Quantification of legume nitrogen (N) rhizodeposition (N derived from roots) and its fate in agroecosystems is crucial for managing soil fertility, land productivity, and agriculture sustainability. In contrast to forage legumes, the N rhizodeposition by grain legumes is nearly unknown. Therefore, N rhizodeposition of four grain legumes and its transfer to subsequent wheat crops was quantified using the ¹⁵N stem labeling method under field conditions. The N rhizodeposition of the grain legumes: peanut, soybean, mungbean, and adzuki bean amounted to 25, 51, 20, and 63 kg N ha⁻¹, respectively. N rhizodeposition was not affected by fertilization, and it was 53–257% more accumulated in topsoil (0–20 cm) than that in subsoil (20–40 cm). However, N rhizodeposition per unit of root biomass in subsoil was 3.5‐times as much as that in topsoil (p < 0.05), indicating the importance of legumes for soil fertility and exploration in subsoil. Remarkably, subsequent wheat utilized 13–85% of legume N rhizodeposition, which contributed to 4–20% of total wheat N uptake. Combining the present data with the literature review, the average N rhizodeposition of legumes (both grain and forage legumes) is 83 kg N ha⁻¹ (n = 75), and one‐fourth of which was utilized by subsequent cereals. Increasing root biomass by 1 g increases rhizodeposition by 53 mg N. In conclusion, legume N rhizodeposition is crucial for the sustainability of legume‐based crop rotations resulting in soil N build‐up and is an important N source for subsequent crops.

中文翻译：

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豆科植物氮素根际沉积及其在农业生态系统中的命运：一项实地研究和文献综述

定量分析豆科植物氮素（根系氮）及其在农业生态系统中的命运对于管理土壤肥力，土地生产力和农业可持续性至关重要。与饲草豆科植物相反，谷物豆科植物的N根基沉积几乎是未知的。因此，在田间条件下，使用¹⁵ N茎标记法对4种豆类作物的N根瘤菌沉积及其向后续小麦作物的转移进行了定量。谷物豆科植物花生，大豆，绿豆和小豆的氮根际沉积量分别为25、51、20和63 kg N ha ^-1， 分别。氮根际沉积不受施肥的影响，表土（0–20 cm）比底土（20–40 cm）多累积53–257％。然而，地下土壤每单位根生物量的氮根际沉积量是表土的3.5倍（p  <0.05），表明豆类对于土壤肥力和地下土壤勘探的重要性。引人注目的是，随后的小麦利用了豆科植物氮的13–85％的氮固氮沉积，这占小麦氮素吸收总量的4–20％。结合现有数据和文献综述，豆科植物（谷物和牧草豆科植物）的平均N根状茎沉积量为83 kg N ha ^-1（n= 75），其中四分之一被后来的谷物利用。根部生物量每增加1 g，根际沉积就会增加53 mgN。总而言之，豆科植物N的根际沉积对于以豆类为基础的作物轮作的可持续性至关重要，导致土壤氮积累，并且是后续作物的重要氮素来源。