Effect Of Copper On The Ammonia Production In The Composting Of Hen Manure

Aerobic composting is the main method for the treatment of livestock and poultry manure,however,the ammonia（NH₃）production during the composting process not only causes nitrogen loss,also pollutes the environment.Therefore,the aim of this project is to investigate the effect of copper on the NH₃production during the composting of poultry manure,in addition,the involving mechanisms will be characterized through microbiology,and provides the references for the NH₃emission reduction in the future.There are two parts in this project.The aim of first part is to find out the suitable copper addition dose for the second part.In the first part,the copper addition doses were 0,30,60,and 100 mg/kg,and the experiment was carried in indoor composting device.Based on the results of first part,the copper addition concentration was 0,100,and 1000 mg/kg,and the experiment was carried in spot composting plant.The relationship between heavy metals,NH₃production,and microorganisms and the main findings are as follows:（1）In the first part,by the comparison of CK（Control Check,0 mg/kg）group,the total NH₃production in the 30,60 and 100 mg/kg group all significantly increased,and the increasing ratio was 19.78%,14.77%and 20.3%respectively（P<0.05）.The NH₄⁺-N concentration in the 30,60,and 100 mg/kg groups was significantly higher than that in the CK group（P<0.05）.The total NH₃production of group 100 mg/kg was higher than that among other three groups,thus the copper addition concentration 100 mg/kg was selected for the next test.（2）In the second part,by the comparison of CK group,the total NH₃emission in 100mg/kg group significantly increased 39.88%（P<0.05）,and the total NH₃emission of the1000 mg/kg group significantly decreased 23.87%（P<0.05）.Through the further analysis,there was more NH₄⁺-N transformation into NH₃in 100 mg/kg group by the comparison of1000 mg/kg group,and the NH₄⁺-N transformation into NH₃could be inhibited in group1000 mg/kg.With the stress of a certain concentration of heavy metal copper,the NH₃production increased during the composting process,but when the concentration of heavy metal copper was too high,the total NH₃production would be reduced.（3）With the appropriate concentration of copper（100 mg/kg）stress,the total bacterial count,copper resistance gene（copA）and NH₃production showed the positive correlation.Based on the analysis of the sample OTUs,the result showed that the copper had little effect on the microbial community structure in the composting.At the phylum level,the increasing of NH₃emissions was related to the abundance of Proteus and Actinomycota;at the genus level,the increasing of NH₃emissions was related to the abundance of Bacillus,Limnochorda,and Ammoniibacillus.In summary,with the stress of low concentration copper（100 mg/kg）,NH₃production can be increased during the composting process of chicken manure,and the much high doses of copper（1000 mg/kg）can inhibit NH₃production;the NH₃production of compost in 21 days in 100 mg/kg group increased 39.88%by the comparison of blank group,and the NH₃production in 1000 mg/kg group reduced 23.87%by the comparison of blank.With the stress of low concentration of copper（100 mg/kg）,the count of total bacteria,copper resistance gene（copA）and the daily yield of NH₃showed positive correlation;but the copper had little effect on the microbial community structure in the composting.At the phylum level,the NH₃emission increasing was related to the abundance of Proteus and Actinomycota.At the genus level,the NH₃emission increasing was related to the abundance of Bacillus,Limnochorda,and Ammoniibacillus.