Organic carbon based amendments can improve soil structure and fertility, as well as increase composition and diversity of soil microbial community. One of the major functions of improving soil fertility is to achieve effective nitrogen (N) management and mineralization. In this study, 746 paired observations were pooled from 20 long-term field experiments to verify the hypothesis that compared to synthetic only fertilization, long-term application of organic fertilization alone or in combination with synthetic fertilization could strengthen multiple internal pathways for soil N supply under various climatic conditions. We found that long-term application of synthetic N fertilizers alone or in combination with phosphorus (P) and potassium (K) led to an increase only in the recalcitrant organic N mineralization rate (M_Nrec) by 210% and 263%, respectively. However, long-term application of organic fertilizers alone or in combination with synthetic N fertilizers increased M_Nrec, labile organic N mineralization rate (M_Nlab) and release of adsorbed ammonium from cation exchange sites (R_NH4a) by 160% and 200%, 153% and 353%, and 1025% and 541%, respectively. This indicates that organic fertilization can strengthen multiple internal pathways for mineral N production. The long-term co-application of organic and synthetic fertilizers stimulated M_Nlab (197%), M_Nrec (151%) and R_NH4a (563%) in subtropical regions, but it had no effect on heterotrophic nitrification (O_Nrec). In contrast, it stimulated M_Nrec (505%), R_NH4a (633%) and O_Nrec (184%) in temperate regions, with no observed effect on M_Nlab. These data confirm that if one N supply source is shut-off under specific climatic conditions the other pathways continue to provide N. The meta-analysis advances our understanding of agroecosystems and as such help to improve frameworks for enhancing soil health.

有机碳改良剂可以改善土壤结构和肥力，并增加土壤微生物群落的组成和多样性。提高土壤肥力的主要功能之一是实现有效的氮（N）管理和矿化。在这项研究中，汇集了 20 个长期田间试验的 746 个配对观察结果，以验证以下假设：与纯合成施肥相比，长期单独施用有机肥或与合成施肥相结合可以加强土壤氮供应的多种内部途径在各种气候条件下。我们发现，长期单独施用合成氮肥或与磷（P）和钾（K）结合使用仅导致顽固性有机氮矿化率（ M _Nrec ）分别增加210％和263％。然而，长期单独施用有机肥料或与合成氮肥结合使用，使M _Nrec 、不稳定有机氮矿化率（ M _Nlab ）和阳离子交换位点吸附铵的释放（ R _NH4a ）分别增加 160% 和 200%，分别为 153% 和 353%、1025% 和 541%。这表明有机肥可以加强矿质氮生产的多种内部途径。长期配施有机肥和合成肥料对亚热带地区的M _Nlab (197%)、 M _Nrec (151%)和R _NH4a (563%)有刺激作用，但对异养硝化作用( O _Nrec )没有影响。 相比之下，它刺激了温带地区的M _Nrec (505%)、 R _NH4a (633%) 和O _Nrec (184%)，但没有观察到对M _Nlab的影响。这些数据证实，如果在特定气候条件下关闭一个氮供应源，其他途径将继续提供氮。荟萃分析增进了我们对农业生态系统的理解，因此有助于改善增强土壤健康的框架。