Minimizing nitrification of fertilizer ammonium (NH4+) can reduce nitrate (NO3−) contamination of groundwater and increase nitrogen (N) use efficiency (NUE). Olive mill wastewater (OMW), hydroalcoholic extracts of Mentha piperita L. (Mp) and Artemisia annua L. (Aa), and synthetic nitrification inhibitor (NI) dicyandiamide (DCD) were investigated. All NIs reduced activity of nitrifying bacteria and NO3− leached and increased efficiency of N metabolism of celery (Apium graveolens L.) during 56 days in a soil mixture fertilized with ammonium sulfate [(NH4)2SO4]. Soil NO3− leaching losses of DCD, OMW, Mp, and Aa treatments were 24%, 26%, 67%, and 78% of the untreated control loss, respectively, at 35 and 56 days after planting (DAP). Decreased nitrification by NIs resulted in greater concentrations of soil NH4+ correlated with less nitrate reductase (NR) activity in roots and leaves and less soil acidification compared to the control. At 35 and 56 DAP, DCD and OMW treatments decreased NR and increased glutamine synthetase activities in leaves and roots, compared to the control. NIs increased leaf and root protein and amino acids. OMW significantly decreased leaching loss of NO3− to 10% of fertilizer N applied to the soil, compared to 38% of applied NH4+-N leached from the control. OMW proved an effective alternative to DCD to improve NUE of NH4+-fertilizers.

中文翻译：

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橄榄磨废水和两种天然提取物作为硝化抑制剂对芹菜（Apiumcreeolens L.）硝化细菌活性、土壤硝酸盐浸出损失和氮代谢的影响

最大限度地减少化肥铵 (NH4+) 的硝化作用可以减少地下水的硝酸盐 (NO3−) 污染并提高氮 (N) 的利用效率 (NUE)。研究了橄榄磨废水 (OMW)、薄荷 (Mp) 和青蒿 (Aa) 的水醇提取物以及合成硝化抑制剂 (NI) 双氰胺 (DCD)。在用硫酸铵 [(NH4)2SO4] 施肥的土壤混合物中，所有 NI 在 56 天内都降低了硝化细菌的活性，NO3− 浸出并提高了芹菜 (Apium Graveolens L.) 的氮代谢效率。在种植后 35 天和 56 天 (DAP)，DCD、OMW、Mp 和 Aa 处理的土壤 NO3− 浸出损失分别是未处理对照损失的 24%、26%、67% 和 78%。与对照相比，NIs 降低的硝化作用导致土壤 NH4+ 浓度升高，与根和叶中硝酸还原酶 (NR) 活性降低以及土壤酸化程度降低相关。与对照相比，在 35 和 56 DAP，DCD 和 OMW 处理降低了 NR 并增加了叶子和根中的谷氨酰胺合成酶活性。NIs 增加了叶和根的蛋白质和氨基酸。OMW 显着降低了 NO3− 的浸出损失，减少了施入土壤的肥料 N 的 10%，而从对照中浸出的 NH4+-N 则为 38%。OMW 被证明是 DCD 的有效替代品，可提高 NH4+ 肥料的 NUE。与对照相比。NIs 增加了叶和根的蛋白质和氨基酸。OMW 显着降低了 NO3− 的浸出损失，降低了施入土壤的肥料 N 的 10%，而从对照浸出的 NH4+-N 的浸出损失为 38%。OMW 被证明是 DCD 的有效替代品，可提高 NH4+ 肥料的 NUE。与对照相比。NIs 增加了叶和根的蛋白质和氨基酸。OMW 显着降低了 NO3− 的浸出损失，降低了施入土壤的肥料 N 的 10%，而从对照浸出的 NH4+-N 的浸出损失为 38%。OMW 被证明是 DCD 的有效替代品，可提高 NH4+ 肥料的 NUE。