. Diaz Zeballos, Cesar P. 1975. Soil testing versus petiole
analysis as a predictor of potato yields in the Columbia Basin.
Unpublished M.S. thesis, Washington State University,
Pullman. 80 p.
6. Leifer, James T. 1976. Potato yield and quality at constant
petiole NOo-N levels. Unpublished M.S. thesis, Washington
State University, Pullman. (Draft stage).
7. McNeal, B. L., R. Kunkel, andN. M. Ellsworth. 1973.
Nitrate movement beneath irrigated potato fields. Agronomy
Abstracts , 65th Annual Meeting. American Society of
Agronomy, Madison, Wisconsin, p. 85.
8. Kunkel, R. B. L. McNeal, and C. B. Kresge. 1974. Effect of
slow-release nitrogen compounds on the yield and quality of
Russet Burbank potatoes in Washington. Agronomy Abstracts,
66th Annual Meeting. American Society of Agronomy, Madison,
Wisconsin, p. 151.
9. McNeal, B. L., R. Kunkel, G. S. Campbell, and C. P. Diaz.
1974. Evaluation of some management alternatives to restrict
nitrate leaching beneath irrigated potatoes. Proceedings
Western Society of Soil Science, June 17-20, 1974, in Irvine,
California, p. 14.
104
-------
SECTION VIII
APPENDIX
Table No. Page
A-l Average EC Values, Soil Solutions, Block 21 Site, 107
1971
A-2 Average Dissolved Cl Values, Soil Solutions, Block 108
21 Site, 1971
A-3 Average Dissolved Inorganic N, Soil Solutions, Block 109
21 Site, 1971
A-4 EC Values, Soil Solutions, Sprinkler Irrigation, Block 110
21, 1970
A-5 Dissolved Cl Values, Soil Solutions, Sprinkler Irri- 111
gation, Block 21, 1970
A-6 Dissolved Inorganic N, Soil Solutions, Sprinkler 112
Irrigation, Block 21, 1970
A-7 EC Values, Soil Solutions, Furrow Irrigation, Block 113
21, 1970
A-8 Dissolved Cl Values, Soil Solutions, Furrow Irrigation, 114
Block 21, 1970
A-9 Dissolved Inorganic N, Soil Solutions, Furrow Irri- 115
gation, Block 21, 1970
A-10 Dissolved Inorganic N, Row-furrow Sets, Irrigation Rate 116
and Sprinkler-irrigated Plots, Othello Station,
Fall of 1972
A-ll EC Values, Row-furrow Sets, Furrow Irrigation Rate 118
and Sprinklerrirrigated Plots, Othello Station, 1972
A-12 Dissolved Inorganic N, Selected Plots, Suspension 120
Fertilizer and Slow-release N Experiments, Othello
Station, 1972
A-13 Average Dissolved Inorganic N, Suspension Fertilizer 122
Experiment, Othello Station, Fall of 1972
A-14 Average EC Values, Suspension Fertilizer Experiment, 123
Othello Station, Fall of 1972
105
-------
APPENDIX (continued)
Table No.
A-15 Dissolved Inorganic N, Row-furrow Sets, Suspension 124
Fertilizer and Fertilizer Factorial Experiments,
Othello Station, Fall of 1972
A-16 Dissolved Inorganic N, 1971 Suspension Fertilizer 125
Experiment, Othello Station, 1972
A-17 Average EC Values, 1971 Suspension Fertilizer 126
Experiment, Othello Station, 1972
A-18 Average Yield, Selected Treatments, 1971 and 1972 127
Suspension Fertilizer Experiments, Othello Station
A-19 Average Dissolved Inorganic N, Fertilizer Factorial 128
Experiment, Othello Station, Fall of 1972
A-20 Average Soil-test P and K Values, Fertilizer 129
Factorial Experiment, Othello Station, 1965-1972
A-21 Average Soil-test P and K values with Depth, Fer- 130
tilizer Factorial Experiment, Othello Station,
Fall of 1972
A-22 Summarized Total Yield Data, Selected Treatments, 131
Fertilizer Factorial Experiment, Othello Station,
1965-1972
A-23 Dissolved Inorganic N, Slow-release N Experiment, 132
Othello Station, Fall of 1972
A-24 Summarized Yield Data, Selected Treatments, Slow- 133
release N Experiment, Othello Station, 1972
A-25 Dissolved Inorganic N, and EC Data, 1971 Plant 134
Population Experiment, Othello Station, Spring
of 1972
A-26 Summarized Yield Data, Selected Treatments, 1971 135
and 1972 Plant Population Experiments, Othello
Station
A-27 Dissolved Inorganic N, 0-30 cm Depth, Suspension 136
Fertilizer Experiment, Moses Lake Area, 1973
A-28 Dissolved Inorganic N, 0-30 cm Depth, Suspension 137
Fertilizer Experiment, Othello Area, 1973
A-29 Dissolved Inorganic N, 0-30 cm Depth, Slow-release N 138
Experiment, Moses Lake Are,a, 1973
A-30 Dissolved Inorganic N, 0-30 cm Depth, Slow-release N 139
Experiment, Othello Area, 1973
A-31 Dissolved Inorganic N, 0-30 cm Depth, Slow-release N 140
Experiment, Othello Station, 1973
106
-------
Table A-l. AVERAGE EC VALUES, SOIL SOLUTIONS, BLOCK 21 SITE, 1971
(mmho/cm)
Treatment
Ql
(low-rate
sprinkler)
Q3
(high-rate
sprinkler)
Wl
(low-rate
furrow)
(high-rate
furrow)
Depth,
cm
60
90
120
180
240
basalt
60
90
120
180
240
basalt
60
90
120
.180,
basalt
£n
ou
on
70
120
160,
basalt
5-5 5-26
.98
1.16 1.01
2.48
1.11
1.92 2.15
1.21 1.09
3.41 3.01
3.18 2.70
1.27 1.27
1.00
2.34 1.19
1.11 1.82
.83 .88
6-11 6-18 6-25
1.97 1.03 1.09
2.42
.95
2.13 2.25 2.53
5 11
1.44 1.55 1.47
1.21 -- 2.20
2.59 - 2.13
1.87 2.29 2.09
1 39
3.07 3.25 4.05
1.07 3.37 2.77
1.21 1.03 1.41
1.33 1.09 1.24
4.85 2.30
1.72 1.97 2.62.
.87 1.86 1.10
7-1 7-8 7-15 7-29
1.47 5.62 3.87 9.67
1.15 1.39 1.43 3.22
1 56 2.18 2.06 1.78
2.01 2.97 2.96 3.02
2.22 1.87 2.38
2.46 2.41 2.48 2.26
3.48 4.57 4.12 1.01
2.06 3.00 3.50 3.06
1.03 1.30 1.36 2.97
.93 1.11 1.20 1.99
2.25 2.35 1.82 1.80
2.05 2.25 2.03 2.34
1.87 .34 2.33
6.53 6.24 5.33 2.46
1.48 2.05 1.68 .89
3.94 4.08 1.98 1.60
1.32 1.31 1.47 2.47
1.56 1.72 1.17 .78
2.34 1.01 1.00 .85
2.15 1.16 .97 .64
215 1 84 1.11
1.04 1.37 1.37 1.04
8-12 8-26
8.10 7.41
2.39 6.50
1.98 2.04
2.00 2.17
5.45 2.37
2.57 2.46
1.77 1.55
1.83 2.48
3.70 1.47
1.08 .93
2.59 1.76
1.81 1.27
5.86 1.22
2.44 .98
.85 .78
2.75 .59
2.81 1.04
.81 .56
.90 .62
.64 .59
.71 .75
.71 .64
9-9
3.19
6.32
2.10
2.20
2.53
2.25
1.15
3.24
1.47
.91
1.32
1.39
1.29
.72
.62
.78
.78
.71
.70
.61
.66
.69
Ql
Q3
Rainfall
1.3 2.4
2.0 3.7
5.0 7.3 11.4
7.5 10.9 17.1
14.8 19.5 25.4 39.3
22.1 29.3 38.1 59.0
51.5 61.4
77.2 92.0
63 64
66.6
97.4
8.7
-------
Table A-2. AVERAGE DISSOLVED Cl VALUES, SOIL SOLUTIONS, BLOCK 21 SITE, 1971
(mg/liter)
Treatment
01
(low-rate
sprinkler)
Q3
(high-rate
sprinkler)
VI
(lov-rate
furrow)
W3
(high-rate
furrow)
Depth.cn
60
90
120
180
240
60
90
120
180
240
60
90
120
180
60
90
120
180
5-5 5-26
73
43 50
257
... ...
53
113 49
58 83
103 97
45 39
38 54
... .._
125 44
35 193
36 30
6-11 6-18 6-25
181 70 77
... . ...
