Seedbed Preparation Techniques and Weed Control Strategies for Strip-Planting Rhizoma Peanut Into Bahiagrass Pastures.

Establishment of rhizoma peanut (Arachis glabrata Benth.; RP) in prepared strips into bahiagrass (Paspalum notatum Flügge) pastures may be a lower-cost alternative to achieve a grass-legume mixture, but research is needed to determine the best methods. The objectives were to quantify the effects of the factorial combination of four seedbed preparation techniques and four weed control strategies. Seedbed preparation techniques were: 1) glyphosate + tillage (bahiagrass sod sprayed with glyphosate followed by deep tillage with a moldboard plow and heavy disking), 2) tillage only (bahiagrass sod tilled as in the previous treatment but no glyphosate applied), 3) no-till (bahiagrass sod sprayed with glyphosate followed by mowing the remaining above-ground biomass to 5-cm stubble height before planting RP), and 4) sod lifted (bahiagrass sod lifted with a sod-cutter to a depth of 8 cm and removed from the strip before planting RP). Weed control strategies were: 1) control (no herbicides, no mowing), 2) mowing (every 28 d to 10-cm stubble height), and single application of herbicides: 3) imazapic (0.29 L ha^-1), and 4) imazapic + 2,4-D amine (0.29 and 0.58 L ha^-1, respectively). Sprout emergence tended to be greater in treatments where tillage occurred (119, 90, 58 and 54 sprouts m^-2 for glyphosate + tillage, tillage only, no-till and sod lifted, respectively). Nevertheless, differences due to seedbed preparation on RP canopy cover and frequency by end of the growing season favored no-till (21% cover and 70% frequency) compared to ≤ 14% for cover and 53% frequency for the other treatments. Results indicate that post-plant competition control is more important than seedbed preparation. Single application of glyphosate to prepare the seedbed (no-till treatment) and post-emergence use of imazapic with or without 2,4-D are viable options for successful establishment of RP in strips into existing bahiagrass pastures with potential to reduce establishment costs.