The withdrawal of DCD nitrification inhibitors hasn't left the cupboard totally bare for farmers looking for ways of reducing nitrogen loss on farms.
Two products still available to them, but they work in different ways and perform different roles to the DCD based inhibitors that have been suspended because of residues found in milk powder.
LessN made by Donaghys is described as a nitrogen utilisation enhancer, which is mixed with dissolved urea fertiliser and sprayed onto pasture.
Donaghys managing director Jeremy Silva says the product is made from naturally occurring microbes and works by increasing the uptake of nitrogen fertiliser by pasture or crops, which allows farmers to halve the urea application.
MrSilva says LessN has been internationally tested in hundreds of trials.
He says it is used by more than 600 New Zealand farmers and is exported to the US and Europe for use on crops.
Fertiliser co-operative Ballance AgriNutrients has withdrawn its nitrification inhibitor DCn but still has a product called SustaiN on the market.
It slows down the process of urea fertiliser breaking down into nitrogen in the soil.
Ballance research and development manager Warwick Catto says it complements DCD but doesn't replace it or have the same effect.
Independent fertiliser consultant and soil scientistDr Doug Edmeades of AcKnowledge says the suspension of DCD products will be a setback in terms of the options available to help farmers deal with nitrogen loss.
He says the research was shaping up to indicate that DCD products could reduce nitrate leaching and greenhouse gas emissions.
But Dr Edmeades says in his view the available science shows none of the products on the market fully stack up in terms of the claims made for them.
He says more research is needed and the loss of DCD-based products provides the opportunity for that.
Dr Edmeades says the focus needs to be on finding an effective way of managing leaching and emissions from urine patches, the most concentrated source of nitrogen in pasture.