107
55
31 52 76
- . ... 57K
56 224 63
97 49
102 88
120 46 148
34
215 220 261
71 257 190
57 52 102
54 56 35
319 110
157 132 183
26 161 35
7-1 7-8 7-15 7-29
95 439 438 765
111 122 134 375
122 276 142 94
152 219 234 239
49 44 163
76 134 58 39
9fi5 11** ^?R (\7
£O3 Jjj J£.O o/
101 175 272 287
ro 70 cc 914
DC / J O 3 £ 1 H
66 52 114 162
86 77 87 100
48 58 67 71
95 18 112
433 418 241 99
238 94 58 157
339 415 126 66
37 40 62 175
71 88 39 27
126 45 29 21
136 56 34 19
192 124 43
35 98 76 34
8-12 8-26
460 510
282 332
269 120
118 147
555 127
46 25
en cn
Jv 3*J
46 148
9A.7 73
c*t/ / O
27 17
191 43
76 38
124 46
114 22
38 21
88 17
74 25
25 11
24 7
15 11
17 15
15 15
9-9
118
684
136
152
153
35
fil
D 1
737
CQ
O?
20
42
31
45
18
14
15
13
16
9
9
10
13
-------
Table A-3. AVERAGE DISSOLVED INORGANIC N, SOIL SOLUTIONS, BLOCK Zl SITE, 1971
(mg/liter)
Treatment
Ql
(low-rate
sprinkler)
Q3
(high -rate
sprinkler;
Wl
(lav-rate
sprinkler)
W3
/K 1 0h»i*ib f A
\*U.J$if catc
furrow)
Depth, cm
£0
90
120
180
240
basalt
60
90
120
180
240
basalt
60
90
120
180
basalt
.60
90
1 9n
i*V
180
basalt
5-5 5-26
40
16 23
150
35
16
22 23
...
17 25
39
102 101
32 «
._ _<_
56 75
31
206 31
"" -"
23 70
33
9 7
6-11 6-18 6-25
27
71 18 28
40
16 44 36
24 Z7 28
14 393
26 34 27
37 33 36
32 30
99 123
43 45 61
22
283 298 387
107 303 175
18 25 50
22 27 28
1330 574 310
77 121 192
55
5 98 10
7-1 7-8 7-15 7-29
90 268 262 428
58 28 16 127
89 114 119 181
125 204 226 143
41 35 125
29 25 38 148
345 371 346 117
158 185 238 147
23 11 16 242
77 14 J9 141
81 69 56 22
50 55 66 652
144 580 15 159
693 688 385 154
162 181 132 128
343 403 150 82
37 42 63 167
118 146 81 48
177 36 70 9
m71 AQ 0
/ 1 **3 3
J44 21 47
18 56 43 32
8-12 8-26
932 760
56 417
116 127
54 121
421 118
54 75
105 35
40 125
313 60
19 12
151 39
51 22
2 46
136 47
SI 19
151 7
105 15
25 2
18 0
7 ?
/ d
11 8
8 1
9-9
653
549
123
129
132
31
21
181
63
8
20
36
5
9
3
19
2
1
4
i
i
0
1
-------
Table A-4. EC VALUES, SOIL SOLUTIONS, SPRINKLER IRRIGATION,
BLOCK 21, 1970
(mmho/cm)
Treatment
Q1R1
(low-rate
sprinkler
rep.l)
Q1R2
(low-rate
sprinkler
rep. 2)
Q1R3
(low-rate
sprinkler,
rep. 3)
Q3R1
(high-rate
sprinkler,
rep.l)
Q3R2
(high-rate
sprinkler,
rep. 2)
Q3R3
(high-rate
sprinkler,
rep. 3)
Depth,
cm
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
basal:
30
60
120
180
basalt
30
60
120
180
jasalt
4/20
.
-
1.25
2.46
1.46
-
3.19
1.54
4.79
1.62
.
2.77
1.07
1.30
2.22
11.51
2.22
2.73
1.76
2.30
5.25
-
-
-
9.29
-
1.01
1.39
1.67
5/28
.
-
-
-
-
-
2.42
4.44
1.94
.
1.61
1.33
1.65
2.18
.
S.5S
3.17
2.42
2.22
13.33
-
2.97
2.69
1.73
.
-
-
-
~
1
6/4 6/8 6/11 6/17 6/19 6/22")
______
3.90 - 7.47 -
1.31 1.18 1.15 - 1.15
2.50 -
1.41 1.33 1.3S - 1.49
......
1.94 -
1.78 1.46 1.34 1.4S - 1.71
3.58 2.55 2.77 2.89 - 2.71
1.72 1.S6 1.S5 1.49 - 1.41
.....
1.25 l.OS - 1.05 1.05 1.02
1.08 1.08 0.96 1.00 0.93 .1.11
1.44 1.33 1.33 1.34 1.31 1.33
1.90 1.77 1.74 1.74 1.68 1.71
1.84 - - - -
6.26 5.45 - - 6.46 7.41
2.10 1.69 1.63 1.62 1.56 1.53
2.16 1.95 1.93 2.00 1.94 1.98
1.96 1.78 1.72 1.77 1.78 1.78
1.45 1.S4 - 1.78 15.07 10.24
1.81
2.06 1.79 - - 1.76
1.78 1.34 1.29 - 1.26 1.26
1.20 1.04 1.01 1.02 l.OS 1.03
-. - - - 11.31
......
1.64 1.25 1.22 1.29 1.25 1.32
2.77 2.22 1.90 2.06 1.94 1.90
2.14 1.78 1.74 1.76 1.70 1.69
7/3 7/21
10.2 7.58
1.18 1.08
1.71
1.40 1.48
_
1.40
1.21 1.34
2.44 2.48
1.4S 1.31
1.48
0.93 4.44
1.01 1.25
1.25 1.S8
1.65 1.18
0.67
6.93 2.87
1.70 2.89
1.78 2.01
1.74 1.66
2.02 2.22
4.65 2.08
1.49 1.73
1.14 3.19
1.07 1.40
11. 6 3.43
4.91
1.78 6.34
1.70 4.20
1.62 1.49
8/5 8/20'
4.00
2.19
1.51 1.52
1.35 1.19
.
1.65 1.63
1.27 1.18
2.06 1.62
1.33 1.18
1.57 1.38
8.85 3.76
1.42 1.27
1.25 1.14
1.64 1.43
.
1.31 1.18
1.76 1.07
3.59 3.36
1.65 1.52
2.02 2.07
1.77 1.14
1.23 1.10
4. IS 1.03
3.93 3.34
2.37 2.66
2.34
5.20 2.39
5.05 1.79
1.53 1.33
9/4
2.83
3.23
3.43
1.26
2.01
1.42
1.65
1.20
1.40
1.51
1.70
1.42
1.18
1.48
1.06
1.76
2.42
2.36
.
1.57
0.93
1.66
3.72
2.53
1.47
1.53
1.37
-------
Table A-5. DISSOLVED Cl VALUES, SOIL SOLUTIONS, SPRINKLER IRRIGATION, BLOCK
21, 1970
(mg/liter)
Treatment
Q1R1
(low-rate
sprinkler,
rep. 1)
Q1R2
(low-rate
sprinkler ,
rep. 2)
Q1R3
(low-rate
sprinkler,
rep. 3)
Q3R1
(low-rate
sprinkler,
rep. 1)
Q3R2
(low-rate
sprinkler ,
rep. 2)
Q3R3
(low-rate
sprinkler,
rep. 3)
Depth,
cm
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
130
basalt
30
60
120
180
basalt
30
60
120
180
basalt
4/20
22
130
17
21
200
61
367
33
.
137
24
9
102
1001
128
182
17
68
432
.
-
872
37
85
22
S/28
-
_
_
34
155
34
.
87
17
9
39
_
364
89
18
17
1109
_
54
48
25
_
6/11 6/22
765
24
24
_ .
.
27 100
141 144
24 25
_
86
19
9
27
_
649
97
19
13
870
»
50
22
832
126
67
15
7/3 7/21
25 19
21 28
_
.
19 28
129 124
19 7
IS
38 292
26 78
9 14
24 11
27
S51 140
118 174
34 104
12 7
28 4
533 103
69 78
46 240
24 43
818 295
417
1S2 426
87 280
11 32
8/5 8/20
268
173 33
31 453
5 0
_
98 0
17 0
86 47
0 0
21 24
750 513
116 77
21 26
12 11
.
23 20
58 15
251 225
12 48
4 18
50 24
12 12
315 63
312 200
68 12
32
233 58
263 103
41 65
9/4
47
263
303
10
.
150
7
24
4
18
53
98
11
SO
-
29
12
57
130
47
34
17
18
32
9
57
16
33
58
-------
Table A-6. DISSOLVED INORGANIC N, SOIL SOLUTIONS, SPRINKLER IRRIGATION,
BLOCK 21, 1970
(mg/liter)
Treatment
Q1R1
(low-rate
sprinkler ,
rep. 1)
Q1R2
(low-rate
sprinkler.
rep. 2)
Q1R3
(low-rate
sprinkler ,
rep. 3)
Q1R1
(high-rate
sprinkler ,
rep.l)
03R2
(high-rate
sprinkler,
rep. 2)
Q3R3
(high-rate
sprinkler
rep. 3) '
Depth,
cm
30
60
120
180
basalt
30
60
120
ISO
basalt
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
>asalt
30
60
120
4/20
_
21.6
130.3
16.8
21.0
200.3
61.4
367.1
33.1
.
78.5
2.0
8.4
132.8
S32.9
103.4
165.9
S.9
74.8
44.3
_
16.8
21.0
904.2
64.5
10.9
180 55. 2
>asalt 1 6.7
5/28 j
.
.
_
-
_
..
