31 March 2015
Nitrogen dollars dissolving in thin air
Millions of dollars’ worth of nitrogen is vanishing into thin air, causing losses to farmers and to New Zealand in
wasted import dollars.
That’s the conclusion reached in field trials completed as part of the Ballance Agri-Nutrients’ Clearview Innovations
Primary Growth Partnership programme to measure ammonia losses from standard urea and urea treated with a nitrogen
stabiliser. These losses occur when the nitrogen in the urea volatilises into ammonia.
While farmers try to avoid the loss by applying urea when wet weather is forecast, research by Landcare Research and
Ballance has shown a good 5 to 10 mm of rain is needed within eight hours of application to reduce ammonia loss – a
finding consistent with research in New Zealand in the 1980s.
Ballance Science Manager, Aaron Stafford, says nitrogen loss through volatilisation is well-known, but the economic cost
is not.
“Around 500,000 tonnes of urea is sold in New Zealand each year and if you use the rule of thumb that 10 percent of
available nitrogen will be lost from volatilisation, that’s the equivalent of 23,000 tonnes of nitrogen which is not
doing its job in the soil and generating a return for farmers. Urea fertiliser contains 46 percent nitrogen, so at $600
a tonne for urea, this means $30 million of nitrogen is lost on average each year as ammonia.”
He says the losses are not only financial, but also environmental, with volatilised nitrogen re-deposited from the
atmosphere – and not necessarily on the farm where the nitrogen losses occurred.
“Farmers have no ability to control where this volatilised nitrogen is re-deposited. It could end up in rivers, lakes or
forests, which is less than ideal environmentally.”
Field trials in the Waikato, Manawatu, Canterbury and Otago were carried out over two successive springs. They showed
that ammonia losses from urea ranged between 11 and 23 percent, with an average of 15 percent - again consistent with
previous independent work. Treating urea withAGROTAIN® nitrogen stabiliser (SustaiN) reduced these losses by an average
of 68 percent. Mr Stafford says the results are consistent with previous research which gave an average 45 percent
reduction in ammonia losses with SustaiN urea over standard urea.
“The data also shows that volatilisation is not a summer-only phenomenon. It can happen at all temperatures.”
He says a product like SustaiN is sold at a premium over standard urea, but that premium is recovered in reduced
nitrogen loss, better pasture response and reduced reliance on immediate rain to minimise volatilisation.
“Farmers will be weighing up cost over performance, both financially and in terms of environmental impacts from nitrogen
losses. With a lot of work in hand now to restore pasture after such a dry summer, the option to use SustaiN makes
financial and environmental sense.”
Further recent trial work by Ballance has meant that the co-operative is now able to offer SustaiN in place of urea in a
wider range of mixes and blends, extending the benefits to applications which include other nutrients. Ballance field
consultants can offer advice on the best blends for maximum benefits for individual farming situations.
ENDS