Polymer Coated Urea Management.

Polymer Coated Urea (PCU) is a temperature dependent, controlled release N fertilizer. The N tends to stay protected within the coating and is released by diffusion over a period of time.  Nitrogen release rate is controlled by soil temperatures--releasing the N in association with increasing plant and root growth. Data with several crops in Idaho and Utah show average yield increases of 11.4%--frequently with simultaneous gains in crop quality. Associated studies show a virtual elimination of N loss mechanisms. Nitrate leaching was reduced by 88%. Ammonia volatilization was reduced by 285%. Nitrous oxide emissions were reduced by 95%. However, care must be taken to protect the coating from fracture. And, adjustments need to be made when using the material on surface applications and when used on frozen soils. Adjustments also need to be made when monitoring nitrate levels in tissue for in-season N management. For example, potato petiole nitrate concentrations tend to be 2,000 mg kg^-1 less when using PCU compared to uncoated urea—despite no loss of crop yield or quality. Additional management implications will be reviewed.