The role of nematodes and their use as bio-indicators in soil health under local conditions

Nematodes form an integral part of the soil food web at several trophic levels. Their rapid responses to changes within their environments provide them with the potential to impart insight into the condition of the soil food web. Three objectives were set to determine the practical use of nematode community structures as a tool for the measurement of soil health: describing the nematode community structure, biodiversity and functionality within Fynbos soils; the characterization of organic and conventional orchards; and the differences in nematode soil communities in differently managed soils in an apple orchard. The number of nematodes in each soil sample was quantified and identified to family level. The functional guild analysis of Fynbos samples indicated that the enrichment and the structure of any given sample was not bound to a certain area, but was representative of each of the four quadrats within the faunal analysis. The characterisation of nematode communities in organic and conventionally managed orchards indicated that herbivores were dominant in all the orchards. All orchard soils were located within Quadrat B of the faunal analysis, indicating enrichment and structure. Different management practices did not show marked differences in community composition and structure. The species richness of Fynbos soils and deciduous fruit orchards was comparable. Soil samples from eight different soil surface treatments were collected from an apple orchard (chemical control of cover crops and weeds, mulch and mulch + effective micro-organism spray). Clear differences in nematode community structure and composition were observed between the different soil applications in the orchard.