Effects of Soil pH on Gaseous Nitrogen Loss Pathway via Feammox Process

Abstract

The application of N fertilizer is one of the most critical soil acidification factors in China, and soil acidification significantly alters biogeochemical processes such as N loss. Anaerobic ammonium oxidation coupled with iron reduction (Feammox) is an important biological process for N loss in natural environments, with the end-products of N2, NO2− and NO3−. However, the response of Feammox pathways to soil pH fluctuation has not been thoroughly studied. In the current study, Feammox pathways and microbial communities were explored through a slurry culture experiment with an artificially adjusted pH combined with a 15N isotope tracing technique and molecular biotechnology. Results showed significant differences in the gaseous N loss through Feammox (0.42–0.97 mg N kg−1 d−1) under different pH conditions. The gaseous N loss pathways were significantly affected by the pH, and Feammox to N2 was the predominant pathway in low-pH incubations. The proportion of N loss caused by Feammox coupled with denitrification increased as the soil pH increased. The gaseous N loss through Feammox increased by 43.9% when the soil pH decreased from 6.5 to 5.0. Fe-reducing bacteria, such as Ochrobactrum, Sphingomonas, and Clostridium increased significantly in lower pH incubations. Overall, this study demonstrated the effects of soil pH on Feammox pathways and extended the understanding of the N biogeochemical cycle in acidic soil.

Fertilizers and Fertilization Strategies Mitigating Soil Factors Constraining Efficiency of Nitrogen in Plant Production

“…The reduction in the root system negatively affects the use of nitrogen in fertilizers and increases the risk of nitrate being washed out from the soil [ 153 ]. Moreover, nitrate nitrogen, which is not taken up by plants, is reduced to gaseous compounds, including N 2 O [ 154 ]. In highly acidic soils, apart from exchangeable aluminum, excessive amounts of manganese (Mn 2+ ) and iron (Fe 2+ ) can also appear, which can further disrupt the proper growth and development of plants [ 155 ].…”

Nitrogen recovery in reclaimed mine soil under different amendment practices in tandem with legume and non‐legume revegetation: A review

“…It is also likely to occur in soils subjected to intensive N fertilizer application. Common N fertilizers like urea (46% N) and ammonium nitrate (35% N) when applied to soils have shown to increase atmospheric N loss leading to environmental pollution (Ma et al, 2021). It is important to monitor N loss through Feammox in global N cycling as it could change our estimates of total N losses from terrestrial ecosystem.…”