Effect of bio-fertilizer HZ-24 on Astragalus mongholicus growth, soil microbial quantity and enzyme activity

A pot experiment was conducted to study the effect of bio-fertilizer HZ-24 on the growth of Astragalus mongholicus and soil rhizosphere microbial quantity and soil enzyme activity, to explore the mechanism of bio-fertilizer HZ-24 in yield increasing and provide a basis for bio-fertilizer HZ-24 application.Astragalus mongholicus was planted in the experiment with six treatments: control, carrier, bio-fertilizer HZ-24, fertilizer treatment (NP), fertilizer+carrier (NP+carrier), fertilizer+bio-fertilizer HZ-24(NP+bio-fertilizer HZ-24); then collected samples from the rhizosphere soil at harvest stage; finally analyzed the number of cultivable microorganisms, urease and phosphatase activities in the soil as well as the effects of different treatments on the number of soil microbes and soil enzyme activities in the rhizosphere soil of Astragalus mongholicus.The results showed that HZ-24 significantly promoted root diameter and root dry weight of Astragalus mongholicus.Compared with the control without fertilization, root dry weight increased by 40.8% and root diameter increased by 36.7%.Compared with chemical fertilizer treatment, the dry weight and root diameter of HZ-24 increased by 16.2% and 19.2%, respectively.Biological fertilizer HZ-24 can increase the number of bacteria and actinomycts in rhizosphere soil and reduce the number of fungi.Compared with the control without fertilization, bacteria and actinomycts increased by 37.3% and 22.7%, while fungi decreased by 19.3%, respectively.Compared with the chemical fertilizer treatment, the bacteria and actinomycete increased by 23.7% and 14.6%, and the fungi decreased by 37.1%, respectively.The activities of urease, acid phosphatase, alkaline phosphatase and alkaline phosphatase in soil increased by 24.2%, 25.9%, 18.1% and 44.2%, respectively, compared with the control without fertilization.The activities of urease, acid phosphatase, alkaline phosphatase and neutral phosphatase increased by 45.7%, 6.7%, 24.8% and 54.0%, respectively, compared with the single application of chemical fertilizer HZ-24.In conclusion, the mechanism of increasing yield of HZ-24 biofertilizer is mainly Pseudarthrobacter spp.that contained in the biofertilizer can change the microbial colony structure of astragalus root, increase the number of bacteria and actinomycetes in rhizosphere soil, and decrease the number of fungi, so that the soil becomes bacterial and fallow.Applying biological fertilizer HZ-24 can significantly increase soil urease, acid phosphatase and alkaline phosphatase activities.It can also increase the nodule weight and enhance the nitrogen fixation ability of nodule, which is conducive to the absorption of nutrients by crop roots.