Greenpeace has launched a new campaign to ban synthetic nitrogen fertiliser and save New Zealand's rivers.

They have launched the campaign in billboard style, with the wording taking aim at company's Ravensdown and Ballance.

Greenpeace campaigner Gen Toop says the billboards are just the first step in making these dirty companies a household name.

Two of the Greenpeace billboards are being installed just a stone's throw from the Ravensdown company headquarters in Christchurch and Ballance's in Mount Maunganui.

Greenpeace has taken issue with synthetic nitrogen fertiliser because of its links to the industrialisation of agriculture, particularly dairying.

'Synthetic nitrogen fertiliser is the fuel that drives industrial dairying. It's spread onto New Zealand dairy farms to grow more grass for too many cows,” says Gen.

'Too many cows and too much synthetic nitrogen fertiliser is trashing our rivers and causing climate breakdown.”

The impacts of the nitrogen cycle breach are already being seen around the world, in the rapid growth in freshwater pollution, oceanic dead zones, and the spike in nitrous oxide emissions.

'We agree with the sentiment that farming practices need to change, and today's ‘future-ready' farmers are already operating their businesses quite differently to the way grandad might have done things,” says a Ballance spokesperson.

'We know from our research, and working with our customers, that the vast majority of New Zealand famers have sustainability front-of-mind, and absolutely want their nutrients to go into growing the premium food and fibre that supports $43 billion of annual primary sector exports – not at the expense of our local environment.

'There is already a lot of policy focused on improving water quality across urban and rural New Zealand, and that's exactly why we're continuing to grow our Farm Sustainability Services team so that we have specialist advisors in every region supporting farmers as they evolve their businesses.

'It's also why we're rolling out our MitAgator tool, which was developed in partnership with the Government and has been independently endorsed by AgResearch, as a breakthrough tool for addressing potential contaminant losses at a farm scale with Farm Environment Plans that deliver genuine environmental gains.”