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The cultivation of perennial crops in marginal land as a feedstock for renewable energy or bio‐based products constitutes a promising alternative to mitigate greenhouse gas emissions since they can be produced without land competition issues and with potentially significant amounts of belowground C storing. The objective of this study was to assess soil C storage capacity of switchgrass on a marginal land (poor soil with limited rooting depth on a hilly area) through a spatialized analysis derived from several soil samples. A significant increase in SOC was observed after 13 years. In general terms, SOC increased by 12 Mg C ha−1. The estimated switchgrass‐derived C was 12.7 (±5.3) Mg C ha−1. A significant positive correlation was observed between the C derived from switchgrass and SOC gain. The increased SOC along the field, however, was patchy, with the highest increments registered in the center of the field, while the lowest ones in the top and bottom of the hill. Soil N stocks have also increased along with the soil C storage, although no direct relationship with C derived from switchgrass was observed. Therefore, it could be stated that growing switchgrass in marginal land can be a valuable option to mitigate the risk of agricultural land abandonment while storing a significant amount of soil C. [ABSTRACT FROM AUTHOR]

Bioethanol will play a significant role in energy structure adjustment and greenhouse gas mitigation in the future, especially in the transport sector. As bioethanol production with grain crops may become obsolete due to food security concerns, the Chinese government has advocated the development of non-grain bioethanol. According to the current actual situation of bioethanol development and China's Liquid Biofuel Development Roadmap, we defined three stages of bioethanol development. We focused on the assessment of bioethanol feedstock resources and bioethanol yield potential in different stages using a comprehensive evaluation system integrating statistical methods, crop growth process models, and geographic information system (GIS) techniques. The considered feedstocks included corn, sweet sorghum, cassava, switchgrass, crop straw, and forest residues. The spatial–temporal characteristics of the regional bioethanol distribution were discussed. The results indicate that the total resources of corn, sweet sorghum, cassava, switchgrass, crop straws, and forest residues were about 257.17, 2083.55, 44.36, 357.56, 1031.62, and 924 million tons at different time points, respectively. In the first stage, the year 2020, the potential bioethanol totaled 21.55 million tons. An advantage in bioethanol development was demonstrated by Northeast China. A positive development situation was also identified in East China, such as in Tianjin. In the second stage, from 2020 to 2030, the potential bioethanol production is estimated to be 145.42 million tons. The bioethanol development potential will increase in South China, in areas such as Yunnan, Guangxi, and Guizhou. In the third stage, the potential bioethanol based on switchgrass is estimated to be 92.99 million tons. The potential bioethanol based on crop straws and forest residues will be 14.76 million tons if 5% of these feedstocks are fully used for producing bioethanol. Regions with a large development potential will be further expanded. Interregional bioethanol flows and international cooperation will help meet the whole nation's requirement. [ABSTRACT FROM AUTHOR]