The Interaction Mechanism Of Nitrogen Transformation And Bacterial Dynamics During Aerobic Composting Of Poultry Manure

Aerobic composting is an effective measure for the resource treatment of livestock and poultry manure,which can realize the harmless treatment,reduction treatment and resource utilization of livestock and poultry manure.However,sanitizer and bactericides often remain in livestock and poultry manure,which reduces the diversity of flora in manure and inhibits the growth and metabolism of microorganisms.The influence of disinfectants and bactericides on the aerobic composting process needs further study.On the other hand,nitrogen is not only one of the odorous substances of compost,but also the main effective substance of organic fertilizer.Studying the transformation behavior and influencing factors of nitrogen in poultry manure composting process is helpful to reveal the mechanism of nitrogen transformation and storage and to provide theoretical basis and practical ideas for reducing nitrogen loss in composting process.Based on the above research deficiencies and actual production needs,this thesis focuses on the following two aspects.Aiming at the characteristics of NaOH and NaClO as fungicides commonly used by small farmers in our country,this paper studies the process method and decomposition process of NaOH and NaClO residual poultry manure aerobic composting.Three kinds of regulators were added to the residual chicken manure of disinfectant:vegetable peel garbage(V),kitchen garbage(F),and decomposed horse manure compost(C).the physical and chemical properties,decomposition rate,and microbial community differences of the compost in the three methods were compared.The results showed that the fermentation temperature of group C was significantly higher than that of group V and group F,and the duration of high temperature was the longest.The decrease of organic matter(OM),total carbon(TC),total nitrogen(TN)and ammonia nitrogen(NH4~+-N)in group C compost was significantly higher than that in group V and group F,and the number of bacteria and fungi and seed germination potential index(GI)were significantly higher than those in group V and group F.The electrical conductivity(EC)and free Na ion content of the three groups of compost decreased significantly with the progress of compost,which indicated that the three composting processes had significant effects in treating NaOH and NaClO residual poultry manure,while group C was superior to group V and F due to its higher fermentation temperature and faster degradation rate.Further analysis and detection of nitrogen substances during composting showed that the aerobic composting of poultry manure had obvious nitrogen assimilation and metabolism characteristics,which was different from the traditional nitrogen nitrification or denitrification metabolism.The assimilation and metabolism of nitrogen had no significant correlation with the degradation and metabolism of lignocellulose,but had significant positive correlation with water-soluble organic carbon,especially water-soluble alkyl carbon and amino carbon.At the same time,the organic nitrogen generated during nitrogen assimilation is mainly produced in solid form,which indicates that the composting process is the transformation process of nitrogen from liquid ammonia nitrogen to solid organic nitrogen,and this transformation is coupled with the transformation of dominant species of microorganisms from Sinibacillus to Bachybacterium,Brevibacterium,and Microbacterium,which indicates that nitrogen assimilation may be the result of the successive and comprehensive actions of different microorganisms in the early,middle and late stages of composting fermentation.In vitro micro-composting experiments also confirmed that the nitrogen assimilation process of compost was significantly influenced by soluble C/N,and higher C/N was beneficial to the occurrence of nitrogen assimilation and the increase of nitrogen assimilation ratio.The results of this paper showed that inoculation of decomposed compost was the most effective composting method to treat disinfectant residue poultry manure.It revealed that soluble organic carbon content and flora structure had significant influence on nitrogen assimilation of compost.The research results could be used to guide the research on nitrogen conversion mechanism in composting process and provide potential ideas and methods for improving nitrogen storage in composting practice.