Abstract: The effects of chemical fertilizer on nematode community composition and diversity were investigated in a field throughout the corn-growing season in the Black Soil Region , Northeast China. 14 families and 16 genera were observed. Cephalobidae , Rhabditidae , A phelenchus , and Tylenchus were found to be the dominant families/ genera. Significant differences were found between sampling dates ( p < 0. 01) and between treatments ( p < 0. 01) in the total number of nematodes during the study period. Ecological indices of diversity , evenness , richness and dominance and the dynamics of the nematode community were compared between the t reatment and the cont rol plot . Shannon index and richness were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to the application of chemical fertilizer.