Effect of Calcium Chloride on Prometryne and Fluometuron Adsorption in Soil

Abstract

The movement and adsorption of soil-applied14C-labeled 2,4-bis(isopropylamino)-6-(methylthio-s-triazine (prometryne) and 1,1-dimethyl-3-(a,a,a-trifluoro-m-tolyl)urea (fluometuron) in the presence of 0.01 and 0.5NCaCl2were studied. The soils were Ca++-saturated Eufaula loamy fine sand and Norge loam. In equilibrium adsorption studies, fluometuron adsorption was decreased and prometryne adsorption was increased by increasing the CaCl2concentration from 0.01 to 0.5N. The mobility of prometryne in the two water-saturated soils was decreased by an increase in CaCl2concentration. Fluometuron mobility was unchanged by the two CaCl2concentrations in Eufaula, but was greater in Norge at the higher CaCl2concentration. The adsorption of each herbicide in the flowing system was less than that predicted by the distribution coefficient. Differences in CaCl2concentration do not appear to influence the mobility of the two herbicides sufficiently at the soil-water flow rate used in this study to require changes in current field application practices.