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.