Not all controlled-release Nitrogen products are created equal…matching the right product with the application method and farming practices is important. The easy answer is: some work, some don’t. However, if used properly, a few products have proven viable.

  • Main options: coated, non-coated, chemical release, and other products
  • All claim to reduce nitrogen loss by delaying total supply until plants need the nutrient
  • Sulfur-coated urea releases N as it slowly degrades by microbial, chemical, and physical
    processes. An additional polymer coat may be applied.
  • Polymer-coated urea: controlled by the properties of the coating
  • Chemical-controlled: react with aldehydes to form fertilizer(s) with low solubility
  • Good reasons to use inhibitors:
              o   High-value crops
              o   Environmentally sensitive land
              o   Areas susceptible to Nitrogen loss
              o   Areas limited to repeat applications [wheat fields, variable terrain]
  • More IN-DEPTH
              o   Sulfur+Polymer Coat: hybrid approach, thin layer of polymer with                       sulfur layer improve consistency of release
              o   Polymer Coat: hydrophobic coating that temporarily isolates nitrogen
                            - Unaffected by nature; release can be predicted
                            - High cost, limited adoption in row crop – widely adapted in                                   high value crops
              o   Urea-Formaldehyde/Methylene Urea: by reacting with aldehydes,                          compounds with high molecular weights and complex chemical s                            structures with low water solubility can be created.
                              - Products can vary depending on manufacturing process
                              - Release pattern is influenced by environmental factors
              o   Urea-Triazones: aldehyde+ammonia reacted with urea in an aqueous                      medium under controlled conditions which results in a liquid fertilizer                  as a stable solution in both a triazone form and unreacted urea                              [UAN].

For more information, check out this study from NDSU: