Earthworm populations as affected by longterm tillage practices in southern Alberta, Canada

The number of earthworms under long-term (25 years) zero tillage and conventional tillage in a dryland wheat-fallow rotation were studied. Data were collected from the fallow phase of the rotation on the same field plots in both 1992 and 1994. Earthworm abundance was determined by handsorting. The results showed that there were significantly more earthworms found under zero tillage than under conventional tillage in both 1992 and 1994. The majority of earthworms were in the 5-15 cm depth in both years. All the earthworms were identified as the endogeic species Aporrectodea caliginosa (Savigny) according to Sims and Gerard (1985). We conclude that there is a significant effect of longterm dryland tillage practices on earthworms in southern Alberta, Canada. (C) 1997 Elsevier Science Ltd.