Sorption–Desorption of Rimsulfuron, Nicosulfuron, and Metabolites in Soils from Argentina and the USA

Abstract

Sulfonylurea herbicides provide broad‐spectrum weed control in a variety of crops. To better understand the potential mobility of these compounds and their metabolites in soil, sorption–desorption studies were conducted using 14C‐labeled compounds: rimsulfuron and its metabolites IN‐E9260, IN‐70941, and IN‐70942; nicosulfuron and its metabolites IN‐HYY21 and IN‐GDC42. Soils were collected from two depths in the upper slope, backslope, and lower slope of landforms in La Pampa, Argentina, and Minnesota, USA. Soil‐water partition coefficients (Kd) ranged from 0 to 21 mL g−1 and were usually ≤2 mL g−1. Metabolite Kd values differed from the parent compound Kd by up to an order of magnitude. For all compounds, desorption was hysteretic. For most compounds tested, Kd values were greater in the US soils, which were higher in organic carbon and pH than the Argentinian soils. At both sites, Kd values were lowest in the upper slope and highest in the lower slope.