Tall Fescue Response to Placement of Urea/Ammonium Nitrate Solution
- J. L. Moyer and
- D. W. Sweeney
Several studies have shown that cool-season grasses may respond more to subsurface (knife) applications of fluid fertilizer than to surface applications. However, optimum depth of knife application has not been clearly identified. A field study was conducted from 1984 to 1986 to determine the effects of 5-, 10-, and 15-cm knife and surface band (dribble) and broadcast applications of urea/NH4NO3 solution at 84 and 168 kg N ha−1 on forage yield and N use of tall fescue (Festuca arundinacea Schreb.), and on soil N levels. The soil is a Parsons silt loam (fine, mixed, thermic Mollic Albaqualf). In 1985 and 1986, 168 kg N ha−1 resulted in higher final forage yields than 84 kg N ha−1. Knife applications at 10 cm generally resulted in the highest forage yield, though not always significantly higher than other placements. Knife placement at 15 cm resulted in lower N uptake in early grass clippings (intermediate harvests), compared with surface and shallower knife applications. The N concentration, N uptake in the final spring harvest, and apparent fertilizer-N recovery by the forage were usually increased by 10-cm placement. Knife applications of N at or below 10 cm resulted in higher inorganic soil N concentrations at intermediate harvests than did surface applications.
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