905O88001
U.S. AGRICULTURAL TILLAGE PRACTICES
IN THE GREAT LAKES BASIN, 1988
Pranas EL Pranckevicius, Katherine Schroer, Barry Manns, Frank Anscombe
U.S. ENVIRONMENTAL PROTECTION AGENCY
GREAT LAKES NATIONAL PROGRAM OFFICE
CHICAGO, ILLINOIS 60604
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U.S. AGRICULTURAL TILLAGE PRACTICES IN THE GREAT LAKES
BASIN, 1988
Agricultural runoff has long been recognized as a major source of nutrients as well as other agricwmral
chemicals to the Great Lakes. The International Joint Commission's Water Quality Board1 reporteSffi^
1989 that monitored and unmonitored tributaries are the largest remaining sources of phosphorus loads
^
to the Great Lakes. Whereas point sources of nutrients have been largely controlled through the building
of waste treatment facilities and the NPDES permit program for regulation of dischargers to surface water,
non-point sources of contamination remain an environmental problem. This problem can be solved,
however, by implementation of Best Management Practices that preserve topsoil, increase yields, and
reduce cropland runoff.
CONSERVATION TILLAGE PRACTICES
Tillage and planting practices which reduce soil erosion by wind or water are known collectively as
conservation tillage. Conservation tillage practices which reduce soil erosion by water are defined as
those which maintain a minimum of 30% of the soil surface covered with residue after planting. For areas
subject to wind erosion, conservation tillage practices, by definition, reduce wind erosion during the
critical erosion period by maintaining at least 1,000 pounds per acre of flat small-grain residue equivalent
on the soil surface.
There are four main types of conservation tillage practices: No-Till, Mulch-Till, Ridge-Till, and Strip-Till. In
addition, Reduced Till is defined as any other tillage and planting system not covered above that meets
the residue requirement. These tillage practices differ in the level of soil disturbance and method of
cultivation. The No-Till practice is recognized as providing maximum reduction of the amount of erosion.
Other methods which do not attain the minimum of 30% residue on the soil surface, or 1,000 pounds
residue per acre are known as conventional tillage practices. The tillage system selected by the farmer is
dependent on both his circumstances (i.e. location, soil type, crop and other site-specific factors) and on
his understanding of productive and prudent farming practices.
The Conservation Technology Information Center (CTIC) has compiled agricultural and tillage data for
counties nationwide. CTIC, located in West Lafayette, Indiana, compiles agricultural and tillage data
provided by the Soil Conservation Service on a county level nationwide. CTIC is part of the National
Association of Conservation Districts. U.S. EPA's Great Lakes National Program Office has analyzed data
1 Great Lakes Water Quality Board Report on Great Lakes Water Quality (1989)
page 2 March 21,1990
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from CTlC's Seventh National Survey of Conservation Tillage Practices for 1988 for counties of the Great
Lakes basin? to show tillage trends in the Great Lakes area:
CROPLAND IN GREAT LAKES BASIN COUNTIES
Cropland accounts for 18,540,298 acres or 18% of the total area of the Great Lakes basin counties»"
(101,733,263 acres) (Figure 1, Great Lakes Basin Acreage). The major cropland areas of the basin
located in northwest Ohio, the Saginaw River and Bay area, and west-central Wisconsin. Figure 5
(Percentage Cropland to Total County Area) shows the distribution of cropland in the Great Lakes Basin
counties. Com is the largest crop in the basin with a total of 7,784,348 acres (42%), followed by soybeans
with 4,519,231 acres (24%) and small grains with 3,139,986 acres (17%) (Figure 2).3 Figure 6, Figure 7,
and Figure 8 show the distribution of corn, soybeans and small grains production in the Great Lakes basin
counties. Major corn growing areas are located in east-central Michigan, south-east Michigan and
northwest Ohio, and in central Wisconsin. Soybean growing is based in norhtwestem Ohio and south of
Saginaw Bay in Michigan. Small grains are grown largely east of Saginaw Bay in Michigan, and in south
easten Wisconsin. Grain sorghum, other crops, pasture, forage crops, and fallow land account for the
remaining 3,096,733 acres (17%) of cropland.4
GREAT LAKES TILLAGE PRACTICES
Conventional tillage practices are used far more than conservation tillage for all crops. Conservation tillage
practices are used in 27% of the cropland. Mulch-Till is the most frequently used conservation tillage
practice, accounting for 68% of all conservation tillage acres. No-Till is used in 24% of all conservation
tillage acres. Ridge-Till and Strip-Till have only minor application in the Great Lakes basin (Figure 3).
Comparison of Figures 5, 6, 7, and 8 (distributions of crop production) with Figures 9, 10, 11, and 12
(distribution of conservation tillage practices) shows graphically that Conservation Tillage practices are
generally lowest in the areas of the greatest production for any particular crop.