34.2
155.5
34.2
.
71.5
9.3
15.6
46.7
_
_
71. S
6.2
9.3
1490.0
«
49.8
31.1
.
..
_
.
-
6/4 6/8 6/11 6/17 6/19 6/22
357.6 - 765.3 ...
40.4 21.7 24.5 - 19.3
64.8 - - 64.8
0 15.2 24.2 - 26.8
-.--«
131.3 - - - -
24.9 30.1 27.0 25. S - 100.3
149.3 109.2 140.9 149.3 - 143.6
34.2 32.5 24.4 31.1 - 24.8
__--
21.8 25.3 - 23.0 23.6 19.7
9.3 10.6 8.1 4.5 9.5 5.8
6.2 5.3 8.8 0.5 10.5 0
6.2 25.8 28.0 18.6 9.5 13.3
7.3 - - - -
37.3 533. 1 - - 760.6 789.0
665.5 66.3 84.8 68.8 65.5 64.8
65.3 5.0 2.4 5.9 3.6 4.8
9.3 1.7 5.7 2.S 13.2 6.8
3.1 1963.9 - 2245.0 1807.4 1148.5
74.4
71.9 71.3 - - 65.0
49.8 57.5 61.6 - 54. 6 SO.l
18.7 12.2 23.7 30.9 19.2 17.6
»
»----
15.6 21.6 23.7 32.3 25.1 31.9
46.7 42.8 41.6 37.2 52.6 43.7
6.2 0 4.1 5.2 0 2.5
7/3 7/21
_ _
.
25.0 19.0
-
21.0 28.0
.
-
19.0 28.0
129.0 124.0
19.0 7.0
4.0
35.0 378.0
17.0 18.0
13.0 4.0
15.0 12.0
-
768.0 180.0
73.0 227.0
9.0 47.0
3.0 5.0
7.0 4.0
300.0
52.0 16.0
51.0 261.0
20.0 50.0
1381.0 183.0
383.0
86.0 723.0
28.0 442.0
6.0 7.0
8/S 8/20
_ _
268.0
173.0 33.0
31.0 453.0
5.0 0
-
98.0 0
17.0 0
86.0 47.0
0 0
21.0 5.0
684.0 182.0
27.0 30.0
18.0 16.0
9.0 10.0
-
23.0 9.0
88.0 7.0
238.0 261.0
2.0 1S.O
0 0
19.0
0 5.0
367.0 24.0
302.0 269.0
37.0 8.0
16.0
509.0 169.0
495.0 67.0
6.0 9.0
9/4
_
47.0
263.0
303.0
10.0
-
150.0
7.0
24.0
4.0
9.0
16.0
85.0
10.0
18.0
-
7.0
5.0
6.0
98.0
5.0
-
0
11.0
74.0
6.0
-
65.0
23.0
41.0
-------
Table A-7. EC VALUES, SOIL SOLUTIONS, FURROW IRRIGATION, BLOCK 21, 1970
(mmho/cm)
u>
Treatment
W3R1
(high-rate
furrow,
rep.l)
U3R2
(high-rate
farrow.
rep. 2)
W3R3
(high-rate
furrow,
rep. 3)
Depth.
cm
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
basalt
4/20
2.83
4.44
0.7S
1.01
0.72
11.31
0.81
1.29
2.08
0.63
2.40
1.32
2.10
0.79
0,91
5/28
1.37
9.49
1.02
1.22
0.67
31.31
4.34
1.25
0.86
0.69
.
.
.
6/4 6/11 6/16 6/22
0.65 0.55 0.66 0.59
0.72 0.65 0.67 0.51
0.80 0.63 1.21 0.95
0.98 0.78 - 0.72
0.73 0.78 0.78 0.75
6.40 1.36 0.77 0.74
0.22 ' 3.03 1.06 0.95
1.39 0.90 0.96 0.86
0.70 0.65 0.58 0.59
l.OS 3.17 0.93 0.70
1.55
S.66 4. 95 2.50 1.17
4.36 3.31 1.37
1.07 1.09 0.89 3.54
1.01 1.03 0.89 0.80
7/3 7/21
0.60
0.56
0.71
0.76 0.68
0.75 0.68
0.69 0.52
0.60 0.55
0.81 0.63
0.61 0.57
0.69 0.66
3.29 2.36
0.59 0.77
0.65 0.73
0.68 0.6S
0.70 0.69
8/5 8/20
0.70 0.51
0.56 0.49
0.67 0.58
0.67 0.60
0.68 0.57
_
0.54
0.65
0.60
0.62
1.22
0.7S 0.64
0.74 0.69
0.67 0.62
0.71 0.60
9/4
0.53
0.53
0.59
0.62
0.63
O.S2
0.50
0.55
0.53
0.55
0.73
0.77
0.77
0.65
0.63
-------
Table A-8. DISSOLVED Cl VALUES, SOIL SOLUTIONS, FURROW IRRIGATION, BLOCK 21,
(mg/liter)
Treatment
W3R1
(hlgh-ratr
furrow
rep. 1)
W3R2
(high-rate
furrow,
rep. 2)
W3R3
(high-rate
furrov,
rap. 3)
Depth
cm
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
180
basalt
4/20
408
21
34
23
707
38
41
77
20
70
33
116
22
24
5/28
44
779
32
48
19
2705
262
35
20
"
-
~
17
0/4 6/11 6/22
11 - 16
17 - IS
19 - 14
21 - 17
17 - 21
369 - 18
94 - 18
84 - 16
16 - 18
S3 - 19
- * .
396 - 54
75
22 - 232
25 - 19
7/3 7/21
17
19
24
22 20
20 20
19 17
17 19
17 18
17 18
19 20
215 218
17 18
17 17
17 15
17 17
8/5
23
19
22
21
20
22
18
20
19
43
15
17
18
16
9/4
17
26
18
18
19
16
17
16
17
17
18
22
19
17
17
-------
Table A-9. DISSOLVED INORGANIC N, SOIL SOLUTIONS, FURROW IRRIGATION, BLOCK
21, 1970
(mg/liter)
Treatment
W3R1
(high-rate
furrow,
rep. 1)
W3R2
(high-rate
furrow
rep. 2)
W3R3
(high-rate
furrow.
rep. 3)
ueptft,
cm
30
60
120
180
basalt
30
60
120
180
basalt
30
60
120
ISO
basalt
4/20
34.5
2S5.0
22.7
29.4
7.6
662.1
38.4
88.8
64.5
12.3
89.4
7.0
84.8
9.0
11. S
5/28
46.7
-
.
255. 0
.
0
9.3
.
-
.
-
6/4 6/11 6/16 6/22
24.9 0* 0 0
34.2 12.1 20.4 10.7
21.8 17.1 90.0 52.6
65.3 25.6 - 15.3
6.2 21.5 14.3 11.6
681.0 120.1 11.7 9.3
208.4 377.7 88.0 82.2
84.0 35.3 38.8 30.0
15.6 12.0 o 0
52.9 307.4 66.1 12.7
- 1951.0
S50.0 $06. 5 215.7 47.6
28.3 298.0 98.9
18.7 254.5 18.9 327.8
3.1 23.8 9.9 0.4
7/3 7/21
0
0
0
3
0
0
14 0
a o
0 7
M 6
248
5 12
0 *
4 3
0 0
8/5 8/20
2 0
0 0
0 0
4 0
4 0
0
3
1
0
0
3
0 2
0 0
0 0
0 0
9/4
0
3
2
0
2
0
0
0
2
0
2
0
0
8
3
Below detectable limit.
-------
Table A-10.
