Resin-Coated Urea Evaluation for Turfgrass Fertilization
- N. W. Hummel
New resin coatings have been developed for producing slow-release fertilizers for turfgrasses. It is important that new fertilizer materials be evaluated so that recommendations can be made for their use. Four experimental resin-coated ureas (RCU) were evaluated for maintenance fertilization of Merion Kentucky bluegrass (Poa pratensis L.) turf grown on an Arkport sandy loam (coarse-loamy, mixed, mesic Psammentic Hapludalfs). The RCUs had an analysis of 41% N and laboratory release rates of 270 d (RCU-270), 100 d (RCU-100), and 70 d (RCU-70). A mixture of the RCU materials (RCU-M), sulfur-coated urea (SCU), urea, a 22-1.8-6.6 with 10% by weight dicyandiamide (DCD), and oxamide were included for comparison. The fertilizers were applied at an annual rate of 196 kg N ha−1, as single-spring or split-spring, and fall applications. The most rapid response to fertilization as measured by fresh weight yields and color ratings was produced by urea, followed in order by SCU, RCU-70, and RCU-100. The release rate of RCU-270 was too slow to produce acceptable color ratings through much of the test at both fertilization times. The most uniform response was produced by RCU-100 at both the single-spring and split treatments. The highest N recovery in the leaf tissue was obtained from oxamide (24 and 59%), the single-spring application of SCU (27 and 58%), and the split applications of RCU-100 (21 and 52%) and RCU-70 (25 and 54%). Nitrogen recovery from SCU was highest in growth periods immediately following fertilization, while recovery was more uniform across growth periods with the RCU-100. Certain RCU fertilizers are well suited for turfgrass fertilization.
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