Vertical distribution of soil nematode communities under different tillage systems in lower reaches of Liaohe River

Vertical distribution of soil nematode communities under conventional tillage (CT), no-tillage (NT) and fallow field (FF) treatments in the Lower Reaches of the Liaohe River was investigated at six soil depths (0–5 cm, 5–15 cm, 15–30 cm, 30–50 cm, 50–75 cm and 75–100 cm). The results show that total nematode abundance gradually decreases with depth, and the highest number of total nematodes is observed at 0–5 cm depth under NT and FF treatments. The number of fungivores and plant parasites is significantly higher under FF and NT treatments than under CT treatment at the 0–5 cm depth. There is significant soil depth effect on the abundances of bacterivores and omnivores-predators, which exhibits a similar trend to that of total nematodes; whereas, no significant tillage effect is found. Tillage effect on soil nematode communities can be reflected by values of relative tillage response of index V. Results of index V indicate that total nematodes, bacterivores, fungivores and plant parasites are mildly inhibited, and omnivores-predators is moderately inhibited under CT treatment; while, under FF treatment total nematodes is mildly, and fungivores and plant parasites are moderately stimulated, respectively.