cr>
DISSOLVED INORGANIC N, ROW-FURROW SETS, FURROW IRRIGATION RATE
AND SPRINKLER-IRRIGATED PLOTS, OTHELLO STATION, FALL OF 1972
Treatment
Average of rows and furrows
Head , Low N , High water
Head , High N , High water
Head, Low N, Low water
Head, High N, Low water
Tail, Low N, High water
Tail, HighN, High water
Tail, LowN, Low water
Tail, High N, Low water
Sprinkler^1 North end
Sprinkler, Middle
Sprinkler, South end
Average of rows
Head, Low N, High water
Head, High N, High water
Head, LowN, Low water
Head , High N , Low water
Tail, LowN, High water
Tail, HighN, High water
Tail, LowN, Low water
Tail, HighN, Low water
Sprinkler, North end
Sprinkler, Middle
Sprinkler, South end
Dissolved inorganic
0-30 30-60 60-120
cm
29
88
45
87
95
86
121
159
137
56
47
32
56
52
127
108
154
164
102
48
71
38
5
4
10
7
10
2
38
94
14
35
14
3
7
13
10
5
5
47
66
11
67
19
9
3
9
16
9
8
74
184
63
20
11
6
6
8
7
3
17
138
179
113
16
14
N, mg/1
120-180 180+
cm
To
29
44
51
157
94
30
88
T3
24
54
67
134
136
53
7
_
TE
40
74
~9
39
75
33
78
TTJ
33
0-30
cm
12
100
36
63
50
118
72
72
129
66
43
9
30
27
40
67
71
76
47
12
76
48
Standard deviation, %
30-60 60-120 120-180
67
125
36
69
75
117
70
48
63
139
116
141
40
109
22
141
16
29
56
47
86
142
73
159
30
132
102
120
115
14
93
72
87
142
94
53
0
142
47
53
14
6
59
81
45
__
41
78
64
28
94
130
112
~0~
30
71
55
20
53
96
141
180+
cm
__
33
33
27
24
39
47
15
6
37
15
-------
Table A-10. (continued) DISSOLVED INORGANIC N, ROW-FURROW SETS, FURROW
IRRIGATION RATE AND SPRINKLER-IRRIGATED PLOTS, OTHELLO
STATION, FALL OF 1972
Treatment
Average of furrows
Head , Low N , High water
Head, HighN, High water
Head, Low N , Low water
Head, High N, Low water
Tail, Low N, High water
Tail, HighN, High water
Tail, LowN, Low water
Tail, HighN, Low water
Sprinkler, North end
Sprinkler, Middle
Sprinkler, South end
Dissolved inorganic N, mg/1
0-30 30-60 60-120 120-180 180t
cm cm
27
121
37
48
83
18
79
217
227
40
55
7
0
7
5
15
0
30
121
17
4
10
12
0
9
24 _
15 33
3 33
11 36
189 180
13
24 ~5
8 170
15Z
77
~9
45
0-30
cm
3
114
50
13
34
85
6
71
109
29
44
Standard deviation, %
30-60 60-120 120-180 180+
11
0
0
141
28
0
137
34
75
35
37
35
0
0
130
57
142
141
19
17
88
133
52
120
86
29
35
29
T7
47
~8
50
aHead = inflow portion of furrow-irrigated field (122 meter run), tail = outflow portion of furrow-irrigated field;
low N and high N = 220 and 450 kg N/ha., banded at planting; low water and high water = wetting of alternate
sides of a given crop row every 2 or 6 days, respectively (normal irrigation practice at the station involves
. an alternate-row interval of 2.5 days).
Sprinkler plots were adjacent to the fertilizer factorial experiment, and received 450 kg N/ha. , banded at plant-
ing, as a uniform fertilizer treatment.
-------
Table A-ll.
EC VALUES, ROW-FURROW SETS, FURROW IRRIGATION RATE AND
SPRINKLER-IRRIGATED PLOTS, OTHELLO STATION, FALL OF 1972
CO
Treatment
Average of rows and furrows
Head*, Low N, High water
Head, HighN. High water
Head , Low N , Low water
Head, HighN, Low water
Tail, Low N, High water
Tail, High N, High water
Tail, Low N, Low water
Tail, High N, Low water
Sprinkler, North end
Sprinkler, Middle
Sprinkler, South end
Average of rows
Head, Low N, High water
Head, HighN, High water
Head, Low N, Low water
Head , High N , Low water
Tail, Low N, High water
Tail, HighN, High water
Tail, Low N, Low water
Tail, High N, Low water
Sprinkler, North end
Sprinkler, Middle
Sprinkler, South end
Electrical conductivity
0-30 30-60 60-120
cm
2.04
3.24
3.08
3.99
3.69
3.69
4.20
5.51
3.70
4.12
3.00
2.19
2.55
3.42
5.15
4.19
4.53
5.11
3.81
3.72
4.65
3.07
1.61
1.77
1.10
1.99
2.81
1.76
2.82
3.95
2.38
3.33
1.79
1.66
1.67
1.46
2.17
3.65
1.92
3.00
3.09
2.47
4.36
1.77
2.01
1.73
1.64
2.25
2.43
2.19
2.89
4.68
2.71
2.37
1.41
1.96
1.72
1.69
2.06
2.50
1.82
4.29
4.34
3.39
2.29
1.40
, mmho/cm
120-180 180+
cm
7728
2.37
2.61
2.71
4.69
3.06
3.78
2.87
1744
2.15
2.67
3.58
4.13
3.51
5.72
1.69
T.73
3.22
3.99
-Z-.05
2.66
T.56
3.03
4.25
T. 17
2.44
0-30
cm
14
34
28
34
28
34
38
31
7
18
14
17
7
26
1
35
29
38
32
1
11
23
Standard deviation, %
30-60 60-120 120-180
6
8
54
15
48
23
7
40
6
60
20
1
7
50
15
44
8
0
36
6
63
33
5
2
8
23
5
29
63
21
29
19
9
4
2
8
15
4
39
5
16
48
Z5
16
TJ
12
26
48
16
32
100
49
"^~"
~7
___
4
28
1
1
25
92
5
180+
cm
~
15
18
13
~7
21
-
~
32
22
13
~Z
14
-------
Table A-ll. (continued) EC VALUES, ROW-FURROW SETS, FURROW IRRIGATION RATE
AND SPRINKLER-IRRIGATED PLOTS, OTHELLO STATION, FALL
OF 1972
Treatment
Average of furrows
Head, Low N, High water
Head, HighN, High water
Head , Low N , Low water
Head, High N, Low water
Tail, Low N, High water
Tail, High N, High water
Tail, Low N , Low water
Tail, High N, Low water
Sprinkler, North end
Sprinkler, Middle
Sprinkler, South end
Electrical conductivity
0-30 30-60 60-120
cm
1.89
3.93
2.75
2.82
3.19
2.85
3.30
7.21
3.67
3.59
2.94
1
1
0
1
1
1
2
4
2
2
1
.56
.88
.74
.BO
.97
,60
.64
.81
.28
.30
.81
2.07
1.75
1.59
2.44
2.36
2.57
1.50
5.03
2.04
2.44
1.43
, mmto/cm
120-180 180+
cm
2.60
2.55
1.85
5.25
TT84
4.05
"7.90
T.73
T.94
2.89
0-30
cm
4
34
36
4
0
11
25
64
13
13
4
Stand
30-60
8
2
4
8
5
38
3
36
0
12
5
60-120
4
3
9
31
2
4
94
27
3
21
1
120-180
9
35
78
13
14
180+
CTTl
15
13
28
"Head = inflow portion of furrow-irrigated field (122 meter run), tail = outflow portion of furrow-irrigated field,
low N and high N = 220 and 450 k| N/ha., banded at planting; low water and high water = wett.ng of alternate
ides of a given crop row every 2 or 6 days, respectively (normal irrigation practice at the station involves
an alternate-row interval of 2.5 days).
bSprinkier plots were adjacent to the fertilizer factorial experiment, and received 450 kg N/ha., banded at plant-
ing , as a uniform fertilizer treatment.
-------
Table A-12. DISSOLVED INORGANIC N, SELECTED PLOTS, SUSPENSION FERTILIZER
AND SLOW-RELEASE N EXPERIMENTS, OTHELLO STATION, 1972
Treatment*
Suspension fertilizers
670 kg /ha. banded.
rep. I
670 kg/ha, banded,
rep. 1
670 kg /ha. banded.
rep. 1
670 kg/ha, broadcast,
rep. 5
670 kg/ha, broadcast.
rep. 5
670 kg /ha. broadcast.
rep. 5
670 kg /ha. banded.
rep. 3
670 kg /ha. banded.
rep. 3
670 kg /ha. banded.
rep. 3
Slow-Release N
NH4N03
340 kg/ha. + 170 kg/ha.
UF
340 kg /ha. + 170 kg/ha.
UF
340 kg/ha. + 170 kg/ha.
SC 20
Date
6/22
8/3
9/1
6/22
8/3
9/1
6/22
8/3
9/1
8/10
8/29
8/10
Dissolved inorganic
0-30 30-60 60-120
cm
590
123
25
139
82
39
714
398
50
279
17
526
216
78
23
136
14
68
378
380
63
84
10
188
125
132
11
315
13
114
191
153
86
45
45
499
N, mg/1
120-180
82
108
18
154
10
154
98
141
83
-
-
180+
_ cm
67
103
46
101
63
115
-
53
81
-
-
Standard deviation, %
0-30 30-60 60-120
cm
68
137
46
142
118
28
74
74
124
127
26
54
46
146
94
129
68
132
94
15
101
78
43
111
49
57
1
43
22
14.0
77
60
86
36
58
75
120-180
50
30
49
46
50
102
50
66
77
.
-
-
180+
cm
39
20
52
32
87
96
-
67
106
_
-
-
-------
Table A-12. (continued) DISSOLVED INORGANIC N, SELECTED PLOTS, SUSPENSION
FERTILIZER AND SLOW-RELEASE N EXPERIMENTS, OTHELLO
STATION, 197Z
Treatment
NH1NO3 ^continued)
340 kg/ha. + 170 kg/ha.
SC ZO
340 kg /ha. +170 kg /ha.
SC 30
340 kg/ha. + 170 kg/ha.
SC 30
500 kg /ha.
500 kg /ha.
340 kg /ha. + 170 kg/ha.
UF
340 kg/ha. + 170 kg/ha.
SC ZO
340 kg /ha. +170 kg/ha.
SC 30
500 kg/ha.
500 kg/ha.
Date
8/29
8/10
8/Z9
8/10
8/Z9
8/10
8/Z9
8/10
8/29
8/10
8/29
8/10
8/29
Dissolved inorganic N, mg/1
0-30 30-60 60-120120-180180+
cm cm
142
294
51
813
81
131
17
6Z.
