Turf Response to Polymer Coated Urea.

Polymer coated urea (PCU) is a controlled release fertilizer which can enhance nitrogen (N) use efficiency (NUE) and reduce N lost as a pollutant, as well as reducing need for repeated fertilizer applications and possibly reducing growth and resulting labor and other costs. Spring and fall applied N fertilizer trials were conducted over two years to determine the optimal N rate as PCU needed to match seasonal turf N needs. PCU [Duration®; DR75 (fall trials) and DR125 (spring trials)] was applied at 50, 75, and 100% of the recommended full rate as compared to an unfertilized control and urea either applied all at once or split monthly. Spring applied PCU showed no initial response until six weeks after application. After which the 75 and 100% rates were equivalent to urea split monthly for biomass growth, verdure, and shoot tissue N. At the 50% rate, there was reduced growth and shoot tissue N, thus, mowing expense, but also resulted in a 4% reduction in verdure. During the fall trials, DR75 at 100% showed greater growth, shoot tissue N, and verdure compared to urea split application for all11 weeks measured. DR75 at 50 and 75% trended towards reduced growth but increased verdure, while shoot tissue N was equivalent. This PCU is effectively applied as a fertilizer at a reduced rate between 50 and 75%, in a two application management system (DR75 for fall and DR120 for spring), although additional quick release N is required to compensate for early season lag in N release. More research is required to determine turf response to repeated application of reduced N over time, as well as to determine reduction of N lost as a pollutant.