Abstract:The effects of long-term application of NP, NPK, pig manure (MCK), pig manure plus NP (MNP) and pig manure plus NPK (MNPK) on the microbial communities in a Chinese Mollisol were investigated by the determination of soil basic prosperities, phospholipids fatty acid (PLFA), acid and alkaline phosphatase activities, and microbial biomass C (SMBC) or N (SMBN). The nil-fertilizer treatment (CK) and fallow plots were utilized as controls. The results showed that the application of pig manure significantly increased the amounts of soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), alkali-hydrolysable nitrogen (AN), and readily available potassium (RAK). Furthermore, the SMBC or SMBN, ACPase or ALPase activities, fungal or bacterial PLFA contents, and fungal-to-bacterial PLFA ratios in the manure treatments were all higher than those in CK or the chemical fertilizer treatments. Long-term application of NP or NPK had inhibited the two phosphatase activities and the growth of most microorganisms. The relationship between monounsaturated fatty acids (MONO) and cyclopropyl fatty acids (CYCLO) or between normal saturated fatty acids (NSAT) and total bacterial PLFAs was positively correlated at 0.01 levels. PCA of PLFA showed that manure and chemical fertilizers affected microbial community structure in different ways. The loading values for the individual PLFA indicated that fungal 18:2ω6,9 was significantly affected by chemical fertilizers application, while the ones of G- or G＋ were affected by organic manure amendment. The higher levels of microbial activities and biomass in the fallow treatment compared with the other treatments were mainly attributed to soil bacterial groups rather than fungal ones.