Although conservation tillage has many benefits on soil and water quality, some farmers are hesitant to adopt this practice due to concerns about potential yield reductions. One obstacle to planting soybeans into heavy corn residue is the potential for slower early growth and yield reductions compared to soybeans planted in conventionally tilled fields. Crop germination, emergence, and growth are primarily regulated by soil temperature, moisture, and nutrient availability to roots.

While fine-textured Mollisols generally have plenty OM that mineralizes and provides N and S to crops, it also tends to keep soils cooler and wetter early in the spring and around planting time. This can limit mineralization, which in turn limits early-season N and S availability to seedlings. Similarly, a lower early-season N and S availability is also expected in coarse-textured soils with low organic matter, such as Alfisols, that are commonly found in southern Illinois. Applying starter fertilizer is a potential practice to address this issue, but more research is needed in Illinois conditions.

Row spacing is also an important practice in intensive management systems. Many studies have shown yield benefits when using narrow rows compared to 30-inch rows. Key benefits of narrow rows include early canopy closure that enables more light interception to drive photosynthesis, weed control, and reduced erosion.

We initiated this project last fall to generate research-based data to optimize soybean production in conservation tillage while conserving natural resources and enhancing environmental sustainability.

The specific objectives are to 1) understand the mechanisms driving soybean growth and yield in conservation tillage systems (i.e., soil temperature, immobilization of N and S, delayed soybean development and nodulation/fixation), 2) evaluate the impacts of starter fertilization and row spacing on soybean nutrient uptake, seed yield, and seed quality, and 3) identify best management practices that optimize soybean production under conservation tillage.

By assessing improved fertilizer management in conservation tillage systems, this project aligns with the priority area of soybean production. The findings of this project will 1) provide insight into the mechanisms contributing to slower growth and reduced yield in conservation cropping systems in Illinois, (2) it will advance our understanding of the role of N and S fertilizer management under these systems.

This project will provide much-needed, practical information to help growers and stakeholders maintain or improve soybean yield and quality, resulting in more sustainable and resilient production systems.