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LSP Report LS7002

Management of Fine Textured Poorly Drained
Soils for Intensive Agriculture


Researcher: Dr. J.A. Stone, Harrow Research Station, Principal Researcher. Aspects of this proposal have been coordinated with a similar proposal being submitted by researchers from the Dept. of Land Resource Science, University of Guelph, to facilitate extrapolation of results to the various soils and climatic conditions across the province.

Funding: $61,364


  1. To contribute to the development of a row crop management package which will improve and maintain soil structure through -
    1. the selection and evaluation of several legume - grass forage mixes relative to which will provide the most improvement in soil structure in the shortest time (1988-90)
    2. the determination of the minimum amount of tillage required to obtain yields equivalent to conventional tillage (fall mouldboard plow) in a corn-soybean rotation and determination of the effect of reduced tillage on soil structure (1988-91)
    3. the evaluation of corn polyculture (intercropping corn with legume and grass forages) under conventional and conservation tillage systems relative to improvements in soil structure, reduction in nitrogen requirements, and effects on yield (1989-91).

Expected Benefits

  1. To minimize losses in soil productivity and environmental hazards resulting from erosion, runoff, and compaction.
  2. To improve the market position of Ontario farmers by providing more efficient use of fertilizer and by lowering fuel costs associated with tillage.

Summary of Research Results

Experiment 2 - The determination of the minimum amount of tillage required to obtain yields equivalent to conventional tillage (fall moldboard plow) in a corn-soybean rotation and determination of the effect of reduced tillage on soil structure.

Agronomic Analysis Weather Effects - Weather conditions in 1988-90, had a very significant overriding influence on soil and plant measurements. In general Corn Heat Units were similar for 1988-90 while rainfall during the same period was variable within growing seasons as well as between years as observed in the low to high rainfall pattern in 1988; the very high to low pattern in 1989; and average early to low mid season and then high rainfall pattern in 1990. 1988 had below normal rainfall with higher than average Corn Heat Units early in the season, resulting in very poor corn plant growth in May, June and July and better than average growth for soybeans. Corn Heat Units were higher than average for 1988 than for 1989-90. Early plant development influenced yields with corn grain yields equivalent to soybeans in 1988. Very wet conditions (flooding in June and July) early and mid season in 1989, delayed corn emergence, days to silking and wet conditions during pollination reduced grain yields although corn height was better than average. Early and mid-season soybean growth was reduced and planting was delayed, restricting soybean yields for 1989. Rainfall during 1990 was above average in May, delaying corn planting and below average for June and July. Early rainfall delayed corn growth while above average Corn Heat Units and rainfall in August and September resulted in average corn and soybean yields.

Rotations - Rainfall accounted for considerable variation in tillage treatments and rotation effects on yields. Each rotation was started in 1987 with corn on Site 1 and soybeans on Site 2. Soybeans improved in yield in 1988 and 1990 after rotation with corn. Similar trends indicate that corn grain yields improved following soybeans in 1987 and 1989 for Site 2. Adverse and variable weather conditions account for the highly significant differences in yields among years and the effects on rotations at both sites and for the large yield differences from year to year. Residue cover varied considerably as a result of the amount of plant material produced the previous year and the type of rotation crop.

Percent residue from the previous corn rotation (87 and 89), produced higher residue cover at Site 1 in 88 and 90, than residue from previous soybeans. At Site 2, 1989 residue from poor corn growth in 88 was similar to the residue produced by the 87 soybean rotation crop.

Tillage Treatments - If corn or soybeans are analyzed by combining sites for each crop, then a significant interaction for soybeans can be observed, indicating that tillage treatments were dependent on year conditions and did not perform consistently from year to year. If analyzed by locations then Site 2 also appears to have tillage interactions which is very close to being statistically significant and dependent on year conditions. This is further supported by plant growth parameters and plant residues, which varied from year and were not consistently significant because of extremes in weather conditions.

Variable weather conditions in 1988, 89 and 90 had a strong influence on soil and plant growth parameters results. Weather conditions had a greater influence on yields and plant growth parameters than rotations. The effects of weather conditions and tillage treatments on soybean yields were inconsistent because of interactions. The best row crop tillage treatment yield results were for fall chisel plowing followed by fall chisel plowing for the corn crop and only spring secondary tillage for the following soybean crop. Ridge tillage similar yields but was the most inconsistent over the years and locations. Percent plant residue was highest for ridge, spring secondary and fall chisel plowed tillage treatments. Soil moistures were higher after corn rotations and chisel plowed tillage treatments of corn and soybeans. Soil aggregate size improved with chisel plowing and minimum spring secondary tillage while ridge tillage maintained water stable aggregate structure better than chisel or moldboard plowing. Rotations did not improve wet aggregate stability over the three years. Bulk density and soil porosity results were inconsistent for tillage treatments and rotations.

Experiment 3 - The evaluation of corn polyculture (intercropping corn with legume and grass forages) under conventional and conservation tillage systems relative to improvements in soil structure, reduction in nitrogen requirements and effects on yield.

Weather conditions had a strong influence on this experiment which was complicated by degraded soil structure and as a result very poor drainage. Corn heat units were average for 1989, slightly below for 1990 and considerably above average for 1991 compared to ten year averages for each month. In 1989, plots were planted and damaged by flooding on two different occasions early in the season.

Plant development was influenced by flooding when compared to other years. 1990 was an average year with no extreme weather conditions but wet conditions in May delayed planting to May 31 for corn and June 1 and 15 for intercrops. Hail damage in late August caused some leaf damage but growth was not reduced. In 1991, a wet May delayed planting as in 1990. This was followed by very hot and dry weather causing very poor intercrop germination, plant stunting, inconsistent tassel and silk development and poor yields.

Results from yield analysis indicated that there were no significant differences for yields among the treatments for any year. Spring and fall tillage did not result in a yield trends, except that fall tillage produced slightly higher yields in 1990 and 91. Planting intercrops at the 3-4 leaf stage resulted in higher yields than planting intercrops at corn planting. Corn yields were enhanced by reed canary grass for spring tillage in 1989 and 90 as compared to no intercrops (Bare). Reed canary grass also supported corn yields in fall tillage in 1990. Hairy vetch supported yields similar to bare treatments in the driest year and 1990. Red clover enhanced yields in the 1989 only when moisture was abundantly available. Hairy vetch and reed canary grass enhanced yields and plant development in normal and stress years as compared to other intercrops.

The project was extended for another year (1992) because of interest in establishing some significant differences for plant growth parameters between corn and intercrops and to study nitrogen relationships between crop production and intercrops. Agronomic measurements and nitrogen samples were assessed. In 1992, wet conditions resulted in very poor intercrop emergence due to flooding conditions which are common for degraded soil conditions.

Soil measurements were taken in 1989 and 1990 and only partial data is on file. Soil parameters were not completed because of the resignation of the soil scientist in late 1990. The position and technical support were frozen at the time.

Yield results obtained over years of extreme weather conditions on plots that were in continuous corn for 26 years indicated that planting intercrops such as hairy vetch or reed canary grass would support yields equal to conventional row crop production.



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Created: 03-23-1996
Last Revised: Tuesday, May 10, 2011 11:19:47 AM