Abstract
ABSTRACT The soil is an important component in the biogeochemical cycling of carbon (C) and nitrogen (N). The objective of this study was to evaluate the changes caused by different types of land use on the C and N stocks in areas of Cerrado at different depths: area under conventional tillage, no-tillage, grazing, eucalyptus and area under native vegetation of Cerrado in the municipality of Luis Eduardo Magalhães, BA, Brazil. The highest C content was found for no-tillage area in the surface layer up to 10 cm; however, there was a decrease in its content along the depths. Areas under no-tillage had lower values of C in the surface layer (0-5 cm) and below 20 cm. Among these, C stocks were significantly lower compared to the use of grass and eucalyptus at the depth of up to 40 cm. Considering the depth of 0-60 cm, the highest C stock was found in areas under native vegetation, 62.81 Mg ha-1, followed by the area under cultivation with eucalyptus, 60.70 Mg ha-1. The lowest C stocks were found in areas under conventional use, 44.87 Mg ha-1. Conventional planting reduced N stocks by up to 61 and 56% when compared to areas under native Cerrado vegetation and eucalyptus plantations, respectively, both at a depth of up to 10 cm. Therefore, land use practices such as eucalyptus cultivation and no-tillage contribute to C and N storage over time.
Highlights
Changes in land use caused by anthropic action have the effect of altering the dynamics of soil organic matter (SOM) and, of carbon (C) and nitrogen (N) stocks, when native areas are converted to agricultural systems (Frazão et al, 2010)
It was found that no-tillage cultivation resulted in a significant difference in the total C content at the surface depth of up to 5 cm, compared to conventional cultivation, pasture and eucalyptus (Figure 1A)
It was observed that no-tillage did not significantly increase the C content at depths below 10 cm compared to areas under eucalyptus cultivation and native Cerrado vegetation, and the low C content is associated with the short time of adoption of no-tillage, which was only 4 years, since C accumulation occurs slowly, taking more than 10 years to become significant (Carvalho et al, 2009; Guareschi et al, 2014)
Summary
Changes in land use caused by anthropic action have the effect of altering the dynamics of soil organic matter (SOM) and, of carbon (C) and nitrogen (N) stocks, when native areas are converted to agricultural systems (Frazão et al, 2010). Associated with inadequate management practices, this effect causes degradation and reduction in agricultural yield (Guareschi et al, 2012; 2014; Costa et al, 2015). In view of this scenario, the adoption of conservation measures for land management and use promotes greater soil conservation, and organic matter residues provide numerous benefits for the soil-plant system, being essential in low-C agriculture (Costa et al, 2015). Research results have shown that soils under eucalyptus plantations can increase C and N stocks when adequately managed (Tchienkoua & Zeach, 2004)
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