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MODELING THE RICE BUDGET IN CHINA USING GIS TECHNOLOGY
Citation:
Bachelet, D., J. Kern, AND M. Tolg. MODELING THE RICE BUDGET IN CHINA USING GIS TECHNOLOGY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-93/244 (NTIS PB94107976), 1993.
Description:
Rice paddles are a source of food for over half of the world population and also the source of a very potent greenhouse gas, methane. sing GIS-linked climate based and yield-based empirical models, we calculated the net primary production (NPP) of rice fields in China. alues varied between 136 1012gC using climate drivers from digital maps to 222 1012gC using published grain production figures for 1988. ssuming either 5% of NPP or 30% of the organic matter added to the soil during rice cultivation were transformed into methane, adding up to a total emission of 7 to 16 1012gC. e also gathered published data on fertilizer inputs and management practices and, using linear regression techniques, calculated the correlation between methane emission and carbon inputs to obtain a total emission value of 10 1012gC. sing our results for NPP (135-222 1012gC), methane emission (7-16 1012gC) and published grain production figures, we balanced the carbon budget of rice paddies estimating soil respiration at 51 1012gC for all Chinese rice fields or 159 gCm-2y-1 for an average Chinese rice field, a number which agrees with published values for similar systems. his result confirmed our assumption that rice soils in China, where rice cultivation has occurred for several thousand years, were neither losing or accruing carbon. owever, any changes in the hydrology of these soils may transform them into significant carbon sources. sing the Food and Agricultural Organization (FAO) digital map of the soils of the world, we estimated soil carbon content for the rice-growing regions of China and quantified the potential carbon losses that would occur if these soils were drained.
