FERTILITY AND TOTAL ORGANIC CARBON IN OXISOL UNDER DIFFERENT MANAGEMENT SYSTEMS IN SAVANNAH OF PIAUÍ, BRAZIL

Abstract

The intensive use of natural resources for food production has ruptured the sustainability of agro-ecosystems. In this context, this study aimed to quantify chemical attributes of Oxisol under five management systems: 1 = conventional tillage (CT); 2 = no-tillage system with millet (NT + M); 3 = crop–livestock integration system with soybean (CL + S); 4 = CL with pasture (CL + P); and 5 = native forest (NF). The following soil depths were studied: 0.00–0.05, 0.05–0.10, and 0.10–0.20 m; and the following traits were quantified: total organic carbon (TOC), soil acidity (pH), soil potential acidity (H + Al) and soil fertility (Ca, Mg, P and K). All treatments modified soil chemical attributes in comparison to NF (p <0.01). The highest phosphorus and potassium levels were observed under CL + S at all evaluated depths. The NT + M treatment increased Ca and Mg levels in layers 0.0–0.05 and 0.10–0.20, whereas CL + S increased base addition (BA), cation exchange capacity (CEC) and  base saturation (BS) levels in layer 0.05–0.10 m. Finally, both CL systems improved soil chemical quality, increased surface TOC and carbon stock in depth.