Incorporating crop residue favors biotic and abiotic nitrogen (N) immobilization, which can effectively conserve active N in soil. Here we summarize the occurrence characteristics of biotic and abiotic N immobilization and affecting factors, and then identify a general pattern of the relative importance of the two processes in soil incorporated with crop residue. When microorganisms decompose crop residue for a source of energy and carbon (C) to support their metabolism, they need N to build cellular components, resulting in N immobilization in biomass. Alternatively, N can be incorporated into soil organic matter (SOM) through the following known mechanisms: ammonium (NH₄⁺) fixation by clay minerals, condensation of ammonia (NH₃) with phenol or quinone rings, and nitrosation of nitrite (NO₂-) with phenolic compounds. The biotic and abiotic contribution to N immobilization is significantly controlled by soil properties and crop residual quality. When a large fraction of C is in the form of labile organic compounds, biotic N immobilization may be important. In contrast, high fraction of lignin-derived phenolic compounds or other recalcitrant organic compounds facilitates abiotic N immobilization. In the N-limited soil, the increase in N availability contributes to microbial activity, which would stimulate biotic processes. However, when microbial metabolism switches from N-limited to C-limited due to the increase in N availability, abiotic processes become important. Abiotic processes even predominate over biotic processes under N-enriched conditions. The relative roles of biotic or abiotic N immobilization in soil incorporated with crop residue are dependent on the availability of C relative to N and soil N availability. Carbon and N availability in turn is related to their forms. Moreover, N availability is affected by soil pH. The mechanisms by which N is immobilized determine the fate of immobilized N and are of vital importance for the management of N availability and losses through combining N fertilizer with crop residue. More investigation is necessary to quantify the contribution of biotic and abiotic processes during the decomposition of crop residue and to determine the factors affecting N immobilization in the field.

掺入作物残渣有利于生物和非生物氮（N）的固定，从而可以有效地保护土壤中的活性氮。在这里，我们总结了生物和非生物氮固定化的发生特征及其影响因素，然后确定了两种过程在掺有农残的土壤中相对重要性的一般模式。当微生物分解农作物残余物作为能量和碳（C）的来源以支持其代谢时，它们需要N才能建立细胞成分，从而将N固定在生物质中。或者，可以通过以下已知机制将N掺入土壤有机物（SOM）中：通过粘土矿物固定铵（NH ₄ ⁺），冷凝氨（NH ₃）带有苯酚或醌环，亚硝酸盐（NO ₂-）与酚类化合物。土壤特性和作物残留质量显着控制了固氮的生物和非生物贡献。当很大一部分C以不稳定的有机化合物形式存在时，生物固氮可能很重要。相反，高比例的木质素衍生的酚类化合物或其他难降解的有机化合物促进非生物固氮。在氮有限的土壤中，氮有效性的增加有助于微生物活性，这将刺激生物过程。但是，当由于氮的有效性增加而使微生物代谢从N限变为C限时，非生物过程变得很重要。在富氮条件下，非生物过程甚至比生物过程占优势。将生物或非生物氮固定在掺有农残的土壤中的相对作用取决于相对于氮的碳有效性和土壤氮有效性。碳和氮的可用性又与其形式有关。而且，氮的有效性受土壤pH的影响。固定化氮的机制决定了固定化氮的命运，并且通过将氮肥与作物残渣结合使用，对于管理氮的有效性和损失至关重要。需要进行更多的研究来量化作物残渣分解过程中生物和非生物过程的贡献，并确定影响田间固氮的因素。氮的有效利用受土壤pH的影响。固定化氮的机制决定了固定化氮的命运，并且通过将氮肥与作物残渣结合使用，对于管理氮的有效性和损失至关重要。有必要进行更多的研究来量化作物残渣分解过程中生物和非生物过程的贡献，并确定影响田间固氮的因素。氮的有效利用受土壤pH的影响。固定化氮的机制决定了固定化氮的命运，并且通过将氮肥与作物残渣结合使用，对于管理氮的有效性和损失至关重要。需要进行更多的研究来量化作物残渣分解过程中生物和非生物过程的贡献，并确定影响田间固氮的因素。