Earthworm communities in conventional wheat monocropping and low-input wheat-clover intercropping systems

Undersow spring cereals, with clover for example

A study of paired, intercropped and conventional wheat fields at four sites in the UK (Schmidt et al. 2001) found that intercropping resulted in higher earthworm (Lumbricidae) abundance, biomass and species diversity than conventional wheat management. Earthworm populations and biomass were greater in wheat-clover Trifolium spp. fields (individuals: 548/m², biomass: 137 g/m²) than conventional wheat fields (194/m²,36 g/m²) from autumn 1995-1997. Abundance varied more between conventional sites (55-408/m²) than between wheat-clover sites (337-733/m²). Population size ratios (wheat-clover:conventional wheat) ranged from approximately 2:1 to 9:1 and the overall mean ratio was 4:1. Species diversity was greater in wheat-clover fields (7-10 species) than conventional fields (5-9 species). White clover Trifolium repens was established in spring, and winter wheat was direct-drilled into the clover sward. Mono-cropped wheat was drilled at the same time. Intercropped fields received reduced applications. Earthworm communities were sampled in spring and autumn using the formalin method (10-12 quadrats of 0.25 m²/field) and an electrical sampling method (5-10 samples of 0.125 m²/field). Community biomass values refer to the live biomass.