Turf Response To Polymer – Sulfur Coated Urea.

Turfgrass is the irrigated crop with greatest acreage in the USA. Nitrogen (N) applied to turfgrass contributes to atmospheric and hydrospheric pollution. Slow release fertilizers [sulfur coated urea (SCU), polymer-sulfur coated urea (PSCU)] were evaluated as a possible solution to maintain turf growth while reducing N lost to the environment. Spring and fall trials on Kentucky bluegrass (Poa pratensis L.) were conducted over two years comparing SCU and PSCU to an unfertilized control and urea applied either all at once or split monthly. Spring application of SCU and PSCU resulted in minimal slow release characteristics, matching response seen by urea applied all at once.  For the first six weeks, urea applied all at once, SCU, and PSCU resulted in increased tissue N concentration (22%, 25%, and 24%, respectfully), growth (11%, 14%, and 10%, respectfully), and verdure (9%, 10%, and 16%, respectfully) compared to urea applied monthly. The remaining 11 weeks, only three weeks were significantly different from urea applied monthly. For these 11 weeks urea, SCU, and XCU showed a decrease for tissue N concentration (12%, 8%, 12%, respectfully), growth (8%, 5%, and 12%, respectfully), and verdure (5%, 4%, 6%, respectfully). Fall applied PSCU resulted in an average increase of 15% tissue N concentration, 9% height and 9% verdure compared to urea split application. SCU compared to split application showed no significant difference for tissue N or height, but an increase of 8% verdure. Urea applied all at once showed a decrease of tissue N and height by 11%, and 6%, respectfully, although no difference in verdure. The PSCU and SCU fertilizers evaluated in this study provide minimal slow release properties, resulting in large spikes of growth.