Development And Application Of The CHINA-DNDC Online Model

Global agro-ecosystems are the main source of non-CO₂ greenhouse gases emission.Appropriate practices of carbon sequestration and emission mitigation have a significant influence on global climate change.However,various agricultural practices usually have comprehensive impacts on greenhouse gas emissions.It is very difficult to accurately quantify the effect of agricultural practices.Quantitative prediction of greenhouse gas emissions from agro-ecosystems under different scenarios is important for the development and application of appropriate agricultural management.Based on the scientific mechanisms related to the generation and emission of farmland greenhouse gases,a number of scientific process models have been developed.Among them,the DNDC model can relatively accurately simulate the processes of soil physiology,crop growth and carbon and nitrogen cycles.It has been widely used in the study of soil carbon and nitrogen dynamics,crop growth and greenhouse gas emissions.Based on the theory of biogeochemistry and the model process developed by the author of the DNDC model,this study re-coded the scientific core process of the DNDC model and developed a model program—the CHINA-DNDC model,which is applicable to the universal internet application.The universal event response function template and the action process of nitrification inhibitor and biomass charcoal are added to improve the scientific reliability and extensibility of the DNDC model.Based on the geography,climate,soil and farmland management information of 2473 county-level sites in China collected by this research group,this paper established a parameter database for the CHINA-DNDC model.It provides the data reference of the initialization parameters for the users of the CHINA-DNDC model,and also supports the supplement and correction of the parameters related to the operation of the DNDC model.This study designed and developed a visual network platform and integrated it with the CHINA-DNDC model and the model parameter database into the CHINA-DNDC online model.As a user interface,the visual network platform is used to query the model parameter database,edit the initialization parameters of the simulation scenario,and acquire the simulated results.The development of the CHINA-DNDC online model provides universality of the computer system environment to the DNDC model and simplifies the application and management of the DNDC model.According to the filed measured data,this study estimated the crop yield and greenhouse gases emission of two sample fields by the CHINA-DNDC online model.The results showed that the simulated value had no significant difference with the measured value.This study also estimated the annual greenhouse gas emissions from paddy fields in Shanghai,Zhejiang,Jiangsu and Anhui as the model application test in estimating greenhouse gases emission.This study also conducted the model application test on the carbon sequestration and emission mitigation research by estimating the effects of five paddy rice field management practices including nitrogen fertilizer reduction,straw returning,mid-season drainage,nitrification inhibitor and biomass charcoal.The results show that each practice has certain positive effects on soil carbon sequestration and emission mitigation.The development of the CHINA-DNDC online model has a great significance of the research and application of the DNDC model.It also provides technology support for the agricultural workers,researchers and governors to formulate and apply appropriate farmland carbon sequestration and emission mitigation practices.