Effects Of Slow-release Nitrogen Fertilizer And Urease/Nitration Inhibitor On Greenhouse Gas Emission From Black Soil Corn Field In Northeast China

Agriculture is the main source of greenhouse gas emissions,and the application of nitrogen fertilizer is one of the most critical factors in the process of agricultural production.The excessive application of nitrogen fertilizer by farmers in pursuit of high crop yields not only results in a large amount of greenhouse gas emissions,but also directly affects crop yields.Therefore,in order to explore the greenhouse gas emission rule of northeast black soil and corn farmland,reduce the greenhouse gas emission,discuss the influence of determination time on the greenhouse gas emission flux of northeast black soil,and determine the optimal determination time of the emission flux,so as to provide the corresponding scientific basis for the greenhouse gas emission reduction of northeast black soil farmland.In this experiment,the representative farmland black soil in northeast China was taken as the research object,and four treatments including conventional nitrogen application?CN?,slow-release fertilizer?SLN?,urea-added nitrification inhibitor and urease inhibitor?NIUI?without nitrogen application?NN?were set up.The relationship between soil temperature,soil moisture and greenhouse gas emission was analyzed through continuous monitoring of greenhouse gas emission flux of spring corn anniversary?2017-2018?by using static box-meteorological chromatography.Explore the greenhouse gas emission characteristics under different treatment conditions and the effect of fertilizer on production and emission reduction.The comprehensive greenhouse effect was evaluated from multiple perspectives,and reasonable nitrogen fertilizer management measures were selected.The main resultsare as follows:1.The application of nitrogen fertilizer promoted the N₂O emission of soil.The cumulative N₂O emission in NN treatment was 1.09 kg·hm^-2,3.00 kg·hm^-2 in CN treatment,and 1.83 kg·hm^-2 in NIUI,which was 39.0%lower than that in CN.SLN of 3.04 kg·hm^-2 was not significantly different from that of CN.2,CN,SLN and NIUI annual cumulative CO₂ emissions are divided into 17.75 t·hm^-2,18.52 t·hm^-2 and 16.89 t·hm^-2,and there is no significant difference between the three treatments?P>0.05?.In corn growing season,cumulative CO₂ emissions under SLN treatment are increased by 5.3%compared with that under CN,and 7.2%in non-growing season.NIUI treated CO₂ cumulative emissions in growing season decreased by 10.5%compared with CN,and increased by 11.6%in non-growing season.3.Soil CH₄ emission fluxes under different treatments fluctuate in different periods,and the flux has positive and negative values,but there is no rule to follow.Cumulative emissions of CH₄ treated by NN,CN,SLN and NIUI are divided into-1.48 kg hm^-2,-1.31 kg hm^-2,-1.36 kg·hm^-2 and-1.54 kg·hm^-2,which indicates that the northeast spring corn field is a weak sink of CH₄ in the atmosphere,and there is no significant difference between the treatments,indicating that the addition of nitrogen fertilizer will not significantly affect the absorption of CH₄ in the northeast spring corn field.4.The N₂O emission coefficients of CN,SLN and NIUI treatments were 0.68,0.69 and 0.26,respectively.The GWP of the four treatments was SLN>CN,>NIUI>NN.There was no significant difference in the yield of CN,SLN and NIUI treatments with the same amount of nitrogen.The GHGI of CN and SLN was significantly higher than that of NIUI,and the GHGI of NIUI was only 17%higher than that of nitrogen free treatment.5.The trend of N₂O and CO₂ emission fluxes in spring corn soil under four nitrogen fertilizer treatments was roughly consistent with the diurnal temperature change trajectory,showing a trend of high day and low night.The variation trend of CH₄ emission flux is different in different periods and has no law to follow.6.If three kinds of greenhouse gases are observed at the same time,the best sampling time after sowing to seedling emergence is from 7:00 to 8:00,the best observation time at seedling stage and jointing stage is from 21:00 to 22:00,the best observation time at grouting stage is from 9:00 to 10:00,and the best sampling time at mature stage and after harvest is from 18:00 to 19:00.7.The total carbon footprint of the production of the four corn treatments was the average carbon footprint size in 2 years?CN>SLN>NIUI>NN?.In addition to NN,the total carbon footprint of NIUI was the least.From 2017 to 2018,NIUI has the lowest carbon intensity and the highest carbon efficiency,respectively 6.71 kg·CO₂·hm^-2 and 4.93 kg·CO₂·hm^-2,while SLN and CN have no significant difference in carbon intensity.