Mixture of winter cover crops improves soil physical properties under no-tillage system in a subtropical environment

The monocrop of winter cover crops is a common practice under no-tillage system (NTS) in subtropical environment but increase diversity of cover crop species can be an alternative to improve soil physical quality, with positive effects on crop production. This study evaluated whether using a greater diversity of cover crop species affects soil physical properties, as well as grain yield of soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.) under NTS in three growing seasons. The experimental design was in randomized blocks with four replications. The treatments were monocrop of black oat (Avena strigosa Schreb.); intercropping of black oat and turnip (Brassica napus L.); and a mixture of black oat, turnip, white oat (Avena sativa L.), rye (Secale cereale L.), white lupine (Lupinus albus L.), and common vetch (Vicia sativa L.). Cover crop biomass yield, soil physical properties, and grain yield of summer crops were evaluated. Using a mixture of cover crops improved soil physical properties by decreasing soil bulk density up to 5 %, increasing soil air-filled porosity at -100 hPa (0.0-0.2 m) up to 27 % and saturated hydraulic conductivity (0.0-0.2 m) up to 300 %. Common bean grain yield and 1000-grain weight in succession to the mixture of cover crops increased by 15 % and 4 %, respectively. Soybean yield components were not affected by treatments. The increased diversity of winter cover crops improved soil physical properties in relation to monocrop in NTS, as well as improved crop yield of common bean, which is a shallower root growth specie, more sensitive to soil constraints.