The Spatial Characteristics Of Greenhouse Gas?CO₂ And N₂O?Emissions With Manure Application In Dry Land Of The North China Plain

Greenhouse gas?GHGs?emissions caused by agricultural activities have become one of the most important factors of global warming.The main components of GHGs are CO₂ and N₂O,whose key emission source is dry land.The GHGs emission level in dry land and its mitigation technology are attracting widespread attentions from the government and researchers.The winter wheat-summer maize cropping system in the North China Plain was studied.The spatial characteristics of CO₂ and N₂O emissions and global warming potential?GWP?in dry land soil of the North China Plain under three fertilization scenarios,chemical fertilizer?NPK?,50%of chemical fertilizer combined with 50%of manure?NPKM?5:5??and 30%of chemical fertilizer combined with 70%of manure?NPKM?3:7??were studied by using SPACSYS model and GIS spatial interpolation.Results shows that:1?The SPACSYS model can capture the dynamic changes of soil CO₂ and N₂O emissions in 3arable lands in the North China Plain,and the correlation between the simulated and observed reaches extremely significant level?p<0.01?.Therefore,the model is suitable to simulate soil CO₂ and N₂O emissions of winter wheat-summer maize cropping system in the North China Plain.It provides a basis for the model to estimate regional greenhouse gas emissions.2?Soil CO₂,N₂O emissions and its GWP of the winter wheat-summer maize cropping system in the North China Plain shows obvious spatial variability in 2010.The areas with high soil CO₂ emission are located at beijing,tianjin,northern jiangsu province,northern anhui province,hebei province and eastern shandong province;High N₂O emission zones are concentrated in eastern and southern shandong province;The region with high GWP is shandong province.In the winter wheat-summer maize cropping system in the North China Plain in 2010,the average CO₂ emission per unit area with chemical fertilizer was 2581 C kg/?ha yr?,the average N₂O emission per unit area was 20.5 N kg/?ha yr?,and the average GWP per unit area was 5,208 C kg/?ha yr?.Compared with single application of chemical fertilizer,manure combined with chemical fertilizer can significantly increase soil CO₂emissions,reduce soil N₂O emissions,and has no significant impact on GWP.3?Similar with 2010,the high soil CO₂ emission area of winter wheat-summer maize cropping system in the North China Plain are located at beijing,tianjin,northern jiangsu province,northern anhui province and eastern shandong province after 40 years of fertilization;High N₂O emission zone is concentrated in shandong province;The area with high GWP is shandong province.Compared with2010,the soil CO₂ emissions in most regions of the North China Plain are increased after 40 years of fertilization under 3 fertilization scenarios,among which the highest increase amount of treatment is chemical fertilizer,reaching 525 C kg/ha;Soil N₂O emissions decreased in all regions;The GWP of most regions are decreased under manure combined with chemical fertilizer treatments.Compared with2010,low amount of manure combined with chemical fertilizer treatment shows the smallest GWP increment under long-term application of the 3 fertilization scenarios for 40 years,which is about half that of the single application of chemical fertilizer and high amount of manure combined with chemical fertilizer treatment.In conclusion,compared with the single application of chemical fertilizer,manure combined with chemical fertilizer significantly increase soil CO₂ emission and reduce soil N₂O emission.In the long run,manure should be applied on the basis of chemical fertilizer,and manure should be adopted to replace 50%of chemical fertilizer in dry land of North China Plain,which is more conducive to reducing greenhouse gas emissions.