Small farms constitute most of the world’s farms and are a central focus of sustainable agricultural development. However, the relationship between farm size and production, profitability, biodiversity and greenhouse gas emissions remains contested. Here, we synthesize current knowledge through an evidence review and meta-analysis and show that smaller farms, on average, have higher yields and harbour greater crop and non-crop biodiversity at the farm and landscape scales than do larger farms. We find little conclusive evidence for differences in resource-use efficiency, greenhouse gas emission intensity and profits. Our findings highlight the importance of farm size in mediating some environmental and social outcomes relevant to sustainable development. We identify a series of research priorities to inform land- and market-based policies that affect smallholders globally.

小型农场构成世界上大多数农场，并且是可持续农业发展的重点。但是，农场规模与产量，获利能力，生物多样性和温室气体排放之间的关系仍然存在争议。在这里，我们通过证据回顾和荟萃分析综合了当前的知识，结果表明，与大型农场相比，较小的农场平均而言具有较高的产量，并且在农场和景观尺度上具有更大的农作物和非作物生物多样性。对于资源利用效率，温室气体排放强度和利润的差异，我们几乎没有确凿的证据。我们的发现强调了农场规模在调解与可持续发展有关的一些环境和社会成果方面的重要性。