Oat Companion Crop Management in Alfalfa Establishment

Abstract

Companion crops may compete with alfalfa (Medicago saliva L.) seedlings, but establishment with preemergence herbicides and without a companion crop may enhance the potential for soil erosion. Objectives of this study were to (i) compare alfalfa establishment techniques involving clipping or chemical control of weeds and (ii) determine differences in morphological development of alfalfa grown under several establishment techniques. Experiments were conducted at two locations in eastern South Dakota in 1989. Seven treatments included clipping the oat (Avena sativa L.) companion crop at boot stage, not clipping the oat, two treatments with oat sprayed with sethoxydim (2‐[I‐(ethoxyimino) butyl]‐5‐[2‐(ethylthio) propyl]‐3‐hydroxy‐2‐cyclohexen‐1‐one) at either S‐(SES) or 15‐cm (SE15) of oat growth, clear seeding (CS), hand weeding (HW), and a control treatment with no weed control. At Aurora, SD, alfalfa yields were greatest in HW and SE5 treatments. Yields were 24 and 36% less for CS and SE15, respectively, than for SES. At Brookings, SD, yield was also greatest for HW; however, CS had the greatest yield among the conventional establishment techniques. Yield for SES was 15% less than CS. At both locations, alfalfa yield was lowest for the two typical companion crop techniques. For typical companion crop and control treatments, mean tap root length, shoot‐to‐root ratio, and shoot length were reduced compared with other treatments. Subsequent alfalfa yields in 1990 were not affected by establishment technique at either location. Chemical control of an oat companion crop provided greater seedingyear alfalfa yields than typical companion cropping and greater protection from soil erosion than clear seeding.

Alfalfa Yield and Quality as Influenced by Establishment Method

“…However, at Calumet, alfalfa was less mature for the oat companion crop harvested for silage than most other treatments. Curran et al (1993) reported a similar interaction for maturity in an alfalfa establishment study conducted in South Dakota. At one location, they observed lower maturities for alfalfa established with an oat companion crop compared with herbicide and control treatments while at another, there were no observed differences in maturity.…”

“…This provides a pure stand of high quality alfalfa forage for harvest (Stute and Posner, 1993). A postemergence application of sethoxydim to oat growing with alfalfa can also optimize alfalfa yields in the establishment year (Curran et al, 1990; Twidwell et al, 1993). Another potential establishment method, which may impart the same benefits without the use of herbicides, would be to spring‐plant alfalfa into the residue of an oat crop that had been planted the previous fall for winter cover.…”

Benefits and barriers to perennial forage crops in Iowa corn and soybean rotations

“…By their second year, alfalfa stands can often be weed-free without any herbicide use 43,44 . Without decreasing yields of succeeding crops, alfalfa has been shown to reduce weed densities to a comparable degree as herbicides [45][46][47] . A recent demonstration of one alternative system has shown that diversifying crop rotations to include triticale and either red clover or alfalfa is nearly as effective as herbicide use in controlling velvetleaf (Abutilon theophrasti Medik.)…”

Quackgrass control in established alfalfa with sethoxydim

“…In alfalfa, sethoxydim gave excellent control of annual grasses during stand establishment (Ott et al 1989;Curran et al 1993). In established alfalfa, control of quackgrass with sethoxydim varied with application rate and inclusion of adjuvants (Albright and Harvey 1988).…”

“…Leroux and Harvey (1986) reported that the CP concentration of first-cut herbage was increased when sethoxydim was applied in early spring, but had no effect when applied in mid-spring. (Ott et al 1989) and for chemical control of small grain companion crops (Curran et al 1993). However, if relatively weed-free forage is a production goal' use of sethoxydim may be warranted in established stands.…”