Data for: Multi-year productivity and nitrate-nitrogen loss from corn and prairie bioenergy cropping systems

Though corn and soybean are widely grown and readily accepted into commodity markets and biofuel facilities, heavy reliance on seeds of those two crops for bioenergy production has been linked to environmental degradation, including nutrient discharge to water, and to constraints on food production. Alternative biofuel feedstock systems might better address this ‘food-energy-environment trilemma.’ Using data from a 9-ha field experiment in Iowa, we evaluated yields from a 14-yr period for four bioenergy feedstock systems: stover harvested from corn grown with and without an unharvested rye cover crop, and prairie vegetation grown with and without fertilizer. We also assessed sub-surface drainage flows and NO3-N concentrations and discharges in leachate from those cropping systems. The continuous corn systems produced mean grain yields of 11.0 to 11.5 Mg ha^-1 yr^-1, while also yielding about 4 Mg ha^-1 yr^-1 of stover. Mean harvested biomass from the fertilized prairie was 83% greater than from the unfertilized prairie and was superior to stover production in the two corn treatments in 11 out of 14 years. Nitrate-N losses in drainage water from the corn systems averaged 12 to 14 kg NO₃-N ha^-1 yr^-1, whereas both the fertilized and unfertilized prairie systems almost eliminated NO₃-N loss. Cover cropping with rye reduced NO₃-N loss in only one out of 13 years and had variable effects on corn yield. Adoption of prairie-based biofuel systems might be driven by placing perennial feedstocks on environmentally sensitive sub-field areas, and by government policies that favor perennial feedstocks over annual crops like corn.

尽管玉米与大豆是广泛种植且已广泛融入商品市场与生物燃料生产设施的作物，但过度依赖这两种作物的籽粒作为生物能源原料，已被证实会引发水体养分流失等环境退化问题，同时也会制约粮食生产。替代性生物能源原料体系或可更好地破解这一"粮食-能源-环境三重困境"。本研究依托爱荷华州一处9公顷的田间试验数据，对4种生物能源原料体系在14年周期内的生物量产量进行了评估：分别为种植与未种植免收割黑麦覆盖作物的玉米田收获的秸秆，以及施肥与未施肥的原生草原植被。同时，本研究还对这些种植体系的地下排水流量、渗滤液中的硝态氮（NO₃-N）浓度与流失量进行了测算。连作玉米体系的籽粒平均产量为11.0~11.5 兆克·公顷⁻¹·年⁻¹，同时可产出约4 兆克·公顷⁻¹·年⁻¹的秸秆。施肥原生草原的平均收获生物量较未施肥草原高出83%，且在14年中的11年里，其生物量产量均优于两种玉米种植处理的秸秆产量。玉米种植体系的排水硝态氮平均流失量为12~14 千克·公顷⁻¹·年⁻¹，而施肥与未施肥的草原体系几乎完全消除了硝态氮流失。仅在13年中的1年里，种植黑麦覆盖作物可降低硝态氮流失，且其对玉米产量的影响存在不确定性。基于原生草原的生物能源体系的推广，或可通过将多年生原料作物种植于环境敏感的田块区域，以及出台扶持多年生原料作物而非玉米等一年生作物的政府政策来实现。