Polymer-coated urea (PCU) is a fertilizer product in which each urea prill is individually coated with a polymer (or plastic) coating. All PCUs are considered a slow or controlled release fertilizer, which is defined by the Association of American Plant Food Control Officials as a fertilizer that contains plant nutrients in a form that extends its availability significantly longer than a reference fertilizer (in this case urea) (Slater, 2014). The way PCU works is that urea dissolves inside the coating and slowly diffuses into the soil over time. The mechanism for the nitrogen-release from PCU includes three phases: (1) lag phase, (2) constant release phase, and (3) release decay phase (Shaviv et al., 2003).
Soil Science Extension
University of Wisconsin Madison