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Agronomy Journal Abstract -

Nitrogen, Phosphorus, and Potassium Effects on Quality and Growth of Kentucky Bluegrass and Creeping Bentgrass1


This article in AJ

  1. Vol. 71 No. 4, p. 564-567
    Received: Aug 14, 1978

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  1. N. E. Christians,
  2. D. P. Martin and
  3. J. F. Wilkinson2



Much of the previous work involving the effects of N, P, and K on the growth and quality of turfgrasses has not involved methods by which the interactions among these nutrients, could be evaluated.

In the present investigation, a double cube, composite, statistical design was used to investigate the N, P, and K requirements of Kentucky bluegrass (Poa pratensis L. ‘Merion’) and creeping bentgrass (Agrostis pdustris Huds., ‘Penncross’) under controlled environmental conditions in sand culture. Nitrogen treatments ranged from 6 to 294 ppm, P from 2 to 98 ppm, and K from 4 to 196 ppm in solution. The objectives of the investigation were to study the effects of a wide range of N, P, and K levels on turfgrass growth and quality, and to observe the nutrient interactions.

Quadratic relationships for dry tissue production of Merion in response to increasing levels of N and K were observed. Tissue production reached a maximum at 125 pprn N and 144 ppm K. Dry tissue production of Penncross in response to N was also quadratic, with a maximum at 96 ppm. Tissue dry weight increased linearly with K to the 196 ppm level. The most desirable quality characteristics for Merion occurred at the N concentration of 96 ppm, and a P concentration of less than 2 ppm. Maximum response to K was not reached at the 196 ppm treatment. Penncross attained these characteristics at a N concentration of 54 ppm and less than 2 ppm P. Again, maximum quality had not been reached at a K level of 196 ppm. Potassium may play a more important role in turfgrass fertilization than was previously realized. Penncross demonstrated maximum root production at a solution concentration of 6 ppm N and 196 ppm K. Minimum production of roots occurred at 150 ppm N and 64 ppm K. An interaction between N and K in solution was observed in the quality response of creeping bentgrass. As the level of K was increased, less N was required to attain maximum quality. It is possible that addition of higher levels of K to this species can affect its requirements for N. Additional work under field conditions will be required to evaluate the importance of this interaction.

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