Abstract Annual legume pastures exhibit high resilience and productivity in Mediterranean climate regions and can be an important source of nitrogen (N) for temperate cereals in integrated livestock production systems. This work seeks to evaluate the inputs of N fixed by annual legume mixtures (composed of 3–4 species and cultivars) grown for one, two or three years in a cropping sequence, and their contribution to soil N availability, N uptake and the grain yield of wheat, and compares this with the cereal rotation of oats and wheat with and without N fertilizer. Two field experiments comprising annual legume-wheat rotations were carried out in two contrasting Mediterranean environments in central Chile, the interior dryland in the eastern part of the coastal mountain rage, and the Andean foothills, over four growing seasons (2008–2011). At both experimental sites two mixtures of annual legumes were used in rotation with wheat. The duration of the pasture phase was between one and three years. In the interior dryland, the shoot DM of mixture M1 (T. subterraneum + M. polymorpha + T. michelianum) was higher than M2 (T. subterraneum + B. penicilius + O. compressus), and in the Andean foothills M4 (T. subterraneum + T. vesiculosum + O. compressus) was more productive than M3 (two cv. of T. subterraneum + T. incarnatum). The amount of N2 fixed by the legume mixtures, estimated by the 15N natural abundance technique, ranged between 28 and 87 kg N ha−1 in the interior dryland, and between 176 and 385 kg N ha−1 in the Andean foothills, representing respectively around 25 and 23 kg N ha−1 fixed for every Mg of shoot DM accumulated by the annual legumes. Wheat grain yields following legume mixtures represented 53–104 % of the 3.39 Mg ha−1 produced after oats with N fertilizer in the interior dryland, and between 68 and 101 % of 6 Mg ha−1 attained after oats in the Andean foothills, in 2011. N use efficiency (NUE) of wheat was significantly (P ≤ 0.05) higher in legume-based crop rotation than after oats with or without N fertilizer, at both sites. Legume mixtures also improved the N uptake (NUPE) and N utilization (NUtE) efficiencies of wheat compared to those observed after oats with N fertilizer, at both sites. Important differences among legume mixtures and the duration of the pasture phase were observed at both sites.

中文翻译：

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在智利中部两种截然不同的地中海环境中，一年生豆科牧草固定的氮对​​小麦生产力的贡献

摘要 一年生豆科牧草在地中海气候区表现出很高的恢复力和生产力，并且可以成为综合畜牧生产系统中温带谷物的重要氮 (N) 来源。这项工作旨在评估一年生豆类混合物（由 3-4 个物种和栽培品种组成）在一个种植序列中种植一年、两年或三年所固定的 N 输入，以及它们对土壤 N 可用性、N 吸收和谷物的贡献。小麦的产量，并将其与使用和不使用氮肥的燕麦和小麦的谷物轮作进行比较。在智利中部、沿海山脉东部的内陆旱地和安第斯山麓的两个对比鲜明的地中海环境中，进行了为期四个生长季节（2008-2011 年）的两项田间试验，其中包括每年豆类-小麦轮作。在两个试验点，一年生豆类的两种混合物与小麦轮作使用。牧场阶段的持续时间为一到三年。在内陆旱地，混合物 M1 (T. subterraneum + M. polymorpha + T. michelianum) 的枝条 DM 高于 M2 (T. subterraneum + B. penicilius + O. compressus)，而在安第斯山麓 M4 (T. .subterraneum + T. vesiculosum + O. compressus）比 M3（两个 cv. of T. subterraneum + T. incarnatum）更有生产力。豆科植物混合物固定的 N2 量，通过 15N 自然丰度技术估计，在内陆旱地介于 28 和 87 kg N ha-1 之间，在安第斯山麓介于 176 和 385 kg N ha-1 之间，分别代表一年生豆科植物积累的每 Mg 茎干 DM 固定约 25 和 23 kg N ha−1。豆类混合后的小麦籽粒产量占内陆旱地施用氮肥的燕麦后产生的 3.39 Mg ha-1 的 53-104 %，而在安第斯山麓使用燕麦后产生的 6 Mg ha-1 的 68-101 % 之间，在2011. 在豆类作物轮作中，小麦的氮利用效率 (NUE) 显着高于 (P ≤ 0.05)，这两个地点的小麦氮肥利用效率 (NUE) 均显着高于使用或不使用氮肥的燕麦。在两个地点，与燕麦施氮肥后观察到的相比，豆类混合物还提高了小麦的氮吸收 (NUPE) 和氮利用 (NUtE) 效率。在两个地点都观察到豆类混合物之间的重要差异和牧场阶段的持续时间。2011 年在安第斯山麓种植燕麦后获得了 68% 到 101% 的 6 Mg ha-1。小麦的氮利用效率 (NUE) 在豆类作物轮作中显着高于 (P ≤ 0.05)两个地点都没有施氮肥。在两个地点，与燕麦施氮肥后观察到的相比，豆类混合物还提高了小麦的氮吸收 (NUPE) 和氮利用 (NUtE) 效率。在两个地点都观察到豆类混合物之间的重要差异和牧场阶段的持续时间。2011 年在安第斯山麓种植燕麦后获得了 68% 到 101% 的 6 Mg ha-1。小麦的氮利用效率 (NUE) 在豆类作物轮作中显着高于 (P ≤ 0.05)两个地点都没有施氮肥。在两个地点，与燕麦施氮肥后观察到的相比，豆类混合物还提高了小麦的氮吸收 (NUPE) 和氮利用 (NUtE) 效率。在两个地点都观察到豆类混合物之间的重要差异和牧场阶段的持续时间。在两个地点，与燕麦施氮肥后观察到的相比，豆类混合物还提高了小麦的氮吸收 (NUPE) 和氮利用 (NUtE) 效率。在两个地点都观察到豆类混合物之间的重要差异和牧场阶段的持续时间。在两个地点，与燕麦施氮肥后观察到的相比，豆类混合物还提高了小麦的氮吸收 (NUPE) 和氮利用 (NUtE) 效率。在两个地点都观察到豆类混合物之间的重要差异和牧场阶段的持续时间。