Bioindication potential of using molecular characterisation of the nematode community: Response to soil tillage

The utility of a high-throughput molecular characterisation (directed - terminal restriction fragment length polymorphism – dTRFLP) of soil nematode community structure was evaluated in a field trial of the effects of tillage intensity. Replicated plots were established in a field previously used for continuous, conventional tillage of spring barley (Hordeum vulgare) and cultivated by: zero tillage; minimum tillage; conventional tillage; deep tillage and conventional tillage with compaction. Nematodes were sampled in spring, summer and autumn for three years after treatment began. Total nematode abundance and Nematode Channel Ratio indicated changes due to the zero and minimum tillage, more nematodes and a greater proportion of fungal feeders, but effects were secondary to those of year and season. The effects of tillage were far easier to interpret when other bioindicators were also taken into account. Increases in soil carbon and fungal biomass in the upper layers of the zero and minimum tillage treatments, observed in parallel studies, corroborated the nematode data. The high-throughput molecular method proved to be well suited for multiple measurements of nematode community structure, although limitations in the resolution of nematode taxa could obscure changes in generic and species composition.