Weed interference with no-till soyabeans influenced by fine-scale covariation between soil properties and cover crop performance

Authors: ESLAMI, SAYED - University Of Birjand; Davis, Adam

Submitted to: Weed Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2018
Publication Date: 10/10/2018
Citation: Eslami, S.V., Davis, A.S. 2018. Weed interference with no-till soyabeans influenced by fine-scale covariation between soil properties and cover crop performance. Weed Research. 58:463-474. https://doi.org/10.1111/wre.12334.
DOI: https://doi.org/10.1111/wre.12334

Interpretive Summary: The proliferation of multiple herbicide resistant weeds increases the need for weed management systems that are less reliant upon herbicides. Weed management in low-external-input (LEI) cropping systems is complicated by tradeoffs between greater reliance on physical weed control methods and the need to protect soil quality. Production of LEI soybeans no-till planted into a rolled-crimped cereal rye cover crop is attracting farmer interest because of its potential to balance such tradeoffs. Experimental work on this approach to date has provided insights at the field scale and above, helping to identify broad recommendation domains for best management practices. For individual growers, however, fine-scale information may also be helpful for making in-field adjustments to refine the system. In a three-year field study in Illinois, we quantified key associations among no-till soybean performance in a rolled-rye system and decameter-scale variation in soil characteristics, cover crop performance and weed growth. Sub-field variation in soil properties had both direct and indirect effects on soybean yield. Local soil potassium limitation was linked to reduced rye height, which in turn indirectly reduced soyabean yields through decreased weed suppression by the cover crop. Slow-draining field areas that were still moist at the time of cover crop termination were associated with lower soybean stands, directly reducing yields. Although the sub-field characteristics influencing soybean and cover crop performance may vary from farm to farm, this study highlights potential gains to be realized in this production system from a better understanding of how such properties covary at fine spatial scales and taking steps to remedy in-field deficiencies.

Technical Abstract: Balancing trade-offs in conservation agriculture between crop yield and soil quality is complicated by the need for adequate weed management, especially in low-external-input (LEI) production systems. Production of LEI soybeans no-till planted into a rolled-crimped cereal rye cover crop is attracting farmer interest. Experimental work on this approach to date has provided inferences at the field scale and above, helping to identify broad recommendation domains for best management practices. For individual growers, however, fine-scale information may also be helpful for making in-field adjustments to refine the system. In a three-year field study in Illinois, we quantified key associations among no-till soybean performance in a rolled-rye system and decameter-scale variation in soil characteristics, cover crop performance and weed growth. Sub-field variation in soil properties had both direct and indirect effects on soybean yield. Local soil potassium limitation was linked to reduced rye height, which in turn indirectly reduced soybean yields through decreased weed suppression by the cover crop. Slow-draining field areas that were still moist at the time of cover crop termination were associated with lower soybean stands, directly reducing yields. Although the sub-field characteristics influencing soybean and cover crop performance may vary from farm to farm, this study highlights potential gains to be realized in this production system from a better understanding of how such properties covary at fine spatial scales and taking steps to remedy in-field deficiencies.