Skip to content

Balancing Act

Nitrogen fertilisers have transformed agriculture, boosted food production and helped feed the world. But they came at a cost to the environment as excess runoff causes algal blooms.

share article

Farmers have been making practice changes to reduce runoff of dissolved inorganic nitrogen

Inventing a process to transform nitrogen in the air into fertiliser was a major scientific breakthrough. Food production, previously limited by the availability of nutrients in soil, has skyrocketed since we began turning the atmosphere’s most abundant element into a form that plants can take up.

On the downside, it is contributing to climate change, and when nitrogen fertiliser runoff ends up in waterways it upsets our delicately balanced coastal ecosystems. But there’s no going back. We can’t feed the world’s expanding population with organic agriculture alone, so we need to be smart about how we use it.

Improving water quality

For 15 years, farmers across the region have been working to reduce dissolved inorganic nitrogen runoff into the Great Barrier Reef lagoon, with support from a range of government-funded programs. They’ve been improving the health of their soils by adopting different farming practices, and using improved technology to more closely match fertiliser application to the needs of plants.

Poor water quality from land use was first identified as a health risk for the Great Barrier Reef in 2001. Dissolved inorganic nitrogen (from excess fertilisers) was one of the key concerns, along with pesticides and sediment runoff. The Wet Tropics is a hotspot for dissolved inorganic nitrogen due to the region’s heavy rainfall, steep mountain range and short sharp rivers, closeness to the Great Barrier Reef and its intensive agriculture along the coastal plain.

Generational change

One of the current programs running in the Herbert catchment around Ingham is engaging over 300 sugarcane growers to reduce nitrogen runoff. Carola Bradshaw, the program’s coordinator, says growers have seen their bottom line, yield and sugar content improve.

“Growers are encouraged by trusted peers and industry experts to try improved farm practices, and many of these new ways of doing things benefit productivity and profitability as well as the environment,” she says.

“Now these growers can share their experiences with others to keep the momentum going. It’s a generational shift and it will take time to change the whole industry, but more and more growers are open to rethinking how they farm and they’re adopting improved approaches to the ones that were previously passed down through the generations.”

Reef smart farming

In the Tully and Johnstone catchments, cane and banana farmers have significantly reduced their nitrogen use over the past few years – so the recent focus has turned to improving the crop’s ability to use the nutrients that are being applied.

Deb Telford, the leader of the project, says there are many factors that can affect nitrogen use efficiency (NUE), or how well plants take up nitrogen.

“Since we started the project, we’ve been doing a lot of soil and leaf testing to identify trends in how we can improve NUE across the district,” she says.

“Through these analyses, we’ve identified further opportunities for improving NUE at an enterprise level. This has included improved weed, disease and variety management, as well as tailored nutrient management strategies that are above and beyond what’s considered industry best practice.”

Fast facts:

  • Nitrogen is the most abundant element in the atmosphere, making up 78 per cent of it.
  • Only a fraction is available in a reactive form that can be used by plants to grow.
  • German chemist Fritz Haber invented the process to produce nitrogen fertiliser (ammonia) from thin air in the early 1900s. Another German chemist, Carl Bosch, made it scalable. It really took off in the 1960s and 70s.
  • The industrial process to make ammonia burns fossil fuel gas, creating substantial greenhouse gas emissions.
  • Nutrient runoff can feed algal blooms, leading to declines in oxygen and a lack of light that can kill fish, coral and seagrass.

The Tully Johnstone and Lower Herbert Water Quality Programs are funded by the Great Barrier Reef Foundation and the Australian Government’s Reef Trust.

related posts.