Biochar Alters the Degradation and Transport of Kasugamycin in Soil and Spinach

Abstract

Biochar has been widely studied to reduce multiple contaminant sources in one matrix (e.g., several heavy metals in soils), yet less attention has been paid to accelerating pesticide degradation while in the presence of any heavy metals, such as when kasugamycin (KSM) and cadmium (Cd) are both present in soil. KSM has a low toxicity compared to other pesticides, yet can be a potential health risk when applied to vegetable crops. The degradation behavior of KSM (100 g ha-1), in the presence of Cd (20 mg kg-1) and biochar (5% by wt.), when growing spinach (Spinacia oleracea), was studied. Biochar increased spinach shoot and root biomass by 51.0%-54.8% and 24.4%-39.0% compared to the KSM treatment only. As compared to treatments that did not receive biochar, biochar application promoted KSM degradation in soil by 8.4-68.4%, and subsequently less KSM was sorbed by spinach roots (18.0-48.4%) and shoots (33.0-33.2%). The KSM degradation rate, with soil depth, was enhanced in the presence of Cd. Biochar also effectively decreased KSM concentration with soil depth, reducing downward KSM migration. KSM degradation, promoted by biochar, led to smaller organic moieties and some macromolecular organic phases. In soils that are contaminated with Cd and where vegetables are raised, it appears that biochar can be used as an environmentally-friendly proponent for promoting KSM degradation, reducing KSM downward transport, and thus protecting environmental and human health.

Keywords: Biochar, degradation, downward migration, Kasugamycin, soil