ABSTRACT
Summary Two experiments were conducted to investigate seeding techniques associated with no-tillage establishment of alfalfa (Medicago sativa L.) in barley (Hordeum vulgare L.) stubble. The objective of experiment 1 was to evaluate the influence of carbofuran (CF) insecticide/nematocide and of P and N fertilizers on seedling weight, plant population, and forage yield. All materials were applied in the row with the seed. The largest seedlings at 10 weeks after seeding occurred with GF + P + N. The smallest seedlings were associated with the check and P treatments. The highest plant populations at 6 and 30 weeks after seeding occurred where CF and CF + P were applied. The smallest plant populations occurred with the check and P treatments. Highest dry-matter yields at first harvest were with CF and CF + P. Yields of the check and P treatments were significantly lower than those of any of the other treatments. Dry-matter yields for the four treatments containing carbofuran were not significantly different at second harvest, but they were about double the yields of the check and P treatments. The objective of experiment 2 was to examine the relationships of seeding rates and row spacings to seedling weight, plant population, weed competition, and forage yield. Seeding rates affected plant population and forage yield but had no significant effect on seedling size as measured by seedling weight 10 weeks after seeding. The 33 kg/ha seeding rate resulted in a significantly higher plant population at 30 weeks after seeding; however, there was no significant increase in forage dry-matter yield over either the 16.5 or 8.2 kg/ha seeding rates. Alfalfa seeded at the 5.5 kg/ha seeding rate yielded significantly less than that at the other seeding rates. At a seeding rate of 16.5 kg/ha, there were no significant differences in seedling weight, plant population, or forage dry-matter yield due to row spacings of 12, 24, and 36 cm.
