Herbicide transport by surface runoff and herbicide retention in a filter strip — Rainfall and runoff simulation studies

Abstract

Runoff studies with simulated rainfall at an intensity of 14 mm/h were carried out on a mesoplot of 1200 m 2 planted with triticale. The herbicides dichlorprop-p, isoproturon, and bifenox were applied to the plots, which had a soil water content of about 30 % [kg/kg]. Runoff in the compressed tractor lanes occurred rapidly, whereas a total runoff over the whole plot started at a total rainfall of 14.0 mm and the initial concentrations of dichlorprop-p and isoproturon were 1400 μg/l. In the total runoff the concentrations ranged from 100 μg/l to 200 μg/l, decreasing with cumulative rainfall. In the second study, experiments with simulated runoff were carried out to investigate the efficiency of a grassed filter strip. Out of a point source water spiked with different concentrations of isoproturon, dichlorprop-p and terbuthylazine flowed with intensities of 400 l/h, 1500 l/h and 2000 l/h. In addition, the grassed filter strip was irrigated with sprinklers with an intensity of about 14 mm/h, which corresponds to its infiltration capacity. The simulated runoff leaving the filter strip was collected and analysed for the herbicides. It was shown that the efficiency of the boundary strip in herbicide retention was mainly due to the infiltration of the runoff in the strip.