Nitrogen Source and Rate Effects on ‘Diamond' Zoysia Putting Green Establishment with Two Sprigging Rates.

Shading on putting greens leads to decline in turf quality and poor recovery particularly on warm-season turfgrass putting greens.  ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.], one of the fine-leaf textured zoysiagrasses, has excellent shade tolerance, high shoot density, and produces both stolons and rhizomes.  ‘Diamond’ zoysiagrass may also tolerate close, frequent mowing at putting green heights lower or equal to 32 mm. The objective of the study was to determine ideal establishment methods for ‘Diamond’ zoysiagrass as a putting green in the transition zone. Two sprigging rates, three N sources, and two N rates were compared as a split block design with three replications at Clemson University, Clemson, South Carolina.  On May 17, 2007, ‘Diamond’ zoysiagrass was sprigging at either 91 m³ ha^-1 and 182 m³ ha^-1 rate.  Urea, ammonium nitrate, and ammonium sulfate were applied at 17 or 34  kg N ha^-1 week^-1.  The N fertilizers were dissolved in water and applied weekly for 10 weeks with a CO₂ backpack sprayer. A light irrigation (an estimation of 10 to 15 mm) was applied immediately after each N application.  Potassium and phosphorus were applied as 19-19-19 at a rate of 49 kg N ha^-1 yr^-1 prior the establishment and as additional in liquid forms at 49 kg K ha^-1 yr^-1 and 24.5 kg P ha^-1 yr^-1, respectively in week 6 after sprigging. Weekly measurements included percent coverage and visual quality and color ratings. Root weight samples were harvested eight weeks and 16 weeks after establishment.  The mowing height was gradually lowed to 32 mm and 25 mm, eight weeks and 10 weeks after sprigging, respectively.  A significant difference occurred in coverage between high and low sprig rates of 91 m³ ha^-1.  Turf color and quality results show that high rates of fertility associated with high rates of sprigs produced 100% turf coverage within 10 weeks.  At 25 mm mowing height, the ball speed reached 3 meters in August regardless of fertilizer and sprig rates significantly faster than 32 mm mowing height.