The purpose of this study was to evaluate the impacts of two amino acids that contrast in their composition: alanine as a neutral amino acid (represent regular amino acid) and methionine (represent sulfur-containing amino acids) on nitrogen (N) dynamics in acidic subtropical forest soil. ¹⁵ N-labeled alanine and methionine were added into forest soil to carry out subsequent incubation experiments for 72 h under 60% and 90% of water-holding capacities (WHC) to investigate their potential impacts. The results showed that under 60% of WHC, alanine and methionine added treatment significantly increased the net ammonification rate, except at the 5th h for alanine addition due to alanine immobilized then to prime the soil N ammonification. Alanine addition induced NO₃⁻-N immobilization before 24 h and then nitrification occurred dominantly between 24 and 72 h. However, methionine addition resulted in a lower NO₃⁻-N compared to control indicating that nitrification was likely inhibited. Only methionine added treatment enhanced significantly the net N₂O emission rate as compared to that in the control at the 72nd h due to nitrifier denitrification possibly. Under 90% of WHC, the net ammonification rate was significantly higher in the alanine added treatment than in the control, but lower in the methionine added treatment at the 5th h. Amino acids addition significantly decreased the net nitrification rate at the 5th h, but greatly increased the net N₂O emissions rate at the 24th h and 72nd h compared to control. Overall, more than 96% of NH₄⁺-N, NO₃⁻-N, and N₂O emissions were recorded from soil native N rather than from the added amino acids. Contrasting effects of amino acids should be considered when studying the mechanisms of soil organic N in contributing to the N transformation in subtropical forest soil.

本研究的目的是评估两种组成不同的氨基酸：作为中性氨基酸的丙氨酸（代表常规氨基酸）和蛋氨酸（代表含硫氨基酸）对酸性环境中氮 (N) 动力学的影响亚热带森林土壤。^将15  N标记的丙氨酸和甲硫氨酸加入森林土壤中，在60%和90%的持水能力（WHC）下进行72小时的后续孵化实验，以研究其潜在影响。结果表明，在60%的WHC下，添加丙氨酸和蛋氨酸的处理显着提高了净氨化率，除了在第5 h添加丙氨酸，因为丙氨酸被固定，然后启动土壤N氨化。添加丙氨酸诱导NO ₃ ^--N 固定在 24 小时之前，然后硝化作用主要发生在 24 和 72 小时之间。然而，与对照相比，甲硫氨酸添加导致较低的NO ₃ ^- -N，表明硝化作用可能被抑制。与对照组相比，仅添加甲硫氨酸的处理在第 72 h 时显着提高了 N ₂ O的净排放率，这可能是由于硝化反应的反硝化作用。在 90% WHC 下，添加丙氨酸处理的净氨化率显着高于对照，但添加蛋氨酸处理的第 5 h 净氨化率较低。添加氨基酸显着降低了第 5 小时的净硝化速率，但大大增加了净 N ₂与对照相比，第 24 小时和第 72 小时的 O 排放率。总体而言，超过 96% 的 NH ₄ ⁺ -N、NO ₃ ^- -N 和 N ₂ O 排放量来自土壤天然氮，而不是来自添加的氨基酸。在研究土壤有机氮促进亚热带森林土壤氮转化的机制时，应考虑氨基酸的对比效应。