For years, growers and other experts have believed that nitrogen losses to the air (volatility) from surface-applied urea could not occur in the cold, but new research has recorded significant losses in those very conditions.
Rick Engel, associate professor in the Department of Land Resources and Environmental Sciences at Montana State University, carried out the research and says that while it's still ongoing, results from the first five campaigns have been unexpected.
“What we have been seeing are some very large losses,” Engel says. “We’ve actually seen some of our largest losses when urea applications are during the late fall or early spring period, even when the soil temperatures are near freezing.”
Engel conducted his study over five campaigns in the hill country of northern Montana, where weather and soil conditions are similar to wheat-growing regions of Canada.
He uses a unique micrometeorological system in the field, which collects ammonia gas over time without disrupting the soil environment. The study was designed to duplicate the common practice of fertilizer application used by wheat growers.
In three of the first five of these cold-weather studies, more than 30% of the applied nitrogen was lost. These losses can add up quickly, especially when conditions are damp as well as cold.
“In the five campaigns we’ve conducted to date, our losses have ranged anywhere from 3% or 4% up to 40%,” Engel says. “The conditions that really seem to promote these ammonia losses from urea are prolonged damp conditions.”
John Hassell, Research & Agronomic Development Manager for Agrotain International, says the research is groundbreaking.
“The fertilizer industry has made assumptions in the past, not based on scientific proof, but rather long-held beliefs,” he explains. “With these advanced techniques, Dr. Engel has documented that our previous way of thinking is basically incorrect — that enzymes continue to work in freezing conditions and that urea loss can and will occur at significant levels.
"This will change the way textbooks are written and students are taught in the future.”
For now, Hassell says the study demonstrates wheat growers can offset much of this potential for loss by using a nitrogen stabilizer, which already is a standard practice for many growers in warmer climates. The Montana State study compared untreated urea with urea that had been stabilized with Agrotain nitrogen stabilizer.
“What we’re finding with Agrotain is that it’s giving us 2 weeks of protection from volatilization losses,” Engel says. “And over an 8-week campaign, we’ll see a reduction in the amount of ammonia lost of about 60% over an untreated product.”