Rill erosion in biochar amended soils

Abstract

Although the increasing interest in biochar as a soil amendment, its antierosive effectiveness is still uncertain. In fact, some investigations demonstrated that biochar positively influences soil erosion, infiltration, and runoff, while others reported that, depending on its origin and/or concentration, it enhances runoff and soil erosion. In this study, plot measurements were performed on two rills incised in a soil amended with an initial biochar concentration in weight of 3% (rill bio3) and 5% (rill bio5) to evaluate its antierosive effect. Specifically, for each rill, the total volume of the eroded mixture (sediment+biochar) was measured using the DoD (DEM of difference), and the biochar and sediment percentages were determined from the measurements of the outflow mixture discharge at three different times during the run. The comparison between the DoDs highlighted that the mixture volume for the bio5 rill (6.3 L) is lower than that for the bio3 one (7.0 L), and, therefore, the higher initial biochar concentration reduced the erosive phenomenon. Moreover, the analysis of the measurements pointed out that the biochar rate on the bio5 rill mixture (32.8%) is higher than that related to the bio3 rill (22.7%). Finally, the treatment with the higher biochar initial concentration decreases the overall erosive phenomenon and produces a higher biochar percentage in the mixture. These combined effects result in a 1.2 L reduction in sediment volume for the bio5 rill compared to that for the bio3 rill.