51
235
27
23.1
47
15
27
13
295
65
23
8
4
20
65
15
42
46
21 -
97
35 -
303
83 -
68 -
17 -
54 -
37 -
179
66 -
47 -
54 -
0-30
cm
147
145
37
120
76
76
45
120
62
76
70
73
68
Standard deviation, %
30-60 60-120 120-180
46
65
28
126
118
64
36
132
63
107
52
89
130
83
65
43
81
76
87
51
76
110
30
72
29
96
180+
cm
-
-
-
-
-
~
-
-
aUF = urea-formaldehyde; SC 20 and SC 30 = sulfur-coated urea. 20% and 30% release of N in 7 days under
standardized conditions.
-------
Table A-13. AVERAGE DISSOLVED INORGANIC N, SUSPENSION FERTILIZER
EXPERIMENT, OTHELLO STATION, FALL OF 1972.
Treatment
One sample
110 kg/ha.
450 kg /ha.
670 kg /ha.
110 kg/ha.
450 kg/ha.
670 kg/ha.
110 kg/ha.
670 kg /ha.
per plot
broadcast
broadcast
broadcast
banded
banded
banded
side-dressed
side-dressed
Paired within-plot samples
110 kg/ha.
450 kg/ha.
670 kg /ha.
110 kg/ha.
450 kg /ha.
670 kg /ha.
broadcast
broadcast
broadcast
banded
banded
banded
No. Reps.
Sampled
6
6
6
6
6
6
3
3
3
3
3
3
3
3
Dissolved inorganic
0-30 30-60 60-120
cm
60
91
117
72
82
87
84
83
55
62
45
63
61
157
15
6 '
60
3
8
22
9
32
15
9
12
6
6
44
25
24
40
9
13
29
26
11
18
24
29
7
11
54
N. mg/1
120-180 180+
cm
16 naa
37 na
47 na
38 na
22
55
34
37 60
15 14
63 _
21
32
na
0-30
cm
29
73
123
88
63
68
34
62
17
16
15
39
40
39
Standard deviation,
30-60 60-120 120-180
55
54
181
126
84
120
97
125
43
75
69
58
36
103
113
66
117
77
97
121
65
49
19
61
137
58
53
63
40
76
53
85
114
69
78
55
25
2
61
74
na
%
180+
cm
na
na
na
na
39
/
79
-------
Table A-14. AVERAGE EC VALUES, SUSPENSION FERTILIZER EXPERIMENT, OTHELLO
STATION, FALL OF 1972
T reatment
One sample per plot
110 kg/ha, broadcast
450 kg/ha, broadcast
670 kg/ha, broadcast
110 kg/ba. banded
450 kg /ha. banded
670 kg /ha. banded
No. Reps.
Sampled
6
6
6
6
6
6
110 kg/ha, side-dressed 3
670 kg/ha, side-dressed 3
Paired wit bin -plot samples
110 kg /ha. broadcast
670 kg /ha. broadcast
110 kg /ha. banded
450 kg /ha. banded
670 kg/ha, banded
3
3
3
3
3
3
Electrical conductivity, xxunho/cro
0-30 30-60 60-120 120-180 180+
cm cm
3.18
3.63
4.05
2.8S
3.28
3.17
3.44
3. 12
3.26
2.81
2.98
3.06
2.79
4.21
1.72
2.19
2.70
1.61
1.88
2.14
1.67
2.64
1.39
2.27
2.14
1.71
1.92
2.29
2.64
2.63
2.41
1.96
1.91
2.49
2.02
1.95
3.13
2.44
2.27
1.88
2.00
2.68
3.51
3.38
3.02
2.85
2.95
3.02
2.99
2.76
3.51
3.17
2.87
3.14
na
a
na
na
na
na
TT98
7.25
0-30
cm
12
49
61
43
21
36
34
22
6
11
11
25
26
23
Standard deviation, %
30-60 60-120 120-180
39
18
56
26
18
30
52
42
11
37
28
25
21
28
54
35
28
8
12
31
26
1
7
10
28
9
10
19
60
28
6
34
14
18
30
12
7
26
15
22
na
180+
cm
na
na
na
na
To
21
ana = sample volume not adequate for analysis
-------
Table A-15.
DISSOLVED INORGANIC N, ROW-FURROW SETS, SUSPENSION FERTILIZER
AND FACTORIAL EXPERIMENTS, OTHELLO STATION, FALL OF 1972
Treatment
Suspension
Suspension
Suspension
Suspension
Factorial -
Factorial -
- 450 kg/ha.
- 670 kg/ha.
-450 kg/ha.
- 670 kg /ha.
X4K*
broadcast
broadcast
banded
banded
Average of rows
Suspension
Suspension
Suspension
Suspension
Factorial -
Factorial -
^450 kg/ha.
- 670 kg/ha.
- 450 kg/ha.
- 670 kg/ha.
N1P4K*
broadcast
broadcast
banded
banded
Average of furrows
Suspension
Suspension
Suspension
Suspension
Factorial -
Factorial -
N = nitrogen
fertilizer i
- 450 kg/ha.
- 670 kg/ha.
- 450 kg /ha.
- 670 kg/na.
K4K4
broadcast
broadcast
banded
banded
R«rk
xiep.
No.
1
4
3
2
1
1
1
4
3
2
1
1
1
4
3
2
1
1
Dissolved
0-30
cm
93
77
84
63
243
39
81
53
104
68
437
42
105
101
64
59
49
36
, P = phosphorus, K = potassium; subscripts 1
30-
2
30
13
5
92
19
0
46
11
9
125
22
4
14
15
1
59
15
and
196S
inorganic
60 60-120
10
43
23
10
55
95
5
75
20
10
57
156
16
11
27
10
53
35
4 indicate
N, mg/1
120-180 180+
cm
7
77 ~
na
15 ~
21 9
172 136
7
58 ~
TT
22
160 132
8
97 ~
~T
20
184 140
Standard deviation, %
0-30
cm
21
47
62
37
114
12
17
35
78
56
65
12
18
36
2
13
57
8
respectively approx. 0 or
1970-1971. 450 k
-------
Table A-16. DISSOLVED INORGANIC N, 1971 SUSPENSION FERTILIZER EXPERIMENT,
OTHELLO STATION, 1972
Treatment
One sample per plot
(Spring, 1972)
100 kg/ha, broadcast
450 kg/ha, broadcast
670 kg /ha. broadcast
110 kg /ha. banded
450 kg/ha . banded
670 kg/ha, banded
110 kg/ha, side-dressed
670 kg/ha, side-dressed
Paired wit bin -plot samples
(Spring, 197ZI
110 kg/ha, broadcast
450 kg /ha. broadcast
670 kg /ha. broadcast
110 kg/ha, banded
450 kg/ha, banded
670 kg/ha, banded
One sample per plot
(Fall. 197Z)
110 kg/ha, broadcast
670 kg/ha, broadcast
110 kg /ha. banded
No. Reps.
Sampled
6
6
6
6
6
6
3
3
3
3
3
3
3
3
6
6
6
6
Dissolved inorganic N, mg/1
0-30 30-60 60-120 120-180 180+
cm cm
105
171
231
107
180
161
68
263
104
213
195
111
217
207
10
IS
15
19
49
97
166
55
110
134
60
153
41
130
97
62
155
199
14
16
18
43
23
61
97
23
69
146
39
142
21
85
81
22
69
162
27
38
34
56
24
88
65 ~
61
73
107
36
100 ~
34
9? ~
120
21
78
94
33
89 na
42 na
99 190
0-30
cm
25
29
24
19
31
46
23
24
9
14
11
27
12
25
25
73
43
79
Standard deviation, '
30-60 60-120 120-180
33
48
53
44
56
69
90
74
21
40
19
58
51
51
101
65
55
89
35
51
36
42
79
56
77
75
24
32
33
10
51
61
63
98
62
62
60
49
51
157
65
73
na*
112
56
43
32
27
41
41
76
55
58
61
&
180+
cm
__
na
na
63
ana = Sample volume not adequate for analysis.
-------
Table A-17. AVERAGE VALUES, 1971 SUSPENSION FERTILIZER EXPERIMENT, OTHELLO
STATION, 1972
Treatment
One sample per plot
(Spring, 1972)
110 kg/ha, broadcast
450 kg /ha. broadcast
670 kg/ha, broadcast
110 kg/ha, banded
450 kg/ha, banded
670 kg/ha, banded
110 kg/ha, side-dressed
670 kg/ha, side-dressed
Paired within-plot samples
(Spring, 1972)
110 kg/ha, broadcast
450 kg/ha, broadcast
670 kg/ha, broadcast
110 kg /ha. banded
450 kg/ha, banded
670 kg/ha, banded
One sample per plot
(Fall, 19721
110 kg/ha, broadcast
670 kg/ha, broadcast
110 kg /ha. banded
670 kg/ha, banded
No. Rep"-
Sampled
'
6
6
6
6
6
6
3
3
3
3
3
3
3
3
6
6
6
6
Electrical conductivity, mmho/cm
0-30 30-60 60-120 120-180 180+
cm cm
3.19
4.42
5.10
3.17
4.01
3.56
2.78
4.76
3.15
5.16
4.62
3.31
5.21
3.85
2.09
2.52
2.42
2.57
2.18
3.23
4.56
2.74
2.48
3.22
2.81
3.26
2.31
3.62
3.17
2.77
3.02
3.96
1.58
1.99
1.91
1.87
2.60 2.64
3.05 3.53
3.38 3.65
2.23 Z.94
2.58 3.16
3.28 3.34
2.36 1.72
3.78 3.36
2.73 2.42
3.22 3.62
3.14 4.06
2.24 2.55
2.45 2.80
3.56 3.30
2.22 2.03
2.16 2.76 na
2.04 2.65 na
2.94 2.96 4.14
0-30
cm
21
20
20
22
30
19
36
18
27
5
24
5
16
20
10
33
29
20
Standard deviation , ffa
30-60 60-120 120-180
42
38
38
9
39
39
18
24
23
15
18
7
5
22
24
38
35
49
16
15
12
7
29
34
17
32
20
4
7
9
17
35
16
15
19
75
13
14
31
30
17
14
naa
42
5
12
2
6
13
8
2
20
47
23
180+
cm
m_
-
_-
na
na
17
ana = Sample volume not adequate for analysis .
