Spatially explicit analyses of sustainable agricultural residue potential for bioenergy in China under various soil and land management scenarios

Sustainability is critical for biomass feedstock supply and crop production. Most studies on agricultural residue estimations ignored the loss of soil organic carbon (SOC) and thus possibly overestimated its resource potential. This study estimated the resource potential of using agricultural residues for bioenergy in China, considering soil conservation, collection cost, and future changes in yield and management. This study carried out a spatial explicit assessment of sustainable agricultural residue potential and their on-farm collection costs. Rothamsted carbon model was used to quantify the grid-specific amount of residue to be retained in soil for sustainable purposes. The results showed that 226 Mt of residues could be collected annually to maintain the current SOC level, which ranges from 0.1% to 39.0% at a mean of 1.1% nationwide. To achieve SOC level above 2% over all arable land in China, the collectable residues would be reduced to 24 Mt. Future yield improvements and no-tillage would significantly increase the collectable residues to 117, 383, and 514 Mt in 2050 under SOC scenarios of above 2%, above 1%, and maintaining current level, respectively. Maintaining the current SOC level, 495 Mt of residues could be collected in 2050 with a cost ≤ 0.98 $⋅GJ−1, which equals 8.6 EJ of energy potential. From the view of high supply potentials and low collection costs, Shandong, Henan, and Jiangsu provinces are the preferred regions to develop residue-based bioenergy production. The results highlighted the differences of resource potential among various SOC scenarios and spatial heterogeneity of residue resource among regions.