Sod‐Seeding and Grazing Effects on Alfalfa Weevils, Weeds, and Forage Yields in Established Alfalfa

Abstract

Alfalfa (Medicago sativa L.) hay production for dairy and equine industries is a profitable enterprise in the Great Plains. However, as stands thin, forage production decreases and weeds increase, resulting in decreased returns. The objective of this research was to determine if alternative management strategies using October sod seeding plus March grazing could be utilized to increase forage production and control pests. Experiments were conducted at four locations in central Oklahoma from 1998–2000. Two ungrazed treatments (with and without pesticides) were compared with three treatments without pesticides but grazed by cattle in March. The three grazing treatments included: no sod seed, ryegrass (Lolium multiflorum Lam.) sod‐seeded in October, and wheat (Triticum aestivum L.) sod‐seeded in October. Grazing by cattle reduced alfalfa weevil (Hypera postica Gyllenhal) larval populations as effectively as insecticide application. In thin stands (<200 stems m−2), total forage yields were increased with alfalfa–grass mixtures by an average of 2.7 kg ha−1. However, alfalfa yields were decreased 0.9 kg ha−1 with sod‐seeded ryegrass (P = 0.05). In thin stands, sod‐seeded grass treatments were more effective at weed suppression than a herbicide treatment. Net returns from cool‐season forage production increased with sod seeding plus March grazing compared with net returns using conventional haying methods. In thin stands (<200 stems m−2), sod seeding of ryegrass or wheat plus March grazing provided greater net returns ($175 ha−1) than conventional practice of using pesticides and haying. In full stands (>250 stems m−2), net returns from conventional alfalfa management (using pesticides and only haying) were comparable to October sod seed plus March grazing treatments.

Overseeding Alfalfa with Rye and/or Annual Ryegrass Can Improve Forage Distribution and Total Production

“…This is to be expected given that the second cutting was taken during the period in spring (mid-May) when annual ryegrass is most productive at this location. The reduction in alfalfa yields in the spring harvests were similar to that observed by Cummings et al (5) and in Wisconsin for alfalfa established with annual ryegrass as a nurse crop (9). Within the CR-AR treatment, the yield contribution of the overseeded species was predominantly (>75% in each year) AR herbage (data not shown).…”

Evaluation of Alfalfa–Tall Fescue Mixtures across Multiple Environments

“…Majak et al (2003) found that cattle fed a diet of 100% alfalfa became bloated 105 times over a 2-yr study period while those fed a 50% orchardgrass-alfalfa mix bloated only twice. Weed suppression may be another important benefit of mixtures over monoculture stands (Cummings et al, 2004). Grasses mixed with alfalfa also have been shown to reduce insect pests like alfalfa weevil Hypera postica (Coleoptera: Curculionidae), as well as potato leaf hopper Empoasca fabae (Hemiptera: Cicadellidae) infestations in young stands (Lamp, 1991;Roda et al, 1996).…”

“…Grasses mixed with alfalfa also have been shown to reduce insect pests like alfalfa weevil Hypera postica (Coleoptera: Curculionidae), as well as potato leaf hopper Empoasca fabae (Hemiptera: Cicadellidae) infestations in young stands (Lamp, 1991;Roda et al, 1996). Weed suppression may be another important benefit of mixtures over monoculture stands (Cummings et al, 2004). From an energy balance perspective, legumebased pastures can supply sufficient N through fixation to supply grazing animals with enough protein and energy to sustain weight gains with much less external energy expenditure and greenhouse gas emission than fertilized grass pasture (Chen et al, 2004).…”

A rotation design to reduce weed density in organic farming

“…Also, weed seeds remain on the soil surface during the alfalfa interval because the field is not tilled; consequently, weed seed survival declines rapidly across time, as noted in Figure 2. Alfalfa competitiveness with weeds decreases in the later years because stand density of alfalfa declines across time 14,15 . 4).…”