Interaction effects of eucalyptus biochar and chlorantraniliprole on soil carbon mineralization under different soil moistures

Biochar can provide beneficial organic matter and habitat for microorganisms in soils polluted with insecticides, potentially mitigating some of the adverse effects on microbial activity.This study aimed to assess the effectiveness of eucalyptus feedstock biochar in remediation of a clayey soil polluted with chlorantraniliprole (CAP) under laboratory conditions through the determination of microorganism activity.The CAP as commercial formulation at recommended dose and tenfold dose (C1 and C10), eucalyptus biochar (produced at 550 C) at 0.5% and 1% (B05 and B1) and their combinations (B05+C1, B05+C10, B1+C1 and B1+C10) were applied on a clayey soil while control treatment has neither biochar nor insecticide application.Soil C mineralization (Cm) was monitored for 46 d at a constant temperature (28 C) under two soil moisture conditions: 50% (50FC) and 80% (80FC) field capacity.Treatments B05, B1, C1, and C10 decreased Cm by for 3.5%, 5.5%, 8.4%, and 14.1% under 50FC and for 3.2%, 6.0%, 7.9%, and 14.6% under 80FC compared to control without biochar and insecticide (P < 0.05).However, co-application of eucalyptus biochar mitigated the negative effects of CAP for more than 4% on Cm.B05+C10 significantly decreased C mineralization compared to B05 and B05+C1 while B1+C10 was significantly lower than B1 but higher than C10 (P < 0.05).Treatments CAP and biochar alone and their combinations significantly decreased Cm compared to control in this study but it is suggested that eucalyptus biochar might have mitigated the negative effects of CAP on Cm by forming complexes with labile organic matter.