The Effect of the Pesticide Carbofuran on Soil Organisms and Root and Shoot Production in Shortgrass Prairie

Abstract

To test the hypothesis that ectoparasitic phytophagous nematodes are a major consumer of primary production in arid grasslands, carbofuran was applied once in each of two successive years at 12 lb active ingredient/acre to plots of undisturbed prairie in northeastern Colorado. Bacterial feeding and phytophagous nematodes were reduced to 10% of the density on untreated plots but microand macro-arthropods were apparently unaffected. Species composition of the fungal flora of the treated soil was greatly changed and colony counts reduced but incidence of mycorrhizae was unaffected. Although root weight measured in the autumn was significantly greater under treated plots (by 130-150 g m-2 and about 25% of NPP) shoot production was not, possibly due to below average summer rainfall in both years. Nevertheless, our results suggest that nematodes may be the most significant consumer in shortgrass prairies.