| Global warming caused by greenhouse gases?GHGs?emissions is one of the most serious issues that the world is facing today.Agricultural is the foremost production activity,but also the important source of GHGs,and agricultural production contributes about 20%of the total GHGs emissions.The soil properties,microbial activity,management practices and the climate conditions can also influence greenhouse gas emissions.Manure application can affect the decomposition and availability of carbon and nitrogen,microbial quantity and activity,and then affect the emissions of GHGs.Although there are many researches toward the effects of manure to GHGs emissions in single site,the overall characteristics about the GHGs emissions of farmland in China remain unclear.The influence of employing manure on soil microbe which is closely linked to the emissions of GHGs also incomplete and ambiguous.Given the scientific problems above,we searched literatures by using China Networks,Wan fang and Web science Springer link with the keywords of“19902017”,"Chinese farmland soil","application of organic fertilizer","soil microbial carbon?SMBC?and nitrogen?SMBN?"and"greenhouse?N2O,CO2 and CH4?"and obtained 195 published papers to construct the data set about the influence of GHGs by the aplication of manure.The database was uesd to study the characteristics of GHGs emissions and SMBC and SMBN from the application of manure in farmland under different conditions?soil properties,management practices and climates?and the influencing factors for SMBC and SMBN by method of Meta-analysis.The study not only can enrich the study of the effects and mechanism of applying manure on GHGs emissions,but also provides the scientific and reasonable measures of fertilizations to achieve the goal of GHGs emissions reduction.The main results and conclusion are as follows:1.The results showed that N2O,CO2 and CH4 emissions were significantly affected by Org-M compared to Min-F?percentage change:-3,+15 and+60%,P<0.05?and Non-F?percentage change:+289,+84 and+83%,P<0.05?,respectively.However,at the same amount of total N input,Org-M decreased soil N2O emission by 13%and CH4 emission by 12%,and increased soil CO2emission by 26%relative to Min-F in upland soils.For paddy soils,N2O,CO2 and CH4 emissions differed by-3%,-36%and+84%between Org-M and Min-F?i.e.,Org-M minus Min-F?.Thus,practices such as application of manure instead of chemical fertilizer and decreasing nitrogen input rate need to be highly considered and optimized under different soils and climate conditions to mitigate GHGs emission in China.2.The area-scaled and yield-scaled fluxes and GHGs global warming potential?GWP?of N2O,CO2 and CH4 were also calculated according to the types of major crops.The yield-scaled fluxes and GWP of CO2 reduced but the area-scaled and GWP of CO2 increased after manure application.The area-scaled and yield-scaled fluxes and GWP of N2O were all decreased after manure application.The area-scaled and GWP of CH4 decreased in wheat and maize field but increased in rice field.After the application of manure,the rice field was a large CH4 emission source.Comprehensive analysis of N2O,CO2 and CH4,after manure application the GWP in wheat and maize field was less than in the chemical fertilizer treatment,but in rice field the GWP was larger in manure treatment(10153 kg CO2-C ha-11 yr-1)than in the chemical fertilizer treatment(7404 kg CO2-C ha-1 yr-1).3.The results indicated that manure application increased SMBC,SMBN,SMBC/SOC and SMBN/TN by 40%,55%,16%and 21%,respectively,across all the observations compared to Min-F.There was a significant positive correlation between SMBC and SMBN and manure carbon and nitrogen input every year?P<0.01?.SMBC/SMBN under manure amendment?6.58 in average?was lower than that with mineral fertilizers?7.86 in average?.4.The meta-analysis was used to conduct to quantify the degree to which climate types,soil properties and agricultural managements regulate the responses of SMBC and SMBN contents,and ratios of SMBC to soil organic carbon?SMBC/SOC?and SMBN to soil total nitrogen?SMBN/TN?under manure amendment compared with Min-F.The study found that the types of manure had the greatest impact on microorganisms,and there was no significant difference between the Min-F and the application of farmer manure with relatively poor nutrient content for the SMBC and SMBN.With the experimental duration increased,the percent change of SMBC and SMBN was slao increased.Variance partitioning analysis showed that differences of soil microbial change between manure and Min-F regulated by soil properties?635%?,climates?1329%?and farming practices?-85%?. |
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