The effectiveness of the nitrification inhibitor DCD

 

The on-going intensification of New Zealand agriculture has led to a demand for technologies that can minimise nitrogen (N) losses from pastoral land to air and water. 

Nitrogen can be lost from soil as the gas nitrous oxide (N2O), which is a potent greenhouse gas that has a warming potential about 300 times greater than carbon dioxide (CO2). It can also be lost in drainage in the form of nitrate, which can potentially contaminant groundwater aquifers or encourage the growth of nuisance weeds and algae in streams and lakes when concentrations are high enough.

One set of technologies developed to conserve soil N or increase the efficiency of N supply to plants is the application to soils of nitrification inhibitors such as dicyandiamide (DCD).  These chemicals slow or “inhibit” the conversion of N from the relatively immobile ammonium (NH4) form to the mobile nitrate (NO3) form (see image).

On-going research led by Dr Cecile de Klein is evaluating the effectiveness of DCD for reducing both nitrous oxide and nitrate leaching losses from pastoral land. Because DCD can help retain N in the top layer of the soil, using DCD has also been observed to increase pasture production. However, the effectiveness of DCD for reducing N losses and increasing pasture production has been observed to vary considerably depending on soil, climate and management factors. In collaboration with Stewart Ledgard at AgResearch Ruakura and researchers from Lincoln University and Landcare Research, Cecile’s team is seeking to more accurately quantify the effectiveness of DCD under grazing conditions at a number of contrasting experimental sites in the North and South Islands.

This research is a collaboration between AgResearch, MAF, PGgRC, DairyNZ, Fonterra, Fertiliser industries, Lincoln University and Landcare Research.