微生物菌剂施用量对土壤化学性质、酶活性及细菌群落的影响OA

The study aimed to determine the application rate of microbial inoculants during the maize season in the wheat-maize rotation zone,and to investigate the effects of different application rates of inoculants on soil chemical properties,enzyme activities,and bacterial community structure of maize.In June 2023,four application rates of microbial inoculants were set up[0 kg/hm²(CK),45 kg/hm²(M1),75 kg/hm²(M2),and 105 kg/hm²(M3)].The variation characteristics of soil chemical properties,enzyme activities,bacterial community structure,and functional metabolism were analyzed,and the relationships between these indicators were identified.In the 0-20 cm soil layer,the M2 treatment significantly increased soil organic matter content by 10.06%,compared with the CK treatment.All inoculant application rates significantly increased soil alkali-nitrogen and available phosphorus contents compared with the CK treatment,by 6.50%-20.12%and 11.58%-42.90%(P<0.05),respectively,with the M3 treatment showing more significant effects.Compared with the CK treatment,soil sucrase activity was significantly increased in the M1 and M3 treatments,and soil alkaline phosphatase activity was significantly increased by 15.94%-76.81%(P<0.05)in all inoculant application treatments compared with the CK treatment.In the 20-40 cm soil layer,compared with the CK treatment,the M2 treatment increased soil organic matter,alkali-nitrogen,and available phosphorus contents by 9.37%,6.10%,and 22.59%,respectively,and soil urease,sucrase,and alkaline phosphatase activities by 16.82%,3.81%,and 97.43%(P<0.05),respectively.As the maize growth stage progressed,there were significant changes in soil bacterial α-diversity and community structure in each treatment.At 15 d after application,compared with the CK treatment,the application of microbial inoculants increased the soil bacterial ACE,Chao1,and Shannon indices.At 30 and 90 d after application,the ACE,Chao1,and Shannon indices of the M3 treatment were lower than those of the other treatments.Compared with the other treatments,the M2 treatment increased the relative abundance of Gammaproteobacteria,Alphaproteobacteria,and Bacteroidia in the soil by 5.16%-7.77%,5.11%-12.85%,and 4.71%-17.00%,respectively.PICRUSt functional prediction showed that the M2 treatment enhanced carbohydrate metabolism at 15 d,promoted energy metabolism,co-factor and vitamin metabolism,translation,and nucleotide metabolism at 15 and 30 d,and made amino acid metabolism stronger at 90 d,thereby benefiting soil nutrient cycling.The study showed that the application of microbial inoculants at 75 kg/hm² could significantly increase soil nutrient content and enzyme activity,and improve the diversity of soil bacterial community structure.However,the application of a high amount of microbial inoculants(105 kg/hm²)might inhibit the development of bacterial community structure.