Nitrogen Mineralization by Bacterial Feeding Nematodes in Different Cropping Systems

Bacterial feeding nematodes excrete N assimilated in excess of that required for growth. Because metabolic and developmental rates differ among nematodes species, we hypothesised that their contribution to N mineralization in soil would differ. Soil-column microcosms amended with an organic substrate, bacteria, and with- or without bacterial feeding nematodes, were leached at 7-day intervals. Cumulative N, as NH4+ and NO3−, leached from columns containing nematodes was consistently greater than from columns without nematodes. Two seasons’ field experimentation (during two subsequent seasons-rabi-2011 and kharif-2012) showed a high N-mineralization in soils observed drawn from soybean cropping system compared to chickpea system across two different sampling dates (i.e. prior to planting and after the harvest of the crop). The mechanisms behind the effects of the nematodes on N mineralization are found to be mainly direct.