June 2017

SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.

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Page 14 of 51 June 2017 | SportsTurf 15 and potassium sulfate (0-0-52 w/ 17% S) are also considered readily available after application. Controlled-release N. Although controlled-release fertilizers have a range of release rates, it is most common that 'slow-release' fertilizers contain a minimum of 50 % of the total N in water-insoluble form. Urea formaldehyde and polymer-coated urea are examples of controlled-release N sources. Compared to WSN products, fertilizers containing controlled-release N sources are more expensive per pound of N, and the color responses and rate of bermudagrass growth are more gradual following application. Advantages of using controlled-release fertilizers include less potential for N leaching and foliar burn, and fewer fertilizer applications. Fewer fertilizer applications means there are fewer times during grow-in that irrigation must be interrupted so that the soil can dry and the field can be fertilized. Application rates are often of 1.5 to 2 times those of quick-release fertilizers. Milorganite, a natural organic source of controlled-release N, and one of the oldest branded fertilizers in the US. The growth of 'Tifway' bermudagrass sprigs on a high school football field in east Tennessee in response to routine fertilization with both highly water- soluble and controlled-release N as well as P and K is pictured on page 12. Plant analysis. Many laboratories also offer plant analysis to estimate the nutrient content of turfgrass tissue. This test can be very helpful as bermudagrass is approaching or at 100 % total groundcover. Plant analysis serves as a 'snapshot' of the nutritional balance in the aerial shoot tissue of bermudagrass. If necessary, nutrients identified as being low or deficient may be applied as a foliar spray. In fact, it is often easier to uniformly apply small amounts of nutrients as a spray. For best results when applying nutrients in solution, it is essential that the spray tips and sprayer operating pressure deliver the intended amount of product and thoroughly moisten the foliage. Interestingly, nutrients enter bermudagrass leaves through tiny cracks or pores in leaves rather than the stomates, and leaf penetration is better at night. To allow for maximum nutrient uptake, bermudagrass should be sprayed during the day and irrigation should be delayed until late in the morning the following day. Tom Samples, PhD, focuses on turfgrass science and management in his role with the Department of Plant Sciences at the University of Tennessee in Knoxville. Dr. John Sorochan is a Professor in the Plant Sciences Dept at the University of Tennessee. Prilled urea. Water provides bermudagrasses with both H and O.

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