Effects Of Nitrogen And Phosphorus Addition On Greenhouse Gas Emission From Alpine Peat Wetland And Its Enzymatic Mechanism

Wetland soil is an important "emission source" and "sink,of greenhouse gases in the world.As a result of industrial development and changes in hunan activities,the amount of atmospheric nitrogen deposition inereased rapidly.The rapid development of animal husbandry will lead to a large number of livestock manure to increase soil phosphorus input.The increase in nitrogen and phosphorus inputs will change the circulation of soil material,which in turn affects greenhouse gas emissions.In this study,alpine peat wetland soil was used as the research object.After the in-situ nitrogen,phosphorus addition test and indoor culture experiments,different nitrogen and phosphorus addition treatments:(control;nitrogen addition:20 kg N·ha-1·yr-1;phosphorus addition:15 kg P·ha-1·yr-1;nitrogen+phosphorus addition:20 kg N·ha-1·yr-115 kg P·ha-1·yr-1)on alpine wetland peat soil properties and greenhouse gases(CO2,N2O,CH4)emissions were analyzed,and through the soil enzyme activity to reveal its emission mechanism.Through the field monitoring of two growing seasons,the main conclusions are:Nitrogen addition treatment increased soil total nitrogen,NH4+-N,NO3'-N content and soil nitrogen availability,then increased soil microbial metabolism substrate,soil root metabolism and microbial biomass,thereby promoting soil carbon,nitrogen and phosphcorus mineralization rates and increasing the urease,acid phosphatase,glucosidase activity,finally significantly increased soil CO2,CH4 and N2O emission rates,and CO2,CH4 and N2O cumulativee missions were increased by 1.06,1.62 and 1.04 times,respectively.Phosphorus addition treatment increased soil total phosphorus and available phosphorus content,so that the surplus phosphorus can be assiailated by microorganisms.Phosphorus addition also increased the microbial biomass and soil carbon,nitrogen and phosphorus mineralization rates.and because of the soil feedback mechanism improved the urease and ?-glucosidase activities,there by increasing the soil CO2 and CH4 emission rates.And soil CH4 cumulative emissions significantly increased by 1.67 times.While the effect of phosphorus addition on soil CO2 emissions has a time lag effect,and the CO2 emission did not significantly increase until the second growing season.As phosphorus addition promoted the absorption of nitrogen by vegetation,and reduced the substrate of nitrification and denitrification,the cumulative emission of N2O was not affected.Nitrogen+phosphorus addition treatment increased soil total nitrogens NH4+-N,NO3'-N,total phosphorus and available phosphorus content,and increased the availability of nitrogen and phosphorus in soil.So that the increase of soil and root metabolism to speed up the breeding of microorganisms,and then increased the microbial biomass and soil carbon,nitrogen and phosphorus mineralization rates.Thereby improving the the urease,acid phosphatase,p-glucosidase activity,and significantly increased soil CO2,CH4 and N2O emission rate,and CO2,CH4 and N2O cumulativee missions were increased by 1.01,3.41 and 0.83 times.There is no significant difference between nitrogen+phosphorus addition and nitrogen addition treatments on CO2 or N2O cumulative emissions.nitrogen and phosphorus has a synergistic effect on soil accumulation CH4 emission to promote the role of the largest.There was no significant difference between single nitrogen and phosphorus addition.