Carbono orgânico do solo e estabilidade de agregados em latossolo sob diferentes usos no Cerrado, MG

Abstract

Inadequate soil management systems reduce aggregate stability, compromising soil organic carbon, soil structure, agricultural productivity, and environmental balance. The objective of this study was to evaluate the stability of aggregates under different cropping systems and soil depths, and to relate this stability to the total organic carbon (TOC) content of Oxisols in the Cerrado biome. The land use types were considered treatments, and soil samples were collected from a farm in the rural area of Uberlândia, Minas Gerais, Brazil, under the following four management systems: (i) native Cerrado vegetation (T1); (ii) a no-tillage system (T2); (iii) conventional tillage system (T3); and (iv) an irrigated grain cropping system (T4). Samples were collected at four depths (0–10, 10–20, 20–40, and 40–60 cm), with four replicates in each system. Four trenches were dug to the targeted depths for sampling. The samples were analyzed for aggregate stability and the aggregate stability index (ASI). The aggregate fractions were examined based on the mesh size of the sieves used (2 mm, 1 mm, 0.5 mm, and 0.25 mm). Additionally, the total organic carbon (TOC) content was determined for each aggregate class. The results were analyzed using an analysis of variance, and the means were compared using Dunnett’s test and Pearson’s correlation. The no-tillage system produced the best results in terms of aggregate stability and TOC levels, surpassing even the native Cerrado in some layers. These results underscore the importance of maintaining vegetation cover and avoiding soil disturbance in order to preserve the soil´s physical and chemical quality. Among intensive systems, conventional tillage caused less degradation than central pivot irrigation. TOC proved to be a good indicator of soil quality, but it should be interpreted alongside other attributes. Conservation practices are essential for the sustainability of Oxisols in the Cerrado.