Short-term effects of winter cover crops and summer cash crops on soil properties in Ultisol under no-tillage system in Southern Brazil

Growing winter cover crops in rotation with summer cash crops in a no-tillage (NT) system improves soil's physical and chemical properties. However, the short-term effects of cover crops on sandy soils in subtropical climates remain poorly understood. A two-year study investigated how winter cover crops and summer cash crops (corn - Zea mays and soybean - Glycine Max) affect Ultisol physical and chemical properties under NT in Southern Brazil. A corn and soybean production system was established with fallow and three winter cover crops: black oat (Avena strigosa), vetch (Vicia sativa), and forage radish (Raphanus sativus). The study analyzed crop yield and selected soil physical properties (soil density, total porosity, macroporosity, microporosity and water infiltration rate) and chemical properties (soil water pH; Ca-Mg-K saturation; Al saturation; exchangeable Ca and Mg; available P and K; effective CEC; CECpH7.0; and potential acidity). Cover crops did not affect corn and soybean yields in relation to the fallow system. Soil macroporosity in the 0-10 cm layer was 34 % greater in soybean subplots than in corn subplots. Corn cultivation resulted in higher soil pHH2O, Ca-Mg-K saturation, and lower Al saturation in the 20-40 cm layer compared to soybean, indicating lower soil acidification. Winter cover crops, especially forage radish, reduced soil acidification, and increased soil Ca and K contents, whereas winter fallowing increased soil acidity by 86 % and reduced overall soil fertility. These results indicate that cover crops play a key role in no-tillage production systems, improving soil fertility and reducing soil acidity.