Earthworm communities in grasslands and horticultural soils

In a survey of 42 farm sites, comprising grassland and two types of horticu ltural farms (growing vegetables or flower bulbs), earthworm communities we re sampled by hand-sorting and a number of soil physicochemical characteris tics recorded. For heavy metals the availability in the soil solution was e stimated based on the measured absolute content. Abundance, biomass and spe cies richness were significantly higher in grassland soils than in horticul tural soils, and within the horticultural farms significantly higher in veg etable than in flower-bulb farms. No epigeic species were found in horticul tural soils. The differences between the various farm types were probably r elated to the intensity of management practices, such as soil tillage, harv esting and crop protection measures, that result in less soil organic matte r of lower quality. The data from the grassland farms were analyzed in conj unction with the physico-chemical soil characteristics, applying canonical correspondence analysis. Community parameters such as species richness and diversity apparently were not related to soil characteristics, but an appre ciable part of the variation in abundance and biomass of several individual species could be explained by factors such as lutum content (particles < 1 6 <mu>m), pH, bio-availability of metal ions and geographical position of t he sample site. It is concluded that repeated surveys of this type may beco me a valuable tool for monitoring soil quality.