Mitigation strategies for soil acidification based on optimal nitrogen management

Highlights

● Soil acidification is determined by proton production and soil buffering capacity.

● Cropland acidification is mainly caused by anthropogenic activities.

● Nitrogen transformations dominate anthropogenic soil acidification processes.

● Acidification stage-specific strategies are needed for managing soil acidification.

● Optimizing N rate and N form is highly effective in mitigating soil acidification.

Abstract

Soil acidification is a serious constraint to food production worldwide. This review explores its primary causes, with a focus on the role of nitrogen fertilizer, and suggests mitigation strategies based on optimal N management. Natural acidification is determined by the leaching of weak acid mainly caused by climate and soil conditions, whereas the use of ammonium-based fertilizers, nitrate leaching and removal of base cations (BCs) by crop harvesting mostly accounts for anthropogenic acidification. In addition, low soil acid buffering capacity, mainly determined by soil parent materials and soil organic matter content, also accelerates acidification. This study proposes targeted mitigation strategies for different stages of soil acidification, which include monitoring soil carbonate content and pH of soils with pH > 6.5 (e.g., calcareous soil), use of alkaline amendments for strongly acidic soils (pH < 5.5) with aluminum toxicity risk to pH between 5.5 and 6.5, and decreasing acidification rates and supplementing BCs to maintain this optimal pH range, especially for soils with low acid buffering capacity. Effective mitigation involves optimizing the rate and form of N fertilizers used, regulating N transformation processes, and establishing an integrated soil–crop management system that balances acid production and soil buffering capacity.

Graphical abstract

Keywords

Soil acidification / nutrient management / nitrogen / soil buffering capacity

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Acknowledgements

This study was financially supported by Research and Development of Technical Approaches and Decision-making Systems for Precise Planting, Fertilization and Acid Control of Red Soil on Sloping Farmland project (2022YFD1900601), and Carbon Account Accounting and Emission Reduction and Carbon Sequestration Technology Research project (Qunonghe202231).

Compliance with ethics guidelines

Pengshun Wang, Donghao Xu, Prakash Lakshmanan, Yan Deng, Qichao Zhu, and Fusuo Zhang declare that they have no conflicts of interest or financial conflicts to disclose. This article does not contain any studies with human or animal subjects performed by any of the authors.

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The Author(s) 2024. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)