Fetures Of Microbial Community In Mineralization Of Organic Fertilizer

With the in-depth development of China’s modern agriculture,the large and unreasonable application of chemical fertilizer has seriously restricted the sustainable development of agriculture and environmental safety.The government is vigorously promoting the use of organic fertilizer,which is rich in organic matter and can improve the physical and chemical properties of soil and promote crop growth.However,the organic matter in organic fertilizer can release nutrients for crops only under the action of microorganisms.It is of great significance to study the characteristics of microbial community and different microbial action in the process of organic fertilizer mineralization for elucidating the biological mechanism of organic fertilizer mineralization.In this study,pig manure organic fertilizer was used as raw material to explore the nutrient release law and microbial community succession in the process of organic fertilizer mineralization,as well as the contribution of bacteria and fungi population to organic fertilizer mineralization,and the influence of microbial diversity on organic fertilizer mineralization.The results are as follows。In the indoor organic fertilizer culture experiment,fungi and bacterial inhibitors were added to explore the effects of fungi and bacterial communities on the mineralization of organic fertilizer respectively.The results showed that the mineralization rate of organic fertilizer increased with the extension of culture time,but the mineralization rate was faster in the early stage of culture and decreased gradually in the later stage.The degradation rate of CK,ZY（addition of fungal inhibitor）and XY（addition of bacterial inhibitor）was 19.5%,9.75%and 9.69%respectively at the end of three months experiment,which indicated that the combined action of bacterial and fungal communities was beneficial to the mineralization of organic fertilizer.However,there was no significant difference between ZY group and XY group,indicating that bacterial community and fungal community had almost the same contribution to the mineralization of organic fertilizer.In the process of organic fertilizer mineralization,the contents of inorganic N and available P in each treatment increased gradually;in the process of cultivation,the content of ammonium nitrogen in each treatment decreased gradually,while the content of nitrate nitrogen increased gradually;the activities of cellulase,β-glucosidase and FDA hydrolase were higher in the initial stage of cultivation,and decreased gradually with the increase of cultivation time.In the process of mineralization,the relative abundance of Proteobacteria and bacteroidete decreased gradually at the level of bacterial phyla,while the relative abundance of Deinococcus thermos and ignavibacterium increased;at the level of fungal phyla,the relative abundance of Ascomycota and Zygomycota increased.At the bacterial genera level,the relative abundance of Lysobacter,salinimicrobium and parapedobacter decreased with the increase of culture time,while that of tureapera increased;at the fungal genera level,the relative abundance of Penicillium,ramcandelaber decreased,while that of pulchromyces increased.The effects of soil microbial diversity on mineralization of organic fertilizer under the same microbial biomass were studied by indoor culture experiment.The results showed that at the end of incubation,the degradation rates of organic manure from pig manure compost were 17.3%,14.8%and 15%respectively in three treatments(P0,inoculating soil suspension with dilution of 10⁰;P1:inoculating soil suspension with dilution of 10^-1;P2:inoculating soil suspension with dilution of 10^-2).The results showed that microbial diversity significantly affected the degradation of organic manure compost under certain conditions,but microbial diversity decreased to a certain extent,itseffect on mineralization of pig manure organic fertilizer was weakened.Due to the mineralization of organic matter in organic fertilizer,the relative contents of total nitrogen,total phosphorus,total potassium and available phosphorus in each treatment increased compared with that in the initial stage;the nitrate nitrogen content in each treatment was at a low level in the initial stage,with the extension of cultivation time,the nitrate nitrogen content gradually increased,the ammonium nitrogen content gradually decreased,and finally remained stable;the activities of cellulase,β-glucosidase and FDA hydrolase decreased with the increase of culture time.During the mineralization process,at the bacterial phyla level the relative abundance of Bacteroidetes in three treatments decreased with the increase of culture time;on the contrary,the relative abundance of Deinococcus thermos increased with time.At the fungal level,the relative abundance of Basidiomycota and Ascomycota increased,while Zygomycota and Chytridiomycota decreased.At the bacterial genera level,the relative abundance of Salinimicrobium and Lysobacter decreased,while the relative abundance of tureapera increased;at the fungal genea level,the relative abundance of Spicellomyces increased first and then decreased in P0 treatment,while the relative abundance of Synchyrium decreased in the three treatments;Mortierella decreased in P0 treatment,and decreased first in P2 treatment.At the bacterial community level,the contents of total nitrogen,phosphorus,potassium and nitrate nitrogen were positively correlated with the relative abundance of Tureapera and Ohtaekwangia,and the contents of ammonium nitrogen,β-glucosidase and cellulase were positively correlated with the relative abundance of Salinimicrobium,Lysobacter and Galbibacter.At the fungal community level,the contents of total nitrogen,phosphorus,potassium and nitrate nitrogen were positively correlated with relative abundance of Mortierella.There was a positive correlation between the relative abundance of Synhytrium,Spizellomyces and the content of ammonium nitrogen,the activity ofβ-glucosidase and cellulase.