Effects of land-use change on chemical attributes of a Ferralsol in Brazilian Cerrado

Abstract

The expansion of agriculture in the Brazilian Cerrado biome occurs at the expense of replacing native forest with pasture and/or crops. Negative environmental impacts, such as soil degradation, have been observed during this process. We aimed to evaluate the effect of different agricultural management systems on chemical attributes and soil organic matter fractions of a Ferralsol in an area of Cerrado, in the municipality of Hidrolândia, Goiás, Brazil. The following management systems were evaluated: (a) pasture (PAST), (b) no-tillage system (NT), organic cultivation (ORG) systems with different years of cultivation (2, 6, 8, and 10 years), and (c) a conventional management system (CS). Further, an area under native Cerrado forest (NF) was selected and used as a reference for steady state. Soil cores were collected at 0.0–0.10, 0.10–0.20, and 0.20–0.40 m depths. Macronutrients, total organic C (TOC), particulate organic C (POC), humic substances, and labile-C (Lab-C) were analyzed. The land-use change effect, driven by deforestation with subsequent pasture and/or crop, was evident by principal component (PC) analysis. In the 0.0–0.10 m soil layer, PC2 showed the isolation of NF from agricultural systems, whereas PC1 exhibited similar phenomena for the 0.10–0.20 and 0.20–0.40 m layers. In all cases, the agricultural systems showed weak correlation to TOC, POC, Lab-C and base saturation, suggesting loss of soil chemical fertility compared to NF. The ORG-8 area differed from other managed systems mainly due to high pH, P content, and base saturation. Soil cation exchange capacity was highly correlated to variables associated with soil organic matter, such as TOC, POC, and Lab-C. This result demonstrates that Cerrado soils are highly dependent on soil organic C dynamics. Conversion of Cerrado into agricultural land decreases soil chemical fertility. However, agroecosystems that reduce soil tillage and increase organic inputs, such as organic cultivation and no-tillage, seem to be suitable options for agricultural activity in Brazilian Cerrado.