Winter cover crops impact on soybean yield and quality in Mississippi Delta

Abstract Cover crops (CCs) improve soil quality, nutrient cycling and main crop yield. However, the benefits vary by CCs, main crops, soils, and climates. For the adoption of CC in cropping systems, it is crucial to identify the CC mix that enhances crop yield, quality and soil sustainability. Therefore, we evaluated the effects of a winter grass mix (GM), a legume mix (LM), and their combination (GM + LM) CCs on soybean ( Glycine max L.) yield and seed quality. The study was a randomized complete block design with four replications. CCs were planted in winter, terminated in spring, followed by soybean planting in 2022 and 2023. Seed yields were measured at harvest, and seed samples were analyzed for quality: protein, oil, fatty acids, and sugars and nutrient compositions. Overall, the incorporation of winter-mix CCs into soybean production resulted in a 3–14% yield reduction compared to winter-fallow. However, LM CCs produced 7–10% higher yields than GM CCs and had superior nutrient uptake capabilities. Soybean seed fiber, oil, and protein content remained unaffected by CC treatments while variations in fatty and amino acid contents were noted among CC treatments and years. The GM treatments resulted in higher phosphorus, magnesium, iron, and manganese content in soybean seeds compared to fallow. In the two-year study, soybean seed yield declined under CC treatments, but LM provided higher yield and better seed quality than GM. Further research across soybean varieties, soils, and climates is needed to quantify and recommend suitable CC mixes for seed yield and quality in the region.