Adaptation and forage productivity of cool-season grasses in the central USA

Authors: VOGEL, KENNETH - Retired ARS Employee; Mitchell, Robert - Rob

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2021
Publication Date: 6/12/2021
Citation: Vogel, K.P., Mitchell, R. 2021. Adaptation and forage productivity of cool-season grasses in the central USA. Agrosystems, Geosciences & Environment. 4(2). Article e20172. https://doi.org/10.1002/agg2.20172.
DOI: https://doi.org/10.1002/agg2.20172

Interpretive Summary: Millions of acres of grasslands have been converted to cropland throughout the central and northern Great Plains USA in the past two decades. This conversion of both native and planted grasslands occurred because of high grain prices due to efforts to increase the production of biofuels. As a result, grain crops such as corn have been used for ethanol production and oilseed crops such as soybeans have been used for biodiesel production. Much of this grassland conversion occurred on land that was marginally productive for corn and soybean. Currently, profits on the marginal lands taken out of grasslands and converted to cropland are lacking or limited. Landowners could convert this land back to grasslands if the converted grasslands were profitable. We evaluated 85 cultivars of 18 cool-season grass species in the eastern (Mead, NE) and western (Sidney, NE) regions of the Central Great Plains. The species included both native and introduced grasses. The grasses that had the best establishment, persistence, and forage yields at Mead were intermediate, tall, and western wheatgrass, smooth and meadow bromegrass, and the R-S hybrids. At Sidney, the best grasses were intermediate, crested, western, and thickspike wheatgrasses, the R-S hybrids, and Russian wildryes. Within these species, there were significant differences for forage yield and crude protein concentration among cultivars. To be economically competitive with grain crops on marginal cropland the best possible grasses need to be used in grazing systems whether they are native, introduced, native-introduced hybrids, or multi-species mixtures of both native and introduced grasses and legumes.

Technical Abstract: Cool-season grass species (18) and cultivars (85) were evaluated for use in seeded grasslands in the tallgrass prairie and shortgrass steppe ecoregions of the central United States at the test locations of Ithaca and Sidney, NE, respectively. Both native and introduced grasses were evaluated in sward trails. Significant differences existed among species and cultivars for all traits evaluated except for in vitro dry matter digestibility (IVDMD) among cultivars within species at Sidney. The grasses that had the best establishment, persistence, and forage yields in the Ithaca trial were introduced wheatgrass (Thinopyrum) and bromegrass (Bromus) species. At the Sidney location, the best species using the same criteria were wheatgrasses (Thinopyrum, Agropryon, Pascopyrum, and Elymus spp.) and wildryes (Psathyrostachys). The only native grasses that were marginally competitive with the introduced grasses were western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve] and thickspike wheatgrass [Elymus macrourus (Turcz.) Tzvelev] at the Sidney location and western wheatgrass at Ithaca. The study was the largest cool-season forage grass multispecies and cultivar sward evaluation to date in these two major land areas. The superior species and cultivars that were identified represent the best cool-season grasses available for restoring marginal croplands to grazed grasslands in these two major land areas.