💡这项突破是什么?
南湖新闻网讯（通讯员 朱俊）近日，我校资源与环境学院作物养分管理课题组在Soil Biology and Biochemistry发表了题为“Microbial mechanisms underlying enhanced nitrogen mineralization: Linking soil organic nitrogen depolymerization to amino acid metabolism”的研究论文，该研究基于华中农业大学沙洋实验站长期定位试验，揭示了轮作与施肥调控稻田土壤供氮能力的差异化机制，为优化农田氮素养分管理提供了新视角。
土壤有机氮矿化是农田土壤供氮的核心过程，“蛋白质→肽→氨基酸→铵”是土壤有机氮矿化的经典路径，这一路径包含大分子的“胞外解聚”和小分子的“胞内代谢”过程，且普遍认为微生物分泌胞外酶将大分子有机氮解聚为小分子产物的“胞外解聚”过程是土壤有机氮矿化的限速步骤。然而，当土壤中碳源和能量供应受限时，微生物对氨基酸的摄取与胞内分解代谢能力可能成为新的瓶颈。在集约化农业管理持续改变有机质质量与养分有效性的背景下，轮作与施肥究竟是主导“胞外解聚”还是“胞内代谢”过程来调控土壤供氮能力，这一科学问题的答案尚不清楚。
该研究着眼于这一科学问题，基于长期定位试验和微宇宙实验，应用宏基因组与代谢组技术，发现休耕-水稻轮作和油菜-水稻轮作的土壤氮矿化速率显著高于小麦-水稻轮作，且休耕-水稻轮作和油菜-水稻轮作的土壤总氮、蛋白质和溶解性有机氮库更大，β-N-乙酰氨基葡萄糖苷酶和蛋白酶活性更强，参与氨基酸代谢通路尤其是丙氨酸、天冬氨酸、谷氨酸代谢及精氨酸生物合成的基因相对丰度更高，“胞外解聚”效应更强。氮磷钾肥施用相对于不施肥也提高了土壤氮矿化速率，但其作用主要归因于微生物对低分子量有机氮化合物利用与代谢能力的提升，“胞内代谢”效应更具主导性。这些发现揭示了作物轮作与施肥影响土壤氮素有效性的路径差异机制，说明优化农田氮素养分管理策略必须充分考虑微生物对底物变化的适应性响应。
图1 作物轮作和施肥调控有机氮解聚和氨基酸周转的概念模型
本研究基于沙洋长期定位试验开展，研究基地始建于2005年，在学校和学院的大力支持下，经过近20年的建设，于2024年正式成立华中农业大学沙洋实验站。试验基地有2015年建立的水旱轮作与土壤养分管理定位试验5个，已规范稳定运行11个种植周期，为团队系统开展长江流域主要轮作制度下的农田养分管理、耕地质量保育、土壤-作物互作、粮油作物单产提升提供了有力的支撑平台。依托长期定位试验，作物养分管理课题组近五年来围绕农田氮磷养分管理和土壤固碳减排先后获批国家自然科学基金面上项目5项和青年科学基金项目（C类）3项。
资源与环境学院2026届博士毕业生赵剑（现为石河子大学农学院讲师）为论文第一作者，鲁剑巍教授为通讯作者。作物养分管理课题组朱俊副教授、任涛教授、博士后方娅婷、博士生盛倩男等参与本研究工作，李小坤教授、丛日环副教授、陆志峰副教授对论文写作提供了帮助。本研究得到国家自然科学基金32372817项目资助。
论文链接：https://doi.org/10.1016/j.soilbio.2026.110289
【英文摘要】
The combination of extracellular depolymerization and intracellular amino acid metabolism jointly shapes soil organic nitrogen (SON) mineralization, but whether agricultural management alters the relative importance of these stages remains unclear. We combined measurements of N mineralization rates, SON pools, and extracellular enzyme activities with metagenomic and metabolomic analyses in a nine-year field experiment comprising three rice-based rotations: fallow-rice (FR), oilseed rape-rice (OR), and wheat-rice (WR), each managed with or without NPK fertilization. Relative to the WR rotation, the FR and OR rotations significantly increased soil N mineralization rates by 36%–60% and 16%–23%, respectively. The FR and OR rotations were characterized by larger pools of total N, protein, and dissolved organic N, higher potential activities of β-N-acetylglucosaminidase and protease, and greater relative abundances of genes encoding these enzymes. Amino acids and peptides were relatively depleted during incubation. Compared with WR rotation, the FR and OR rotations showed greater relative enrichment of amino acid and peptide related metabolites and higher relative abundances of genes involved in amino acid metabolic pathways, particularly alanine, aspartate, and glutamate metabolism and arginine biosynthesis. The relative abundances of genes encoding key enzymes, including glutamate dehydrogenase and acetylornithine aminotransferase, were positively associated with N mineralization rates. NPK fertilization increased N mineralization rates and was associated with higher relative abundances of genes encoding leucine aminopeptidase and genes involved in arginine biosynthesis, but it decreased the relative abundance of genes encoding protease. Collectively, our results show that crop rotation and fertilization regulate different stages of the SON mineralization pathway. Crop rotation effects are linked to coordinated variation in substrate supply, activities of organic N-depolymerizing enzymes, and potential for amino acid metabolism, while fertilization shifts microbial N acquisition toward low-molecular-weight organic N.
