A SOUTHERN Cross University (SCU) researcher told News Of The Area nitrate levels removed from a trial of woodchip bioreactors in local blueberry and cucumber farms are the highest levels of nitrate ever recorded in a field bioreactor trial in the world.

The woodchip bioreactors were designed by Local Land Services and trialled locally by SCU after Coffs Harbour City Council identified in 2019 and 2020 that there were water quality issues from intensive agriculture in the area.

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Southern Cross University, Coffs Harbour City Council and Local Land Services have since worked together to find solutions to the high levels of nitrate from fertiliser run-off that was twenty eight thousand times more than water quality guidelines.

The woodchip bioreactors that may reduce nitrates by up to eighty percent by helping reduce surface run-off from farms.

The bioreactors were trialled in the Coffs Coast region where water quality is being affected by nitrogen pollution from expanding agricultural intensification like protected cropping (hothouse) and blueberry farm run-off.

Drainage from these practices can enter streams without any treatment.

The two studies were led by the University’s PhD researchers Shane White and Praktan Wadnerkar, who are based at the National Marine Science Centre in Coffs Harbour.

“Our bioreactors stimulate bacteria to consume the nitrate as a food source by using woodchips as a substrate,” said Mr White, lead author of one of the reports.

“The woodchip bioreactors are designed to convert nitrate to the harmless di-nitrogen gas.

“Both bioreactors capture farm run-off, releasing lower nitrogen-laden water to the creek that would otherwise enter nearby waterways during rain events.”

Mr Wadnerkar, who authored the second report, said releasing untreated hothouse drainage creates a significant risk to local waterways.

News Of The Area spoke with Mr Praktan Wadnerkar about the importance of reducing nitrate levels before they reach our waterways.

“With nitrate concentration twenty eight thousand times more than water quality guidelines, the risks include causing algal bloom anda reduction in oxygen content and it is the biggest threat to the downstream marine park.

“We encourage farmers to continue to improve on-farm practices and provide options to protect our valuable waterways while maintaining agricultural productivity.”

Mr Wadnerkar said the blueberry and cucumber farmers they worked with were very happy and cooperative about the bioreactor trial because they see the fertiliser run-off as a financial loss.

The research project was funded by the Coffs Harbour City Council Environmental Levy Grants program.

The reports are available on the Coffs Harbour City Council website.

Visit the Monitoring our waterways section at www.coffsharbour.nsw.gov.au/Environment/Compliance-and-reporting/Monitoring-our-waterways.