We examined how the long-term manure application and reduced tillage had exerted influence on the dynamics of nematodes community in the field. We collected soil samples from the four types of field where managed with the different combination of manure/fertilizer application and conventional/reduced tillage, at regular intervals, over the cultivation period of corn (Zea mays). Sampling was conducted for different depth of soil layer, 0-5cm and 20-25cm below the top-soil. Nematodes were extracted with Baermann method, counted and classified into two groups; plant-feeding and free-living. Then we calculated the density of each group.
In the case of the free-living nematodes density, the increasing was greater in 0-5 layer than 20-25, and greater in the manure applied field than in fertilizer applied. Reduced tillage was favorable for them. While plant-feeding nematodes, the density was higher in fertilizer applied than in manure applied. It was suggested that The combination of conventional tillage and fertilizer had a mutually potentiating effect on the increasing of them. Besides, There was a significantly negative correlation between the density of total nematodes and the proportion of plant-feeding nematodes in each sample.
From these results, we considered that the emvironment where free-living nematodes increase can be unfavorable to plant-feeding nematomdes.
