Plant diversity and cattle grazing affecting soil and crop yield in tropical sandy soils

The use of cover crops and increased plant diversity in agricultural systems can improve soil quality. The objectives of this study were to evaluate the short-term impacts of plant functional diversity and cattle grazing on: (i) soil organic C and N stocks and their fractions, (ii) soil microbial biomass and activity, (iii) enzymatic activity, and (iv) soybean yield in sandy soils of the Brazilian Cerrado. The experiment consisted of four systems, with soybean as first crop followed by: (i) fallow (Very low diversity); (ii) single grass as cover crop (Low diversity); (iii) MIX with palisade grass intercropped with Niger, turnip rape, crotalaria, and estilosantes as cover crops (Medium diversity); and (iv) MIX under cattle grazing (High diversity). The High diversity system had the higher soil total N stock (1.32 Mg ha(-1)), and a microbial biomass C, microbial quotient, and soybean yield 146%, 147%, and 20% higher than the other systems. The increase in soil microbial biomass and enzymatic activity accounted for the higher soybean yields in the systems. These results demonstrate the potential for soil quality improvements and soybean yield with greater functional plant diversity and cattle grazing in sandy soils of the Brazilian Cerrado.