| Dryland farm of the Loess Plateau is an important source and/or sink of nitrous oxide(N2O), Carbon dioxide (CO2), methane (CH4) emission and it plays an important role inagricultural production in our country. Net exchange of the three greenhouse gas betweenatmosphere and soil composed of global warming potential of the crop production systems.There are not too many researches about the significant effect of biochar on N2O, CO2, CH4emission and then achieve mitigation and sink enhancement about dryland ecosystem. So wehypothesized that the biochar would affect the emission of greenhouse gas from drylandecosystem, which was also influenced by fertilization. In order to prove the hypothesis, wesetted a natural field experiment of the spring maize in the dry farmland on the Loess Plateau.The closed static opaque chamber-gas chromatography was used to continuously monitor theN2O, CO2, CH4emission of dryland farm under different addition of biochar(0,10,20,30thm-2) during the spring maize season on the Loess Plateau. And the possible influence factorswere analyzed by using the correlation analysis in this study. The aim of the research was tooffer some scientific evidences to adjust and control the greenhouse gas emission byreasonably adding the biochar to the dry farmland. The main results were showed as follows:1. Biochar amendments inordinately increased the soil temperature of the surface (0cm)and at a depth of10cm, decreased the soil nitrate nitrogen (NO3--N) and ammonium nitrogen(NH4+-N) content of the top soil (0~20cm) under N fertilizer condition. But no significantdifference of soil moisture of the top soil (0~20cm) was found with biochar amendment.2. Biochar amendments decreased the N2O flux and cumulative N2O emission with thenitrogen application.30t hm-2biochar amendment (C3N1) significantly decreased thecumulative N2O emission compared with no biochar with N fertilizer (C0N1)(P<0.01).Whether biochar or not, N fertilizer significantly increased N2O flux and cumulative N2Oemission under the maize growing season. The correlation analysis showed that N2O flux hada significant positive correlation with NO3--N and NH4+-N content (P<0.001) but significantnegative correlation with soil temperature of the surface (0cm)(P<0.01) and at a depth of10cm (P<0.05). Comprehensive analysis of the results showed that the decrease of NH4+-N content could be the major influence factor of N2O emission reduction.3. Biochar amendments decreased inordinately CO2flux and cumulative CO2emissionduring the maize growing season.20t hm-2biochar amendment significantly decreased theCO2flux and cumulative CO2emission (P<0.05) compared with no biochar and no Nfertilizer condition (C0N0).30t hm-2biochar amendment of had a significant decrease effecton CO2flux and cumulative CO2emission (P<0.05) compared with C0N1. The correlationanalysis showed that CO2flux had no significant correlation with soil moisture before andafter cuting the maize plant, but had a significant positive correlation with soil temperature (0cm and10cm). The soil temperature was the key impact factor of CO2emission.4. Obvious fluctuation was found in agricultural CH4emission, and negative emissionsmeans the dry farmland is the CH4reservoir during spring maize growing season. CH4fluxand cumulative CH4emission had an insignificant difference between different treatments.The correlation analysis showed that CH4flux had a significant positive correlation with soilmoisture but no significant correlation with soil temperature under different treatments. CH4flux had a significant negative correlation with NH4+-N content under no N fertilizertreatments, but no significant correlation with NO3--N and NH4+-N content under N fertilizertreatments. The change of soil moisture from the rainfall was the major impact factoradjusting CH4emission.5. N fertilizer had a significant effect on warming potential and greenhouse gasintensity of maize farmland. Biochar amendments also changed the warming potential andgreenhouse gas intensity of maize farmland. The grater the biochar application rate, the lowerthe warming potential and greenhouse gas intensity with nitrogen fertilizer.30t hm-2biocharamendments significantly decreased the warming potential and greenhouse gas intensitycompared with no biochar and10t hm-2biochar. Under conditions of no nitrogen fertilizer,20t hm-2biochar amendments had little effect on warming potential of farmland but had anincreasing trend on greenhouse gas intensity.The preliminary results indicated that biochar amendment could decrease the N2O, CO2flux and cumulative emission with N fertilizer during spring maize growing season in drylandfarm of the Loess Plateau and had an effective control of warming potential and greenhousegas intensity of maize farmland. |
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