Establishment and Persistence of Yellow‐Flowered Alfalfa No‐Till Interseeded into Crested Wheatgrass Stands

Abstract

Crested wheatgrass [Agropyron cristatum (L.) Gaertn., A. desertorum (Fisch. ex Link) Schult., and related taxa] oft en exists in near monoculture stands in the northern Great Plains. Introducing locally adapted yellow-fl owered alfalfa [Medicago sativa L. subsp. falcata (L.) Arcang.] would complement crested wheatgrass. Our objective was to evaluate eff ects of seedingpropyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} sod suppression, and seeding rate on initial establishment and stand persistence of Falcata, a predominantly yellow-fl owered alfalfa, no-till interseeded into crested wheatgrass. Research was initiated in August 2008 at Newcastle, WY; Hettinger, ND; Fruitdale, SD; and Buff alo, SD. Eff ects of treatment factors on plant frequency during initial establishment were infl uenced by site environments. Late summer and spring were suitable seeding dates. Clethodim sod suppression increased seedling frequency in most cases. Seedling frequency increased as seeding rate increased from 0.56 to 7.84 kg pure live seed (PLS) ha -1 . Specifi c seeding dates, clethodim sod suppression, and high seeding rates did not greatly improve initial establishment when site environments were poor. Residual eff ects of seeding date and sod suppression post establishment were not signifi cant at most locations, but seeding rate eff ects were evident. Initial establishment and persistence of Falcata alfalfa was successful at Newcastle, indicating that interseeding in late summer or spring using low seeding rates (≤3.36 kg PLS ha -1 ) without clethodim can be eff ective. Assessing grass canopy cover, soil texture, and management (e.g., haying) is necessary to determine the suitability of crested wheatgrass sites for interseeding.

Establishment and Stand Development of Alfalfa Interseeded into Native Grass Mixture: Cultivar and Row Spacing Effects

“…Interseeding alfalfa is considered risky in the semiarid southern High Plains (Misar et al, 2016) because the existing grass root systems and canopy interfere with the emergence of alfalfa seedlings (Fisher and Thornton, 1989). Competition between grass and alfalfa inevitably continues throughout their association (Chamblee and Collins, 1988).…”

“…2016. The period from initial emergence to final emergence was considered the initial establishment or seedling stage (Misar et al, 2016), whereas the rest of the trial period was considered established or crown (hypocotyledonary node with axillary buds) development stage. Number of seedlings emerged was counted within 10-cm row lengths from 10 central rows along a diagonal transect in each plot.…”

“…The differential summer decay rates suggested that cultivars vary in their ability to establish in dry conditions. Misar et al (2016) indicated that an effective initial emergence would result in better stand development for alfalfa than a poor emergence. They pointed out that inadequate precipitation, high interspecific competition from companion grasses, and heavy clay soil are detrimental to the initial establishment for ssp.…”

“…However, a majority of the trials were conducted under irrigation. Alfalfa has been tested for persistence under different seeding rates, seeding dates, harvest management, and sod suppression in various areas of the United States and world (Barney et al, 1974; Groya and Sheaffer, 1981; Kallenbach et al, 2002; Misar et al, 2016), but not in mixtures with native grass at varied row spacings in the southern High Plains.…”

Row spacing of alfalfa interseeded into native grass pasture influences soil‐plant‐water relations

“…Despite its benefits, farmers in the southern High Plains (SHP) have perceived the crop as a heavy water user. Moreover, problems with stand decline (Misar et al, 2016) and diminished water output from irrigation wells due to depletion of the Ogallala Aquifer (Allen, Baker, Segarra, & Brown, 2007) have limited the use of alfalfa in the SHP.…”