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EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Vegetable growers have been primary users of ammonium nitrate to supply
additional nitrogen. With this material, there is little concern about
volatile loss of nitrogen when it is applied on the soil surface and
irrigated or rained in. However, ammonium nitrate is difficult to obtain
these days, so vegetable growers are left looking for alternatives.
Many are using urea. When urea is spread on the soil, there is the
potential for volatile nitrogen loss as the urea is converted into the
ammonium form. This can be quite significant when soil temperatures are
high, as they are now. Losses can range from 10 to 25 percent within two
to three days when soil temperatures are near 75oF, and the urea is not
irrigated or rained in with a 0.5 inch or more of water.
Urea can be treated with the product Agrotain, which is a urease
inhibitor, to slow the rate of conversion of the urea into the ammonium
form. By doing this, it reduces the potential for volatile nitrogen
loss. Agrotain can be quite effective for at least two weeks. During
this time period, there is usually a good probability of measurable
rainfall to move the urea into the soil. So if you are using urea as a
surface broadcast, consider having it treated with Agrotain or pray for
rain right after the application. Note, when urea is incorporated into
moist soil, volatile nitrogen loss should be minimal and use of Agrotain
will not be necessary.
