Assessing influences of farmyard manure addition, elevated CO2, soil sterilization, soil types, and soil moisture on clothianidin dissipation kinetics

Abstract

Aim: To investigate the effects of farmyard manure addition, elevated CO2, soil sterilization, dry conditions, field-capacity conditions, and submerged conditions on clothianidin dissipation from the soil, as well as the effects of different pH levels, namely, pH 4.0, 7.0, and 9.2, on its dissipation from the aqueous solutions. Methodology: Samples were processed by the QuEChERS method from the soil and the dipping and shaking method from the aqueous solution, and then analyzed by Shimadzu HPLC-PDA. Results: The results revealed that clothianidin dissipation from soil and aqueous solution best fit first-order kinetics, with the coefficient of determination r2 value < 0.90. In the soil, varying clothianidin dissipation was recorded with significant impact and their decreasing dissipation rate was as follows: submerged conditions (t1/2103.7–107.5 days) > elevated CO2 (t1/2115.7–143.3 days) > farmyard manure addition (t1/2130.8–150.5 days) > field-capacity conditions (t1/2158.4–215.0 days) > dry conditions (t1/2250.8–334.4 days) > soil sterilization (t1/2342.0–376.2 days). In the aqueous solution, clothianidin dissipation was slow at pH 4.0 (t1/2430 days) but fast at pH 9.2 (t1/2273.6 d days). Interpretation: The findings suggest that clothianidin dissipation could be positively affected by FYM addition, elevated CO2, soil sterilization, dry conditions, field-capacity conditions, submerged conditions, and aqueous pH level in all the treatments. This information would help gain a better understanding of clothianidin dissipation in the environment for good agricultural practices,proper risk assessment, and monitoring guidelines. Key words: Aerobic-anaerobic degradation, Microbial activity, Organic carbon content, Persistence half-life period