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Acta Prataculturae Sinica ›› 2017, Vol. 26 ›› Issue (10): 118-128.DOI: 10.11686/cyxb2017016

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Impacts on alfalfa productivity and soil fertility of partially replacing phosphate fertilizers with microbial fertilizers

QI Juan1, YAO Tuo1, BAI Xiao-Ming1, GAO Meng-Ying1, MENG Xiang-Jun2   

  1. 1.College of Grassland Science, Gansu Agricultural University, Key Laboratory of Grassland Ecosystem, Ministry of Education, Sino-US Center for Grazingland Ecosystem Sustainability, Lanzhou 730070, China;
    2.Gansu Grassland Technical Extension Station, Lanzhou 730010, China
  • Received:2017-01-18 Online:2017-10-20 Published:2017-10-20

Abstract: A field experiment was carried out to study the effects on alfalfa yield, soil microbial characteristics and soil enzyme activities, of partially replacing phosphate fertilizers with microbial fertilizers, and comprehensive evaluation were conducted using grey relational analysis. The aim of the research was to explore the effect of the biological fertilizer and to scientifically determine the optimum optimal application rate for alfalfa. The experiment had seven treatments: P100, 100% phosphate fertilizer (80 kg/667 m2); M100, phosphate solubilizing bacteria+nitrogen-fixing bacteria (0.5 kg/667 m2); P75M25,75% P+25% M; P50M50, 50% P+50% M; P25M75, 25% P+75% M; R100, 100% nitrogen-fixing bacteria; CK (no fertilizer). P100 increased the alfalfa yield significantly at the first cut, while the treatment P75M25 had produced the highest yield (P<0.05) at the second cut. Comparing the total yield from two cuts with CK, P50M50 was highest yielding and increased the alfalfa yield by 60.45%, while P100 had the second highest yield, which increased about 58.40% than CK. Partially replacing phosphorus fertilizers with microbial fertilizers increased soil microbial population. P50M50 significantly increased the number of bacteria, fungi and actinomyces in the 0-10 cm soil layer at the first cutting by 204.6%, 174.5% and 33.2%, respectively, compared to CK. P50M50 and P25M75 improved soil enzyme activity significantly in the 10-20 cm soil layer at the first cut. Grey correlation analysis indicated that sucrase had the highest grey correlation value (0.842), followed by yield (0.814), while microbial biomass of phosphorus and carbon had lower grey correlation value (0.512 and 0.513), respectively. The treatment P50M50 demonstrated soil fertility improvement while reducing the application rate of chemical fertilizers, and was therefore agronomically beneficial.