Field crop residue estimate and availability for biofuel production in China

Abstract

Exploitation of crop residue biomass resources will improve soil quality, future energy security, global carbon balance, and sustainable crop production. The present study was performed in order to evaluate residue quantities and distribution of field crops in the 31 provinces of China mainland with the latest residue indices, based on a province or a region. The annual average total residue in China (750.36Mt) was composed of 660.76Mt field residues (88.1%) and 89.60Mt process residues (11.9%) on an air dried basis, in 2008 and 2009. Grain cereals of rice (200.56Mt, 30.35%), wheat (145.91Mt, 19.45%), and maize (153.85Mt, 23.28%) were the major crops which produced 500.32Mt field residue, accounting for 73.08% of the total field residue. The annual field residues produced in the 31 provinces varied between 1.26Mt (Beijing) and 71.59Mt (Henan). The field residue was distributed in regions according to the order: Northwest China (54.23Mt, 8.21%)<North China (75.66Mt, 11.45%)<Southwest China (80.67Mt, 12.21%)<Northeast China (89.61Mt, 13.56%)<Central-South China (179.11Mt, 27.11%)<East China (181.47Mt, 27.46%). The SCE of the total crop residue was distributed in the top three regions: Central-South China (112.04Mt)>East China (104.36Mt)>Northeast China (55.02Mt). The average residue yield was between 4.14tha−1 and 8.65tha−1 and the residue density was between 17.82tkm−2 and 224.45tkm−2 in these six regions. The total residue quantity for biofuel production could potentially reach 314Mt (42%), which is composed of the unused (196Mt) and the directly combusted fuel (118Mt).