Atributos físicos e carbono orgânico sob diferentes sistemas de cultivo no Cerrado mato-grossense

Abstract

Soil Organic Matter is one of the most important indicators of the quality and sustainability of native and cultivated ecosystems, mainly in tropical regions. Soil organic matter influences soil chemical and physical properties, such as CEC, aggregation, water retention and nutrient supply to plants. This study aimed to evaluate the physical attributes and distribution of organic carbon in soil aggregates under different management. Samples of soil aggregates were collected in layers 0-0.1; 0.1- 0.2 and 0.2-0.3m, in areas without soil disturbance for more than 30 years, with a diversified production system (Soy-Corn+legumes; Rice-polycultures; SoyCorn+brachiaria) in rainfed and irrigated conditions and non-regenerative cultivation systems, without soil disturbance for more than 5 years, and with lower plant diversification (Soy-Cotton and Soy-Corn). In regenerative cultivation systems (irrigated and rainfed), in addition to the deformed samples, undisturbed soil samples were also collected, in the same layers mentioned. The deformed samples were used for chemical and particle size analyses, determination of the weighted average diameter, geometric average diameter, aggregate stability index, and determination of organic carbon content in macro and microaggregates. The undisturbed samples were used to determine soil density and total porosity. Data were analyzed using the Kruskal-Wallis test (three-factor analysis) and t-test (two-factor analysis), with multiple comparisons of factors (p<0.05). Soil density and total soil porosity did not differ in both the rainfed and irrigated systems. The irrigated system had aggregates with larger weighted and geometric mean diameters, and a higher aggregate stability index. The rainfed and irrigated regenerative systems had higher organic carbon contents in macro and microaggregates.