Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that govern its cycle are not well-described. To promote a holistic understanding of soil N dynamics, we need an integrated model that links soil organic matter (SOM) cycling to bioavailable N in both unmanaged and managed landscapes, including agroecosystems. We present a framework that unifies recent conceptual advances in our understanding of three critical steps in bioavailable N cycling: organic N (ON) depolymerization and solubilization; bioavailable N sorption and desorption on mineral surfaces; and microbial ON turnover including assimilation, mineralization, and the recycling of microbial products. Consideration of the balance between these processes provides insight into the sources, sinks, and flux rates of bioavailable N. By accounting for interactions among the biological, physical, and chemical controls over ON and its availability to plants and microbes, our conceptual model unifies complex mechanisms of ON transformation in a concrete conceptual framework that is amenable to experimental testing and translates into ideas for new management practices. This framework will allow researchers and practitioners to use common measurements of particulate organic matter (POM) and mineral-associated organic matter (MAOM) to design strategic organic N-cycle interventions that optimize ecosystem productivity and minimize environmental N loss.

土壤有机氮 (N) 是植物和微生物的关键资源，但控制其循环的过程并未得到很好的描述。为了促进对土壤氮动态的整体理解，我们需要一个综合模型，将土壤有机质 (SOM) 循环与非管理和管理景观（包括农业生态系统）中的生物可利用氮联系起来。我们提出了一个框架，该框架统一了我们对生物可利用氮循环中三个关键步骤的理解的最新概念进展：有机氮（ON）解聚和溶解；矿物表面的生物可​​利用氮吸附和解吸；和微生物 ON 周转，包括同化、矿化和微生物产品的回收。考虑这些过程之间的平衡，可以深入了解生物可利用氮的来源、汇和通量率。通过考虑对 ON 的生物、物理和化学控制之间的相互作用及其对植物和微生物的可用性，我们的概念模型将 ON 转化的复杂机制统一在一个具体的概念框架中，该框架适用于实验测试并转化为新管理的想法实践。该框架将允许研究人员和从业人员使用颗粒有机物 (POM) 和矿物相关有机物 (MAOM) 的常见测量值来设计战略性有机氮循环干预措施，以优化生态系统生产力并最大限度地减少环境氮损失。我们的概念模型将 ON 转换的复杂机制统一在一个具体的概念框架中，该框架适合进行实验测试并转化为新管理实践的想法。该框架将允许研究人员和从业人员使用颗粒有机物 (POM) 和矿物相关有机物 (MAOM) 的常见测量值来设计战略性有机氮循环干预措施，以优化生态系统生产力并最大限度地减少环境氮损失。我们的概念模型将 ON 转换的复杂机制统一在一个具体的概念框架中，该框架适合进行实验测试并转化为新管理实践的想法。该框架将允许研究人员和从业人员使用颗粒有机物 (POM) 和矿物相关有机物 (MAOM) 的常见测量值来设计战略性有机氮循环干预措施，以优化生态系统生产力并最大限度地减少环境氮损失。