A Diversified Organic Cropping System: Impacts on Crop Production and Soil Health in S. Canada


Xueming Yang, Craig Drury, Mary-Anne Reeb, Dan Reynolds, “A Diversified Organic Cropping System: Impacts on Crop Production and Soil Health in S. Canada”. 3rd Global Soil Biodiversity Conference, poster presentation, March 12-16, 2023, Dublin, Ireland.


Including cover crops in the cereal rotation would not only benefit the crop yield but also could improve soil health. Cereal rotation, such as soybean-winter_wheat-corn rotation, is popular in southwestern Ontario; however, this rotation leaves the soil bare for 15 – 16 months in one cycle of rotation (3 years). While the soil is bare, it not only make nutrients (e.g. N and P) left in the soil vulnerable to leaching, but it also destroys valuable organic matter in the soil. So this rotation is not an ideal cropping system in term of soil fertility and biodiversity. A feasible way to help farmers achieve the dual benefits of crop production and soil health is to grow crops, such as cover crops, between the cash crops. Here, we investigated an evergreen farming practice in southern Ontario, which included two seasons of legume cover crops in a 3-yr organically managed soybean-winter_wheat-corn rotation. In this rotation one legume season (including crimson clover, hairy vetch, and red clover treatments) were seeded after winter wheat harvest and another legume (a mix of above three legumes) were inter-seeded into corn field at corn V5-7 stages. In this production system, legume cover crops were used as the primary N source for the grains (corn and winter wheat), also included was a conventional control (with synthetic fertilizers) without legume cover crops as check. Growing two seasons of winter-hardy legume cover crops in rotation yielded a system of 5 crop seasons in 3 years which provided year-round cover on cropland. Results showed that compared to no cover crop CK, cover crops left less residual soil nitrogen (~50 kg N/ha less) in the soil by late November, which were normally lost through over-winter leaching in the region. In early May before corn planting, significant amounts of above-ground biomass N (150 - 200 kg N/ha) were incorporated into the soil as primary N nutrient for corn from the legumes seeded into wheat stubble, and the same time about 5.5 - 8.5 Mg/ha biomass were incorporated into the soil. The legumes seeded into corn fields showed a variable covering, some years with a full cover and other years a patchy cover dependent open the weather (~40 kg N/ha and ~1.5 Mg biomass/ha per year). In the three-year transition period, average corn grain yields (14.5% moist) were 13.1 and 13. 0 Mg/ha for hairy vetch and red clover which were similar to check (13.8 Mg/ha). In the four-year organic period after the transition, average corn grain yields were 11.3 Mg/ha, 11.1 Mg/ha and 9.9 Mg/ha for hairy vetch, crimson clover and red clover which were about 72 – 82% of corn yield in check (13.7 Mg/ha). Soybean yields were similar among treatments in the year of transition and by the four years after the transition, with an average of 3.2 Mg/ha. Over 8 years (2022 data included) of the experiment, the average conventional winter wheat yield has been 5.1 Mg/ha and 4.1 Mg//ha for organic. The effects on selected soil health parameters are under study will be presented at the 3rd Global Soil Biodiversity Conference. This study highlighted the impacts of diversified and legume-based cropping on grain production and soil health in southwestern Ontario.