Dynamics of Metolachlor in Sandy Clay Loam Soil and Its Residues in Maize and Soybean Janaki P.*, Meena S., Chinnusamy C. AICRP-WC, Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, 641003, Tamil Nadu, India *email: janakibalamurugan@rediffmail.com
Online published on 13 January, 2016. Abstract Metolachlor, a chloracetanilide herbicide used for weed control in a variety of crops including maize, cotton and soybean. Metolachlor is commonly found in surface and groundwater when this product is used. Considering the importance, this study was aimed to evaluate the dynamics of metolachlor in soil of tropical environment under soybean and maize and its terminal residues in crop produce. In the present field study, two rates of metolachlor application was studied and found that the metolachlor residues were persisting in soil up to harvest irrespective of dose and crops. No residues were detected in the grain and stalk/straw of the maize and soybean at the time of harvest. Field dissipation followed first-order kinetics and the dissipation was faster in soil under soybean than maize with the half life of 16 and 18 days respectively. In laboratory leaching experiment, 43–45% of the applied metolachlor was recovered from the upper surface of 0–5 cm depth and found that its mobility in the sandy clay loam soil was moderate. Metolachlor sorption fits the freundlich isotherm well with the Kf value of 1.54 and its sorption depends on soil organic carbon with the Kk value of 398 mL/g. The desorption of metolachlor is close to sorption, and has the hysteresis coefficient of 0.905 in the sandy clay loam soil. Top Keywords Metolachlor, sorption, leaching, persistence, soybean, maize. Top |