Abstract:

【Objective】 Soil biological fertility reflects soil quality directly. Understanding of soil biological characteristics and microbial community as affected by long-term fertilization could provide a theoretical basis for improvement of soil quality and development of the sustainable agriculture. 【Method】 In this paper, the effects of long-term application of N, NP, NPK, pig manure (M), and MNPK (pig manure plus NPK) on total phospholipids fatty acid (PLFA), soil micro-biomass-C, N and P, and selected hydrolase activities were investigated in a paddy soil derived from yellow-brown earth. 【Result】 Compared to CK or application of chemical fertilizer only, the application of pig manure only or pig manure plus NPK significantly increased SMB-C, N, P, PLFA, fungi PLFA, fungi/bacterial rate, soil alk-phosphatase, protase, and urease activity, fungal-to-bacterial PLFA ratios, and enhanced the growth of AM fungi. Long-term application of N only inhibited soil alk-phosphatase activity and the growth of most microorganisms. Principal Component Analysis (PCA) of PLFA showed that, microbial community structure was affected by manure and chemical fertilizers application in different ways. The loading values for the individual PLFA indicated that fungal and monounsaturated fatty acids (MONO) were mainly influenced by organic manure application, while those of actinomycete was affected by application of chemical fertilization only. 【Conclusion】 Combined application of organic manure and chemical fertilizer could significantly enhance SMB-C, N, P, PLFA, fungi PLFA, fungi/bacterial rate, and improve soil biological fertility. It will be favorable to soil quality.

Key words: long-term fertilization, paddy soil, PLFA, alk-phosphatase, protease, urease