ACID SULFATE SOILS
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Acid sulfate soils are naturally occurring soils and sediments that contain iron sulfides, most commonly pyrite. When these soils are exposed to air through drainage, excavation, or other disturbances, the sulfides react with oxygen and water to produce sulfuric acid. This acidification can lead to significant environmental degradation, including the release of toxic metals, which can harm plant and aquatic life. These soils are prevalent in coastal regions, river deltas, and wetlands, where the conditions for sulfide formation are typically found.
Globally, acid sulfate soils pose a significant challenge for land management and agriculture, particularly in regions with low-lying coastal areas. In Southeast Asia, for example, vast tracts of land have been degraded due to the improper management of these soils, leading to loss of agricultural productivity and damage to ecosystems. Similarly, in parts of Africa, Australia, Northern Europe and USA, acid sulfate soils have hindered sustainable land use, requiring costly remediation efforts to restore affected areas. The global distribution of acid sulfate soils is extensive, making it an international concern that requires cooperative research and management strategies.
Internationally, the recognition of acid sulfate soils as a critical environmental issue has led to increased collaboration among scientists, policymakers, and land managers. The acid sulfate soil working group, under the International Union of Soil Sciences (IUSS), have been involved in raising awareness and developing guidelines for the identification, management, and mitigation of acid sulfate soils. Efforts to share knowledge and best practices globally are crucial in addressing the challenges posed by these soils, as their impacts are felt across borders and ecosystems. As climate change and sea-level rise further exacerbate the exposure of acid sulfate soils, international cooperation becomes even more essential to mitigate their harmful effects.
History
Acid sulfate soils were first documented and described in the 19th century, with one of the earliest known references being made by the German chemist and agronomist, Justus von Liebig, in the 1840s. He observed the effects of soil acidification in areas where drainage had exposed sulfide-rich soils to oxygen. However, it wasn’t until the mid-20th century that the specific processes leading to the formation of acid sulfate soils, particularly the oxidation of iron sulfides like pyrite, were systematically studied and understood. Early research in the Netherlands, Australia, and Southeast Asia during the 1940s and 1950s further expanded the knowledge of these soils, leading to the development of management strategies to mitigate their negative impacts.
The Acid Sulfate Soils Working Group has had long and active service in promoting acid sulfate soil science and management. For example, building on the first International conference on acid sulfate soils in Wageningen held in 1972, the past three International Acid Sulfate Soil Conferences (held in Finland 2012, USA 2016 and Australia 2023) have all attracted well over 100 attendees from around the globe. The 10th International Acid Sulfate Soil Conference will be held in Luleå, Sweden featured a pre-conference tour, oral sessions, poster session, a mid-conference tour, a conference dinner, and a post-conference field trip.
HISTORY
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WORKING GROUP
The International Union of Soil Sciences’ Working Group Acid Sulfate Soils serves to promote acid sulfate soil science and management. Acid sulfate soils are located on all continents and if mismanaged can cause severe environmental degradation.
Initially established as a Working Group, the Acid Sulfate Soil Commission has been in existence for over 30 years and is especially active in convening regular international conferences and symposia devoted to acid sulfate science and management.
CONFERENCES
WELCOME TO
THE 10TH INTERNATIONAL ACID SULFATE SOILS CONFERENCE
CONFERENCE – 15-17 SEPTEMBER 2025
EXCURSION – 18-20 SEPTEMBER 2025