Energy efficiency in biomass production is a major challenge for a future transition to sustainable food and energy provision. This study uses methodologically consistent data on agroecosystem energy flows and different metrics of energetic efficiency from seven regional case studies in North America (USA and Canada) and Europe (Spain and Austria) to investigate energy transitions in Western agroecosystems from the late nineteenth to the late twentieth centuries. We quantify indicators such as external final energy return on investment (EFEROI, i.e., final produce per unit of external energy input), internal final EROI (IFEROI, final produce per unit of biomass reused locally), and final EROI (FEROI, final produce per unit of total inputs consumed). The transition is characterized by increasing final produce accompanied by increasing external energy inputs and stable local biomass reused. External inputs did not replace internal biomass reinvestments, but added to them. The results were declining EFEROI, stable or increasing IFEROI, and diverging trends in FEROI. The factors shaping agroecosystem energy profiles changed in the course of the transition: Under advanced organic and frontier agriculture of the late nineteenth and early twentieth centuries, population density and biogeographic conditions explained both agroecosystem productivity and energy inputs. In industrialized agroecosystems, biogeographic conditions and specific socio-economic factors influenced trends towards increased agroecosystem specialization. The share of livestock products in a region’s final produce was the most important factor determining energy returns on investment.

中文翻译：

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旧世界和新世界中的农业生态系统能源转移：区域规模的轨迹和决定因素。

生物质生产中的能源效率是未来向可持续食品和能源供应过渡的主要挑战。这项研究使用关于农业生态系统能量流和能源效率效率的不同度量的方法学上一致的数据，该数据来自北美（美国和加拿大）和欧洲（西班牙和奥地利）的七个区域案例研究，以调查从19世纪末到后期的西方农业生态系统的能源转换二十世纪。我们对指标进行量化，例如外部最终能源投资回报率（EFEROI，即每单位外部能量输入的最终产量），内部最终EROI（IFEROI，在本地再利用的每单位生物质的最终产量）和最终EROI（FEROI，最终产量）每单位总投入消耗）。过渡期的特点是增加最终产品，同时增加外部能量输入和稳定的当地生物质再利用。外部投入并未取代内部生物质再投资，而是增加了内部投入。结果是EFEROI下降，IFEROI稳定或增加，FEROI的趋势有所不同。在过渡过程中，影响农业生态系统能源状况的因素发生了变化：在十九世纪末至二十世纪初的先进有机农业和前沿农业中，人口密度和生物地理条件解释了农业生态系统的生产力和能源输入。在工业化的农业生态系统中，生物地理条件和特定的社会经济因素影响着农业生态系统专业化趋势的发展。