In most terrestrial ecosystems, nitrogen (N) is an essential and often limiting element for living organisms. There is competition for the available N between roots, rhizosphere organisms and the overall soil food web. N derived from biological fixation in the soil reaches the above ground terrestrial food web through two pathways: from root uptake, and by successive predation on soil organisms. Considering the importance of N in terrestrial ecosystems, investigations of food web interactions for N through the food web in time and space are a prerequisite for better understanding of primary production and nutrient cycling. Here we reviewed N partitioning in the soil based on stable isotope (¹⁵N and ¹³C) ratio mass spectrometry studies of the food webs. Bacteria stratification in peds and down the soil profile, as represented by Pourbaix diagrams, delineate metabolic functions and N fixation parameters. We proposed a model for the path of N through the soil to the above ground sub-system. There are two main paths: one from root nutrient uptake to the aerial parts of the plant, and the other through the soil food web from successive consumption by predation of soil organisms, to the above-ground terrestrial food web. There are insufficient data available on the bacteria-bacterivore feeding pathway, but it would appear that besides specialized bacterivorous protists, other protists and nematodes tend to be more generalized microbivores. Understanding the pathway of N transfer better, and its regulating parameters for functional guilds within trophic levels, has implications for the sustainable management of our environment, agriculture sustainability, forest soil management, and remediation of disturbed environments.

在大多数陆地生态系统中，氮（N）是活生物体不可或缺的元素，通常是限制性的元素。根，根际生物与整个土壤食物网之间存在有效氮竞争。来自土壤中生物固定的氮素通过两种途径到达地面上的地面食物网：从根部吸收和通过对土壤生物的连续捕食。考虑到氮在陆地生态系统中的重要性，调查食物网在时间和空间上通过食物网对氮的相互作用是更好地了解初级生产和养分循环的前提。在这里，我们基于稳定同位素（¹⁵ N和¹³C）食物网的比例质谱研究。如Pourbaix图所示，细菌在脚下和土壤剖面中的分层，描绘了代谢功能和固氮参数。我们提出了氮穿过土壤到地上子系统的路径的模型。有两种主要途径：一种是从根部吸收养分到植物的地上部分，另一种是通过从土壤生物的捕食中连续食用到地上食物网，通过土壤食物网。关于细菌-噬菌体进食途径的可用数据不足，但似乎除了专门的细菌性原生生物外，其他原生生物和线虫也倾向于是更普遍的微生物。更好地了解氮的传播途径，