Tall Fescue and Smooth Bromegrass. I. Nitrogen and Water Requirements1
- H. V. Eck,
- Tito Martinez and
- G. C. Wilson2
Irrigated cool-season grasses are needed in the Southern High Plains to extend grazing provided by winter wheat (Triticum aestivum L.) pasture and native range. Little information is available concerning their N requirements in relation to irrigation water application. The main objective of this study was to determine the N and water requirements for sustained high production of tall fescue (Festuca arundinacea Schreb.) and smooth bromegrass (Bromus inermis Leyss.). ‘Fawn’ tall fescue and ‘Southland’ smooth bromegrass were grown on Pullman clay loam (fine mixed thermic, Torrertic Paleustoll) under fertilizer N rates of 0, 168, 336, 504, and 672 kg ha-1year-1 on three water regimes. The N source was NH4NO3 except in a companion study in which feedlot manure was used.
In one year of the 3-year study when all irrigation treatments could be compared, adequately watered (W-2) and fertilized (672 kg N/ha) tall fescue yielded 15.2 metric tons/ha, whereas similarly treated smooth bromegrass yielded 12.0 metric tons/ha. With moderate water (W-I) and adequate N, however, smooth bromegrass yielded 6.9 and tall fescue yielded 5.2 metric tons/ha. With moderate water distributed for cool-season forage production (W-3), respective yields of similarly fertilized tall fescue and smooth bromegrass were 11.9 and 10.9 metric tons/ha. Also in 1976, first cuttings produced 77, 62, and 82% of total seasonal yields on W-l, W-2, and W-3 plots, respectively.
Over the 3-year period, yield increases were almost directly proportional to the amount of N applied through 336 kg/ha. Yield increases per kg of applied N (to 336 kg/ha) were 12.1, 24.1, and 17.9 kg on W-l, W-2, and W-3 plots, respectively. Feedlot waste, at N rates equivalent to those applied as- NH4NO3, was about one-half as efficient as NH4NO3 in increasing yields.
In the Southern High Plains, the most efficient irrigation management for tall fescue and smooth bromegrass is for early spring production with subsistence irrigation for the rest of the year.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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