Response of Three Kentucky Bluegrass Cultivars to Sprayable Nitrogen Fertilizer Programs
- Richard W. Moore,
- Nick E. Christians and
- Micheal L. Agnew
Developing fertilizer programs that match anticipated maintenance levels for Kentucky bluegrass (Poa pratensis L.) is important because cultivars differ in their response to N management. Our objective was to determine the response of ‘Vantage’, ‘Park’, and ‘Majestic’ Kentucky bluegrass to urea, ureaform, methylene urea, and methylol urea applied at a yearly rate of 1.952 kg N 100 m−2 in three application programs: heavy spring, balanced, and late fall. Data collected included visual quality, clipping yield, thatch depth, shoot density, and root weight. Quality ratings were generally highest for the heavy spring program. Urea produced quality ratings that were equal to or higher than the other N sources. Clipping yields were 20 to 67% lower for Majestic than for Vantage or Park. Thatch development was 23% greater in Majestic than in Vantage in 1987 and 16% more in 1988. Majestic produced 18% more thatch accumulation than Park in 1987 and 26% more thatch in 1988. Majestic had more total root mass than Vantage or Park in the spring of 1986 and in the spring and fall of 1987. In the fall after a severe drought (1988), Majestic had 53 and 43% more total root mass than Park and Vantage, respectively. Plots treated with urea produced 6 to 18% more clippings than the other N sources each year. Quick-release N sources performed better than slow-release types. The late fall program resulted in 9% more root mass than the balanced program and 8% more than the heavy spring program at the 0- to 5-cm depth in 1987.
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