AGRONOMY GUIDE
Purdue University


AY-176
Fertilization

Fertilizing Grasses with Nitrogen
C. L. Rhykerd, C. H. Roller, K. L. Washburn, Jr., S. J. Donohue, K. L. Collins, L. H. Smith and M. W. Phillips
Departments of Agronomy and Animal Sciences
Introduction
Forage research the past five years has resulted in breakthroughs in hay yields, protein production, and longevity of stands. Hay yields of 8 to'
10 tons, or more, per acre have been obtained. Yields of this magnitude will result in a protein yield of 2,000 to 3,000 pounds per acre. With proper management and liberal fertilization, highly productive stands have been maintained for more than five years.
With the advent of lower cost commercial nitrogen fertilizer and the threat of the alfalfa weevil, an experiment was initiated on the Purdue University Agronomy Farm at Lafayette to investigate the yield potential of several cool-season grasses under intensive management. On April 8, 1966, Potomac orchardgrass, Kentucky 31 tall fescue, Lincoln smooth bromegrass, and reed canarygrass were seeded individually with oats as a companion crop. Currently herbicides are available for use with forage Seedings which make it possible to obtain three to five tons of forage the seeding year. The soil type was Chalmers silty clay loam. At seeding, 305 pounds of 25-25-0 was applied per acre. The oat crop was harvested for grain on July 22 and the straw removed.
Research Plots Established
In April, 1967, research plots were established on the four grasses and ammonium nitrate was broadcast at rates of 0, 12.5, 25, 50, 100, 200 and 400 pounds of actual nitrogen per acre per harvest. The initial application of nitrogen was in early April with the following applications being applied immediately after each hay harvest. The last cutting received no nitrogen after harvest.
Cutting Management
Cutting management depended upon the morphological characteristics of the individual grasses. Five cuttings were obtained annually from orchardgrass and tall fescue since these grasses head out in early May and the regrowth does not joint. This permits orchardgrass and talI fescue to be harvested at approximately five-week intervals. Smooth bromegrass and reed canarygrass head out about the middle to the latter part of May and the stems of the regrowth joint. Approximately six to seven weeks are required for stem elongation of these two grasses to ensure rapid regrowth and maintenance of stand. Therefore, only four cuttings of smooth bromegrass and reed canarygrass were obtained.