Abstract Intercropping exploits species complementarities to achieve sustainable intensification by increasing crop outputs per unit land with reduced anthropogenic inputs. Cereal/legume intercropping is a classical case. We carried out a global meta-analysis to assess land and fertilizer N use efficiency in intercropping of maize and soybean as compared to sole crops, based on 47 studies reported in English and 43 studies reported in Chinese. The data were extracted and analyzed with mixed effects models to assess land equivalent ratio (LER) of intercropping and factors affecting LER. The worldwide average LER of maize/soybean intercropping was 1.32 ± 0.02, indicating a substantial land sparing potential of intercropping over sole crops. This advantage increased as the temporal niche differentiation between the two species was increased by sowing or harvesting one crop earlier than the other as in relay intercropping, i.e. with only partial overlap of the growing periods of the two species The mean fertilizer N equivalent ratio (FNER) was 1.44 ± 0.03, indicating that intercrops received substantially less fertilizer N than sole crops for the same product output. These fertilizer savings are mainly due to the high relative maize yield and the lower N input in the intercrop compared to the input in sole maize. This meta-analysis thus shows that exploiting species complementarities by intercropping maize and soybean enables major increases in land productivity with less fertilizer N use. Both LER and FNER increased as the difference in growth duration increased for maize and soybean, but were not affected by fertilizer N rate. LER increased when soil organic matter increased but FNER did not change with soil organic matter.

中文翻译：

---

玉米和大豆间作提高了土地和肥料氮利用效率；荟萃分析

摘要 间作利用物种互补性，通过增加单位土地的作物产量并减少人为投入来实现可持续集约化。谷物/豆类间作是一个经典案例。我们基于 47 项英文报告的研究和 43 项中文报告的研究，进行了一项全球荟萃分析，以评估与单一作物相比，玉米和大豆间作的土地和肥料氮利用效率。提取数据并使用混合效应模型进行分析，以评估间作土地当量比 (LER) 和影响 LER 的因素。世界范围内玉米/大豆间作的平均 LER 为 1.32 ± 0.02，表明间作与单一作物相比具有巨大的土地节约潜力。这种优势随着通过比另一种作物更早播种或收获而增加两个物种之间的时间生态位差异而增加，例如在中继间作中，即两个物种的生长期仅部分重叠 平均肥料氮当量比（FNER） ) 为 1.44 ± 0.03，表明对于相同的产品产量，间作作物比单一作物吸收的氮肥少得多。这些化肥的节省主要是由于与单种玉米相比，间作玉米的相对较高的产量和较低的氮投入。因此，该荟萃分析表明，通过间作玉米和大豆来利用物种互补性能够在减少氮肥使用的情况下大幅提高土地生产力。LER 和 FNER 都随着玉米和大豆生长持续时间差异的增加而增加，但不受施氮量的影响。当土壤有机质增加时 LER 增加，但 FNER 不随土壤有机质变化。