Leaching of Five Thiocarbamate Herbicides in Soils

Abstract

The depths of leaching of S-ethyl dipropylthiocarbamate (EPTC), S-propyl butylethylthiocarbamate (pebulate), S-propyl dipropylthiocarbamate (vernolate), S-ethyl hexahydro-lH-azepine-l-carbothioate (molinate), and S-ethyl cyclohexylethylthiocarbamate (hereinafter referred to as R-2063) were compared in five different types of soils contained in glass columns. The depths of leaching in mineral soils were directly correlated with the water solubilities of the herbicides. The order of leaching from greatest to the least was molinate, EPTC, vernolate, pebulate, and R-2063. With all compounds tested, the depth of leaching decreased as the clay content of the soil increased. Leaching depth also decreased as organic matter increased. In peat soil containing 35% organic matter, no movement out of the treated zone could be detected with any of the thiocarbamate herbicides tested when leached with 8 in of water.