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 2 successive yr at 12 lb a.i./ac to plots of undisturbed prairie in NE Colorado. Bacterial feeding and phytophagous nematodes were reduced to 10% of the density on untreated plots, but micro- and 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 wt. measured in the autumn was significantly greater under treated plots (by 130-150 g/m2 and about 25% of net primary production) shoot production was not, possibly due to below-av. summer rainfall in both yr. The results suggested that nematodes may be the most significant consumer in shortgrass prairies.<new para>ADDITIONAL ABSTRACT:<new para>Carbofuran was applied once in each of two successive years at 12 lb a.i./acre to plots of undisturbed prairie in northeastern Colorado, USA. Bacterial feeding and phytophagous nematodes were reduced to 10% of the density on untreated plots but micro- and macro-arthropods were apparently unaffected. Species composition of the fungal flora of the treated soil was greatly changed and colony counts were reduced but the incidence of mycorrhizae was unaffected. Although root weight measured in the autumn was significantly greater under treated plots (by 130 to 150 g/m2 and about 25% of NPP) shoot production was not, possibly because of below average summer rainfall in both years. Results suggest that nematodes may be the most significant consumer in shortgrass prairies. [AS]