Effects of Nitrogen Fertilizer on an Old Stand of Crested Wheatgrass1
- William J. McGinnies2
Nitrogen fertilizer, in the form of urea, was applied to a 16-year-old stand of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] at rates of 0, 22, 45, 67, 90, and 112 kg N/ha/yr. Annual and biennial applications were made over a 6-year period starting in 1962. Average herbage yield was increased by the addition of N at all rates. The greatest increase in herbage yield per kg N applied was at the 22-kg/ha rate; the increase in yield per kg N applied declined as the rate of N increased. Total average herbage yield was highest at the 67-, 90-, ll2-kg rates. Annual fertilizer applications produced significantly higher average yields than biennial applications. The unfertilized plots declined in productivity during the period covered by the study, but as little as 22 kg N/ha/yr appeared to prevent the stand deterioration.
A one-time-only application of 0, 22, 45, 67, 90, 112, 135, 180, 225, and 449 kg N/ha was applied in 1962. The 22- and 45-kg/ha rates increased herbage yield in the first year, and 67- to 225-kg/ha rates increased yields through 1965. The 449 kg/ha rate increased yield through 1966, but had no significant effect in 1967.
The magnitude of the response to N and the relative efficiency per kilogram applied depended upon moisture availability.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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