Influence of Chlorsulfuron Contamination on Ratios of Biomass Carbon and Nitrogen to Total Organic Carbon rnand Nitrogen in Soil

摘要

@@The extent and seriousness of the contamination of soils by pesticides still remain to be rndetermined. In agricultural systems, herbicides are the largest class of pesticides used (Shea,rn1985). Chlorsulfuron is one of the most important sulfonylurea herbicides with important rnfeature of very high herbicidal activity, which results in extremely low application rates of rn10～40 g ha-1 (Blair and Martin, 1988). The sulfonylurea herbicides can persist in the soil for rnmore than 1 year (Brown, 1990). Therefore, there has been considerable interest in the side rneffects of these chemicals on non-target organisms, including soil microorganisms (Greaves rnand Malkomes, 1980). It is generally recognized that the microbial biomass is the eye of the rnneedle through which all organic materials that enter the soil must pass (Jenkinson, 1988).rnChanges in the microbial biomass-C (Cmic) can provide an early indication of long-term rntrends in the total organic-C (Corg) of soils (Carter, 1986). The Cmic/Corg ratio has been rnfound useful as an index of changes in soil organic matter resulting from land management rnchanges (Hart et al., 1989). Many studies were done on relative effect of heavy metals on the rnratio of Cmic/Corg but few studies have laid particular attention to the effect of herbicides rnon this ratio. The present paper reports on the Cmic/Corg and microbial biomass-N/total N rn(Nmic/Ntotal) ratios in soil as affected by chlorsulfuron.