Abstract A better understanding of nitrogen (N) behavior and agronomic practices is needed to improve biological nitrogen fixation (BNF) and N use efficiency under field conditions. This study aims on investigating the potential for the use of biological agents that can fix atmospheric N and are related to multiple mechanisms benefits to improve cowpea (Vigna unguiculata (L.) Walp.) development and productivity, leading to a positive residual effect on wheat (Triticum aestivum L.) development. The study was set up under a no-till system in a Rhodic Haplustox, in a randomized complete block design, with four replicates. Treatments were tested in a full factorial design and included: i) three types of inoculation (without inoculation – control; Bradyrhizobium sp. inoculation (strains SEMIA 6462 and SEMIA 6463) – the conventional inoculation of cowpea; and Bradyrhizobium sp. combined with A. brasilense (strains Ab-V5 and Ab-V6) – the co-inoculation); and ii) five N rates (0 to 160 kg N ha−1) applied as urea-15N isotope. The residual effects of inoculations and N application rates applied during the cowpea growing season were evaluated on wheat (successor crop). Co-inoculation was found to increase cowpea grain yield by 40.5% and 14.1% compared to the control and Bradyrhizobium sp. inoculation when N was omitted and up to 37.6% and 50.8% when N was applied. Co-inoculation increased N use efficiency, N recovery and N accumulation on cowpea, leading to improved crop growth. The co-inoculation also provided a positive residual effect on wheat resulting in increased plant N accumulation, crop development, and greater wheat grain yield compared to the control (increase of 7.8%) and Bradyrhizobium sp. inoculated plants (increase of 5.8%). Co-inoculation was found to increase N use efficiency on cowpea by 216.5% and 35.5% and on wheat by 159.3% and 29.5% compared to control and Bradyrhizobium sp. inoculation, respectively. The fertilizer N recovery was, on average, 22.2% by cowpea, while fertilizer N recovery by wheat was

中文翻译：

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从肥料中回收氮和对 Bradyrhizobium sp. 的利用效率响应。和巴西固氮螺菌与豇豆-小麦作物序列中的施氮量相结合

摘要 需要更好地了解氮 (N) 行为和农艺实践，以提高田间条件下的生物固氮 (BNF) 和氮利用效率。本研究旨在调查使用生物制剂的潜力，这些生物制剂可以固定大气氮，并与改善豇豆 (Vigna unguiculata (L.) Walp.) 发育和生产力的多种机制益处相关，从而对小麦产生积极的残留影响(Triticum aestivum L.) 发展。该研究是在 Rhodic Haplustox 的免耕系统下建立的，采用随机完整区组设计，有四个重复。处理在全因子设计中进行测试，包括：i) 三种接种类型（无接种 - 对照；慢生根瘤菌属物种。接种（菌株 SEMIA 6462 和 SEMIA 6463）——豇豆的常规接种；和 Bradyrhizobium sp。结合 A. brasilense（菌株 Ab-V5 和 Ab-V6）——共同接种）；和 ii) 五个 N 比率（0 到 160 kg N ha-1）作为 urea-15N 同位素应用。在豇豆生长季节，对小麦（继作作物）接种的残留影响和施氮量进行了评估。发现与对照和慢生根瘤菌相比，共同接种使豇豆籽粒产量提高了 40.5% 和 14.1%。省略 N 时接种，施氮时接种率分别高达 37.6% 和 50.8%。共接种提高了豇豆的氮利用效率、氮回收和氮积累，从而改善了作物生长。共接种还对小麦产生了积极的残留效应，导致植物氮积累增加、作物发育、与对照（增加 7.8%）和 Bradyrhizobium sp. 相比，小麦籽粒产量更高。接种植物（增加 5.8%）。发现与对照和慢生根瘤菌相比，共同接种可将豇豆的氮利用效率提高 216.5% 和 35.5%，将小麦的氮利用效率提高 159.3% 和 29.5%。分别接种。平均而言，豇豆的氮肥回收率为 22.2%，而小麦的氮肥回收率为