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LSP Report LS7004

Soil Stewardship Cropping Systems for Corn &
Soybean Production in Ontario


Researcher: Dr. B.D. Kay, Land Resource Science, University of Guelph, Principal Researcher

Funding: $566,442


  1. To develop cropping systems which will improve soil structure and sustain or increase soybean production on soils of different texture.
  2. To define the red clover establishment procedures, the subsequent management of the red clover, and the primary tillage following the legume, which give the greatest soil structural enhancement and nitrogen benefits to succeeding corn crop when red clover is underseeded in cereals and corn.
  3. To evaluate different forage species, relative to red clover for soil improvement and financial feasibility when direct seeded and underseeded in cereals.
  4. To identify the mechanisms controlling the rate of change of soil structure on different soils under different tillage and cropping practices and thereby develop the capability of both extrapolating the results from the above studies to a broader range of soil conditions as well as identifying potential new and innovative ways of adjusting tillage and cropping systems to improve soil structure.

Expected Benefits

  1. New cropping systems which provide rapid improvement in soil structure will contribute to decreased erosion and long term sustainable productivity.
  2. Decreased costs of production through reduced tillage and decreased nitrogen requirements.

Summary of Research Results

A dramatic increase in the land area utilized for corn and bean production in Ontario has occurred since 1960. The move towards row crops has been accompanied by increasing reliance on off-farm inputs. Increasing emphasis on row crop production has also resulted in detrimental changes in the physical properties of some soils. New cropping systems are required which will maintain or improve soil structure, reduce nitrogen fertilizer use and increase profitability in row crop production.

This study has focused on the use of forages (particularly legumes) and a reduction in tillage as possible ways to improve soil structure and reduce nitrogen use. Four aspects have been investigated:
  1. assessment of cropping systems for soybeans utilizing different tillage and combinations of preceding crops,
  2. refinement of management practices for the use of red clover as a companion crop underseeded in corn or cereals,
  3. evaluation of different forage species as cover crops and
  4. development of the capability to predict the response of a range of different soils when forages are used to improve soil structure.

Crop Rotation and Tillage Effects on Soybean Production - A series of 2-year field experiments were conducted from 1988 to 1991 evaluating the effect of cropping history and tillage practice on soil structure, potential for soil erosion, and soybean productivity. The field trials were located on a Fox sandy loam in Waterloo county near Ayr, Guelph silt loam in Oxford county near Woodstock, and a Brookston clay loam in Essex county near Comber. The preceding year cropping treatments were: 1) Corn, 2) Wheat, 3) Wheat underseeded with red clover, 4) Soybeans, and 5) Fall rye cover crop established following soybeans. The tillage systems evaluated were: 1) Zero-till, 2) Spring tandem disc, and 3) Fall moldboard plow. On the silt loam and clay loam soils a field cultivator was used following tandem discing to improve seedbed conditions. In the zero-till treatments, fall rye and red clover were chemically killed by spraying at least two weeks prior to soybean planting.

Soils tended to be the most structurally stable following either wheat or wheat that was underseeded with red clover and the least stable following soybeans. Structural stability was not improved by the inclusion of fall rye after soybeans. Seedbeds in the spring following soybeans also were associated with higher proportions of fine aggregates than were observed following other previous crop treatments, particularly with the zero-till system.

The potential for soil erosion was lower in the zero-till than in the fall moldboard plow tillage system. The extent by which soil erosion was reduced by zero-tillage following the various preceding crops was proportional to residue cover differences among the tillage systems. In fact, the relatively small residue cover differences between zero-till and fall plowing following soybeans alone were associated with similar soil erosion losses. Occasionally, there was evidence that increasing soil structural stability also decreased the potential for soil erosion.

On all three soil types, zero-till planting soybeans following wheat that was underseeded with red clover was associated with seed yield reductions of at least 15% when compared to fall moldboard plowing. Similar yield reductions were associated with zero-till planting into wheat residues on the silt loam and clay loam soils and into corn residues on the silt loam soil. Whenever soybean seed yield response to tillage was significant, yields following spring tandem discing were usually intermediate to fall moldboard plow and zero-till yields. When soybeans or fall rye were the preceding crop(s), seed yields among the tillage systems tended to be similar. Inferior soybean seed yields in the tandem disc and zero-till tillage systems were usually associated with a greater incidence of insect damage from slugs and/or seed corn maggot in 1990 and disease damage from rhizoctonia root rot in 1991.

There was no evidence that rotating soybeans with a crop other than itself would result in higher yields within the time frame of this study. Actually, when soybeans were planted without tillage, seed yields were often reduced when soybeans followed crops other than soybeans.

These trials demonstrated the ability of a zero-till system, provided that residue cover was significantly increased, to minimize the potential for soil erosion. However, zero-till planting following crops that left relatively high amounts of residue cover (ie. wheat, wheat underseeded with red clover, and corn) often resulted in significant soybean yield reductions when compared to fall moldboard plowing. Soybean yield reductions with zero tillage following high residue producing crops appear to be caused by pests rather than by inferior soil physical properties.

Nevertheless, zero tillage is still recommended for soybean production on sandy loam soil following all crops except winter wheat plus red clover. Furthermore, zero tillage is also recommended following soybeans on loams or clays loams. The option of spring cultivation only (without any primary tillage) appears to be feasible on loams and sandy loams which are well-drained following all crops tested but wheat and red clover. Conservation tillage on clay loams could involve fall primary tillage (e.g., chisel plowing or offset discing) since spring cultivation alone often resulted in yields which were lower than both moldboard plowing and zero tillage.



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Created: 03-23-1996
Last Revised: Tuesday, May 10, 2011 11:23:52 AM