Nitrogen, Phosphorus, and Potassium Effects on Quality and Growth of Kentucky Bluegrass and Creeping Bentgrass1
- N. E. Christians,
- D. P. Martin and
- 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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