Water erosion in a long-term soil management experiment with a humic cambisol

Abstract

Water erosion, the main factor in soil degradation, is strongly influenced by soil cover and management. The objective of this study was to determine soil and water losses under natural rainfall conditions from 1993 to 2012 in the southern Santa Catarina Plateau, Brazil, in 3.5 × 22.1 m plots with crops in rotation to study the following management treatments: conventional tillage (CT), minimum tillage (MT), and no-tillage (NT), and a treatment with bare soil (BS). The soil cover remaining after tillage was negatively affected by the increase in soil tillage intensity. Soil losses were strongly affected by the management system, while water losses were less affected. Soil losses were 85.29, 6.41, 2.00, and 0.82 Mg ha-1 yr-1 in the BS, CT, MT, and NT treatments, respectively, while water losses were 38, 24, 15, and 9 % of the rainfall, respectively, in the annual mean. Soil losses in spring/summer were similar to those of autumn/winter in the CT, MT, and NT treatments, while water losses were influenced by the time of year in all soil management systems. The accumulated soil losses in the MT and NT treatments tended to stabilize over the period evaluated, whereas they increased an average of 88.12 Mg ha-1 yr-1 in the BS and 7.23 Mg ha-1 yr-1 in the CT treatments. The accumulated water losses had a linear response, with positive angular coefficients for all treatments. The relationship between annual soil and water loss data was significant in the BS treatment; in the CT, MT, and NT treatments, this relation was not significant.