A reduction in the overall carbon intensity (CI) of a crop-based biofuel can be achieved by cutting down the CI of the biofuel’s feedstock, which in turn correlates significantly to agricultural management practices. Proposals are being made to incentivize low-carbon biofuel feedstocks under U.S. fuel regulatory programs to promote sustainable farming practices by individual farms. For such an incentive scheme to function properly, robust data collection and verification are needed at the farm level. This study presents our collaboration with U.S. private sector companies to collect and verify the corn production data necessary for feedstock-specific CI calculation at the farm level, through a carefully designed questionnaire, to demonstrate the practicality and feasibility of data collection at scale. We surveyed 71 farms that produced 0.2 million metric tons of corn grain in 2018 in a Midwestern U.S. state to obtain information on key parameters affecting corn ethanol feedstock CI, such as grain yields, fertilizer/chemical application rates, and agronomic practices. Feedstock-specific CI was calculated in the unit of grams (g) CO₂ equivalent (CO₂e) of greenhouse gases per kilogram (kg) of corn produced. Results showed large CI variations—from 119 to 407 g CO₂e kg⁻¹ of corn—due to the farm-level inventory, while the production-weighted average CI for all surveyed farms was 210 g CO₂e kg⁻¹, comparable to the national average CI of 204 g CO₂e kg⁻¹. The nitrogen fertilizer type applied and rate were identified as key factors contributing most to CI variations at the farm level. The estimated N₂O emissions from fertilizer and biomass nitrogen inputs to soil accounted for 51% of the overall farm-level CI and therefore need to be better monitored at farm level with high resolution. We concluded that this feedstock-specific, farm-level CI evaluation has the potential to be used to incentivize low-carbon feedstock for biofuel production.

可以通过减少生物燃料原料的 CI 来降低基于作物的生物燃料的整体碳强度 (CI)，这反过来又与农业管理实践显着相关。正在提议根据美国燃料监管计划激励低碳生物燃料原料，以促进个体农场的可持续农业实践。为使此类激励计划正常运行，需要在农场层面进行可靠的数据收集和验证。本研究介绍了我们与美国私营部门公司的合作，通过精心设计的问卷，收集和验证农场级特定原料 CI 计算所需的玉米生产数据，以证明大规模数据收集的实用性和可行性。我们调查了 71 个生产 0 的农场。2018 年在美国中西部的一个州生产 200 万吨玉米，以获取有关影响玉米乙醇原料 CI 的关键参数的信息，例如粮食产量、肥料/化学品施用率和农艺实践。原料特定的 CI 以克 (g) CO 为单位计算每生产一公斤 (kg) 玉米需要₂当量 (CO ₂ e) 的温室气体。结果显示，由于农场级别的库存，CI 变化很大——从 119 到 407 g CO ₂ e kg ^-1玉米，而所有调查农场的生产加权平均 CI 为 210 g CO ₂ e kg ^-1，可比到 204 g CO ₂ e kg ^-1的全国平均 CI 。施用的氮肥类型和施用量被确定为对农场水平的 CI 变化贡献最大的关键因素。估计 N ₂从肥料和生物量氮输入到土壤的 O 排放占整个农场级 CI 的 51%，因此需要在农场级以高分辨率进行更好的监测。我们得出的结论是，这种针对特定原料的农场级 CI 评估有可能用于激励低碳原料用于生物燃料生产。