Impactos da substituição da vegetação original do Cerrado brasileiro em sistemas agrícolas: alteração do carbono orgânico do solo e d13C

Abstract

The Brazilian savannah (cerrado) is an area of expansion of agribusiness. Among the various environmental changes related to deforestation of the savannah stand out impacts related to soil organic matter such as the imbalances in stocks and the changing nature of soil organic carbon. The objective of these study was to evaluate changes in nature (δ13C) and quantity (C%) of soil carbon after conversion of the dense savannah vegetation in areas under different lan duses (pasture, soybeans, corn / soybean rotation), management (conventional and zero tillage) developed in soils with different textural characteristics. The results showed that the average data set of non-managed grazing was the most distanced from the value obtained in cerrado soil. Another factor that determined the lowest concentrations of organic carbon was the presence of sandy soil. The results showed that the carbon C4 grasses in areas occupied by pastures, with or without management, replaced the original C3 carbon originated by cerrado. In the areas of conventional tillage, and no-tillage soybean, and consortium soybean/corn, no clear trend of impoverishment or enrichment of carbon and the carbon substitution as well as the incorporation of different nature of the carbon could be found.

Keywords

• brazilian savannah
• total carbon
• carbon isotope
• agricultural systems