Seasonal Rainfall Effects on Pesticide Leaching in Riverside, California

The objective of this study was to investigate the extent to which precipitation affects the mobility of pesticides in a sandy loam soil which received no additional irrigation. During a four month period, 172 mm of rain fell on the experimental plots to which ordram, simazine and carbofuran had been applied at a rate of O.OOlkg active ingredient mm2. A qualitative evaluation of soil cores taken upon conclusion of the study indicated that the bulk of the pesticide applied was not detectable below a depth of 0.76 m. The use of two sampling techniques, split barrel mobile drill auger vs bucket-auger, to collect the samples, enabled a comparison which indicated that the use oi a bucket-auger to collect contaminated samples in dry sandy soils, may not be the most appropriate method.