Chemical characterization of soil organic matter in differents management practices in the Cerrado-Pantanal ecotone

Different land uses and occupations have a direct impact on edaphic attributes, which can be identified by soil quality indicators, with organic matter being an excellent edaphic quality indicator. The objective of the work was to chemically characterize soil organic matter (SOM) in different management systems in the municipality of Aquidauana, Mato Grosso do Sul, Brazil. Soil samples were collected in five areas with different management practices, in addition to an area of native Cerrado forest (NF), and the managed areas were: exposed soil (ES), conventional tillage system (CTS), no-tillage (NTS), permanent pasture (PP) and sugarcane (SC). In addition to the determination of bulk density (Bd), total organic carbon (TOC) contents and stocks were quantified, as well as carbon (C) contents and stocks of the humified fractions: humic acid (AH), fulvic acid (AF) and humin (HUM), with subsequent calculation of HA/FA and alkaline extract/humin (AE/HUM) and TOC stratification index (SI). There were no significant changes for Ds after six years of implementation of management systems. TOC levels and stocks were higher in PP and NTS areas. The HUM fraction was predominant, with higher contents and stocks of all fractions for the PP and NTS areas, demonstrating the greater intensity of the humification process in these management systems, with greater stability of C in the soil after six years of experiment. The PCA indicated a difference between the areas that present conservation practices in the ES and CTS areas. The NF, NTS, PP and SC areas contribute to SOM stabilization.