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Bioenergy could help limit global warming to 2°C above pre‐industrial levels while supplying almost a fourth of the world's renewable energy needs by 2050. However, the deployment of bioenergy raises concerns that adoption at meaningful scales may lead to unintended negative environmental consequences. Meanwhile, the full consolidation of a bioenergy industry is currently challenged by a sufficient, resilient, and resource‐efficient biomass supply and an effective conversion process. Here, we provide a comprehensive analysis of how stable isotope approaches have accelerated the development of a robust bioeconomy by advancing knowledge about environmental sustainability, feedstock development, and biological conversion. We show that advances in stable isotope research have generated crucial information to (1) gain mechanistic insight into the potential of bioenergy crops to mitigate climate change as well as their impact on water and nutrient cycling; (2) develop high‐yielding, resilient feedstocks that produce high‐value bioproducts in planta; and (3) engineer microbes to enhance feedstock conversion to bioenergy products. Further, we highlight knowledge gaps that could benefit from future research facilitated by stable isotope approaches. We conclude that advances in mechanistic knowledge and innovations within the field of stable isotopes in cross‐disciplinary research actions will greatly contribute to breaking down the barriers to establishing a robust bioeconomy. [ABSTRACT FROM AUTHOR]

Biofuel feedstocks grown on marginal lands, such as those that experience ephemeral waterlogging, reduce interference with food agriculture. As early‐season extreme precipitation events in the U.S. Midwest continue to increase, waterlogging tolerance may play an important role in the productivity of annual biofuel cropping systems. We assessed the establishment and yield of photoperiod‐sensitive sorghum [Sorghum bicolor (L.) Moench] and maize (Zea mays L.) after extreme early‐season rainfall events in central Illinois. We used paired sorghum and maize transects, spanning from low‐lying poorly drained areas to higher better drained areas, to evaluate the response of both cropping systems throughout the 2020 growing season. Sorghum maintained 25% mean emergence rates in areas that experienced the most severe waterlogging, but maize failed to establish under the same conditions. Despite the low establishment, sorghum yields in the poorly drained areas were upwards of 50% of those found in the better drained, whereas maize yields were zero areas in the poorly drained locations. The yield compensation in sorghum resulted from increased tillering, higher productivity per stem, and subsequently higher productivity per plant, which illustrates the greater phenotypic plasticity of sorghum compared to maize. Land managers who are currently seeking to grow annual cellulosic feedstocks on soils that are vulnerable to transient soil waterlogging will likely have more success with photoperiod‐sensitive bioenergy sorghum than maize. Core Ideas: Sorghum emergence was greater than maize in poorly drained, wet locations.Sorghum yields in the wet areas were greater than expected based on emergence.Greater tillering and leaf area explained sorghum yield compensation in wet areas.Sorghum may be more resilient to early‐season soil waterlogging than maize. [ABSTRACT FROM AUTHOR]

Tallgrass prairie restorations can quickly accrue organic C in soil and biomass, but the rate of C accumulation diminishes through time and is highly variable among more mature prairies. Long-term soil organic carbon ( SOC) accumulation in prairies has been linked to edaphic factors such as soil texture, soil moisture, and SOC content, but it is unclear how these factors affect the ecosystem processes that are responsible for observed differences in C accumulation rates in older prairies. We measured belowground plant and SOC pools and fluxes within 27-36-year-old restored tallgrass prairies in order to quantify total C storage, determine the net ecosystem production of C ( NEP-C), and explore which edaphic factors influence the ecosystem processes responsible for divergent NEP-C. We found that 11% of organic C was stored in biomass, and we estimate that one-third of post-restoration C sequestration has occurred in biomass, thereby highlighting biomass as a large but often overlooked C pool. Belowground biomass and soil C pools were notably smaller than those reported for remnant prairie, suggesting that future belowground C accumulation could still occur. During this study, the prairies appeared to be a net source of C, although the range of NEP-C values encompassed zero. Sand content positively affected NEP-C via increased belowground biomass production-C inputs, and SOC negatively affected NEP-C due to increased soil respiration C outputs. However, soil moisture had a smaller negative effect on soil respiration, indicating that both SOC and soil moisture play important roles in determining prairie C balance. [ABSTRACT FROM AUTHOR]