Modification to Imazaquin Degradation in Soil Amended with Farm Manure

Abstract

The effects of two farm manures, bovine manure (BM) and chicken manure (CM), on imazaquin degradation in a sandy loam soil were studied under laboratory conditions. The degradation of imazaquin in BM and CM-amended soil (10% by w/w) was about 2.4 and 1.5 times, respectively, faster than that in unamended soil. Different amendment ratios of BM to soil lead to different degradation rates of imazaquin. However, higher mix ratio did not necessarily increase the degradation, and the optimal active degradation of imazaquin was observed at the approximate mix ratio of 10:1 of soil to BM. Imazaquin degradation rate was enhanced 2∼ 4 times in non-sterilized soil over that in SGI (sterilization by gamma irradiation) soil. In non-sterilized soil, biological mechanisms accounted for 48.7% to 74.6% of imazaquin degradation, which suggested that microbial transformation was the primary pathway for imazaquin degradation in soil. The degradation rate of imazaquin for SSA (sterilization by sodium azide) treatment was 1.33 and 1.26 times, respectively, over that for SA (sterilization by autoclaving) and SGI treatments. Imazaquin degradation half-life (13.2 d) in SGI soil with non-sterilized BM was 3.2 times faster than that in SGI soil without BM. In contrast, the slow degradation rate (0.0173 d−1) was observed in SGI soil with water-extracted nutrients from sterilized BM. The organic matter and water-extracted nutrients from sterilized manure had no effects on imazaquin degradation in soil.