School of Geography, Nanjing Normal University, Nanjing 210023, China.
Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China.
Environ Sci Technol. 2022 Mar 15;56(6):3791-3800. doi: 10.1021/acs.est.1c07997. Epub 2022 Feb 28.
Dissimilatory nitrate reduction to ammonium (DNRA), the nearly forgotten process in the terrestrial nitrogen (N) cycle, can conserve N by converting the mobile nitrate into non-mobile ammonium avoiding nitrate losses via denitrification, leaching, and runoff. However, global patterns and controlling factors of soil DNRA are still only rudimentarily known. By a meta-analysis of 231 observations from 85 published studies across terrestrial ecosystems, we find a global mean DNRA rate of 0.31 ± 0.05 mg N kg day, being significantly greater in paddy soils (1.30 ± 0.59) than in forests (0.24 ± 0.03), grasslands (0.52 ± 0.15), and unfertilized croplands (0.18 ± 0.04). Soil DNRA was significantly enhanced at higher altitude and lower latitude. Soil DNRA was positively correlated with precipitation, temperature, pH, soil total carbon, and soil total N. Precipitation was the main stimulator for soil DNRA. Total carbon and pH were also important factors, but their effects were ecosystem-specific as total carbon stimulates DNRA in forest soils, whereas pH stimulates DNRA in unfertilized croplands and paddy soils. Higher temperatures inhibit soil DNRA via decreasing total carbon. Moreover, nitrous oxide (NO) emissions were negatively related to soil DNRA. Thus, future changes in climate and land-use may interact with management practices that alter soil substrate availability and/or soil pH to enhance soil DNRA with positive effects on N conservation and lower NO emissions.
异化硝酸盐还原为铵（DNRA），这一在陆地氮（N）循环中几乎被遗忘的过程，可以通过将可移动的硝酸盐转化为不可移动的铵来保存 N，从而避免硝酸盐通过反硝化、淋溶和径流而损失。然而，土壤 DNRA 的全球模式和控制因素仍然知之甚少。通过对来自 85 项陆地生态系统发表研究的 231 个观测结果的荟萃分析，我们发现全球平均 DNRA 速率为 0.31±0.05mgNkg-1d-1，在稻田土壤（1.30±0.59）中明显高于森林（0.24±0.03）、草地（0.52±0.15）和未施肥农田（0.18±0.04）。土壤 DNRA 在较高的海拔和较低的纬度下显著增强。土壤 DNRA 与降水、温度、pH 值、土壤总碳和土壤总 N 呈正相关。降水是土壤 DNRA 的主要刺激因素。总碳和 pH 值也是重要因素，但它们的影响是特定于生态系统的，因为总碳刺激森林土壤中的 DNRA，而 pH 值刺激未施肥农田和稻田土壤中的 DNRA。较高的温度通过降低总碳来抑制土壤 DNRA。此外，一氧化二氮（NO）排放与土壤 DNRA 呈负相关。因此，未来的气候变化和土地利用变化可能会与改变土壤基质可用性和/或土壤 pH 值的管理实践相互作用，从而增强土壤 DNRA，对 N 保护和降低 NO 排放产生积极影响。
