Response Of Greenhouse Gas Emission Characteristics In Spring Maize Field To Nitrogen Reduction Combined With Biochar Application

In recent years,the research of biochar is more and more extensive,which can improve soil quality and reduce greenhouse gas emission.Due to the high greenhouse gas emissions from the farmland caused by the spring maize cultivation,environmental pollution and climate change have become the hot issues of global concern,therefore,the problem of alleviating environmental pollution has become the most serious one.In this study,a two-year bio-carbon experiment was carried out.Four different bio-carbon gradients（0,8,16,24 t/hm²）and three nitrogen fertilizers（0,150,300 kg/hm²）were used under normal water and water control during growth period,it is of great significance to clarify the characteristics of greenhouse gas emission,soil physical and chemical properties and the variation of maize yield in order to increase grain yield and reduce environmental pollution.The main findings are as follows:（1）Nitrogen reduction combined with biochar application can change soil physical properties,decrease soil bulk density and soil compactness,increase soil water content,and increase particulate and soluble organic carbon,microbial biomass carbon and nitrogen content.The content of soil organic matter reached its maximum at a carbon application rate of 24 t/hm²,with C₂₄,C₁₆,and C₈treatments increasing by 24.88%,18.16%,and14.03%compared to C₀treatments,respectively.（2）Nitrogen reduction combined with biochar can inhibit CO₂,N₂O,and CH₄emissions.The correlation analysis showed that there was a significant positive correlation between CO₂emission flux and soil temperature and soil water content（P<0.01）,and a significant positive correlation between CH₄emission flux and soil temperature（P<0.01）.There was a significant positive correlation between CH₄emission flux and microbial biomass carbon,nitrogen,and particulate organic carbon（P<0.05）.N₂O emission flux was positively correlated with soluble organic carbon significantly（P<0.01）.In the normal irrigation N₁₅₀treatment at jointing stage,C₂₄,C₁₆,and C₈decreased by 10.26%,6.09%,and 1.64%compared to C₀,respectively.（3）There were significant differences in the comprehensive warming potential under different biochar and nitrogen fertilizer application rates.The comprehensive warming potential of maize field treated with N₀was the lowest.Excessive application of nitrogen fertilizer will increase the comprehensive warming potential of corn fields.Adding biochar to spring corn farmland soil can reduce greenhouse gas emission intensity.In the normal irrigation N₁₅₀treatment,C₂₄,C₁₆,and C₈reduce greenhouse gas emission intensity by27.54%,19.76%,and 12.81%compared to the control C₀treatment.（4）The combination of biochar and nitrogen fertilizer can help improve crop yield.After drought stress,corn yield significantly decreased compared to normal irrigation.The combination of reduced nitrogen fertilizer and biochar has a better yield increase effect,and the best treatment combination is C₂₄N₁₅₀.To sum up,biochar combined with reduced nitrogen fertilizer can improve soil physical structure,promote maize plant growth and development,and reduce greenhouse gas emissions from farmland.Among the 24 treatments,C₂₄N₁₅₀was the best treatment combination,which could promote the best growth effect of spring maize.