Abstract:
【Objectives】 Being a major part of low-yielding soil types in Anhui province, lime concretion black soil restrains crop yields from increasing and stabilizing owing to its intrinsic properties. Based on a long-term fertilization experiment, responses of soil microbial properties to different fertilizer application were explored, which can provide a theoretical mechanism and support for improving lime concretion black soil ecological function and enhancing soil productive sustainability.【Methods】 The long-term fertilization experiment, located in Yangliu Village of Anhui Province, was started since 1981, wheat and corn have been rotationally planted, all the straws are removed out of the plots after harvest. Five treatments were designed: non-fertilized (CK), mineral fertilizer (NPK), organic fertilizer(M), mineral plus organic fertilizer (mineral N∶organic N =1∶1, MNPK), and mineral plus organic fertilizer with higher amount of nitrogen (HMNPK). We investigated number of bacteria, fungi and actinomycete, microbial biomass-carbon(SMBC) and microbial biomass-nitrogen (SMBN), and activities of urease, invertase, acid and neutral phosphatase. Principal components analysis was used to evaluate soil micro-ecosystem quality in different fertilization.【Results】 1) Compared with CK, the organic fertilizer treatments (M、 MNPK and HMNPK) significantly increased soil culturable microbes by 15.68-22.80 times, especially bacteria and actinomycete, the maxima were in treatment of M and MNPK with value of 30.50105 and 15.50 104 cfu/g, respectively. The fungi was inhibited by M, but increased obviously by NPK. 2) The SMBC and SMBN were reinforced by the organic fertilizers (M, MNPK and HMNPK), in which the maximal increments in SMBC and SMBN appeared in treatment of MNPK (119.74% and 88.46%); NPK treatment enhanced the SMBC significantly(38.87%), but affected SMBN slightly. 3) The activities of soil urease and invertase were increased significantly by long-term application of organic fertilizer, while that of acid phosphatase was not. The effects of the NPK treatment on these enzyme activities were opposite to organic fertilizer. 4) Two principal components were extracted from the initial 9 indicators. The major contributors of primary component were bacteria, actinomycete, SMBC, SMBN, urease and invertase, and the secondary contributors were fungi, acid and neutral phosphatase. Being evaluated comprehensively by principle components analysis, the micro-ecosystem qualities in treatments of MNPK and HMNPK were in the 1st level, M in the 2nd level and NPK and CK in the 3rd level.【Conclusions】 The comprehensive best microbial ecological function in lime concretion black soil is found in the long-term organic plus inorganic fertilization condition, then is the mere organic fertilizer application and worst is the pure mineral fertilizer application and non-fertilization.