Agricultural Science Research Journal




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Vol. 2 No.

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Pumijumnong N
Arunrat N


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Agricultural Science Research Journal Vol. 2(12), pp. 614- 622, December  2012

ISSN-L: 2026-6073 ©2012 International Research  Journals  



Full Length Research Paper


Reliability and evaluation of the potential of the i_EPIC model to estimate rice yields in Thailand


Nathsuda Pumijumnong and *Noppol Arunrat


Faculty of Environment and Resource Studies, Mahidol University, Salaya, Phutthamonthon, Nakhon Pathom 73170, Thailand


*Corresponding Author’s E-mail: 




The Interactive Environmental Policy Impact Calculator (i_EPIC) model is an important tool for future agriculture and food security in Thailand. Its application requires both the identification of errors and the assessment of reliability and potential of the i_EPIC model and GIS technique in simulating rice yields. Rice yields estimated by EPIC (version 0509) were compared with agricultural statistics reports from Thailand’s Office of Agricultural Economics (OAE), Ministry of Agriculture and Cooperatives (MOAC). Validation of rice yield data proved to be satisfactory: the mean relative error (MRE %) for major rice (rainy season) being 11.77, mean absolute error (MAE %) 1.22 and root mean square error (RMSE %) 43.06. The corresponding errors for second rice (dry season) were 10.44, 26.01 and 34.91, respectively. Our results show that overall model reliability, with model efficiency (EF%), is 98% for major rice and 97% for second rice, indicating that i-EPIC model performance is reliable for estimating rice yields in Thailand. To improve data accuracy for other variables such as soil, weather and crop information is needed.


Key word: i_EPIC model, EPIC0509, rice, Geographic Information Systems (GIS), Thailand