Effects Of Different Fertilizer Practices On Greenhouse Gas Emissions And The Corresponding Econimic And Comprehensive Effects

Climate change has become a global environmental problem.The main cause of climate warming is due to the rise of greenhouse gases.CO₂,CH4 and N2O were the major greenhouse gases.Agriculture was an important source of greenhouse gases and contributes 13.5%to the total global GHG emissions.The Liaohe Plain was one of the important major grain-producing areas in China,was a corn gold belt.Research and screening of simple corn high yield and high efficiency,low carbon,low fertilizer and farming management measures to guide the efficient low carbon agriculture has a long term.With five measures of the non-nitrogenous fertilizer control?CK?,the regular fertilization by farmers?F?,the regular fertilization by farmers with biochar?FC?,the pyridine-coated urea?FP?,the regular fertilization by farmers with straw semi-farm return?FS?,this study selected the optimal fertilization measure in brown soil of maize for the high-yield,high-efficiency,low-emission and low-carbon by the analysis of CO₂?N2O emissions,soil inorganic nitrogen,maize production life cycle carbon footprint,maize yields and O/I ratio.The results of the experiment in the Liaohe Plain in 2016 showed that:?1?Soil temperature was the main factor affecting the soil CO₂ emissions,and has significant correlation between CO₂ emissions;Largest CO₂ emission flux in the Bell stage,covering whole growth period of spring maize 26.0%,at this point the crop grows most vigorous,and top dressing increases soil organic matter content and promotes soil CO₂ emissions.?2?The seasonal variation of N2O:flux in soils during the growth period of spring maize was basically the same,the N2O emission peak is mainly affected by fertilization and was closely related to soil moisture content and soil temperature;The N2O accumulation of the fertilization treatment in the maize growth period was higher than CK treatment,Compared with F treatment,FP,FC and FS were reduced by N2O27.2%,23.7%and 6.5%.The FP treatment had the most effective emission reduction.?3?The dynamic trend of the soil inorganic nitrogen content in the effect of the fertilization were basically the same,but the soil ammonium nitrogen and the soil nitrate nitrogen content value in different treatments was not,and the soil ammonium nitrogen content was higher in the effect of the fertilization,then decreased gradually accompanied with the corresponding increased of the nitrate nitrogen content,with the emergence of N2O emission peak.and because of the difference of soil temperature and moisture in the base fertilization and top dressing,change widths of soil inorganic nitrogen content were different.FP treatment showed a significant effect in inhibiting the conversion of soil inorganic nitrogen from ammonium to nitrogen,reducing the N2O loss and possible risk of leaching in inorganic nitrogen fertilizers;?4?Compared with F treatment,FP,FS and FC treatments all ensured the high and stable yield of maize,which was 4.4%,2.1%and 9.8%higher than F treatment.The largest carbon footprint of corn in the production process was the direct N2O emissions and the carbon emissions of fertilizer production process,Respectively,accounting for 55.1%-62.8%and 31.5%-38.0%of the total carbon footprint.The conclusion was that the most suitable fertilization measure in high-yield,high-efficiency,low-emission and low-carbon was FP treatment with the comprehensive index being the optimal by analyzing the weight index of the yield,O/I ratio,N2O field emission and carbon footprint and other factors of spring maize production process.