There is an imperative to accurately assess the environmental sustainability of crop system interventions in the context of food security and climate change. Previous studies have indicated that the incorporation of legumes into cereal rotations could reduce overall environmental burdens from cropping systems. However, most life cycle assessment (LCA) studies focus on individual crops and miss environmental consequences of inter-annual crop sequence and nutrient cycling effects. This review investigates state-of-the-art representation of inter-crop rotation effects within legume LCA studies. A literature review was undertaken, starting with a search for all peer-reviewed articles with combinations of ‘LCA’, ‘legumes’ and ‘rotations’ or synonyms thereof. In total, 3180 articles were obtained. Articles were screened for compliance with all of the following requirements: (i) reporting results based on LCA or life cycle inventory methodology; (ii) inclusion of (a) legume(s); (iii) the legume(s) is/are analysed within the context of a wider cropping system (i.e. rotation or intercropping). Seventy articles satisfying these requirements were analysed. We identified three broad approaches to legume LCA. Most studies involved simple attributional LCA disregarding important interactions across years and crops in rotations. N-fertilizer reduction through legume residue N carryover is either disregarded or the benefit is attributed to the following crop in such studies, whilst N leaching burdens from residues are usually attributed to the legume crop. Some studies applied robust allocation approaches and/or complex functional units to enable analysis of entire rotation sequences, accounting for nutrient cycling and break crop effects. Finally, a few studies applied consequential LCA to identify downstream substitution effects, though these studies did not simultaneously account for agronomic effects of rotational sequence changes. We recommend that LCA studies for legume cropping systems should (i) evaluate entire rotations; (ii) represent nitrogen and ideally carbon cycling; (iii) for attributional studies, define at least two functional units, where one should encompass the multifunctional outputs of an entire rotation and the other should enable product footprints to be calculated; (iv) for CLCA studies, account for both agronomic changes in rotations and markets effects; (v) include impact categories that reflect hotspots for agricultural production.

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在生命周期评估中代表作物轮作：豆类 LCA 研究综述

在粮食安全和气候变化的背景下，准确评估作物系统干预措施的环境可持续性势在必行。先前的研究表明，将豆类纳入谷物轮作可以减少种植系统的整体环境负担。然而，大多数生命周期评估 (LCA) 研究侧重于单个作物，而忽略了年际作物序列和养分循环效应对环境的影响。这篇综述调查了豆科植物 LCA 研究中作物间轮作效应的最新表现。进行了文献综述，首先搜索所有具有“LCA”、“豆类”和“轮换”或其同义词组合的同行评审文章。共获得 3180 篇文章。对物品进行筛选以符合以下所有要求：(i) 根据 LCA 或生命周期清单方法报告结果；(ii) 包括 (a) 豆类；(iii) 在更广泛的种植系统（即轮作或间作）范围内分析豆类。对满足这些要求的 70 篇文章进行了分析。我们确定了豆类 LCA 的三种广泛方法。大多数研究涉及简单的归因 LCA，忽略了跨年和轮作作物的重要相互作用。通过豆类残留物减少氮肥 在此类研究中，要么忽略 N 结转，要么将益处归因于后续作物，而残留物的 N 浸出负担通常归因于豆类作物。一些研究应用了稳健的分配方法和/或复杂的功能单元来分析整个轮作序列，考虑养分循环和破坏作物的影响。最后，一些研究应用相应的 LCA 来确定下游替代效应，尽管这些研究并没有同时考虑轮作序列变化的农艺影响。我们建议豆科作物种植系统的 LCA 研究应该 (i) 评估整个轮作；(ii) 代表氮和理想的碳循环；(iii) 对于归因研究，定义至少两个功能单元，其中一个应包含整个轮换的多功能输出，另一个应能够计算产品足迹；(iv) 对于 CLCA 研究，考虑轮作中的农艺变化和市场效应；