LIMITATIONS OF UREA AS A NITROGEN SOURCE

By Brad Brown, Extension Cereal Specialist, Parma R&E Center

Urea’s high N analysis and easy handling have made it the most popular dry N source for southern Idaho. Our reliance on urea in-creased with 9-11, and the loss of ammonium nitrate from the market-place.

While urea has much to recom-mend it as a dry N source, it has its limitations. There is potential for loss of ammonia N from urea applied as a top-dress to soils, particularly if sub-sequent rainfall is sufficient to dissolve urea but not enough to move it beyond the surface and into the soil. A number of factors affect ammonia loss including soil surface pH, clay content, organic matter, temperature, and soil moisture to name a few. A Montana publication, “Management of Urea Fertilizer to Minimize Volatilization” Montana State University Extension Bulletin EB173 covers many of the principles involved with ammonia volatilization from urea. The publication is available online for downloading at http://msuextension.org/publications/AgandNaturalResources/EB0173.pdf.