| Animal manure produced in livestock industry became one of the important pollution sources of NH3 and greenhouse gas(CH4,N2O)emissions.Therefore,how to reduce the gas emissions of the animal production industry was the core task of realizing the green development of animal industry.In order to explore the impacts of biochar and microbial agent on the NH3,CH4 and N2O emissions from liquid manure storage,this study selected four types of alkaline biochar including walnut shell charcoal(G),coconut shell charcoal(Y),coal-based carbon(M)and bamboo charcoal(Z)to investigate the their adsorptions of ammoniacal nitrogen,and then examined the effects of biochar and microbial agent(J)addition on the NH3 and greenhouse gas(CH4,N2O)emissions during the storage of liquid pig manure.This was of great significance for testing whether biochar and microbial agent control technologies reducted gas emission effects of liquid manure.The main results were as follows:(1)The adsorption capacity of different biochars for ammoniacal nitrogen in water increased with the increase of the initial concentration,but none of them reached adsorption saturation,and they were mainly multi-molecular layer adsorption and uneven adsorption.(2)When estimated the ammonia nitrogen adsorption capacity of biochar,the conditions for the ammonia volatilization process needed to be considered:① when the pH of biochar was greater than 9.0,the influence of ammonia volatilization process should be considered at all equilibrium concentrations;② when the pH of Biochar was 7.5 to 9.0,ammonia volatilization should be considered when the concentration of ammonia nitrogen solution ranged from 10 to 375 mg·L-1.(3)The addition of biochar increased the cumulative emissions of liquid manure NH3,CH4 and N2O,and the increase was 1.23～5.10,1.00～3.30 and 0.54～6.49 times that of the treatment without biochar.In the treatment of adding biochar,the amount of adsorbed N on the biochar accounted for 2.21%,2.29%and 21.37%of the N loss,which was much smaller than the total N loss of NH3 and N2O.(4)The total greenhouse gas emissions from the addition of biochar increased by 68%-628%,of which the total greenhouse gas emissions of the combined application of biochar and microbial agent were 3.06%-43.88%lower than the total greenhouse gas emissions of the single application of biochar.The increased NH3-N losses of all biochar treatments also played an important role in indirect greenhouse gas emissions(6%-14%),while N2O emissions contributed very little to the total greenhouse gas emissions.(5)The pH of all treatments increased by 1.00～2.45;the content of TN and TOC decreased as expected;the addition of biochar accelerated the loss of TAN content in manure,but increased the germination index of seeds.(6)In all biochar treatments,the acidic functional groups of biochar increased by 1.17-8.62 times,and the total pore volume and BET of biochar also changed(both Y and M increased,and G decreased).After the 42th day,the adsorption capacity of all biochars to N eached the peak,and the adsorption capacity of biochar M to N was the strongest.The addition of microbial agent had no obvious effect on the properties of biochar.In summary,when the pH of alkaline biochar was higher than the pH of pig manure,it may promote the emissions of NH3 and greenhouse gases(CH4 and N2O)in liquid pig manure,and was not suitable as a liquid manure gas reduction additive.It was recommended to further research on the emission reduction effects of low pH biochar(<liquid manure pH)or acid-modified biochar(pH<7)should be carried out to provide technical support for the scientific management of liquid manure. |
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