Open AccessValidation of revised DNDC model for methane emissions from irrigated rice fields in Thailand and sensitivity analysis of key factors
Author(s) -
Smakgahn Kruamas,
Fumoto Tamon,
Yagi Kazuyuki
Publication year - 2009
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008jg000775
Subject(s) - environmental science , paddy field , methane , biomass (ecology) , greenhouse gas , straw , atmospheric sciences , agronomy , biogeochemical cycle , simulation modeling , soil science , mathematics , environmental chemistry , chemistry , ecology , geology , biology , mathematical economics , organic chemistry
The original Denitrification–Decomposition (DNDC) model and a revised version were tested against data from field observations of methane (CH 4 ) emissions from irrigated rice fields in Thailand. The revised DNDC model, which was modified for use in Japanese rice fields by revising the crop growth and soil biogeochemical submodels, yielded better simulation results than the original model. In most cases, daily CH 4 fluxes predicted by the revised DNDC model agreed well with observations. Seasonal CH 4 emissions simulated by the revised model showed significantly higher correlation with observations than those obtained with the original model. Errors in the simulation appear to have resulted from uncertainties in both the input parameters and the model descriptions. Sensitivity analysis revealed that the revised DNDC model is highly sensitive to the concentration of reducible soil Fe, the rate of rice straw incorporation, and rice root biomass. Therefore, uncertainties in these factors may strongly affect the prediction of CH 4 emissions. These results suggest that for reliable prediction of CH 4 emissions from Thai rice fields, further work is needed to improve the estimates of reducible soil Fe, to quantify the rate of straw incorporation, and to parameterize the crop submodel for the dominant rice varieties grown in Thailand.