Dep. of Civil and Environmental Engineering, South Dakota School of Mines & Technology, Rapid City, SD, 57701, USA.
USDA-ARS, Northern Great Plains Research Lab., Mandan, ND, 58554, USA.
J Environ Qual. 2020 Nov;49(6):1515-1529. doi: 10.1002/jeq2.20158. Epub 2020 Nov 5.
In the northern Great Plains (NGP), wheat is the primary grain commodity. There is a need for the NGP to have a detailed analysis of environmental impacts for wheat-based agricultural production systems to better understand regional agroecosystems. This article provides a cradle-to-field gate life cycle assessment (LCA) for NGP dryland wheat (Triticum aestivum L.) production. The environmental impacts for winter wheat production using crop rotation and agricultural intensification are quantified. Fourteen no-till crop rotations ranging in duration from 2 to 6 yr were evaluated and compared using data from a historical 13-yr replicated rotation study (>300 observations). Midpoint LCA categories chosen for this comparison are energy, agricultural land use, climate change potential, freshwater eutrophication, and freshwater ecotoxicity due to their direct links with agricultural management practices. The NGP farmers commonly use a fallow period every other year due to moisture limitations. This specific agricultural practice and allocations within rotations are critical considerations within agricultural LCAs. Two aspects of fallow considerations and a sensitivity analysis were also performed. The allocated midpoint impacts between crops in rotational studies averaged 0.31, 0.79, 0.62, and 0.63 kg CO eq. per unit of winter wheat when energy, economic, mass, and cereal unit allocations were used, respectively. Economic analysis of the studied experimental crop was performed; results demonstrated that crop insurance policies improved diversification economics by 20%. Agricultural diversification benefits and burdens were better represented by endpoint damage assessments than by midpoint impact analysis.
在大平原北部地区（NGP），小麦是主要的粮食商品。需要对基于小麦的农业生产系统进行详细的环境影响分析，以更好地了解该地区的农业生态系统。本文对 NGP 旱地小麦（Triticum aestivum L.）生产进行了摇篮到田间门的生命周期评估（LCA）。量化了采用轮作和农业集约化生产冬小麦的环境影响。评估了持续时间从 2 年到 6 年不等的 14 种免耕轮作，并使用历史上为期 13 年的重复轮作研究（超过 300 次观测）的数据进行了比较。选择能源、农业土地利用、气候变化潜力、淡水富营养化和淡水生态毒性这四个中点 LCA 类别，是因为它们与农业管理实践直接相关。由于水分限制，NGP 农民通常每隔一年休耕一次。这种特定的农业做法和轮作中的分配是农业 LCA 中的关键考虑因素。还进行了休耕考虑的两个方面和敏感性分析。在轮作研究中，作物之间的分配中点影响平均为 0.31、0.79、0.62 和 0.63 kg CO eq. 当分别使用能源、经济、质量和谷物单位分配时，单位冬小麦。对所研究的实验作物进行了经济分析；结果表明，作物保险政策使多样化经济提高了 20%。终点损害评估比中点影响分析更能代表农业多样化的收益和负担。
