Water, Sediment and Nutrient Retention in Native Vegetative Filter Strips of Southern Brazil

Abstract

Vegetative filter strips (VFS) are areas adjacent to watercourses with the purpose of reducing sediment and nutrients contained within runoff water from cropland. The aim of this study was to evaluate the retention of water, sediment and nutrients in VFSs with 5, 10, 20 and 30 m widths exposed to simulated runoff water. The VFS chosen for this study were populated by native herbaceous vegetation with a predominance of grasses from South of Brazil. To simulate runoff water, a flow of 30 L min-1 was applied to all plots. Simulated runoff water contained 3.22 g L-1 of sediment and the nutrients concentration was 62.2; 40.9 and 170.3 mg L-1 de P, NH4-N and NO3-N, respectively. As expected, we found the VFS (30 m) could retain a greater quantity of nutrients (>80%), water (66%) and sediment (84%). However, we found the VFS (of width 10 m) was the most efficient when considering area against nutrient (>70%), water (42%) and sediment (73%) retention. With a ever expanding human population and intensive land use in Brazil, efficient use of VFSs could reduce water pollution from agriculture field.