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SWEEP Report #57a

Field Testing of Cover Crop Systems for Corn
and Soybean Production

Roger Samson, Allison Arkinstall and Jeff Quinn, Resource Efficient Agricultural Production (REAP) Canada, Ste. Anne de Bellevue, Quebec.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View / Download Final Report  [111 KB pdf]

Associated SWEEP/LSP Research



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Completed: June, 1992

Key Words:

catch crop, cover crop, rye, oilseed radish, corn, soybeans, red clover, hairy vetch, no-till

Executive Summary

Experiment 1. Field Testing of Cover Crop Systems

Promising cover crop species including hairy vetch, oilseed radish and winter rye were evaluated on 6 farms in southwestern Ontario. Cover crops proved to be economical by either reducing production costs or increasing yields. Oilseed radish appeared to be the most promising new cover crop as it showed potential to reduce production costs, improve weed control and increase corn yields. Hairy vetch provided similar yields and input costs as red clover when used as a legume cover crop prior to corn. Promising rye management systems included using winter rye as a double crop forage before conventionally planted soybeans and using winter rye as a weed suppressing mulch for no-till soybean production.

Experiment 2. Evaluation of the N Contribution of Cover Crops using a Nitrogen Soil Test

Corn grown on plots fertilized with manure and/or cover crops (oilseed radish, red clover and hairy vetch) were sampled biweekly after planting to determine spring soil N transformations and to determine if the N soil test (taken in the top 30 cm of soil at time of sidedress) was a useful indicator of N availability from these sources. Other researchers working in the U.S. corn belt have shown that 21 ppm NO3-N is the critical N level, above which no N fertilizer response is observed, when legumes and manure are the N sources used for corn production. In this study, N fertilization of sites having NO3-N levels of 23 ppm produced a corn yield response at two sites. A value of approximately 25 ppm NO3-N appeared to be a better indicator of fertilizer N response in this one year study. Use of an N soil test appears to be a valuable tool in identifying sites which have an excess supply of N, rather than predicting fertilizer N requirements. It could be a useful tool in helping farmers better understand and manage the N cycle on farms with cover crops and manure as N sources.


Evaluation Summary

(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)
The study was divided into a number of sections dealing with various aspects of catch crop and cover crop management.

Experiment 1.1 was divided into 3 parts, each comparing some aspect of the use of rye in a soybean production system. No significant difference in soybean yield was observed. The rye harvested for a forage system gave the only positive economic return.

Experiment 1.1a studied the use of winter rye as a double crop forage before soybeans. The treatments were winter rye spring plowed (control) and rye harvested as a forage (test). The harvested rye produced hay with low crude protein and low digestibility. Soybean yield was low due to weed pressure.

Experiment 1.1b compared rye killed with herbicide to mow killed for use as a mulch for soybean production. The rye in the mowed plot regrew and crabgrass was affected very little by the mowing. The entire plot area was sprayed with herbicide and inter-row cultivated. The mowed treatment appeared weedy even with the grass treatment.

Experiment 1.1c compared no-till soybeans and no cover crop with no-till soybeans into winter rye which was killed with a herbicide. Both treatments received a comprehensive herbicide program. It was observed that the soybeans with the rye had better weed control.

Experiment 1.2 compared red clover frost seeded into winter wheat to hairy vetch drill seeded into winter wheat in early May and the effect of both treatments on corn the following year. No significant difference in biomass production of the interseeded legumes was observed. However, because of weather conditions, the red clover produced more biomass than anticipated. No significant difference in corn yield was observed between treatments in the year following the legume interseeding.

Experiment 1.3 compared solid and liquid manure as a nutrient source with oilseed radish catch crop for corn. The treatments were manure incorporated with and without the oilseed radish catch crop. No significant difference between corn yield occurred between liquid swine manure with and without the oilseed radish. However the control treatment received 60 kg N/ha side dressed. A significant difference in yield occurred between the solid manure treatments. The treatment with the oilseed radish yielded more than the control. However since the soil N and the ear leaf N were similar the difference in yield was attributed to decreased weed pressure in the test plot.

Experiment 2.1 evaluated the nitrogen contribution of cover crops. The cropping system studied was corn following red clover and hairy vetch cover crops. The treatments were frost seeded red clover (control) and May drill seeded hairy vetch (test), with 0, 40, and 80 kg N/ha. Two depths were sampled at the prescribed corn height to determine if movement of nitrogen had occurred in the hairy vetch plot. No significant difference between nitrogen levels at the lower depth (30-60 cm) was found. At the shallow depth (0-30 cm) the level of NO3 was higher under the red clover plot.

Experiment 2.2 evaluated the nitrogen contribution of oilseed radish as a catch crop with manure fertilized corn. The treatments were a control and oilseed radish, with 0, 40, 80 kg N/ha on two separate farms. All of the sampling dates on the first farm resulted in the oilseed radish plots having higher levels of NO3 than the control. The level of NO3 increased from 8 ppm to 23.1 ppm in the 36 days between the first and last soil sampling. The control plots showed a significant response to fertilizer while the oilseed plots did not. The oilseed radish plots on the second farm were similar to the control plots in the amount of NH4 and NO3 in the soil tests. The level of NO3 increased in both treatments between the first and last soil samples. Both treatments responded significantly to the addition of fertilizer. It was indicated that the oilseed radish yield was less than the first farm and this was given as the reason for the response to fertilizer in the oilseed radish plots.


The studies were conducted for only one year and the sample size was extremely small. For that reason the studies can not be considered to indicate trends but are only observations of what happened in that year.

In Experiment 1.1a it was observed that the weed pressure was less in the harvested plots. The explanation given for the lower weed growth was the removal of nitrogen from the system with the harvested rye. However the rye forage was reported to be low in crude protein and would not be a very large source of nitrogen. The reduced weed pressure could be likely due to the removal of weeds through the harvesting of the rye.

The report indicates that oilseed radish increases soil nitrogen levels. Oilseed radish is not a legume and therefore can not increase soil nitrogen levels. However, it may conserve N which otherwise could be lost.

Associated SWEEP/LSP Research:

  • SWEEP Report #12 - Choice and Management of Cover Crop Species and Varieties for Use in Row Crop Dominant Rotations
  • SWEEP Report #19 - Studies on the Control of Problem Weed Species in Conservation Tillage Systems
  • SWEEP Report #19A - Weeds of Corn, Soybeans, and Winter Wheat Fields Under Conventional, Conservation and No-Till Management Systems In 1988 and 1989
  • SWEEP Report #32 - Optimal Herbicide Use in Conservation Tillage Systems
  • SWEEP Report #36 - Red Clover Cover Crop Studies 1987-1990
  • SWEEP Report #43 - The Use of Cover Crops for Nutrient Conservation
  • LSP 7005 - Crop Rotations and Cover Crop Effects of Erosion Control, Tomato Yields and Soil Properties in Southwestern Ontario
  • LSP 7009 - A Cover Cropping Strategy for First Early Potato Production

Future Research: ( ) indicates reviewers suggestion for priority, A - high, C - low.

None required. Future research of this type is not justified unless a much stricter scientific method is followed.




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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 04:11:47 PM