-------
Table A-18. AVERAGE YIELD, SELECTED TREATMENTS, 1971 AND 1972
SUSPENSION FERTILIZER EXPERIMENTS, OTHELLO STATION
a
(quintal/hectare)
Treatment
110 kg /ha. broadcast
450 kg/ha, broadcast
670 kg/ha, broadcast
110 kg /ha. banded
450 kg /ha. banded
670 kg /ha. banded
110 kg/ha, side-dressed
670 kg/ha, side-dressed
No. Reps.
Sampled
6
6
6
6
6
6
3
3
197
Total
641
874
867
681
803
768
650
879
1
No. 1's
344
503
418
402
288
253
383
321
1972
Total
740
878
920
796
821
790
737
851
No. 1's
592
704
690
676
637
590
570
582
Quintal/hectare - cwt/acre x 1.12.
-------
Table A-19. AVERAGE DISSOLVED INORGANIC N, FERTILIZER FACTORIAL
EXPERIMENT, OTHELLO STATION, FALL OF 1972a
G
CO
Treatment
N1P1K1
N4P1K1
N1P4K1
N4P4K1
N1P1K4
N.P.K.
414
N1P4K4
N4P4K4
Dissolved inorganic
0-30 30-60 60-120
cm
60
38
55
47
79
48
127
59
19
23
79
25
23
60
58
49
29
81
60
136
25
134
30
144
N, mg/1
120-180
66
181
90
142
49
181
43
195
180+
cm
-
184
c
na
-
na
88
na
0-30
cm
19
16
104
30
51
91
80
31
Standard deviation, %
30-60 60-120 120-180
48
53
184
68
24
170
66
77
32
62
63
89
16
89
80
104
66
26
116
86
39
54
96
61
180+
cm
«.
53
na
-
na
32
na
-
^Average for replicates 1, 3, and 5.
"N = nitrogen, P = phosphorus, K = potassium; subscripts 1 and 4 indicate respectively
approx. 0 or approx. 450 kg_/ha. of the fertilizer-nutrient (N, P-,0,. or K O) applied
annually for 1965-1967 and 197-0-1971. 450 kg/ha, of N applied to all plots in 1972.
Wheat grown to "mine" residual N from the plots in 1968 and 1969.
cna = Sample volume not adequate for analysis.
-------
vO
Table A-20. AVERAGE SOIL-TEST P AND K VALUES, FERTILIZER FACTORIAL
EXPERIMENT, OTHELLO STATION 1965-1972a
(ppm, soil basis)
Treatment
N1P1
N4P1
N1P4
N4P4
N1P1
N4P1
N1P4
Kl
Kl
Kl
Kl
K4
K4
K4
1965
3.3
3.9
4.8
2.2
3.8
2.4
1.7
2.1
Phosphorus
1967 1968
5.5
5.9
30+
28+
5.6
5.4
31 +
27.0
6.1
9.6
31+
31 +
7.9
6.6
29+
31+
1970
10.7
7.0
33.3
29.1
11.0
8.1
31.7
29.2
1972
11.0
10.8
36.3
36+
13.8
10.2
36+
36+
1965
116
112
170
106
234
114
110
106
Potassium
1967 1968 1970
102
98
134
96
194
150
162
112
110
118
146
114
282
216
186
168
127
138
160
125
248
168
170
142
1972
105
128
140
105
248
180
182
162
Composited samples from the surface 20 cm of soil for replicates 1, 3, and 5, at the
beginning of the season indicated.
N = nitrogen, P = phosphorus, K = potassium; subscripts 1 and 4 indicate respectively
approx. 0 or approx. 450 kg/ha, of the fertilizer nutrient (N, PO^C or K,O) applied
annually for 1965-1967 and 1970-1971. 450 kg/ha, of N applied to all plots in 1972.
Wheat grown to "mine" residual N from the plots in 1968 and 1969.
-------
Table A-21. AVERAGE SOIL-TEST P AND K VALUES WITH DEPTH, FERTILIZER
FACTORIAL EXPERIMENT, OTHELLO STATION, FALL OF 1972a
(ppm, soil basis)
Treatment
N
N
^O
^O
N
N
N
N
T^ T^
T^ T£"
1P4K1
4P4K1
1P1K4
^piK,,
414
iPA
144
APA
444
0-30
cm
11.0
11.5
57.0
53.0
10.6
12.4
36.4
49.0
Phosphorus
30-60 60-120
5.0
3.0
12.3
11.1
3.4
3.2
11.4
10.9
6.9
4.8
6.2
8.5
3.9
4.7
8.0
7.0
120-180
13.8
15.7
17.5
18.3
11.8
12.6
17.4
23.8
180+
cm
5.9
4.2
--
7.0
12.8
--
0-30
cm
114
115
136
97
377
221
195
195
Potassium
30-60 60-120
73
74
93
83
130
100
83
77
83
81
86
86
98
84
86
80
120-180
119
109
114
123
139
94
144
128
180+
cm
_ _
107
125
-
95
88
145
--
aAverages for replicates 1, 3, and 5
b
N = nitrogen, P = phosphorus, K = potassium; subscripts 1 and 4 indicate respectively
approx. 0 or approx. 450 kg/ha, of the fertilizer nutrient (N, P2Oc or K2°) applied
annually for 1965-1967 and 1970-1971. 450 kg/ha, of N applied to all plots in 1972.
Wheat grown to "mine" residual N from the plots in 1968 and 1969.
-------
Table A-22. SUMMARIZED TOTAL, YIELD DATA, SELECTED TREATMENTS, FERTILIZER
FACTORIAL EXPERIMENT , OTHELLO STATION, 1965-1972a
Treatment
N1P1
N4P1
Kl
Kl
N1P4K1
N4P4
N1P1
N4P1
N1P4
N4P4
Kl
K4
K4
K4
K4
1965
Potatoes
1966 1967ac
(quintal/ha . )
423
608
545
709
577
641
600
785
167
422
396
430
196
512
296
707
104
270
271
252
136
287
214
327
1967b
d
206
427
438
377
278
476
308
452
Wheat
1968
(hl/ha.
30
77
53
74
37
89
36
77
1969
)C
7
17
5
20
7
17
6
14
Potatoes
1970 1971
236
412
293
491
197
411
243
601
(quintal/ha
375
492
572
540
520
519
573
650
1972
.)
416
520
582
493
645
539
651
640
Averages for replicates 1, 3, and 5.
N = nitrogen, P = phosphorus, K = potassium; subscripts 1 and 4 indicate respectively
approx. 0 or approx. 450 kg/ha, of the fertilizer nutrient (N, P2°c or K7°) aPPlied
annually for 1965-1967 and 1970-1971. 450 kg/ha. of N applied to all plots in 1972.
Wheat grown to "mine" residual N from the plots in 1968 and 1969.
°1967 a = non-fumigated, 1967 b = fumigated.
Quintal/hectare = cwt/acre x 1.12.
eHectoliter/hectare = bu/acre x 0.87.
-------
Table A-23.
DISSOLVED INORGANIC N, SLOW-RELEASE N EXPERIMENT OTHELLO
STATION, FALL OF 1972a
CO
ro
Treatment
NH4N03
340 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
500 kg/ha.
(NH4)2S04
340 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg /ha. + 170 kg /ha.
340 kg/ha. + 170 kg/ha.
500 kg/ha.
Urea
340 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
500 kg/ha.
SC 100
340 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
340 kg/ha. + 170 kg/ha.
500 kg/ha.
SC 20
500 kg/ha.
SC 30
500 kg /ha.
UF
SC ZO
SC 30
UF
SC 20
SC 30
UF
SC 20
SC 30
UF
SC 20
SC 30
5
0-30
cm
71
77
178
68
74
101
66
43
105
110
95
112
118
201
114
63
191
279
127
61
103
203
issolved
30-60
7
86
2
5
8
5
10
24
9
26
13
6
9
39
4
14
7
20
16
13
9
5
inorganic N, mg/1
60-120 120-180 180+
cm
3
84
4
11
17
5
8
11
39
76
28
25
8
7
8
7
13
26
4
21
4
49
naC
164
129
53
na
14
52
na
48
na
73
na
51
101
na
38
58
79
83
39
32
40
na
na
-
_
24
na
na
-
na
na
_
na
-
0-30
em
32
39
76
30
69
46
44
36
60
25
57
47
87
91
41
na
.
na
na
na
-
-
12
56
86
7
28
89
103
Standard deviation, %
30-60 60-120 120-180
150
142
133
125
143
173
116
131
93
67
129
142
99
49
35
71
172
111
41
89
74
173
115
100
100
61
34
114
119
14
45
64
173
78
54
103
152
75
66
109
132
33
87
95
na
92
82
117
na
47
119
na
109
na
90
na
49
42
na
104
28
73
124
73
89
13
180+
cm
_
na
na
_
93
na
na
-
na
na
na
-
na
na
na
na
-
-
For replicates 1, 3. and 5.
