The impacts of N fertilizer, pesticides and green manure on aquatic oligochaetes in irrigated ricefields were investigated in experimental plots. Populations, determined by the wet sieving of soil cores, were dominated by the Tubificidae Limnodrilus hoffmeisteri. Total densities ranged from 0 to 40 000 m-2. Oligochaete numbers increased in response to additions of urea N. An inhibitory effect of carbofuran on oligochaete populations was observed during the first season of experimental pesticide treatments, but not during the following year. The green manure Sesbania rostrata stimulated population development more than Azolla microphylla. Populations in plots maintained as wet fallow remained low throughout the crop cycle. Population dynamics were associated with the crop cycle. Peak densities were achieved 30–50 days after transplanting.
Simpson, I.C.; Roger, P.A.; Oficial, R.; Grant, I.F. Impacts of agricultural practices on aquatic oligochaete populations in ricefields. Biology and Fertility of Soils (1993) 16 (1) 27-33. [DOI: 10.1007/BF00336511]