The extensive usage of ammonium sulfate as the leaching agent to extract rare earth elements led to widespread ammonia nitrogen (NH₄⁺-N) pollution in the tailing soils of ion-adsorbed rare earth deposits in southern China. However, the cost-effective technologies to tackle with the long-term retention of NH₄⁺-N in the rare earth mining soil have been largely unresolved. In this study, we developed a cost-effective approach to activate soil nitrification by the co-application of alkaline materials and organic fertilizer. The co-application of 0.3 % of organic fertilizer and 0.1 % ∼ 0.2 % of CaO or MgO or Mg(OH)₂ stimulated a soil NH₄⁺-N decrease rate of 2.01–7.58 mg kg⁻¹ d⁻¹ and a soil NO₃⁻-N accumulation rate of 1.56–7.09 mg kg⁻¹ d⁻¹. Noting that only if the soil pH was elevated to 7.81–9.00, the NH₄⁺-N decrease rate and NO₃⁻-N accumulation rate were dependent on the proton consumption capacity of the alkaline materials. The application of CaCO₃ could not stimulate soil nitrification possibly due to the soil pH was uncapable to be elevated to above 7.68. The qPCR, amplicon sequencing, and nitrification inhibitor batch incubation results demonstrated that organic fertilizer supplied active ammonia-oxidizing bacteria Nitrosomonas europaea. The proliferation of Nitrosomonas europaea in the alkaline materials and organic fertilizer co-applied soil was responsible for the soil nitrification. Furthermore, the application of commercial denitrifying bacteria inoculum promoted the removal of accumulated NO₃⁻-N. The findings of this study provide a lost-cost technology to remove NH₄⁺-N from the rare earth mining soil.

大量使用硫酸铵作为浸出剂提取稀土元素，导致我国南方离子吸附型稀土矿床尾矿土壤普遍存在氨氮（NH ₄ ^{+ -N）污染。}_{然而，解决 NH 4} ⁺ -N 在稀土采矿土壤中长期滞留的成本效益技术在很大程度上尚未得到解决。在这项研究中，我们开发了一种经济高效的方法，通过共同施用碱性物质和有机肥来激活土壤硝化作用。0.3%的有机肥和0.1%～0.2%的CaO或MgO或Mg(OH) _{2 的}共同施用刺激土壤NH ₄ ⁺ -N的减少率为2.01–7.58 mg kg ⁻¹d ⁻¹和土壤 NO ₃ ⁻ -N 积累率为 1.56–7.09 mg kg ⁻¹ d ⁻¹。注意到只有当土壤 pH 值升高到 7.81–9.00 时，NH ₄ ⁺ -N 减少率和 NO ₃ ^- -N 积累率才取决于碱性物质的质子消耗能力。施用CaCO ₃不能刺激土壤硝化作用可能是由于土壤pH值不能升高到7.68以上。qPCR、扩增子测序和硝化抑制剂批次孵育结果表明，有机肥料提供了活性氨氧化细菌Nitrosomonas europaea. Nitrosomonas europaea在碱性物质和有机肥共施土壤中的增殖是土壤硝化作用的原因。_{此外，商业反硝化细菌接种物的应用促进了累积的NO 3} ^- -N的去除。本研究结果提供了一种从稀土矿区土壤中去除NH ₄ ⁺ -N的成本损失技术。