10 Agronomy Winter wheat A POWERHOUSE IN SUSTAINABILITY AND PRODUCTIVITY Lisa Ashton and Alexandra Dacey ONGOING RESEARCH SHOWS THAT CROP ROTATION IS AN IMPORTANT CONSIDERATION IN GROWING SUSTAINABLE AND PROFITABLE CROPS — and winter wheat is one of the crops that growers should consider including. With a list of benefits, including improving soil health and quality, pest management, and boosting overall productivity, winter wheat is a strong choice for Ontario grain farmers to include in their rotation. Winter wheat acreage has fluctuated over the past two decades in Ontario, with a recent high of 1.1 million seeded acres in 2021, according to Statistics Canada. While there can be initial barriers and costs to growing winter wheat, the positive outcomes it can produce for the entire crop production system and the environment are observed over time. These outcomes include enhancing crop yields, soil organic matter, soil structure, nutrient availability, soil biodiversity, and mitigating plant pests and pathogens. Maintaining Ontario’s winter wheat production into the future will be critical to building resiliency in cropping systems and achieving productivity goals. SOIL HEALTH BENEFITS The practices and management systems that improve soil health are wide-ranging and regionally specific in their implementation and the outcomes they produce. Farmers in Ontario have implemented several best management practices (BMPs) to enhance the health of their soils, including diverse rotations, cover cropping, reduced tillage, and improved nutrient management. Diversifying rotations is not traditionally adopted to achieve soil health outcomes. Farmers adopt a diverse rotation to avoid depleted soil quality and manage pathogens, pests, and weeds. However, according to the Comprehensive Assessment of Soil Health — The Cornell Framework, diversifying rotations is increasingly explored as a strategy for its soil health benefits. Planting winter wheat in crop rotations contributes to upholding soil health principles, including building soil organic matter, keeping soils covered, diversifying crops, and maintaining living roots. Farmers across Ontario put these principles into action, which are further expanded upon in Ontario’s Agricultural Soil Health and Conservation Strategy, New Horizons. Including winter wheat in a corn and soybean rotation also gives farmers a larger time window to plant a cover crop such as red clover, adding nitrogen and organic matter to the soil. This additional cover crop contributes to the soil’s overall health by reducing and preventing wind erosion, keeping the nutrient-rich topsoil in place for the following year’s crop. PRODUCTION BENEFITS Planting winter wheat can also boost productivity in the entire cropping system. Dr. Ikechukwu V. Agomoh and his collaborators found that, within their study, that soybeans grown in three-year rotations with winter wheat and corn in southwestern Ontario produced the largest soybean yields and the greatest positive impacts on soil health indicators, likely owing to the cereal crops for enhancing carbon inputs into soil. In particular, compared with continuous soybean systems, soybean yields were 48 to 52 per cent greater for the three-year rotations with wheat and corn. Adding winter wheat to a monoculture cropping system or two-crop rotation can also help mitigate disease, weed, and pest pressure. For example, frog-eye leaf spot in soybeans can be reduced; weeds can be controlled by providing canopy cover during later fall and early spring; and the life cycle of western corn rootworm can be disrupted by adding winter wheat to a rotation. BUILD SOIL ORGANIC MATTER Winter wheat can enhance soil organic matter in soils when it is added to a rotation. KEEP SOILS COVERED Winter wheat keeps soils covered over the winter and spring months and its stubble also covers soil after harvest. DIVERSIFY CROPS Diversifying rotations can contribute to above and below ground biodiversity and resilience. MAINTAIN LIVING ROOTS Winter wheat ensures there are living roots in the soil during winter and spring months.
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