On the methodology of nematode extraction from field samples: comparison of methods for soil extraction.

The commonly used nematode extraction methods were compared using three soil types and four nematode species. The comparison was repeated in three trials by the same operator to estimate operator reproducibility. Extraction efficiency was dependent upon method, soil type, and nematode species, and reproducibility was not particularly satisfactory for routine analyses. Extraction by any method tested was less than 50% efficient. Quantitative nematode extraction methodology needs serious attention.