Fertiliser company Ballance Agri-Nutrients has lost a High Court battle to stop rival Ravensdown from patenting the delivery method of a product that could have a big impact on making farming more sustainable.

The two fertiliser giants have been locked down in a legal dispute over the method of applying nitrification inhibitors to grazed pastures, which are used to reduce nitrate leaching into waterways, reduce nitrous oxide emissions and increase pasture production.

Ravensdown also claims its method, eco-n that was developed by Lincoln University, will reduce potassium, calcium and magnesium leaching. The method sprays or irrigates pasture with nitrification inhibitors - it is the delivery method not the product that has been patented.

Last week, High Court Justice Patricia Courtney dismissed Ballance's appeal to stop Ravensdown from patenting its method.

The company had already received pre-grant approval from the Commissioner of Patents.

In her judgment, Justice Courtney said Ravensdown believed its method was new because it directly targets the soil, and such inhibitors had not been used in this way before.

Court documents showed New Zealand's nitrous oxide emissions from animal excreta, mainly urine, account for 50 per cent of the country's nitrous oxide emissions, which make up 20 per cent of the country's total greenhouse gas emissions.

Another leading source of nitrogen is found in fertilisers.

Ballance claims the method is not "new or inventive" and therefore did not qualify for an invention under the Patent Act.

Ballance head of research Warwick Catto told the Business Herald during the trial last year that if Ravensdown was given patent approval it would benefit the company's bottom line "in the tens of millions".

"It will have a significant economic impact. It will reduce competition and prices increase when a monopoly is introduced," Catto said.

But Ravensdown chief executive Rodney Green said the news couldn't have come at a better time for the Christchurch-based company.

"Our building has been yellow stickered. It's still standing, it's suffered a bit. We were five minutes' walk from the Cathedral, near the Avon River, it was a lovely space."

Green said the battle had cost the company almost $1 million and "we now hope it is over".

The company can now have patents granted in Argentina and Australia, and New Zealand, and had patents pending in Europe and the US, he said.

Green said Ravensdown and Lincoln University had "heavily invested" in eco-n and they felt it was important to patent the technology in order to protect its intellectual property.

The company is operating from its factory in Hornby but is determined to return to central Christchurch.

"We will go back to the CBD, to make sure Christchurch has a heart. Business needs to go back to make that happen," Green said.