EFFECTS OF METAM SODIUM FUMIGATION ON SOIL MICROBIAL ACTIVITY AND COMMUNITY STRUCTURE

Metam sodium (MS) is a widely used soil fumigant with broad biocidal a ctivity. The impart of MS on soil microbial community structure and fu nction is largely unknown, We investigated the effects of fumigation w ith field-relevant doses of MS in soil microcosms using traditional he terotrophic activity measures (C acid N mineralization), a substrate-u tilization assay, and fatty acid analysis. Our results suggest that fu migation,vith MS results in persistent changes (at least 18 wk) in het erotrophic activity and fatty acid composition of the microbial biomas s, Lack of recovery of heterotrophic activity and changes in fatty aci d composition after fumigation suggest that MS has the potential to al ter important microbially mediated functions such as nutrient cycling and pollutant degradation, Preliminary fatty acid data suggest that ac tinomycetes and other gram-positive organisms may recover preferential ly after fumigation with MS, Although community fatty acid analysis sh ows promise as a screening tool in soil microbial toxicity studies, mo re detailed information can be obtained from analysis of phospholipid fatty acid (PLFA) and other specific lipid fractions.