Desorption of atrazine in biochar-amended soils: Effects of root exudates and the aging interactions between biochar and soil

The effects of wheat root exudates and the aging interactions between biochar and soil on atrazine desorption from biochar-amended soil were carefully examined. Compared with CaCl2 solution, wheat root exudates significantly increase the desorption of atrazine from biochar, mainly by promoting the desorption of atrazine adsorbed on biochar with specific forces. Wheat root exudates were effectively separated into three components with different electrical properties, namely, anionic, neutral, and cationic components. Mainly due to the carboxyl-containing compounds, the anionic component was the main active component in the wheat root exudates that enhances the desorption of atrazine from the biochar. Additionally, wheat root exudates can increase the desorption of atrazine from biochar-amended soil. The promotion of atrazine desorption by root exudates was more obvious in soils with low organic matter contents, where atrazine was mainly adsorbed by biochar. The aging interaction between the biochar and soil increased the total desorption rate and rapid desorbing fraction of the atrazine in the soil, most likely due to the reduction of the biochar sorption capacity in the aged biochar-amended soil.