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Title: FIELD VALIDATION OF THE DNDC MODEL FOR GREENHOUSE GAS EMISSIONS IN EAST ASIA CROPPING SYSTEMS.

Author
item CAI, ZUCONG - NANJUNG, CHINA
item SAWAMOTO, TAKUJI - TSUKUBA, JAPAN
item LI, CHANGSHENG - U. NEW HAMPSHIRE
item KANG, GUODING - NANJING, CHINA
item BOONJAWAT, JARIYA - BANGKOK, THAILAND
item MOSIER, ARVIN
item WASSMANN, REINER - IMK-IFU, GERMANY
item TSURUTA, HARUO - TSUKUBA, JAPAN

Submitted to: Global Biogeochemical Cycles
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2003
Publication Date: 10/1/2003
Citation: Cai, Z., Sawamoto, T., Li, C., Kang, G., Boonjawat, J., Mosier, A.R., Wassmann, R., Tsuruta, H. 2003. Field validation of the DNDC model for greenhouse gas emissions in east asia cropping systems. Global Biogeochemical Cycles. 17:1107.doi:10.1029/2003GB002046.

Interpretive Summary: The atmospheric trace gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are major contributors to global warming and, in historical terms, their concentrations are increasing rapidly. These trace gases are long-lived in the atmosphere and well mixed so that emissions from one part of the world directly influence atmospheric warming throughout the planet. Food production contributes approximately 70 and 40 % of global atmospheric input of N2O and CH4 to the atmosphere, respectively and cropped soils have the potential to sequester atmospheric CO2. Rice-based agriculture is an integral part of global food production and plays a major role in global greenhouse gas exchange. Almost half the people in the world eat rice at least once a day. Rice farms cover 11 percent of the world's arable area. Total rice paddy area in Asia is 1.38 million km2, which accounts for 90% of global rice area (1.55 million km2) and ~20% of total world cropland area for grain production. Rice based crop production is presently undergoing a new revolution. Large scale mechanical tillage, direct seeding rather than transplanting, mid-season draining of rice fields, changing from two rice crops per year to one rice crop and one upland crop, incorporation of rice residue rather than burning, and new rice varieties are among the large changes in rice-based agriculture production management that are either being considered or taking place today across Asia. A demand for predicting effects of the new changes in rice production management in Asia on global atmosphere as well as the local environmental conditions is emerging. To answer the challenge, the process-oriented model DNDC was validated against field data from China, Japan and Thailand. The study was conducted as a part of an Asian Pacific Network for Global Change Research project on "Land Use/Management Change and Trace Gas Emissions in East Asia".

Technical Abstract: Validations of the DeNitrification-DeComposition (DNDC) model against field data sets of trace gases (CH4, N2O and NO) emitted from cropping systems in Japan, China and Thailand were conducted. The model simulated results were in agreement with seasonal N2O emissions from a lowland soil in Japan from 1995 to 2000 and seasonal CH4 emissions from rice fields in China but failed to simulate N2O and NO emissions from an Andisol in Japan as well as NO emissions from the lowland soil. Seasonal CH4 emissions from rice cropping systems in Thailand were poorly simulated because of site specific soil conditions and rice variety. For all of the simulated cases, the model satisfactorily simulated annual variations of greenhouse gas emissions from cropping systems and effects of land management. However, discrepancies existed between the modeled and observed seasonal patterns of CH4 and N2O emissions. By incorporating modifications based on the local soil properties and management, DNDC model could become a powerful tool for estimating greenhouse gas emissions from terrestrial ecosystems.