Abstract: The relationship between long-term fertilization and cropland soil fauna was studied at the station's experiment research network for soil fertility and fertilizers in Shaanxi Loess soil from Jul. 2001 to Oct.2002 in Shaanxi. Six types of long-term fertilization were carried out in this study including control (CK), abandonment (ABAND.), nitrogenous and phosphorus and potassium fertilizers (NPK), straw and NPK (SNPK), organic material and NPK (MNPK) and double MNPK. Seventy-two soil samples were collected and 5 495 species of cropland soil fauna were obtained by handsorting and Cobb method at 4 times, belonging to 6 phyla, 11 classes, 22 orders, 61 familia, 2 superfamilia and 35 genus. The result showed that different fertilization had significant effect on cropland soil fauna (F = 2.24，P <0.007). The number of crop soil fauna was related to soil physicochemical properties caused by long-term fertilization. The result of principal component analysis, focusing on the number of 15 key soil fauna species group's diversity, evenness of community and the total soil fauna individuals, indicated that the effects of SNPK, NPK, MNPK and 1.5MNPK were significantly different on cropland soil fauna, in which, SNPK and NPK had a positive effect on cropland soil fauna，and MNPK and 1.5 MNPK had a negative effect, others cannot been explained. By principal component Ⅰ, the synthetic effect of different fertilization on the total soil fauna individuals and the group was most significantly, and the effect was little on evenness and diversity. By value of eigenvectors, the maximum one was 9.6248, and the least one was -1.0904, which means that the effects of six types of fertilization on cropland soil fauna are unbalance.

Key words: Cropland soil fauna, Community, Long-term fertilization, Principal component analysis, Loss soil of Shaanxi