Compartments of organic matter in an Oxisol under different types of no-tillage systems

The objective of this study was to evaluate the changes in soil carbon (C) as well as its fractions of physical (particulate organic carbon associated with minerals), chemical (fulvic and humic acids and humins), and oxidizable (F1, F2, F3, and F4) forms of an Oxisol under no-tillage systems (SPD) under different successions and crop rotations in the Cerrado area. In order to do this, the areas of consolidated SPD (10 to 20 years) under the same soil and climatic conditions were selected in Montividiu (GO), with soybean-corn succession (SSM), soybean-millet succession (SSMt), soybean-millet-bean-cotton rotation (RSMFA), crop-livestock integration (ILP), and a native cerrado (CE) area used as a control treatment In each area, samples were collected at depths of 0.0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.40 m, respectively. The no-tillage system with crop rotation, followed by no-tillage system with crop-livestock integration, were the ones that presented the greatest potential to increase total carbon content in soil, presenting higher C contents of the granulometric, humic, and oxidizable fractions of the soil organic matter (SOM), compared with the other areas of no-tillage systems with succession of the respective evaluated crops. The no-tillage areas with corn and soybean/millet succession systems showed a similar pattern in soil C accumulation, as well as in the compartments of SOM evaluated