Effects of method, rate and time of application of nitrogen fertilizer on seed production of tall fescue

Abstract

The production of seed of tall fescue (Festuca arundinacea Schreber) provides an opportunity to diversify the agriculture of the Peace region with a new, un-subsidized, soil-conserving, cash-crop. Nitrogen fertility and nutrition are major components of the production of any grass-seed crop. A field study was conducted on the nitrogen (N) fertilizer requirements for optimizing seed yield and quality of tall fescue grown in the Peace region. Row-crop stands (30-cm spacing) were established at four sites in two consecutive seeding years (1993 and 1994), with two consecutive seed crops being harvested from each stand. A total of 18 N fertilizer treatments was applied to the first seed crop, a factorial combination of two methods (surface-broadcast, granular, ammonium 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-April 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-broadcast N applied in mid-September after removal of the harvest crop residue. Seed yield and quality were not affected by the time of N application. When compared with broadcast application, soil-injection of N fertilizer significantly reduced whole-plant dry matter (DM) yield and seed yield/seedhead by 7 and 9%, respectively, 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, specific seed weight, germination, or on the proportion of clean seed. When compared 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 and 150 kg ha−1 rates of N, respectively. The first- and second-year seed yields averaged 1319 and 952 kg ha−1, respectively, for the 1993 seeding year, and 1630 and 716 kg ha−1, respectively, for the 1994 seeding 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. Key words: Tall fescue, Festuca arundinacea Schreber, nitrogen fertility, grass seed production, grass seed quality