Wetland soils

Four conditions are required for a soil to become anaerobic and support reducing reactions and the development of soil morphological features. If these chemical transformations occur in the soil’s upper layers:

• The soil must be saturated to the point of excluding atmospheric oxygen.
• The soil must contain a source of organic matter that can be oxidised or decomposed.
• The soil must contain a population of respiring microbes that will oxidise the organic matter.
• The water must be stagnant or slow moving.

Wetland soils can be identified using soil morphological indicators such as:

• the accumulation of organic matter
• gleyed soil colours
• soil mottling
• iron or manganese segregations
• oxidising root channels and soil pore linings
• reduction of sulphur and carbon (e.g. acid sulfate soils).

Wetland soils impact directly on other wetland characteristics, e.g. water quality, fauna, vegetation, and can be a reflection of the physical processes occurring in the wetland, e.g. water inflow, water chemistry, filtering of pollutants.

Wetland soils assessment reports and supporting information

The following reports provide information and background to support the identification of wetland soils.

Soil indicators of Queensland wetlands: Statewide assessment and methodology

The report details and discusses findings of a statewide assessment of wetland soil indicators conducted by the Department of Natural Resources and Water during 2007 and 2008 under the Queensland Wetlands Program.

Soil Indicators of Queensland Wetlands: Field Guide

The field guide has been developed to assist in the field identification of wetland soil indicators in Queensland.

Soil Indicators of Queensland Wetlands Phase 1: Literature Review and Case Studies

The report highlights two case studies of wetlands within Southern and Central Queensland to test if predictable relationships exist between soil indicators identified within the literature and wetland status for Queensland wetland soils.

Indicators of Reduction in Soils

The report outlines the Indicator of Reduction in Soils (IRIS) method for identifying wetlands and demonstrates how to use the method on wetlands in Queensland. Field indicators of ephemeral wetlands can be hard to find in dry times. Wetland soils—identified by reducing conditions—become a major indicator of existence and extent.

Wetland soil case studies

The proposed wetland soil indicators were tested in 58 wetlands, representing a range of wetland classes, climatic zones and biogeographical regions. Thirty-nine case studies have been developed.

Additional information

• The Extraordinary Story of Peat and Carbon
• Reports and publications
• Mapping
• Interpreting data
• Soil survey types
• Land evaluation schemes
• The Australian Soil Resource Information System is a collation of the best available, nationally consistent data and information on Australia’s soil and land resources. A national soils layer is available which has broadscale to point-scale information.

Last updated: 6 September 2023