Investigating carbon and nitrogen: interactions in perennial systems on marginal land

土地利用的变化和对化石燃料的依赖使碳(C)和氮(N)循环脱钩，导致温室气体(GHG)在大气中积累。在气候多变性增加的不断变化的全球环境中，保持农业生产力和减少我们对化石燃料的依赖仍然是一项挑战。使用生物能源作物是应对这一挑战的创新方法。虽然目前全球约15%的能源生产来自生物质，但预计到2050年，生物质将占全球可再生能源的50%。从玉米等粮食作物中提取的第一代生物能源作物，或仅在优质农田上生产生物能源作物，在生态上是不可持续的，并威胁到全球粮食安全。这可以通过在边际土地上建立多年生或第二代生物能源作物系统(PBCS)来解决。多年生生物能源作物通过广泛的根系开发和循环养分，建立土壤碳储备，减少温室气体排放。然而，这一潜力还没有得到很好的量化，调节PBCS中土壤C和N动态的相互作用机制也还没有被探索。这项研究计划提供了关于碳长期同化的新知识，并表征了边缘土地上施肥和未施肥的PBCS的温室气体排放的时间特征。它还将讨论冻融循环(FTC)持续时间和温度对温室气体排放和碳、氮动态的影响。该方法涉及温室气体时间采样，并包括严格的土壤采样和分析。同时，研究温室气体排放与土壤C、N动态之间的相互作用也加深了我们对PBCS管理的理解。这也将有助于增进我们对边际土地上多氯联苯的碳固存和温室气体排放潜力的认识。在评估多氯联苯的气候中立性以及它们可能被纳入碳信用额度或总量管制与交易计划时，这些信息是必不可少的。

Land-use change and reliance on fossil fuels have decoupled carbon (C) and nitrogen (N) cycles, contributing to the accumulation of greenhouse gases (GHG) in the atmosphere. In a changing global environment with increased climate variability, maintaining agricultural productivity and reducing our reliance of fossil fuels remains a challenge. Using bioenergy crops is an innovative approach to address this challenge. Although ~15% of global energy production is currently derived from biomass, it is projected to account for 50% of global renewable energy sources by the year 2050. First generation bioenergy crops, derived from food crops such as corn, or the production of bioenergy crops on prime agricultural land solely is not ecologically sustainable and threatens global food security. This can be addressed by establishing perennial, or second generation, bioenergy crop systems (PBCS) on marginal land. Perennial bioenergy crops exploit and recycle nutrients through an extensive root system building soil C reserves and decreasing GHG emissions. However, this potential has not yet been well quantified and the mechanisms of interaction that regulate soil C and N dynamics in PBCS remains unexplored. This research program provides new knowledge on the long-term assimilation of C and characterizes temporal GHG emissions in fertilized and unfertilized PBCS on marginal land. It will also address the impact of freeze-thaw cycle (FTC) duration and temperature on GHG emissions and C and N dynamics. The methodological approach involves temporal GHG sampling and includes rigorous soil sampling and analysis. Investigating the interactions between GHG emissions and soil C and N dynamics concurrently enhances our understanding of PBCS management. This will also help advance our knowledge on the C sequestration and GHG emission potential of PBCS on marginal land. This information is essential when assessing the climate neutrality of PBCS and their potential incorporation into a carbon credit, or cap and trade program.