Abstract Including legumes in winter, both as cover crop or for grain harvest, is recommended for avoiding long periods of bare fallow and supplying N for succeeding crops in the rotation. The aims of this study were to i) quantify the contribution of N derived from biological nitrogen fixation (N_BNF) in vetch (Vicia sativa L. or Vicia villosa L.) and field pea (Pisum sativum) in the Central Pampas region of Argentina, ii) evaluate the response to seed inoculation in terms of %N derived from air (%Ndfa), biomass production and N_BNF in both crops and iii) determine grain yield response to nitrogen fertilization of maize (Zea mays L.) sown after field pea and vetch with and without inoculation. %Ndfa was assessed in 16 experimental sites using the natural 15N abundance method. Response to inoculation in vetch and field pea and the residual effects on the following maize was evaluated during two years. On average, 60 % of N demand of vetch and field pea was met by BNF. Seed inoculation increased %Ndfa in field pea and vetch, and a positive impact on aboveground biomass and N_BFN was observed in vetch. Maize yield did not respond to N fertilization when planted after inoculated vetch, and the largest responses to N fertilization were observed when vetch and field pea were not inoculated. Legume inoculation had a strong impact at the system level, especially in fields that vetch or field pea was not previously cultivated, reducing the economic optimal nitrogen fertilizer rate in the succeeding maize.

中文翻译：

---

豌豆和紫云英的生物固氮：对潘潘地区玉米接种和残留效应的响应

摘要 在冬季包括豆类，无论是作为覆盖作物还是用于收获粮食，都建议避免长时间裸露，并为轮作中的后续作物提供氮。本研究的目的是 i) 量化源自生物固氮 (N_BNF) 的氮在阿根廷中部潘帕斯地区的野豌豆（Vicia sativa L. 或 Vicia villosa L.）和豌豆（Pisum sativum）中的贡献， ii) 评估种子接种对种子接种的响应，包括空气中的氮 (%Ndfa)、生物​​量产量和两种作物的 N_BNF，以及 iii) 确定在豌豆后播种的玉米 (Zea mays L.) 对氮肥的谷物产量响应和野豌豆接种和不接种。使用天然 15N 丰度方法在 16 个实验地点评估了 %Ndfa。在两年内评估了对野豌豆和豌豆接种的反应以及对后续玉米的残留影响。平均而言，BNF 满足了紫云英和豌豆 60% 的氮需求。种子接种增加了豌豆和紫云英中的 %Ndfa，并且在紫云英中观察到了对地上生物量和 N_BFN 的积极影响。接种紫云英后种植的玉米产量对施氮没有反应，未接种紫云英和豌豆时观察到对施氮的最大响应。豆科植物接种在系统水平上有很强的影响，特别是在以前没有种植过豌豆或豌豆的田地，降低了后继玉米的经济最佳氮肥施用量。种子接种增加了豌豆和紫云英中的 %Ndfa，并且在紫云英中观察到了对地上生物量和 N_BFN 的积极影响。接种紫云英后种植的玉米产量对施氮没有反应，未接种紫云英和豌豆时观察到对施氮的最大响应。豆科植物接种在系统水平上有很强的影响，特别是在以前没有种植过豌豆或豌豆的田地，降低了后继玉米的经济最佳氮肥施用量。种子接种增加了豌豆和紫云英中的 %Ndfa，并且在紫云英中观察到了对地上生物量和 N_BFN 的积极影响。接种紫云英后种植的玉米产量对施氮没有反应，未接种紫云英和豌豆时观察到对施氮的最大响应。豆科植物接种在系统水平上有很强的影响，特别是在以前没有种植过豌豆或豌豆的田地，降低了后继玉米的经济最佳氮肥施用量。未接种野豌豆和豌豆时观察到对施氮的最大反应。豆科植物接种在系统水平上有很强的影响，特别是在以前没有种植过豌豆或豌豆的田地，降低了后继玉米的经济最佳氮肥施用量。未接种野豌豆和豌豆时观察到对施氮的最大反应。豆科植物接种在系统水平上有很强的影响，特别是在以前没有种植过豌豆或豌豆的田地，降低了后继玉米的经济最佳氮肥施用量。