The Effects of Biochar-Amended Tropical Soils on Herbicide Pollution: Column Leaching Studies

Absorption of Herbicides in Biochar-Amended Tropical Soils

Abstract

Biochar is a carbon-rich material that can be used to improve soil quality and reduce herbicide leaching. This study investigated the use of biochar to reduce the leaching of two herbicides, atrazine and diuron, from tropical soils in Belize. Column leaching experiments were conducted following the OECD 312 guidelines. Three different soil types were sampled from agricultural sites in Belize and amended with 2.5% (w/w) rice husk biochar. Extreme rainfall events were simulated to present a worst-case scenario of herbicide leaching event. The results showed that the application of biochar to both loam and sandy silt loam soils reduced the leaching of both atrazine and diuron. The column leaching linear Kd (m3/kg) of atrazine in biochar amended loam was 0.15 and for biochar amended sandy silt loam was 0.8. Leachate analysis showed that samples collected from the biochar-amended soils had a much lower herbicide concentration than soils that were not amended with biochar. These results suggest that tropical soils amended with 2.5% rice husk biochar can reduce the leaching of atrazine and diuron, thus protecting human health and the natural environment from water contamination.