Nematodes As Indicators of Changes in Agricultural Management.

Though nematodes are often associated with yield loss and plant disease by agriculturists, plant parasitic nematodes (PPN) make up only a fraction of the nematode community living in soils. Spanning nearly every trophic group, nematodes occupy key positions as primary and intermediate consumers in the soil food web and can therefore be used as measures for soil health and productivity. We looked at nematode community structure at the trophic level as one component of measuring the effect of a novel microbial inoculant LEM (Local Effective Microorganisms) on soil health and crop productivity. Two years of data collected on soybean (Glycine max) plots receiving a composted broiler litter show an increase in bacterial-feeding and fungal-feeding nematodes among LEM-treated plots after two years of application. Using Student’s comparison of means, PPN were found to be higher in LEM plots compared to the controls, though the relative proportion of PPN to the total nematode community was not significantly greater and soybean yields were not significantly different. As part of this research, we also collected data from soils previously managed for two years with and without LEM under forage production receiving swine effluent or under soybean production receiving composted broiler litter amendments. Analysis between treatments and systems of nematode community structure indicated significant differences in maturity, structure and diversity indices when compared using one-way analysis of variance (P = 0.0003, P < 0.0001 , P < 0.0001) respectively. While many of the indices developed by ecologists use nematodes to monitor the recuperation of non-agricultural soils after a disturbance, these indices, which measure colonizers and persisters, could be useful tools for measuring the health and resilience of agroecosystems. This research will provide valuable information on how nematode communities respond to different agricultural management systems and specifically how they respond to the application of LEM.