Microbial Community Of Pig Manure Compost And Its Effect On Seed Germination In Xining Region

China is a large agricultural country with a large output of agricultural waste.Composting connects organic waste and soil carbon pool,which is the focus of future industrial development.Xining is located in Qinghai-Tibet Plateau,where the low temperature and hypoxia hinder the disposal and utilization of livestock wastes.The short production time of organic fertilizer limited the production of organic fertilizer and increased the cost of enterprises in Qinghai Province.Therefore,Xining city in the Alpine region is taken as the research area,local animal manure and rape straw as the research materials,adding multi-enzyme strains,complex microbial agent and ventilation treatment.In this experiment,the effects of physical and chemical properties,microbial community and composting treatments on germination rate,germinative force and germination index of herbage seeds were determined.Finally,the effects of composting treatments were evaluated comprehensively by grey relevancy method.In order to select suitable compost fermentation technology in alpine region,accelerate compost maturity process,reduce production cost,and strive to improve fertilizer efficiency.The study found:(1)In the treatment of different microbial agent,the temperature of the pile with the addition of multi-enzyme strains and the complex microbial agent kept above 50℃ for 5days.The p H of all the piles ranged from 7.5 to 8.5,and the p H value of the piles adding complex microbial agent was significantly higher than that of the piles adding multienzyme strains and the control group at the end of composting(P<0.05).At the end of composting,EC values were all lower than the limit EC value of 4.0 m S/cm,and the EC values of the piles with multi-enzyme strains and complex microbial agent were significantly lower than those of the control group(P<0.05).The C/N gradually decreased and stabilized with the extension of composting time.In the bacterial community,the richness and diversity of the addition of the complex microbial agent are higher than the treatment of the addition of the multi-enzyme strains.At the phylum level,Proteobacteria,Bacteroidetes,Actinobacteria and Firmicutes were the four dominant phyla in the compost community.Firmicutes and Chloroflexi showed an increasing trend with the change of compost temperature,while Proteobacteria showed a decreasing trend with the addition of multi-enzyme strains and complex microbial agent.Ascomycetes were the most abundant phylum in the fungal community,and the relative abundance of the treatment with the addition of multi-enzyme strains was higher than that of the other two treatments.At the genus level,the relative abundance of the Luteimonas and Pseudomonas in the treatment of multi-enzyme strains and complex microbial agent is lower than that of the control group.The relative abundance of Acinetobacter was higher in the treatment with the addition of multi-enzyme strains than in the other two treatments.In the fungal community,Lophotrichus was the dominant bacterium in the warming stage of the multi-enzyme strains and the control group,the Coprinellus was the dominant bacterium in the cooling stage.In the pile of the multi-enzyme strains,the relative abundance of the Clostridium sensu stricto is higher than the other two piles.(2)In the ventilation treatment,the ventilation group reached high temperature above 50℃ on the second day,and the temperature continued above 55℃ for 5 days.During the process of compost fermentation,the p H values of ventilated and unventilated treatments fluctuated between 7.5 and 8.5.The EC value is lower than 4.0 m S/cm.With the extension of time,the C/N decreases continuously and finally becomes stable,and the C/N of ventilated treatment is lower than that of unventilated treatment at the end.The results of Chao1 index,observed richness and phylogenetic diversity showed that the diversity and richness of bacterial communities increased with the change of temperature.At high temperature and cooling stage,the bacterial community richness and diversity of ventilation treatment were significantly lower than that of no ventilation treatment(P<0.05).The diversity and richness of fungal community increased first and then decreased.At the phylum level,Proteobacteria,Bacteroidetes,Actinobacteria,Firmicutes,Chloroflexi and Deinococcus-Thermus were the main dominant bacteria in the compost bacterial community.The relative abundance of Proteobacteria in ventilation treatment decreased gradually,and the Bacteroidetes in each temperature stage was higher than that in no ventilation treatment.The relative abundance of Actinobacteria in high temperature and cooling stage was higher than that in no ventilation.In fungal communities,Ascomycota decreased and Basidiomycota increased with the change of temperature.At the genus level,in the ventilation treatment,the relative abundance of Clostridium sensu stricto in the high temperature stage was lower than that in the no ventilation treatment.The relative abundance of Ascobolus was the highest in the high temperature stage,and the Zopfiella was the highest in the cooling stage.Environmental factors such as p H,C/N,temperature,organic matter and electrical conductivity were the main factors affecting bacterial community,followed by water content and TN.(3)In the experiment on seed germination and growth of Medicago sativa ’Beilin201’of leguminous Medicago sativa,the germination rate of each treatment reached more than80%,indicating that they were completely non-toxic.The germinating index reached more than 70% except the ventilation treatment with the addition of multi-enzyme strains,which all reached the requirement of harmlessness.(4)Grey correlation method was used to analyze the compost maturity of 6treatments.The results showed that the ventilated piles were well decomposed,while the unventilated piles were basically decomposed.In this study,the addition of multi-enzyme strains and complex microbial agent in the reactor could prolong the duration of high temperature,reduce the EC value.In this treatment,the relative abundance of Firmicutes and Chloroflexi was increased,and the Luteimonas and Pseudomonas was decreased.The addition of multi-enzyme strains was conducive to the increase of relative abundance of Ascomycota and Clostridium sensu stricto;adding complex microbial agent can improve the richness and diversity of bacterial community.Ventilation treatment can make the reactor heat up quickly and prolong the duration of high temperature.It is beneficial to reduce C/N and promote compost decaying.It is beneficial to reduce the relative abundance of Proteobacteria,increase the relative abundance of Bacteroidetes,increase the relative abundance of Actinobacteria at high temperature and cooling stage,and reduce the relative abundance of Clostridium sensu stricto at high temperature stage.Compost extract had no toxicity to ’Beilin 201’ alfalfa seeds.The ventilation treatment with the addition of multi-enzyme strains and the ventilation and no ventilation treatment with the addition of complex microbial agent reached the requirement of harmlessness.The results of grey correlation method show that the ventilated pile is well decomposed,while the unventilated pile is basically decomposed.