About 20 Taranaki farmers use a Ravensdown product withdrawn from the market after traces were found in New Zealand milk.
Eco-N, used to boost pasture growth and reduce nitrogen leaching, contains an ingredient called dicyandiamide (DCD), which has been added to an international list of substances subject to food safety testing.
Taranaki Farmwise consultant Michael Joyce said research had shown Eco-N did not provide a significant boost to pasture growth in Taranaki conditions.
It was a product that had to be sprayed on to pasture, so it was not as "farmer-friendly" as urea.
Its withdrawal would not have much impact in Taranaki, he said.
A spokesman for Ravensdown, a Christchurch-based farmers' co-operative, told the Taranaki Daily News yesterday only about 20 Taranaki farmers used Eco-N. About 500 farms nationally use the products, with most being in the South Island.
Taranaki Regional Council director of resource management Fred McLay said the product's withdrawal showed nitrogen inhibitors were not a silver bullet for the management of nutrients.
Lincoln University professor of soil science Keith Cameron, who was involved in the development of DCD products, said it had been safely used for more than 30 years and it was harmless to humans.
"It's actually safer than the table salt that you would use on your fish and chips." But because it was not officially listed as an acceptable chemical internationally, there was zero tolerance.
Environment Canterbury principal planning adviser Leo Fietje told Fairfax yesterday the move would have a minor impact. "It will mean a short-term blip, or increase if you like, in leaching into groundwater but bear in mind that farmers don't have to currently use it . . . they won't be in breach of anything."
There were other ways to manage nitrate leaching and the move does not compromise the long-term goal of stopping the discharge, he said.
Ballance Agri-Nutrients has not sold a similar product, called DCn, since July last year and had not promoted its use on pasture since late 2010.
- © Fairfax NZ News
Should ratepayers fork out for increased security to keep vandals at bay in Pukekura Park?Related story: Cameras set to catch vandals