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: https://www.ndsu.edu/fileadmin/soils/pdfs/goos-franzen-meeting-2.pdf