Soil, water and nutrients losses in the agroforestry systems in Sobral county, Ceará, Brazil

Abstract

Alternatives to agricultural practice should be better considered in Brazilian semi-arid region. The soil and the environmental conditions associated with intensive cropping practices increase the susceptibility of the erosive processes. In order to test the hypothesis that agroforesty systems reduce soil erosion, the following crop systems were evaluated: agrosilvipastoral (AGP), silvipastoral (SILV), traditional cropping cultivated between 1998 and 1999 (TR98), traditional cropping cultivated between 2002 and 2003 (TR02), forestry reserve 1 (RL1) and forestry reserve 2 (RL2). Soil and water colletors were installed in the areas and were sampled in the rain season of 2003. Water and soil losses and P, Na ,K, Ca, Mg, Fe, Cu, Zn, Mn and organic carbon contens were evaluated. The results showed the highest losses in the forestry reserve 1(RL1) and TR98 areas, respectively. Considering Agroforestry and conventional systems, the highest soil and/or water losses were observed in the systems that promoted higher soil mobilization as AGP, TR98, and CI systems. The contents of total nutrients and organic carbon losses were proportional to the soil and water losses.