Using wetland processes to enhance nitrogen removal in farming landscapes

Abstract

Losses of nitrogen from intensive agricultural production areas can lead to elevated nitrogen in downstream aquatic ecosystems, with associated impacts on their health and function. Nitrogen has been identified as a threat to the health and resilience of the Great Barrier Reef, with a target of 70% reduction in end-ofcatchment anthropogenic dissolved inorganic nitrogen loads in some catchments flowing to the Great Barrier Reef. This presentation will reveal how wetlands and wetland processes can be used, as part of a whole-ofsystem approach, to tackle the challenge of reducing nitrogen entering the Great Barrier Reef.
Recent Queensland studies identified denitrification as the key nitrogen removal processes in wetlands. The amount of nitrogen removed through denitrification, and the features required to maximise denitrification, will be explained. Treatment wetlands and denitrifying bioreactors have been trialled in Queensland to reduce nitrogen in run-off and shallow groundwater. The nitrogen removal performance and costeffectiveness of these systems will be discussed.
The presentation will explain the conditions required for cost-effective nitrogen removal and show how site selection, design and management is critical. It proposes a whole-of-system, ’treatment train’ approach to reduce nitrogen loads in agricultural catchments, building upon and complementing best practice agronomic management using treatment systems and wetlands at different scales in the landscape. Replicating and returning natural wetland processes to catchments can sustain agricultural production, improve water quality and the health of aquatic ecosystems, providing multiple benefits.