2 Great Lakes counties were selected using ARC/INFO based upon 1:2,000,000 scale digital
hydrography files (Table: Great Lakes counties). This list of counties includes counties not wholly within
the Great Lakes Basin.
3 Small grains includes crops such as wheat, oats, barley, rye, rice and others.
4 Forage crops are grasses and/or legumes planted as part of crop rotation. Other crops are those
not specifically listed as vegetable and truck crops, peanuts, tobacco, etc.
pages March 21.1990
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The com crop is grown with a greater percentage of conservation tillage than any other crop. For example,
conservation tillage is used for 38% of the total com crop, but only 25% of the soybean crop and 20 j
percent of small grains (Figure 4). Conservation tillage practices account for less than 10% of all other \ -
crops grown.
Conservation tillage practices are most prevalent in com production areas in northwest Indiana, central
Wisconsin, and central Michigan (Figure 10). LaPorte and Porter counties in northwest Indiana have the
two highest rates of conservation tillage use for com production in the basin, 95.2% and 89%. On the
other hand, the top eleven counties having the highest proportion of cropland to their acreage (79.7% -
68.2%) had very low rates of conservation tillage use. These counties, all in northwest Ohio, have rates of
conservation tillage application ranging from 12.8% up to a high of 45.2% and averaging around 23.7%.
Kathy, work on this paragraph a bit These varying rates of conservation tillage are partly
attributable to differences in soil types. Some soils with a high clay content cannot support conservation
tillage practices, since the soil may become too hard to permit drainage, thereby drowning seed or
denying sufficient moisture to near surface soil. During the early 1980's, USEPA-GLNPO helped to
support demonstrations of conservation tillage in the Black Creek Indiana watershed, itself part of the
Maumee River basin. One outcome of these studies was to show that high farm yields were obtainable in
certain high clay soils, given sufficient drainage systems. Construction of such systems (e.g., parallel tile
outlet terraces) is expensive and the drainage systems require the availability of outlet streams. Figure 2
does not adjust for soil types and thus does not indicate one likely reason for varying rates of conservation
tillage. However, it is useful for displaying the absolute rates of conservation tillage adoption among
counties.
IMPACT OF CONSERVATION TILLAGE PRACTICES UPON GREAT LAKES WATER
QUALITY
The effectiveness of conservation-tillage practices upon nutrient and other agricultural chemical runoff is
difficult to judge on a regional or lake-wide scale. However, recent research supported by U.S. EPA in the
Lake Erie basin found no significant differences in runoff, tile flow, and pesticide losses between No-Till
and fall plowing on test plots5. Corn-producing areas which may benefit from greater use of conservation
tillage practices include northwest Ohio and east-central Michigan.
5 Logan etal., 1989
page 4 March 21,1990
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From 1987 through 1989, USEPA-GLNPO helped to sponsor comprehensive visual surveys by the Soil
and Conservation Service of conservation tillage in counties in Ohio, Indiana, and Michigan that drain to
Saginaw Bay and Lake Erie. These have tended to essentially confirm traditional Soil and Conservation
District "best professional judgment* estimates regarding "no till" prevalence, but indicate less adoption of
other conservation tillage practices than previously estimated for these areas.
Comparison of overall crop production to conservation tillage practices use for the states of the Great
Lakes basin show the following trends:
The states of...,...,... need to play stronger roles in implementing....
RECOMMENDATIONS
Several universities are pursuing development of remote, satellite monitoring of tillage practices that hold
promise of obtaining more precise estimates in the future. However, differing estimation methods over
time and around the Great Lakes basin tend to make district-by-district comparisons and historical trends
somewhat problematic. Support appcication of remote sensing technologies to secure up to date
information on crops, and tillage practices employed. This would help to
Continue to support CTIC, and continuosly monitor agricultural trends in the Great Lakes basin.
pages March 21,1990
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Figure 1.
GREAT LAKES BASIN ACREAGE
100-
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TOTAL AREA
CROPLAND
CONSERVATION TILLAGE
Figure 2.
CROPLAND IN GREAT LAKES BASIN COUNTIES
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0 CORN
• SOYBEANS
• SMALL GRAINS
• ALL OTHER CROPS
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TOTAL CROPLAND ACRES
CONSERVATION TILLAGE ACRES
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Figure 3.
CONSERVATION TILLAGE PRACTICES
IN GREAT LAKES BASIN COUNTIES
in
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H CORN
• SOYBEANS
• SMALL GRAINS
• ALLOTHERCROPS
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NO TILL
RIDGE TILL
STRIP TILL
MULCH TILL
REDUCED TILL
Figure 4.
TILLAGE PRACTICES IN GREAT LAKES BASIN COUNTIES
(by crop)
CO
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2-
CONVENTIONAL TILLAGE
NO TILL
OTHER CONSERVATION TILLAGE PRACTICES
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