Energy holds a key role in farm systems. Cultivation is based on the conversion of solar energy into biomass of interest. Fossil energy allows mechanized and high-yield agricultural production system, but has a strong impact on climate change, and its supply is compromised in the next decades. Energy flows stand between two worlds: while energy is a strategic component of the economy, it is also a thermodynamic state variable for describing ecosystems. This situation reemphasizes the need for energy flow analysis in farm systems. There is a great variety in the approaches used to compute energy flows at farm scales. Yet, their main characteristics and the ways they handle farm sustainability issues need to be clarified. This review identifies ten kinds of energetic approaches, i.e., (i) conventional energy analysis, (ii) pluri-energy analysis, (iii) agroecological energy analysis, (iv) exergy analysis, (v) cumulative exergy consumption, (vi) extended exergy account, (vii) cumulative exergy extraction from the natural environment, (viii) eco-exergy, (ix) cosmic exergy analysis, and (x) emergy assessment. These approaches are analyzed through key features to discuss their ability to address resources’ efficiency issues and identify promising outcomes for energy assessment of farms. This analysis emphasizes the lack of clear definition of system boundaries in farm-scale studies. In addition, most of the studies mainly focus on socio-economic flows through a sectoral perspective. Yet, internal biomass flows that play a role in maintaining agroecosystem functionality can also be considered according to a circular/systemic perspective. Then, integration of soil organic matter in the energy balance leads to significant changes in energy efficiency evaluation playing a function of biotic energy storage in the farm system. Hence, some recommendations are provided to perform an exhaustive energetic assessment of farm systems as well as future lines of research to be investigated.

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对农业生产系统的活力评估。回顾

能源在农场系统中起着关键作用。耕种是基于将太阳能转化为目标生物质。化石能源可以实现机械化和高产的农业生产系统，但对气候变化影响很大，其供应在未来几十年内将受到影响。能量流在两个世界之间流动：虽然能量是经济的战略组成部分，但它也是描述生态系统的热力学状态变量。这种情况再次强调了对农场系统中的能量流分析的需求。用于计算农场规模的能量流的方法种类繁多。但是，它们的主要特征和处理农场可持续性问题的方式需要澄清。这篇综述指出了十种能量方法，即（i）常规能量分析，（ii）多元能量分析，（iii）农业生态能分析，（iv）火用分析，（v）累积火用消耗，（vi）扩大火用帐户，（vii）从自然环境中提取的累积火用，（viii）生态用火，（ix）宇宙用分析和（x）能值评估。通过关键功能对这些方法进行了分析，以讨论它们解决资源效率问题和确定有希望的结果以进行农场能源评估的能力。该分析强调在农场规模研究中缺乏对系统边界的明确定义。此外，大多数研究主要从部门角度关注社会经济流动。然而，根据循环/系统的观点，也可以考虑在维持农业生态系统功能中发挥作用的内部生物质流。然后，土壤有机质在能量平衡中的整合导致能效评估发生重大变化，发挥了农场系统中生物能量存储的作用。因此，提供了一些建议来对农场系统以及未来的研究路线进行详尽的精力评估。