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Acta Prataculturae Sinica ›› 2026, Vol. 35 ›› Issue (1): 25-39.DOI: 10.11686/cyxb2025075

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Effects of microbial inoculants combined with organic calcium protein on alfalfa growth and soil enzyme activity

Ying ZHANG(), Shan-mu HE, Ao-lei HE, Chang-ning LI, Tuo YAO()   

  1. Key Laboratory of Grass Ecosystem of Ministry of Education,College of Pratacultural Science,Gansu Agricultural University,Lanzhou 730070,China
  • Received:2025-03-11 Revised:2025-05-06 Online:2026-01-20 Published:2025-11-13
  • Contact: Tuo YAO

Abstract:

To investigate the effects of the combined application of microbial inoculants and organic calcium protein on alfalfa (Medicago sativa) growth and soil enzyme activity, three candidate strains [Bacillus mycoides (Y1), Bacillus mojavensis (LrM2), and Pseudomonas synxantha (M1)] were used to prepare a microbial inoculant applied at three concentrations (108, 109, and 1010 cfu·mL-1). Each inoculant concentration was paired with five supplementation levels of organic calcium protein (2%, 4%, 6%, 8%, and 10%) in a pot experiment. The effects of these treatments on alfalfa growth traits, nutritional quality, root morphology, and soil enzyme activity were evaluated. The results showed that: 1) All treatments promoted alfalfa growth. The highest dry yield in the first crop (1.47 g·30 plants-1) was achieved with treatment D4 (1010 cfu·mL-1 microbial inoculant+6% organic calcium protein), while treatment B5 (108 cfu·mL-1 microbial inoculant+8% organic calcium protein) yielded the highest in the second crop (5.5 g·30 plants-1). 2) The combined application significantly enhanced alfalfa’s total root length, root diameter, root surface area, and root volume. At a fixed inoculant concentration, these parameters initially increased and then decreased with increasing organic calcium protein supplementation. 3) Alfalfa plants in treatment C5 (109 cfu·mL-1 microbial inoculant+8% organic calcium protein) showed the highest relative feed value (RFV=226.56), whereas treatment D5 (1010 cfu·mL-1 microbial inoculant+8% organic calcium protein) resulted in the maximum total chlorophyll content. 4) Compared to the application of microbial inoculant alone, the combined treatment significantly increased the activities of soil alkaline phosphatase, sucrase, catalase, and urease. 5) Based on the technique for order preference by similarity to ideal solution (TOPSIS) evaluation, treatment D4 not only enhanced alfalfa growth but also improved soil enzyme activity, demonstrating high potential for practical agricultural application.

Key words: Medicago sativa, microbial inoculants, organic calcium protein, nutritional quality, soil enzyme activity