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Efficacy of using cover crops in 2 of the 3 growing seasons on nitrogen supply in an organic soybean-winter wheat-corn rotation

Principal Investigator: Xueming Yang

Research Institution: Agriculture and Agri-Food Canada

Timeline: April 1, 2018 – March 31, 2023  


  • Examine how winter-hardy leguminous cover crops (red clover, crimson clover, white clover and hairy vetch) planted after winter wheat harvest perform.
  • Determine if these legumes (when under-seeded into the standing corn at the V-5-6 stage of corn) will survive under corn shade and regrow in the following spring.
  • Determine cover crop biomass N in the spring before termination for corn planting vs. the cover crop biomass N in the previous late fall (at freeze-up).
  • Understand the impact of cover crop type and crop residue incorporation methods on soil mineral nitrogen status during the corn growing season.  
  • Determine the grain yield and protein content in corn, as well as in wheat and soybean. 
  • Determine the impacts of cover crops on soil quality/fertility by measuring:
    • soil nutrients, mainly N, P, K, Ca, Mg and S.
    • soil organic matter content.
    • labile organic matter pools (particulate organic matter / water soluble carbon).


  • Best management practices (BMPs) will be developed for an effective leguminous cover crop strategy and tillage practice in a soybean – winter wheat –  corn rotation that provides leguminous fixed-N to both corn and winter wheat while maintaining/improving soil fertility and soil health.

Scientific Summary:

The overall goal of this study is to develop a new rotation system for organically managed cropping systems in southern Ontario.  This rotation may include two seasons of winter-hardy legume cover crops in an organically-managed soybean-wheat-corn rotation (two legume crops and three main crops in three years), which can supply corn and wheat with sufficient amounts of nitrogen (fixed by legumes) and at the same time maintain/improve soil fertility/health. The proposed rotation would have living crops in the summer growing period as well as in the late fall and spring (i.e., winter wheat would be the winter cover in one of the years and the winter-hardy legume cover crops would be the winter cover in the other two years). Farmland under this rotation would have year-round cropping.

External Funding Partners:

Organic Science Cluster-3 via Agriculture and Agri-Food Canada.

Funding for this project has been provided by Agriculture and Agri-Food Canada.