Spatial and temporal dynamics of agricultural residue resources in the last 30 years in China.

The availability and distribution of biomass resources are important for the development of the bioenergy industry in a region. Biomass resources are abundant in China; however, the raw material is severely deficient, which makes the Chinese bioenergy industry an embarrassment and a contradiction. Unclear reserves and distribution and changing trends of biomass resources are the reason for this situation. A collection coefficient model of Chinese agricultural residue resources was established and the spatial and temporal pattern dynamics of agricultural residue resources in the last 30 years were analyzed. The results show that agricultural residue resources increased in stages from 1978 to 2011, including a rapid increase from 1978 to 1999, a significant fall from 2000 to 2004, and a slow increase from 2004 to 2011. Crops straw and livestock manure are the main ingredients of agricultural residue resources with proportions of 53-59% and 31-38%, respectively. However, the former has gradually decreased, while the latter is increasing. This mainly resulted from the strategic reorganization of the Chinese agriculture structure and the rapid development of large-scale livestock breeding and agricultural mechanization. Large regional differences existed in Chinese agricultural residue resources, and three distribution types formed, including resource-rich areas in North China, Northeast and Inner Mongolia, resource-limited areas in Central and Southwest China, and resource-poor areas along Northwest and Southeast coasts. This pattern is a reverse of the distributions of climatic conditions, water resources, economic development, human resources, and technological levels. Finally, it can be predicted that livestock manure and biomass conversion technology at low temperature will play increasingly significant roles in bioenergy industry development.