Evolution of the soil organic matter content after 15 years of crop livestock system.

Soil organic matter (SOM) is sensitive to changes in land use and is a key indicator of soil quality. This work evaluates the evolution of the organic matter of an oxisol under a crop-livestock integration system (CLS) installed in 2005 and located in the Cerrado Biome, in Sete Lagoas, Brazil. The CLS system consists of four plots of 5.5 ha each, which in the spring/summer were cultivated in annual rotation with the crops of soybean+intercropping Urochloa, corn+Urochloa consortium, sorghum+Megathyrsus consortium and Megathyrsus pasture. In autumn/winter, after crops? harvesting, succession pasture was used with beef cattle grazing. An area of native savanna (?cerrado?), above the experimental site, is used as a reference site. The organic matter content was measured by the method of wet digestion. The SOM values under CLS showed a tendency to approach the soil under native Cerrado. There was no significant difference in the global average levels and the analysis of the time series shows a general trend of increasing values under the CLS. There was a stability of SOM after 2012, with an average value of 4%.