That loss of potency can be particularly challenging for fields where no-till, or less tillage, is the preferred technique and crop residue is significant, industry specialists say.
But even in clean pastures and forage fields, Agrotain has been shown to slow the loss of nitrogen for weeks.
And recent studies in California and Arizona have documented increased harvests in specialty crops, such as lettuce.
One study at the University of Arizona’s Yuma Field Station showed that lettuce yields rose by about 2.6 tons per acre to 19.5 tons when Agrotain Plus was used in addition to the standard UAN 32, at an application rate of 134 pounds of nitrogen (N) per acre.
The treatment method was sidedressed and shanked in, with a split application—at 30 days after planting and then at 50 days after planting. At a rate of 200 pounds of N per-acre, the increase in yield was slightly less, about 1.5 tons per acre.
Agrotain Ultra is the more recent trade name for the original product called Agrotain, which has a urease inhibitor as the active ingredient.
Another formulation called Agrotain Plus has an additional nitrogen stabilizer, a nitrification inhibitor, which holds ammonia in the soil longer.
Basic Agrotain is a liquid and can be used with dry urea or tankmixed with liquid urea-based fertilizers, such as urea ammonium nitrate or UAN. Agrotain Plus is a dry concentrate.
Charles Sanchez, the director of the Yuma field station who oversaw the iceberg lettuce trials there about three years ago, says Agrotain slows nitrogen loss. The harvest yield increase he saw was not that impressive.
“But I can say for certain the urease inhibitor works.”
Separate studies by University of California Cooperative Extension in Monterey County also showed increases in lettuce yields with Agrotain Plus, for both surface drip irrigation and shallow-buried drip irrigation, though at smaller rates than in the Arizona trials.
Tim Hartz, vegetable Extension specialist with UC Davis, says the crops he works with do not use surface application of fertilizer, so the urease inhibitor part of Agrotain is really not needed.
Urease is an enzyme that promotes volatilization. Once fertilizer is tilled in or absorbed into the soil via irrigation or rainfall, a urease inhibitor has little or no effect. Agrotain Plus contains the urease inhibitor and a nitrification inhibitor, which acts through a separate mechanism to slow nitrogen loss.
Dow Chemical has a stand-alone nitrification inhibitor, but it is not yet registered for use in California, Hartz says. “The only legally approved nitrification inhibitor in California is the one contained in Agrotain Plus. But it’s not sold separately.”