Sediment transport in runoff on rugous soil surface submitted to simulated rainfall

Abstract

Soil management influences water erosion and sediment size in runoff. With the objective of quantifying sediments in runoff and their relation to runoff velocity (Rv), random roughness (RR), and Ir index, this experiment was carried out from 2003 to 2006, on a typical Hapludox with the following soil management systems submitted to chiseling: i) bare soil with plowing+two disking tillage (BSC); ii) plowing+two disking tillage (CTC); iii) no tillage with crop residues burned (BNTC); and iv) traditional notillage (TNTC). CTC, BNTC and TNTC treatments were cultivated with crop rotation and the BSC treatment was not cultivated. Five simulated rainfall tests were applied, with intensity of 64 mm h-1 and duration of 20, 30, 40, 50 and 60 min. RR was influenced by the residual effect of soil management and by simulated rainfall, and affected the Rv in the three initial rainfall tests. Sediments carried by runoff were influenced by soil management and by simulated rainfall. Most of the sediments were in the size range from 0.5 to > 2 mm, with a higher quantity of fine sediment in BNTC and TNTC treatments than in the other treatments. The D50 index of sediments changed with soil management system and with rainfall tests, decreasing with the increase of the RR and increasing with the increment of Rv and Ir index.