EFFECTS OF METHOD, RATE AND TIME OF APPLICATION OF NITROGEN-FERTILIZER ON SEED PRODUCTION OF TALL FESCUE

The production of seed of tall fescue (Festuca arundinacea Schreber) p rovides an opportunity to diversify the agriculture of the Peace regio n with a new, un-subsidized, soil-conserving, cash-crop. Nitrogen fert ility and nutrition are major components of the production of any gras s-seed crop. A field study was conducted on the nitrogen (N) fertilize r requirements for optimizing seed yield and quality of tall fescue gr own in the Peace region. Row-crop stands (30-cm spacing) were establis hed at four sites in two consecutive seeding years (1993 and 1994), wi th two consecutive seed crops being harvested from each stand. A total of 18 N fertilizer treatments was applied to the first seed crop, a f actorial combination of two methods (surface-broadcast, granular, ammo nium nitrate 34-0-0, and soil-injected 28-0-0 solution), three times ( early- to mid-September, early- to mid-October, and early- to mid-Apri l prior to the first seed harvest), and three rates (50, 100, and 150 kg ha(-1) N). The second seed crop received 68 kg ha(-1) of surface-br oadcast N applied in mid-September after removal of the harvest crop r esidue. Seed yield and quality were not affected by the time of N appl ication. When compared with broadcast application, soil-injection of N fertilizer significantly reduced whole-plant dry matter (DM) yield an d seed yield/seedhead by 7 and 9%, respective ly, but the two methods of N application had no differential effect on clean seed yield ha(-1) , fertile tiller density, harvest index, thousand-seed weight, specifi c seed weight, germination, or on the proportion of clean seed. When c ompared with N at 50 kg ha(-1), whole-plant DM yield was increased by 6 and 8%, and clean seed yield/seedhead by 15 and 14%, with the 100 an d 150 kg ha rates of N, respectively. The first- and second-year seed yields averaged 1319 and 952 kg ha(-1), respectively, for the 1993 see ding year, and 1630 and 716 kg ha(-1), respectively, for the 1994 seed ing year. The cumulative seed productivity over the 2 production years was similar for the two seeding years, being 2271 kg ha(-1) for 1993 and 2346 kg ha(-1) for 1994. Each seed crop of tall fescue requires an available N supply from the soil in the range of 100 to 150 kg ha(-1) N to maximize seed yield and quality.