Effect of the evolutionary stage of voçorocas on soil erosion in the atlantic forest biome, in Pinheiral – RJ

Abstract

Erosion causes damage to crops, soil, siltation and pollution of river basins. Thus, the objective was to evaluate the loss of nutrients and soil in different evolutionary stages of gullies in the Ribeirão Cachimbal watershed, Pinheiral - RJ. The gullies were morphologically classified into initial, juvenile, mature and senile. Deformed and undeformed samples were collected at a depth of 0.00-0.10 m on the inner face of each gully. Analyzes were carried out to evaluate fertility, total organic carbon (TOC), soil density (Ds) and granulometry. A systematic flight using a drone was carried out over the gullies to estimate their respective areas, in May 2017. Based on the results of chemical and physical attributes and gully dimensions, the amounts of soil mass and nutrients removed were calculated. The highest values of area, volume, Ds and soil mass removed were quantified in the senile stage gully (1069.23 m², 1709.35 m³, 1.28 Mg m³ and 2187.97 Mg, respectively). The highest removed values of Ca²⁺ (46.22 kg) and TOC (482.18 kg) were observed in the senile gully, while those of Mg²⁺ (15.09 kg) in the juvenile gully and K⁺ and Na⁺ in the initial gully (3.96 and 3.77 kg, respectively).