Herbicides vs Oat Companion Crops for Alfalfa Establishment1

Abstract

AbstractHerbicides are effective for use in establishing alfalfa (Medicago sativa L.) without the use of a companion crop. The objective of the study was to assess the economic feasibility of the herbicide method as compared to the companion crop method and to determine some of its advantages and disadvantages.Productivity of ‘Vernal’ alfalfa established with or without a companion crop was determined at four locations in Minnesota. Oats (Avena sativa L.), harvested for either hay or grain, was used as the companion crop. Four herbicide treatments (EPTC, EPTC + 2,4‐DB, trifluralin, and benefin) were used for weed control when the alfalfa was grown alone. The EPTC soil incorporated treatment plus a postemergence treatment of 2,4‐DB on the alfalfa at the 3 to 4 trifoliolate‐leaf stage was the most effective treatment for controlling weeds.With prices of $27.56/MT for alfalfa hay, $4.20/100 kg for oat grain, and $16.54/MT for oat straw, the net return (excluding costs common to all methods) favored alfalfa establishment with oats harvested for grain and straw.During the establishment year the oat hay companion crop yielded 5.17 metric tons (12% moisture)/ha, while alfalfa grown alone yielded 4.03 metric tons/ha. Oat grains averaged 2,205 kg/ha, and straw yields averaged 5.46 metric tons/ha. Stand counts of alfalfa in the fall of the seeding )year were generally higher for alfalfa grown without a companion crop, but this did not affect the following year's yield.With prices of $27.56/MT for alfalfa hay, $4.20/100 kg for oat grain, and $16.54/MT for oat straw, the net return (excluding costs common to all methods) favored alfalfa establishment with oats harvested for grain and straw.