Fractions of soil organic matter under pasture, tillage system and crop-livestock integration

The aim of this study was to evaluate the total organic carbon and the chemical (humic acid - FAH, fulvic acid - FAF, humin - Hum) and textural (organic carbon associated particles - COp, organic carbon associated with minerals - COam and carbon management index - IMC) of soil organic matter (SOM) in samples of an Oxisol under no-tillage (NT) with crop-livestock integration (ILP), compared to one NT area without ILP and areas of natural Cerrado (CE) and pasture (PA) in southwestern Goias. Soil samples were collected in the 0-5, 5-10, 10-20 and 20-40 cm in a completely randomized design. Among the cultivated areas the ILP presented in the upper soil layers the highest COT, COp, COam, Hum C-FAH/C-FAF and respect, having been checked in COT, COp, and COam Hum similar to those quantified in CE area in the deeper layers of the soil. In some depths evaluated, areas of NT and ILP had higher IMC compared to PA area. Areas of NT and PA showed no statistical difference in the COT, COam and C-FAH/C-FAF relationship, however, the NT area proved to be forwarding to greater stability of SOM, as it showed similarities in levels C of Hum, FAH, COp and IMC in relation to areas of CE and ILP in some depths evaluated.