Data Sheet 1_Comparative life cycle assessment of perennial and annual crop production: impact of farming systems and management practices.docx

The Intermediate Wheatgrass (IWG) Thinopyrum intermedium (Host) Barkworth & D.R. Dewey, marketed under the trade name Kernza® has been tested in France with a group of farmers since 2017. The Life Cycle Assessment (LCA) is a recognized methodology to assess the potential environmental impacts and resources consumption associated with a production system. An attributional LCA following ISO 14040/44 was conducted, focusing on static comparisons. The main purpose of this paper was to estimate the “cradle-to-farm gate” environmental effects caused by the cultivation of intermediate wheatgrassin comparison with the main crops produced, among which soft wheat and maize grain stand out. This research has been achieved with 6 farmers, 3 under organic and 3 under conventional production. A comparative assessment was carried out per year and under 3 years of crop rotation to determine contributions to the environmental impact. Several impact categories were evaluated, including global warming potential (GWP), ozone depletion (OD), freshwater eutrophication (FE) freshwater ecotoxicity (FEC) and acidification (AC). Intermediate wheatgrass (IWG) shows significantly better environmental performance per hectare than annual crops due to its perennial nature with limited soil preparation and lower input requirements. Conversely, IWG performs worse per ton due to its relatively low grain yield. IWG results shows higher contribution of mechanical practices than cash crops with 70% for GWP and OD and 20% with FE, AC and FEC due to low use of fertilizers and pesticides over the 3yr. Grain yields of organically grown crops are lower than those of conventionally grown crops, regardless of the crop. Conventional management shows higher environmental impacts than organic per hectare on IWG but also on annual crops in each category. Conversely organic management on IWG conduct to higher GWP and FE per volume due to regular mechanic weeding, inducing fuel consumption, and organic manure applied before sowing. The results on IWG show significant difference on environmental performance per hectare and per ton between establishment year inducing soil preparation, sowing and fertilization and succeeding years with limited practices except weed management and/or mulching.

以商品名Kernza®推广的中间偃麦草（Intermediate Wheatgrass, IWG，学名Thinopyrum intermedium (Host) Barkworth & D.R. Dewey）自2017年起便在法国与农户群体开展田间试验。生命周期评估（Life Cycle Assessment, LCA）是评估生产系统潜在环境影响与资源消耗的公认方法学。本研究遵循ISO 14040/44标准开展归因式生命周期评估，聚焦静态对比分析。本研究的核心目标为估算中间偃麦草种植相较于主流大田作物（其中以软质小麦与籽粒玉米最为典型）所产生的“从摇篮到农场大门”环境效应。本次研究联合6位农户完成，其中3位采用有机种植模式，3位采用常规种植模式。研究按年度开展对比评估，并结合3年轮作周期，以明确各生产环节对环境影响的贡献占比。本次评估涵盖多项环境影响类别，包括全球变暖潜势（Global Warming Potential, GWP）、臭氧消耗潜势（Ozone Depletion, OD）、淡水富营养化（Freshwater Eutrophication, FE）、淡水生态毒性（Freshwater Ecotoxicity, FEC）以及酸化潜势（Acidification, AC）。由于中间偃麦草为多年生作物，土壤耕作频次有限且生产投入需求更低，因此每公顷种植的环境表现显著优于一年生作物。但与之相对，由于其籽粒单产相对偏低，按单位体积计算的环境负荷则更高。与经济作物相比，中间偃麦草的机械作业环节贡献了更高的环境影响占比：全球变暖潜势与臭氧消耗潜势的70%、淡水富营养化、酸化潜势与淡水生态毒性的20%，这源于3年种植周期内化肥与农药使用量极低。无论种植何种作物，有机种植的籽粒单产均低于常规种植模式。无论是中间偃麦草还是一年生大田作物，按每公顷计算，常规管理模式的环境影响均高于有机模式。但与之相对，中间偃麦草的有机种植模式下，单位体积产品的全球变暖潜势与淡水富营养化负荷更高，这源于播种前需定期开展机械除草以消耗燃油，且需施用基肥有机肥。针对中间偃麦草的研究结果显示，在种植建立初期（含土壤耕作、播种与施肥环节）与后续轮作年份之间，每公顷与单位体积的环境表现存在显著差异：后续年份仅需开展杂草管理和/或覆盖作业，其余生产环节投入有限。