Bioavailability and phytotoxicity of clomazone to corn depend on soil characteristics and can be estimated by in situ pore water

BACKGROUNDThe injury caused by residual herbicides in soils to subsequent crops has been frequently reported and is largely related to soil physicochemical properties. Elucidating the interactions between herbicide toxicity and soil properties could help assess its phytotoxicity based on local soil characteristics. Here, the influence of soil properties on the accumulation and toxicity of clomazone as a model compound to corn was explored to obtain a universal indicator for estimating the toxicity of herbicides against crops.RESULTSThe phytotoxicity of clomazone to corn differed in the five tested soils with the median inhibitory concentration (IC50) values, according to the added concentration, fluctuating between 2.80 and 26.97 mg/kg. The uptake of clomazone by corn was primarily affected by its sorption onto soils and showed a positive correlation with the concentration of clomazone in in situ pore water (CIPW) (R2 ≥ 0.775, P < 0.001). In contrast to results derived from traditional soil clomazone concentrations (Csoil) determined through organic solvent extraction, consistent IC50 values (1.344–1.626 mg/L) were obtained based on CIPW in all five soils with a much lower coefficient of variation.CONCLUSIONSThese findings indicate that measuring the concentration of clomazone in in situ pore water provides a reliable and comparable method for evaluating its bioavailability and phytotoxicity on corn. Using CIPW rather than Csoil as a herbicide indicator is more accurate for assessing its actual phytotoxicity. These results are important for the scientific application of clomazone and the safe production of corn. © 2024 Society of Chemical Industry.