Turf and Landscape - Know Your Soluble Fertilizers 3

This is the third in a series on soluble fertilizers for use in turf and landscapes. This post is on ammonium nitrate, a nitrogen fertilizer.

Ammonium Nitrate is typically marketed in prilled form containing 33-34% N. It is highly soluble and is also marketed in solution form; generally it will be offered in combination with urea containing 28, 30 or 32% N. Prilled ammonium nitrate may be bright white in color, indicating that the prill has been coated with magnesium chloride, or beige in color, indicating that the product has been coated with a mixture of clays. Both of these coatings reduce the hygroscopicity of the product and improve handling properties. Ammonium nitrate and urea cannot be mixed together in dry form because of severely reduced handling properties. Ammonium nitrate produces only 1.8 pounds of acidity per pound of N applied upon nitrification, and thus is not as acidifying as ammonium sulfate. The salt index of ammonium nitrate, 2.99, is less than that of ammonium sulfate and thus there is less potential for turfgrass burn immediately after application. Ammonium nitrate generally does not impart as dark green a color as does ammonium sulfate and the longevity of the response is not as great.

Reprinted from "Selected Fertilizers Used in Turfgrass Fertilization" by J.B. Sartain & J.K. Kruse, University of Florida Cooperative Extension.