Early energy analyses of agriculture revealed that behind higher labor and land productivity of industrial farming, there was a decrease in energy returns on energy (EROI) invested, in comparison to more traditional organic agricultural systems. Studies on recent trends show that efficiency gains in production and use of inputs have again somewhat improved energy returns. However, most of these agricultural energy studies have focused only on external inputs at the crop level, concealing the important role of internal biomass flows that livestock and forestry recirculate within agroecosystems. Here, we synthesize the results of 82 farm systems in North America and Europe from 1830 to 2012 that for the first time show the changing energy profiles of agroecosystems, including livestock and forestry, with a multi-EROI approach that accounts for the energy returns on external inputs, on internal biomass reuses, and on all inputs invested. With this historical circular bioeconomic approach, we found a general trend towards much lower external returns, little or no increases in internal returns, and almost no improvement in total returns. This “energy trap” was driven by shifts towards a growing dependence of crop production on fossil-fueled external inputs, much more intensive livestock production based on feed grains, less forestry, and a structural disintegration of agroecosystem components by increasingly linear industrial farm managements. We conclude that overcoming the energy trap requires nature-based solutions to reduce current dependence on fossil-fueled external industrial inputs and increase the circularity and complexity of agroecosystems to provide healthier diets with less animal products.

早期的农业能源分析表明，与更传统的有机农业系统相比，工业化农业的劳动力和土地生产率较高，但能源投资回报率 (EROI) 却有所下降。对近期趋势的研究表明，生产和投入使用效率的提高再次在一定程度上提高了能源回报。然而，大多数农业能源研究仅关注作物层面的外部投入，掩盖了畜牧业和林业在农业生态系统内再循环的内部生物质流的重要作用。在这里，我们综合了 1830 年至 2012 年北美和欧洲 82 个农场系统的结果，首次显示了农业生态系统（包括畜牧业和林业）不断变化的能源状况，并采用多 EROI 方法来解释农业生态系统的能源回报外部投入、内部生物质再利用以及所有投资投入。通过这种历史循环生物经济方法，我们发现总体趋势是外部回报大幅降低，内部回报很少或没有增加，总回报几乎没有改善。这种“能源陷阱”的驱动因素包括作物生产越来越依赖化石燃料的外部投入、基于饲料谷物的集约化畜牧生产、林业减少以及日益线性的工业化农场管理导致的农业生态系统组成部分的结构性瓦解。我们的结论是，克服能源陷阱需要基于自然的解决方案，以减少目前对化石燃料外部工业投入的依赖，并增加农业生态系统的循环性和复杂性，从而以更少的动物产品提供更健康的饮食。