Estimation of crop residue in China based on a Monte Carlo analysis

Accurate crop residue resource estimation is important for bioenergy development. This is done by the ratio of residue to grain (R/G), which is usually regarded constant and is widely used for crop residue estimation though uncertainty is inevitable in practice. In this study, a Monte Carlo algorithm was applied to estimate national crop residue by R/G taken from published reports in China. The estimated result was further mapped in pixels by geographic information system. In 2009, the amount of crop residue was found to be 802.32 million tons (Mt), with 679.36 and 947.28 Mt as the lower and upper limits for 95% confidence limits. Chinese crop residue was dominated by rice, wheat, and corn, accounting for 74.57% (598.29 Mt). From 1949 to 2009, the amount of crop residue increased by four times, accompanied by component change. The spatial distribution of crop residue in China is markedly heterogeneous. Compared to the shortage of crop residue in northwest China, there is an abundant crop residue of about 334 Mt in eastern China, attracting 90% of the country's electricity or heat generation plants.