UF = urea-formaldehyde; SC 20 and SC 30 = sulfur-coated urea, 20% and 30% release of N in 7 days under standardized
conditions.
na = Sample volume not adequate for analysis.
-------
c
u>
Table A-24. . SUMMARIZED YIELD-DATA, SELECTED TREATMENTS, SLOW-RELEASE
N EXPERIMENT, OTHELLO STATION, 1972a
(quintal/hectare)0
b
Treatment
NH4N03
340 kg /ha.
340 kg/ha. + 170 kg/ha. UF
.340 kg/ha. + 170 kg/ha. SC 20
340. kg/ha. -I- 170 kg/ha. SC 30
500 kg /ha.
(ICH ) SO
*4 2 4
340 kg /ha.
340 kg/ha. 4- 170 kg/ha. UF
340 kg /ha. + 170 kg /ha. SC 20
340 kg/ha. 170 kg/ha. SC 30
500 kg /ha.
Urea
340 kg /ha.
340 kg/ha. + 170 kg/ha. UF
340 kg/ha. 4- 170 kg/ha. SC 20
340 kg /ha. + 170 kg /ha. SC 30
500 kg /ha.
Total
741
764
860
756
782
793
702
654
721
740
731
749
663
744
716
No. 1's
601
579
617
547
584
613
491
441
589
493
584
560
466
532
468
Treatment
SC 100
340 kg/ha .
340 kg/ha. + 170 kg/ha. UF
340 kg/ha. + 170 kg/ha. SC 20
340 kg/ha. + 170 kg/ha. SC 30
500 kg/ha.
SC 20
500 kg/ha.
SC 30
500 kg/ha.
Total
712
720
741
709
689
792
844
No. 1's
596
551
548
580
484
575
626
*Average for replicates 1, 3, and 5.
bUF = urea-formaldehyde; SC 20 and SC 30 = sulfur-coated urea, 20% and 30% release of N in 7 days under standardized
conditions.
°Quintal/ha. = cwt/acre x 1.12.
-------
Table A-25. DISSOLVED INORGANIC N AND EC DATA, 1971 PLANT POP-
ULATION-EXPERIMENT, OTHELLO STATION, SPRING OF 1972
Treatment
Low population.
Low population.
High population.
High population.
lowN*
high N
low N
highN
No. Reps.
Sampled
6
6
6
6
0-30 cm
H9
135
129
92
Dissolved inorganic N, tr.g/1
30-60 60-120 120-180 180+ cm
101
74
80
60
30
32
20
20
43 nab
32
34 na
21
Electrical coi
0-30 cm 30-60
3.32 3.10
3.55 2.94
3.56 3.11
2.59 2.74
uJuctivity ,
60-120
2.62
2.46
2.31
2.15
120-180 180+ cm
3.00 na
2.59
2.55 na
2.78
Standard deviation, %
Standard deviation, %
Low population,
Low population.
High population ,
High population ,
low N
highN
low N
highN
6
6
6
6
27
64
25
38
99
88
49
56
95
54
37
33
152 na
58
64 na
83
15
34
12
10
42
46
24
18
24
14
9
B
28
13
19
26
na
"
na
*Low copulation and hieh population =44000 and 73000 plants/ha.. respectively; low N = 110 and 187 kg N/ha. for the low and high plant
populations, respectively; high N = 450 and 752 kg N/ha. for the low and high plant populations, respectively.
na = Sample volume not adequate for analysis.
-------
Ul
Table A-26. SUMMARIZED YIELD DATA, SELECTED TREATMENTS, 1971 AND 1972
PLANT POPULATION EXPERIMENTS, OTHELLO STATION
(quintal/hectare)
L
Treatment
Low population,
low N
Low population,
highN
High population,
low N
High population,
highN
No. Reps.
Sampled
6
6
6
6
1971
Total
573
708
749
790
No. 1's
291
309
454
278
1972
Total
681
782
693
825
No. 1's
547
598
566
595
aQuintal/hectare = cwt/acre x. 1.12.
Low population and high population = 44000 and 7 3000 plant/ha., respectively; low N = 110
and 187 kg N/ha. for the low and high plant populations, respectively; high N = 450 and
752 kg N/ha. for the low and high plant populations, respectively.
-------
Table A-27. DISSOLVED INORGANIC N, 0-30 CM DEPTH, SUSPENSION FERTILIZER
EXPERIMENT, MOSES LAKE AREA, 1973a
1
Treatment R
FIBaL 79
F4BaL 213
FIBaD 101
F4BaD 88
FIBrL 29
F4BrL 128
FIBrD 59
F4BrD 117
Dissolved
F
5
19
3
28
10
6
6
7
1/2
16
10
64
10
6
48
13
17
August 1
7i~
Reps R
33 39
80 86
56 146
42 91
IS 83
61 56
26 110
47 97
Std. deviation, "i
F 1/2
180
37
100
104
50
117
100
100
25
90
123
60
83
113
100
65
\
Reps
119
128
99
133
86
105
139
108
R
8
15
11
10
5
77
10
3
Dissolved N,
F 1/2
79 26
238 16
165 31
139 19
70 12
69 73
28 10
50 33
August 14
mg/1
Reps
38
90
69
56
29
73
16
29
Std. deviation, %
R F 1/2 Reps
50 10
53 42
46 104
90 97
40 21
144 128
80 25
100 52
35 99
50 143
61 110
53 120
33 122
106 75
70 73
149 116
Go
Rill irrigation, sandy site, 3 replicates sampled.
F4 = HO and 450 kg/ha, of N, P2O, and K,O respectively. Ba = banded, Br = broadcast. L = suspension fertilizer, D= dry fertilizer.
op row, F = irrigation furrow, 1/2 = f/2 way between row and furrow. Reps = average values for the three replicates. Planted May 1-2,
"Fl and
R = crop
harvested October 4-5. Russet Burbank potatoes.
-------
Table A-Z8. DISSOLVED INORGANIC N, 0-30 CM DEPTH, SUSPENSION FERTILIZER
EXPERIMENT, OTHELLO AREA, I973a
Treatment
FIBaL
F4BaL
FIBaD
F4BaD
FlBrL
F4BrL
FIBrD
F4BrD
FIBaL
F4BaL
FIBaD
F4BaD
FlBrL
F4BrL
FIBrD
F4BrD
R F
13
ISO
13
70
107
18 5
8
18
8
45
8
17
21
39
7
11
5
141
11
13
15
43
5
14
4
142
9
40
26
53
20
17
N. mgTT
1/2
10
21
16
21
30
54
15
18
11
42
9
26
15
20
8
15
Reps R
July 17
9 39
104 152
13 54
34 114
51 144
94 82
9 13
16 67
August 10
8 50
76 80
8 88
28 53
21 81
37 80
12 29
14 55
-§tdT
F
120
157
18
54
67
65
80
86
100
147
78
100
85
121
50
24
deviation ,
1/2
30
114
63
38
70
56
27
61
82
95
111
58
93
80
100
40
~%
Reps R
57 14
62 81
47 17
69 49
69 23
77 37
63 13
41 30
84 10
48 87
86 7
45 33
65 21
51 33
76 11
39 16
Dissolved N, ing /I
F 1/2 Reps
15 15
39 73
14 14
32 32
16 23
59 35
6 7
21 14
9 6
67 65
2 6
29 12
10 13
48 20
3 10
12 8
Au
15
65
15
38
21
44
9
22
Std.
R F
just 22
64 27
135 113
94 71
98 47
65 88
105 80
62 83
27 43
August 30 it 31
8
73
5
25
15
34
B
12
90 122
145 161
14 100
24 45
110 90
100 123
64 167
88 75
deviation. %
1/2 Reps
67 32
127 32
57 42
38 30
100 29
80 39
57 60
43 48
33 98
165 67
117 104
133 56
31 60
85 58
20 82
88 79
Co
-vl
Solid-set sprinkler system, silt loam site. 3 replicates sampled.
Fl and F4 = 110 and 450 kg/ha. N, PjO., and K-O respectively. Ba = banded, Bi = broadcast. L = suspension fertilizer, D = dry fertilizer.
R = crop row, F = irrigation furrow, 1/2 =^1/2 way between row and furrow. Reps = average values for the three replicates. Fumigati.
with Telone C at 230 liters/ha. (25 gal/acre). Planted April 30-24, harvested October 17-19. Russet Burbank potatoes.
.gation
-------
Table A-29. DISSOLVED INORGANIC N, 0-30 CM DEPTH, SLOW-RELEASE N EXPERIMENT
MOSES LAKE AREA, 1973a
b
Treatment
170 kg/ha.
170 kg/ha.
170 kg/ha.
