Nitrification inhibitors

NZAGRC-funded research aims to identify novel nitrification inhibitors suitable for New Zealand’s soil types, environments and food safety regulations.

Current projects

Project title Lead organisation/s
Testing development and optimisation of a novel nitrous oxide inhibitor AgResearch
Efficacy of nitrification inhibitors in reducing urine-derived nitrate leaching in volcanic soils Pastoral Robotics Ltd


Nitrification inhibitors are chemical compounds that reduce nitrous oxide emissions by suppressing the action of microbes in the soil, known as nitrifiers, which convert nitrogen into nitrate. Nitrous oxide is a by-product of this action. See the Science of Nitrous Oxide page for more information on this and other microbial processes in the nitrogen cycle.

New Zealand dairy cows

Nitrification inhibitors can be added to fertiliser or deposited directly onto grazed pasture. They are widely available overseas and, until 2011, an inhibitor called dicyandiamide (DCD) was used on some New Zealand farms. However, the discovery of trace residues in milk led to the withdrawal of DCD from the New Zealand market, meaning that New Zealand farmers have limited scope to reduce nitrous oxide emissions from urine patches.

Work funded by the NZAGRC in recent years has identified a potential novel inhibitor in both field and laboratory trials that has demonstrated similar efficacy to DCD, but without the same risks. The advantage of this inhibitory product is that it is already widely used for other purposes, is approved for use in both humans and animals and has internationally agreed residue limits in food.

Research is now addressing short-term data needs associated with the product, including modes of action, further evidence of efficacy in the field, and the impact on nitrogen leaching. Longer-term data needs include effectiveness and longevity of the compound in a range of New Zealand soil and environmental conditions.

Other alternatives to DCD are also being explored in work funded by New Zealand’s contribution to the Global Research Alliance and are expected to be available in the future.