Nitrogen (N) fertilizer applied as anhydrous ammonia, UAN solutions or urea can be lost if adverse (primarily wet) weather conditions precede the uptake by crops. According to DuPont Pioneer, controlled-release nitrogen fertilizers can reduce these losses by delaying the initial release of N and providing it gradually to better match its availability with crop uptake needs.
Controlled-release, also called slow-release or delayed-release, N fertilizers include coated ureas, non-coated "chemical-release" forms and other products. The higher cost of controlled-release products generally excludes their use in cases where conventional N fertilizers can perform the same function adequately. These products may be most useful for:
- High-value crops (i.e. seed crop)
- Environmentally sensitive areas
- Fields highly susceptible to N losses
- Fields with limited opportunities for repeat applications
- Contest plots
- Foliar applications
Most growers of commodity row crops who use controlled-release products likely apply most of their crops' N needs with conventional products and only use controlled-release products to supplement their primary N fertilization program.