Performance of Bluegrass Varieties at Two Cutting Heights and Two Nitrogen Levels¹

Abstract

Abstract Dwarf type Poa pratensis L. selections (‘Merion,’ ‘Newport,’ and Washington State University selections 602, 402, 104, and 205) and “tall” or erect types (‘Park’ and ‘Delta’) were planted in replicated plots 2.5 ✕ 3.1 m on a Caldwell silt loam soil. Levels of P, K, and Ca were considered adequate for normal turfgrass growth. The plots were allowed to establish for 1 year and were then split into four subplots of two cutting heights (1,27 and 2.54 cm) and two nitrogen levels (3.6 and 1.1 kg/92.9 m 2 per season). The plots were mowed once weekly for 20 weeks and all clippings were saved for yield and nitrogen analysis. Cores of soil 10.2 cm in diameter and 20.3 cm deep were analyzed for roots at the end of the season each year. There were significant differences (P = .05) in yield of shoots among varieties in the first but not the second treatment year. Significant differences were found in root yield among varieties both years. Cutting heights produced significant differences both years. Most shoots in 1957 were produced at the 2.54‐cm cutting height, but more shoots in 1958 were produced at the 1.27‐cm height. Significantly more shoots were produced both years from the highest N rate. The same treatment produced significantly fewer roots both years. The high N treatment resulted in higher tissue nitrogen content, but the greatest percentage nitrogen was recovered by the grass with the low N treatment. Shoot:root ratios were computed and are shown.