Herbicides vs Oat Companion Crops for Alfalfa Establishment¹

Abstract

Herbicides 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.

Alfalfa Yield and Quality as Influenced by Establishment Method

“…Total forage yields for the two harvests made in the year following establishment did not differ among treatments at either location (Table 1). This result is consistent with the results of a number of other alfalfa establishment studies in which various companion crop and herbicide treatments were compared (Brothers et al, 1994; Curran et al, 1993; Schmid and Behrens, 1972).…”

Is the Companion Crop Harmless to Alfalfa Establishment in the Highlands of East Anatolia?

“…Seeding rates of 0, 60, 120 and 180 kg ha )1 in the companion crop produced 3294, 4451, 4718 and 5131 kg ha )1 hay yield, respectively. These results are similar to those of Schmid and Behrens (1972), who also obtained greater hay yields in the seeding year when the companion crop was harvested at the early dough stage compared with solo sowings. Latta and Blacklow (2001) found that sowing barley at higher rates increased yield compared with low seeding rates in the establishment year.…”

Effect of Weed Control and a Companion Crop on Alfalfa and Sainfoin Establishment, Yields and Nutrient Composition

“…These less vigorous plants, in western Canada, tend to produce less forage in the establishment year (year 1) and in the subsequent year (Waddington and Bittman 1983). However, in climates that are warmer than western Canada, forage plants seem to recover from initial stress during the fall of year I and stands established with or without companion crops produce similar yields in year 2 (Hansen and Krueger 1973;Klebesadel and Smith 1960;Schmid and Behrens 1972). Genest and Steppler (1973) (Jeffersen et al 1983).…”