Effects Of Exogenous Nitrogen,Phosphorus And Copper On Methane Oxidation In Five Soils Of Northern Hainan Island

In recent years,Global warming is becoming a hot topic for people to focus on climate change.Greenhouse gases,such as CH4,CO2 and N2O,are the main factors affecting global warming.The ratio of CH4 content to total greenhouse gas is relatively small,but its warming potential is relatively large.Soil CH4 oxidation affects the content of atmospheric CH4,and plays an importsant role in the global carbon cycle and csarbon balance study.The input of nitrogen,phosphorus and copper is an important factor that affects the atmospheric CH4 of soil oxidation and absorption.Under the condition that the initial methane concentration was 15?l/l,soil water content was 15%,26 ? constant temperature shading,the oxidative absorption capacity of different soil types on low concentration CH4 and its response to different concentrations of nitrogen,phosphorus and copper were evaluated by indoor culture test of 5 kinds of soil in Northern Hainan.The results show that:(1)There are some differences in the CH4 oxidation capacity of 5 soils,such as Humi-Udic Andosols(H1),Hapli-Udic Andosols(H2),Udi-Vitric Andosols(H3),Rhodi-Udic Ferralosols(T2)and Hapli-Udic Ferralosols(T3).Among them,Udi-Vitric Andosols(H3)Methane oxidation rate is the highest,175.39 ng/(kg · h),Secondly,the oxidation rate of methane in Hapli-Udic Andosols(H2)and Hapli-Udic Ferralosols(T3)is 151.73 ng/(kg h),132.55 ng/(kg h).The CH4 oxidation rate of Humi-Udic Andosols(HI)and Rhodi-Udic Ferralosols(T2)is low,between 68.57?75.64 ng/(kg h),and there is no significant difference between the two soils(p>0.05).(2)Add(NH4)2SO4 at 0,20,60,100,200,300 mg N/kg,the CH4 oxidation of 5 kinds of soil had a significant inhibitory effect,the average inhibition rate was 32,17%,50.61%,29.93%,36.28%and 24.8%.With the increase of the concentration of exogenous N,the inhibition of soil CH4 oxidation gradually increased.(3)Add KH2PO4 at 0,25,50,75,100,125 mgP/kg,the CH4 oxidation of 5 kinds of soil was promoted and first promoted after inhibition.With the increase of the concentration of exogenous p,Hapli-Udic Ferralosols(T3)gradually enhanced effect.The CH4 oxidation promoting effect of H2 and T2 is first enhanced and then weakened.The CH4 oxidation promotion of Humi-Udic Andosols(H1)and Udi-Vitric Andosols(H3)were enhanced first and then weakened and then inhibited.Calculate the exogenous P concentration corresponding to the maximum oxidation rate of CH4 in the five soils according to the fitting equation,they were 53.14 mg/kg,54.43 mg/kg,40.65 mg/kg,78.31 mg/kg,57.68 mg/kg.(4)Add CuSO4 · 5H2O by 0,50,100,200,300,mgCu/kg,the CH4 oxidation of 5 kinds of soil was promoted and first promoted after inhibition.With the increase of exogenous Cu concentration,The promotion effect of Humi-Udic Andosols(H1),Hapli-Udic Andosols(H2)and Udi-Vitric Andosols(H3)was enhanced first and then weakened.The CH4 oxidation promoting effect of Rhodi-Udic Ferralosols(T2)and Hapli-Udic Ferralosols(T3)was weakened and then inhibited.According to the fitting equation,the external Cu concentration corresponding to the maximum CH4 oxidation rate of 5 kinds of soil was calculated,they were 223.39 mg/kg.231.52 mg/kg.231.43 mg/kg.144.50 mg/kg.205.40 mg/kg.(5)Addition of(N:0+P:75,N:20+P:75,N:60+P:75,N:100+P:75,N:200+P:75,N:300+P:75 mg/kg)(NH4)2SO4 and KH2PO4 to add both N&P.It is found that N&P can inhibit soil CH4 oxidation by adding exogenous nitrogen at the same time.The relieving effect of Hapli-Udic Andosols(H2)and Rhodi-Udic Ferralosols(T2)is higher,this is likely to be related to the background value of soil available phosphorus.(6)Addition of(N:0+Cu:100,N:20+Cu:100,N:60+Cu:100,N:100+Cu:100,N:200+Cu:100,N:300+Cu:100 mg/kg)(NH4)2S04 and CuSO4·5H2O to add both N&Cu,N&Cu tests showed simultaneous addition of exogenous nitrogen CH4 oxidation inhibiting significantly mitigation.The addition of N and Cu to the CH4 of Rhodi-Udic Ferralosols(T2)has obvious promoting effect,and with the increase of exogenous nitrogen concentration,the promotion effect of soil CH4 oxidation was enhanced first and then decreased.Simultaneous addition of N&Cu to the exogenous N inhibits the mitigation of soil CH4 oxidation as the concentration of exogenous N increases.