Pedosphere 34(1): 191--199, 2024
ISSN 1002-0160/CN 32-1315/P
©2024 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Promotion effects of salt-alkali on ammonia volatilization in a coastal soil |
Zhenqi SHI1,2, Dongli SHE1,2 , Yongchun PAN1,2, Yongqiu XIA3 |
1 College of Agricultural Science and Engineering, Hohai University, Nanjing 210098 (China);
2 Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization, Carbon Sequestration and Emission Reduction, Nanjing 210098 (China);
3 Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China) |
| ABSTRACT |
| Coastal ecosystems are highly susceptible to salt-related problems due to their formation process and geographical location. As such ecosystems are the most accessible land resources on Earth, clarifying and quantifying the effects of salt-alkali conditions on N concentration and ammonia (NH3) volatilization are pivotal for promoting coastal agricultural productivity. The challenge in establishing this effect is to determine how salt-alkali conditions impact NH3 volatilization through direct or indirect interactions. An incubation experiment using a coastal soil from a paddy farmland, combined with the structural equation modeling (SEM) method, was conducted to reveal the net effects of salt-alkali on NH3 volatilization and the role of environmental and microbial factors in mutual interaction networks. The specific experimental design consisted of four salt treatments (S1, S2, S3, and S4: 1‰, 3‰, 8‰, and 15‰ NaCl by mass of soil, respectively), four alkaline treatments (A1, A2, A3, and A4: 0.5‰, 1‰, 3‰, and 8‰ NaHCO3 by mass of soil, respectively) and a control without NaCl or NaHCO3 addition (CK), and each treatment had three urea concentrations (N1, N2, and N3: 0.05, 0.10, and 0.15 g N kg-1 soil, respectively) and three replicates. At the N1, N2, and N3 levels, NH3 volatilization increased by 9.31%–34.98%, 3.07%–26.92%, and 2.99%–43.61% as the NaCl concentration increased from 1‰ to 15‰, respectively, compared with CK. With an increase in the NaHCO3 concentration from 0.5‰ to 8‰, NH3 volatilization increased by 8.36%–56.46%, 5.49%–30.10%, and 30.72%–73.18% at the N1, N2, and N3 levels, respectively, compared with CK. According to the SEM method, salinity and alkalinity had positive direct effects on NH3 volatilization, with standardized path coefficients of 0.40 and 0.19, respectively. Considering the total effects (net positive and negative effects) in the SEM results, alkalinity had a greater influence than salinity (total standardized coefficient 0.104 > 0.086). Nitrogen concentrations in the incubation system showed a direct positive effect on NH3 volatilization (standardized path coefficient = 0.78), with an obvious decrease under elevated salinity and alkalinity levels. Additionally, gene abundances of nitrogen-transforming microbes indirectly increased NH3 volatilization (total indirect standardized coefficient = 0.31). Our results indicated that potential NH3 emissions from coastal saline areas could be enhanced more by soil alkalization than by salinization. |
| Key Words: alkalinity,coastal ecosystem,NH3 emission,N-transforming microbe,salinity,structural equation modeling |
| Citation: Shi Z Q, She D L, Pan Y C, Xia Y Q. 2024. Promotion effects of salt-alkali on ammonia volatilization in a coastal soil. Pedosphere. 34(1): 191–199. |
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