The effect on earthworms of ploughing, tined cultivation, direct drilling and nitrogen in a barley monoculture system

SUMMARY Dilute formalin was used to sample earthworm populations after the second (1969) and sixth (1973) harvests from a continuous barley experiment in which the cultivation treatments include deep (30 cm), normal ploughing (20 cm) and tined (three passes to 20 cm) cultivations and no tillage (direct drilling), at four nitrogen rates: 0, 50, 100 and 150 kgN/ha. Eight species of Lumbricidae were found, with Allolobophora chlorotica and A. longa co-dominant in both years, joined by A. caliginosa in 1973. In 1969, Lumbricus spp., particularly large Lumbricus terreslris , tended to be more numerous in the untilled plots. In 1973, the total populations had increased by 170%, with 50–100% more earthworms in untilled than ploughed plots, one third more with 50 and 100 kg N/ha fertilizer than with no nitrogen, and one-third more in the slightly heavier sandy clay loam soil than the lighter loam. Most earthworm species reacted in the same way, and the reasons for any unusual reactions are discussed.