Disponibilidade de nutrientes e atividade enzimática do solo em sistemas integrados de produção agropecuária em terras baixas

Abstract

Systems that provide the maintenance of organic matter are directly linked to the availability of nutrients for crops, as they affect the chemical, physical and biological parameters of the soil. Nitrogen is the element that is most influenced by the adopted production system. Due to the complex dynamics of this nutrient in flooded soils, it is necessary to know the changes that integrated production systems imply in the availability of N in these soils. Faced with this problem, the hypotheses are: integrated agricultural production systems that include rice and animal production promote the biological quality of a soil when compared to rice monoculture systems; microbial biomass is responsible for storing part of the N in soybean-irrigated rice rotation systems and that irrigated rice cultivation systems affect the chemical and microbial attributes of lowland soils. The general objective of this study is to characterize chemical and microbial attributes of lowland soils under integrated agricultural production systems. An experiment designed in randomized blocks with three replications, where five treatments were tested: S1 – control (fallow rice, without animal presence); S2 – succession with low diversity (grazed rice-ryegrass); S3 – rotation with moderate diversity (rice – grazed ryegrass – soybeans – grazed ryegrass – rice); S4 - rotation with high diversity (rice – ryegrass + grazed white clover – grazed Sudan grass – ryegrass + grazed white clover – soybeans – ryegrass + grazed white clover – corn – ryegrass + grazed white clover – rice); S5 – Low diversity rotation: Rice – ryegrass + white clover + grazed cornichão – grazed succession field – ryegrass + white clover + grazed cornichão – grazed succession field – ryegrass + white clover + grazed cornichão – grazed succession field – ryegrass + white clover + grazed cornichão – rice). The results demonstrated that systems that include leguminous cover crops in addition to soybeans have a greater capacity to store potentially mineralizable nitrogen, becoming a contribution to rice cultivation.