Effect of Soil Properties on the Persistence of Linuron and Diphenamid in Soils¹

Abstract

Abstract Initial and residual toxicity of linuron and diphenamid in 11 soils of Kentucky was studied for 17 months under greenhouse conditions, using a bioassay technique. Correlation of ED 50 values for these herbicides with the physical and chemical properties of the soils was determined. Organic matter content showed the highest and most consistent correlation with ED 50 values. Exchangeable sodium also showed significant correlation with ED 50 but only at certain periods of the study. Amount of clay in the soils was not correlated with ED 50 values even though the cation exchange capacity and ED 50 were correlated. The kind of clay might have some influence on the results obtained in the study. Organic matter content seemed to play the greatest role in the disappearance of linuron and diphenamid in soils.