Do irrigated companion oat crops reduce alfalfa yield and profits?

Abstract

Establishment of 'Anchor' alfalfa with a companion oat crop was compared to direct-seeding the alfalfa on a sprinkler-irrigated site in 1982, 1983, and 1985. 'Beaver' alfalfa was added to the treatments in 1983 and 1985. An oat crop monoculture treatment was also included. Alfalfa-oat mixtures exhibited significant (P < 0.05) oat grain yield reductions of 9, 24, and 18 % in the three seeding years, respectively. Oat forage yields tended to be reduced in oat-alfalfa mixtures by 3, 12, and 8 %, respectively, but these reductions were not statistically significant (P > 0. 05). The forage yields of direct-seeded alfalfa were 26, 20 and 20 % higher (significant at P < 0.05) in the first production year (year following seeding) than oat-alfalfa mixture stands. In the second production year, yields were 22 % higher (P < 0.05) only in the 1982 seeding. Establishment method effects on stand density were significant (P < 0. 05) in the 1982 and 1983 seedings where the direct-seeded alfalfa had 50 and 25 % higher plant densities, respectively. Economic analysis of net returns per hectare indicated that the establishment method with the best returns varied among the three seedings years.