| With global warming becoming a common environmental hotspot issue in various countries,farmland is increasingly receiving attention as an important source of greenhouse gas emissions.Methane(CH4),carbon dioxide(CO2)and nitrous oxide(N2O)are the main atmospheric greenhouse gases.The study found that organic fertilizer has a significant effect on the reduction of greenhouse gas emissions from farmland with longterm application of chemical fertilizers.Therefore,how to realize the scientific and rational use of organic fertilizer and reduce the greenhouse gas emissions from farmland during the application process is the current research hotspot and focus.This study takes the typical rice-wheat rotation system in the Jianghuai hilly area as the research object,setting 100%nitrogen fertilizer(UF),organic fertilizer+80%nitrogen fertilizer(OF20),organic fertilizer+60%nitrogen fertilizer(OF40)and 100%organic fertilizer(OF)Four treatmentss,using static chamber-gas chromatography to measure the CH4,N2O and CO2 emissions of the rice field ecosystem,analyze the changes in the potential for greenhouse gas temperature increase and the intensity of greenhouse gas emissions in rice fields by different fertilization treatmentss,and propose the farmland in the region Reasonable fertilization measures to reduce emissions and increase production,the research results show that:(1)The emission characteristics of CO2,CH4 and N2O in the wheat and rice seasons are different.The emission dynamics of CO2 emissions in the wheat and rice seasons are similar,but the emissions are different,mainly affected by temperature;CH4 emissions in the wheat season Small,showing the phenomenon of CH4 absorption,and large emissions in the rice season,which mainly become the "source" of CH4;N2O emission is the opposite of CH4.(2)Compared with UF,the emissions of CH4 and N2O treated by OF20 in the wheat season were reduced by 16.88%and 15.76%,respectively.The emissions of CH4 and N2O treated by OF20 in the rice season were reduced by 8.21%and 50.12%respectively;Will increase N2O emissions in the wheat season,but OF40 and OF treatment in the rice season will significantly increase N2O emissions.The OF40 and OF treatments in the wheat season increased by 6.19%and 10.82%,respectively,while the OF40 and OF treatments in the rice season were 44.09%and 7.55%,respectively.Compared with UF,the CO2 emissions from OF20 treatment in the rice season increased by 7.67%,while the wheat season increased by 7.04%.There was no significant difference in CO2 emissions from the remaining treatments.Comparing the temperature increasing potentials of the treatment units,the order of magnitude is:OF40>OF>UF>OF20.OF40 and OF treatments increase the comprehensive temperature increasing potential of greenhouse gases under the rice-wheat rotation mode,increasing by 44.05%and 41.25%,respectively;Organic fertilizer instead of OF20 treatment will not increase.(3)The change trend of soil moisture in different treatments is basically consistent.CO2 emissions in the wheat and rice seasons are significantly positively correlated with soil temperature,CO2 emissions in wheat fields are significantly negatively correlated with soil moisture,rice fields are positively correlated,and CH4 emissions in rice fields are extremely significantly correlated with soil temperature and positively correlated with soil moisture.The nitrate nitrogen content of the soil during the growth period of wheat presents the rule of high in the early stage and low in the late stage,while the opposite is true in the rice season.The content of ammonium nitrogen in the wheat season is relatively high during the booting period.The rice season mainly shows high contents in the seedling and tillering stages and low contents in the booting and harvesting periods.The CO2 emissions in the wheat season have a significant correlation with nitrate nitrogen and ammonium nitrogen during the greening and jointing stages,respectively.The N2O emissions have a significant correlation with nitrate nitrogen and ammonium nitrogen during the greening and booting stages.The CO2 emissions during the rice booting stage were significantly correlated with ammonium nitrogen.(4)Compared with UF treatment,grain yields of OF40 and OF treatments in wheat season decreased by 1.18%and 4.25%,respectively,and OF20 treatment did not increase yield significantly;OF20 and OF40 treatments could significantly increase rice yield,by 3.03%and 3.26%respectively.Compared with the UF treatment,the application of organic fertilizer and combined application of organic fertilizer had no significant effect on the appearance and processing quality of rice,but had a significant effect on cooking and eating quality;the organic substitution ratio of chemical fertilizer had no significant effect on the grain quality of wheat season.According to the total output of wheat and rice,compared with UF,the organic substitution of chemical fertilizers significantly affects the total output of rice-wheat ecosystem and grain quality.The results of this experiment show that considering the comprehensive effect of greenhouse gas,OF20 treatment is the best,which can not only reduce greenhouse gas emissions,but also ensure high yield of rice and wheat. |