170 kg/ha.
390 kg /ha.
390 kg/ha.
390 kg/ha.
390 kg/ha.
170 kg/ha.
170 kg/ha.
170 kg/ha.
170 kg/ha.
390 kg /ha.
390 kg/ha.
390 kg/ha.
390 kg /ha.
NH4NO3
Urea
SCU 100
SCU 25
NH.NOo
Urea
SCU 100
SCU 25
NH4NO3
Urea
SCU 100
SCU 25
NH4NO3
Urea
SCU 100
SCU 25
R
61
71
38
40
118
138
31
34
14
16
10
9
20
11
13
20
Dissolved
F
7
8
4
10
12
18
10
26
138
71
87
60
328
269
93
128
N, mg/1
1/2
7
8
6
10
16
36
10
12
36
20
16
35
53
44
34
27
Reps
Augu:
25
29
16
20
49
64
17
24
R
3t 1
82
132
55
43
74
48
61
44
August 14
63
36
38
34
134
108
47
58
57
56
90
100
80
27
62
30
Std.
F
29
38
25
40
42
28
80
96
88
69
82
72
49
6
80
114
deviation, %
1/2
43
88
133
70
106
22
90
50
58
65
69
109
28
57
91
15
Reps
106
90
123
89
115
95
88
74
85
72
110
95
124
131
88
91
G
CD
aFurrow irrigation, sandy site, 3 replicates sampled.
bSCU 100 and SCU 25 = sulfur-coated ureas releasing 100% and 25% of their N, respectively, dur-
ing the standard 7-day leaching test. R = crop row, F = irrigation furrow, 1/2 = 1/2 way be-
tween row and furrow, Reps = average values for the three replicates. Planted May 1,
harvested October 8. Russet Bur bank potatoes.
-------
Table A-30. DISSOLVED INORGANIC N, 0-30 CM DEPTH, SLOW-RELEASE N EXPERIMENT,
OTHELLO AREA, 1973a
Treatment
170 kg /ha. NH.NO,
170 kg/ha. Urea
170 kg /ha. SCU 100
170 kg/ha. SCU25
500 kg /ha. NH.NO.,
500 kg/ha. Urea *
500 kg/ha. SCU100
500 kg/ha. SCU25
170 kg /ha. NH NO,
170 kg/ha. Urea °
170 kg/ha. SCU100
170 kg/ha. SCU2S
500 kg/ha. NH NO,
500 kg /ha. Urea
500 kg/ha. SCU100
500 kg/ha. SCU25
R
16
22
25
38
202
253
143
55
17
30
45
31
54
129
110
93
Dissolved
F
19
15
17
6
20
6
14
16
16
17
25
21
65
54
39
23
N, mg/1
1/2 Reos R
14
15
23
22
40
29
21
29
23
42
29
17
31
4O
30
23
July 17
16 81
17 77
22 16
22 24
87 18
96 63
60 52
33 51
August 1
19 18
30 73
33 62
23 45
50 50
74 88
60 20
46 134
Std.
F
11
33
12
133
50
150
43
69
63
77
40
67
51
74
23
74
deviation ,
1/2
29
100
9
55
20
31
33
31
57
95
52
65
42
83
30
48
Reps R
40 10
47 16
23 26
82 32
115 27
135 23
120 51
75 99
34 15
38 15
38 26
39 30
52 42
65 27
74 59
81 52
Dissolved N, mg/1
F 1/2 Reos R
19 12
7 10
18 13
15 20
36 22
34 31
25 28
34 36
23 17
15 14
18 24
20 20
31 34
46 22
49 33
36 20
August 22
14 140
11 88
19 73
22 47
28 82
30 35
34 63
56 34
August 30 & 31
18 60
15 33
23 46
23 60
35 26
32 19
47 41
36 67
Std. deviation. To
F 1/2 R«DS
53
100
61
33
53
29
12
32
26
33
33
30
13
17
51
81
67 64
20 88
54 51
75 66
73 35
39 29
11 40
56 67
59 38
29 25
25 35
25 35
21 16
9 41
21 41
35 43
LJ
VO
Solid-set sprinkler system, silt loam site, 3 replicates sampled.
SCU 100 and SCU 25 = sulfur-coated urea releasing 100% and 25% of their N, respectively, during the standard 7-day leaching test. R - crop row,
F = irrigation furrow, 1/2 = 1/2 way between row and furrow. Reps = average values for the three replicates. Planted April 19, harvested
October 17. Russet Burbank potatoes.
-------
Table A-31.
DISSOLVED INORGANIC N, 0-30 CM DEPTH, SLOW-RELEASE N
EXPERIMENT, OTHELLO STATION, 1973a
Treatment
170 kg /ha. NH.NO,
170 kg /ha. Urea *
170 kg/ha. SCU 100
170 kg/ha. SCU 25
500 kg /ha. NH.NO,
500 kg/ha. Urea
SOO kg/ha. SCU 100
500 kg/ha. SCU 25
170 kg/ha. NH.NOj
170 kg/ha. Urea
170 kg/ha. SCU 100
170 kg/ha. SCU 25
500 kg/ha. NH.NO-
SCO kg /ha. Urea
500 kg /ha. SCU 100
500 ka/ha. SCU 25
R
98
54
73
45
1387
708
924
251
18
19
12
19
36
32
36
26
Dissolved
F
21
30
13
19
40
54
48
15
31
27
28
35
394
436
360
197
N/mg/l
1/2 Reps
Ju
61 60
55 46
20 35
35 33
429 619
187 317
394 455
54 107
Std.
R F
Ly 24
125 33
72 27
96 39
29 21
108 73
65 46
74 38
123 53
August 10
22 23
23 23
18 19
32 29
150 194
110 193
191 196
33 85
33 55
47 7
42 89
21 31
31 61
72 62
39 38
23 129
deviation ,
1/2
105
93
30
26
111
94
87
98
73
48
44
41
65
83
79
42
Reps R
48 29
44 28
77 51
39 38
95 289
102 232
95 320
99 219
43 50
33 40
47 30
42 52
97 347
109 330
95 494
70 230
Dissolved N, mg/1
F 1/2 Reps
20 22
28 34
11 17
20 23
35 88
33 33
66 129
38 33
30 19
25 26
35 16
34 26
35 107
54 43
34 172
52 36
Augu
24
30
26
27
137
99
166
97
R
st 23
35
21
37
55
94
132
129
135
August 30 It 31
33
30
27
37
163
142
234
106
52
45
27
37
110
97
121
100
Std. deviation. To
F 1/2 Reps
25
7
46
30
9
52
35
13
43
36
40
27
9
15
32
48
41 24
21 17
35 80
39 36
66 70
46 80
138 59
33 72
58 50
42 27
75 39
31 36
130 85
35 92
149 101
28 82
aFurrow irrigation, silt loam site; 3 replicates sampled.
bSCU 100 and SCU 25 - sulfur-coated ureas releasing 100% and 25% of their N, respectively, during the standard 7-day leaching test. R = crop row.
F = irrigation furrow, 1/2 = 1/Z way between row and furrow. Reps = average values for the three replicates. Planted May 1, harvested
October 30 and November 2, Russet Burbank potatoes.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-158
I. RECIPIENT'S ACCESSION-NO,
4. TITLE AND SUBTITLE
Nitrogen and Irrigation Management to Reduce
Return-flow Pollution in the Columbia Basin
5. REPORT DATE
September 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Brian L. McNeal
Bobby L. Carlile
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Agronomy and Soils
Washington State University
Pullman, Washington 99163
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
S-801187
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research and Development
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
inal-May 1971 to October 1974
14. SPONSORING AGENCY CODE
EPA-ORD
5. SUPPLEMENTARY NOTES
6. ABSTRACT " ~ ~
Cooperative field studies have evaluated dissolved-N levels and leaching and
corresponding crop yields, for potato production practices in the Columbia Basin
area of Washington. High dissolved-N levels (with resultant high potential for
return-flow pollution) were found throughout the growing season in well-managed
potato fields, with levels decreased by decreasing fertilization rate, use of slow-
release N fertilizers or nitrification inhibitors, or sprinkler application of N
fertilizers.
Careful water management with solid-set sprinkler proved capable of maintaining
dissolved-N within the root zone of subsequent crops by season's end, even on very
sandy sites. Alternate-furrow irrigation proved effective in "trapping" banded
fertilizer N within the plant root zone on heavier-textured furrow-irrigated soils
Periodic "mining" of residual N by other crops in the rotation would still be
necessary to prevent eventual return-flow contamination, however.
Site-to-site sampling variability necessitates the use of composited soil
samples, rather than fixed-position soil solution extraction cups, for adequate
monitoring of N in soils of this area. Neither dissolved soil N nor plant petiole
nitrate-N proved to be reliable predictors of crop N needs under the conditions
tested.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Water pollution, nitrogen, irrigation,
ground water, soil water, potatoes
b.lDENTIFIERS/OPEN ENDED TERMS
soil water samplers,
extraction cups, petiole
analyses, nitrates,
Columbia River Basin
c. COSATI Field/Group
02-C
. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report}
Unclassified
21. NO. OF PAGES
151
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
£U.5. GOVERNMENT PRINTING OFFICE: 19/6-657-695/6116 Region No. 5-11
141
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