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Crop Science Abstract -

Interaction of Nitrogen, Phosphorus, and Potassium on Evapotranspiration Rate and Growth of Kentucky Bluegrass


This article in CS

  1. Vol. 39 No. 1, p. 209-218
    Received: Mar 6, 1998

    * Corresponding author(s): sebdon@pssci.umass.edu
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  1. J. S. Ebdon ,
  2. A. M. Petrovic and
  3. R. A. White
  1. Dep. of Plant and Soil Sciences, 12F Stockbridge Hall, Univ. of Massachusetts, Amherst, MA 01003



Research is limited concerning the interactive effects of nitrogen, phosphorus, and potassium on turfgrass evapotranspiration (ET) rate. Previous research has emphasized the influence of N on growth and ET. In this study, a central composite experimental design was used to investigate the interactive effects of N, P, and K on Kentucky bluegrass (Poa pratensis L. ‘Majestic’) water use and growth under field conditions. Five treatment levels for each nutrient were used; N treatment levels ranged from 49 to 588 kg ha−1 yr−1, P from 0 to 86 kg ha−1 yr−1, and K from 0 to 348 kg ha−1 yr−1. Clipping yield and ET (measured in 25-cm diam. bucket-type lysimeters) were recorded on a weekly basis. A field study conducted in 1988 evaluated N, P, and K applied alone while in a 1989 field study N, P, and K combinations and interactions were evaluated. Applied alone, P and K had no effect on ET or shoot growth independent of the rate applied. Unless a high level of N was applied (588 kg ha−1 yr−1), N had no affect on shoot growth or ET. Shoot growth (clipping yield) and ET were highly correlated (r = 0.79, P ≤ 0.001) in the single nutrient study. There was an interaction between N, P, and K on shoot growth and ET. Shoot growth response was highly correlated with ET response when fertilized in the normal range of P for the soil type evaluated (0, 21.5, 43 kg P ha−1 yr−1). Evapotranspiration rate response to N, P, and K applied in combination were distinctly different from nutrients applied alone. At medium to high levels of N and P (294 kg N and 43 kg P ha−1 yr−1 and higher), water use increased in response to increasing K applied. Conversely, at N and P levels routinely applied to this species and soil type (147 kg N and 21.5 kg P ha−1 yr−1 and lower), increasing K levels minimized water use. Further research is needed to study specific interactions.

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