Farmers' fertilizer cuts boost water quality in Great Barrier Reef catchments
Two new studies link reduced synthetic fertilizer use by farmers to measurable improvements in water quality across river basins feeding the Great Barrier Reef.
A comprehensive analysis of 100 years of fertilizer records reveals a 25-50% decline in synthetic nitrogen and phosphorus use across most Great Barrier Reef catchments, especially in sugarcane regions. Concurrently, a separate assessment of nearly four decades of water-quality data from nine monitoring sites—spanning an area the size of New Zealand—found that 75% of locations showed improved conditions, with lower dissolved inorganic nitrogen at catchment outlets.
Researchers from TropWATER at James Cook University, CSIRO and other partners attribute these trends to changes in farming practices, including earlier fertilizer application and the adoption of cover crops like sunn hemp. They argue that cleaner runoff will support faster coral and seagrass recovery during bleaching events. The findings arrive as Australia prepares its 2028 UNESCO report on progress under the Reef 2050 water-quality plan. GBRMPA chief scientist Roger Beeden highlighted the value of long-term monitoring in distinguishing genuine trends from episodic events.
Why it matters
Cleaner runoff enhances the reef's resilience to climate stress, supporting biodiversity and tourism.
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