The adsorption of diquat by soil colloids as a factor in herbicide applications

The adsorption of dicquat dibromide as affected by available soil moisture and concentration of diquat was studied on Blount silt loam soil in east central Indiana. The diquat under varying concentrations and soil moisture conditions was topically applied to twenty-seven, 1/2 meter square sample plots with the surface vegetation removed to expose bare soil.The soil texture of the research site was determined using the Bouyoucos hydrometer method. From the texture analysis, the highly adsorptive montmorillonite clay was determined to be the major adsorptive surfaces available to the diquat radical. With the montmorillonite clays being the major adsorptive surfaces, it was concluded that the applied diquat was completely adsorbed by the soil colloids.Using a modified Langlois-Stemp-Liska procedure for pesticide extraction and clean-up, the major effect of the herbicide concentrations and the soil moisture conditions on the adsorptive capacity of the soil colloids for the diquat radical was determined to be at the level of degrees of adsorption.Ball State UniversityMuncie, IN 47306Thesis (M.S.)--Ball State University, 1974