Modulating Leaching of Mesosulfuron Methyl, Iodosulfuron Methyl and Transformation Products: Effects of Rainfall Intensity, Flow Patterns and Organic Amendments.

In light of the environmental pollution risks, the effect of rainfall and flow conditions and addition of farmyard manure on leaching potential of mesosulfuron, iodosulfuron methyl and their transformation products (TPs) was evaluated. Leaching was higher under 300 mm rainfall compared to 150 mm. Discontinuous flow conditions led to lower residues of the parent herbicides but higher concentrations of their TPs. Among different TPs, mesosulfuron (M1), 2-[3-(4-hydroxy-6-methoxy pyrimidin-2-yl) ureido sulfonyl]- 4 - methane sulfonamido methyl benzoate (M2), metsulfuron methyl (I1) and methyl-2-(amino-sulfonyl) benzoate (I2) was detected. M2 has the highest mobility followed by M1 and I1 suggesting highest potential contamination risk of M2 to lower soil profiles and groundwater. Addition of farmyard manure to soil reduced leachability of both parent herbicides and TPs, highlighting its potential to mitigate groundwater contamination and providing a sustainable approach to minimizing herbicide pollution. However, future studies are required to assess the effect of various organic matter amendments on the leaching of herbicides.