Loss of nitrate reducer blow for environment

Dairy farming has lost its best tool for breaking down cow urine and future-proofing land intensification with the recall today of nitrate-reducing products from shelves.

This is a blow for the dairy industry, the main farming user, and on efforts to reduce nitrates leaching into water and greenhouse gas emissions from nitrous oxide.

The active ingredient of the brands eco-n and DcN - nitrification inhibitors sprayed on grazed pastures to control nitrogen losses from cow urine patches - has been added to an international list of substances that must be tested by organisations such as the United States Food and Drug Administration.

Milk powder tests in New Zealand have since revealed low levels of the biodegradable ingredient dicyandiamide, more commonly known as DCD, coincided with the times of the year that the products were applied.

Tougher testing could put milk exports at risk as there are no standards for maximum levels of the ingredient and zero residues cannot be guaranteed.

Eco-N's owner, Christchurch-based fertiliser co-operative Ravensdown, says DCD has been safely used around the world for 30 years, but it had taken the precaution of suspending its product for the rest of the year to retain New Zealand's dairy export reputation.

Chief executive Greg Campbell said research by the company and the Ministry for Primary Industries (MPI) showed there were no food safety issues with DCD or eco-n.

"What's changed is that last year, organisations like the US Food and Drug Administration added DCD to a list of substances to test for. This, combined with increasingly sophisticated scanning technology now presents a possible trade risk.

"Given the risk to NZ's dairy export reputation, Ravensdown has taken the initiative and is suspending the single product which uses DCD for this calendar year."

He said there had never been a set of international standards around maximum residue levels in food products because DCD had been used safely for a long time.

''Because no standard exists for DCD, no detectable presence is acceptable. And because zero detection of DCD cannot be guaranteed, Ravensdown has taken the responsible, voluntary step to suspend its use while the trade issues are resolved.''

To assess DCD on farmland the MPI last December set up a working party of ministry officials, Fonterra and other dairy companies and the fertiliser companies of Ravensdown and Ballance which sells DcN.

Food regulators around the world are tightening testing in line with more demanding markets and in some countries there is no tolerance to residues outside of standards.

Milk markets remain sensitive from the incident several years ago when Chinese infants died and thousands left sick drinking melamine-contaminated milk produced by Chinese factories.

DCD is a compound widely used in some industries including electronics, pharmaceuticals and food packaging.

Farmers have used the ingredient since 2004 in products, first developed by Lincoln University scientists, to reduce their environmental footprint by slowing the rate that soil bacteria can convert ammonia into nitrate and nitrous oxide.

Farmers will have to rely on other techniques such as testing, nutrient  planning and expert advice plus precise fertiliser application to keep nitrates down.

Campbell said reducing nitrate leaching would continue to be vital for sustainable farming and the effectiveness of nitrification inhibitors was well proven and had helped farmers to face stricter environmental requirements.

He said the company would look for the ministry to seek new international standards for DCD which could be a lengthy process. Ravensdown's's eco-n product makes up about 1 per cent of its annual sales.

Other countries use DCD in cropping by applying it to nitrogen fertilisers.

Fairfax Media