Alfalfa–Grass Mixtures in Comparison to Grass and Alfalfa Monocultures

Abstract

Core Ideas Alfalfa–grass mixtures are good alternative to alfalfa and grass monocultures. In the establishment year, alfalfa dominated the mixture, whereas as stands got older, grasses increased their contribution to the biomass. Alfalfa had higher crude protein, whereas grasses had higher fiber digestibility. Alfalfa–grass mixtures improved forage seasonal distribution. The most common binary mixture in the northern Great Plains is smooth bromegrass (Bromus inermis L.) (SBG) with alfalfa (Medicago sativa L.). However, other mixtures might have advantages over SBG–alfalfa. The objective was to compare forage yield, nutritive value, seasonal distribution, and persistence of grasses in monoculture or binary mixtures with alfalfa. A field experiment was established in 2010 in Fargo, Prosper, and Carrington, ND, and results were evaluated until 2013. Several wheatgrass species not commonly used in alfalfa–grass mixtures were tested. All grass species produced higher forage yield in binary mixtures with alfalfa than in monoculture. Binary mixtures had higher persistence in normal rainfall conditions and improved forage nutritive value. Alfalfa contributed with higher crude protein, whereas grasses had higher digestibility of the fiber. Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D.R. Dewey], not commonly included in mixtures with alfalfa, had greater biomass yield than many of the grasses in mixture with alfalfa, although not significantly different from SBG–alfalfa mixture. In the establishment year, alfalfa dominated the mixture (77–99% of total biomass), whereas as stands got older, grasses increased their contribution to the harvested biomass. In the third production year, grass in the mixtures was, on average, 50% of the total biomass. Alfalfa–grass mixtures with grasses other than SBG had similar or greater yield than SBG–alfalfa, increasing the number of potential grass choices that can be used in mixtures. In general, alfalfa–grass mixtures had greater forage yield and nutritive value than grass monocultures.

Grass–Legume Forage Systems Effect on Phosphorus Removal from a Grassland Historically Irrigated with Reclaimed Wastewater

“…Our study revealed that a year × forage system interaction affected herbage accumulation of the different forage systems tested. Similar to the results of our study, herbage accumulation differences among forage treatments were more pronounced in the establishment year compared to the succeeding production year [37,49]. For the legume monocultures, that lack of year effect on herbage accumulation was in complete contrast to the grass monocultures and grass-legume mixtures that favored greater herbage accumulation in the second year.…”

“…For the legume monocultures, that lack of year effect on herbage accumulation was in complete contrast to the grass monocultures and grass-legume mixtures that favored greater herbage accumulation in the second year. Hence, we surmised that the legumes had a faster rate of establishment and stability in this study environment compared to the grass monocultures and the grass-legume mixtures similar to the observation made by Aponte et al [37]. However, contrary to our assumption of the legumes in this study, Bork et al [50] reported that legumes (alfalfa and clover) were slow to reach maximum biomass production relative to the grasses.…”

“…For this study relative to the literature, herbage accumulation values for tall fescue cultivars BarOptima Plus E34 and Fawn were within the range of 3.1 to 15.6 Mg ha −1 reported in several studies [37,52,60]. However, alfalfa herbage accumulation in this study was lower than the four years average of 9.4 Mg ha −1 reported by Aponte et al [37]. Varietal trials in Nevada by Davison et al [61] reported greater annual herbage accumulation for alfalfa relative to this study and indicates the erratic nature of alfalfa responses under water-scarce environments.…”

“…In semiarid Nevada, the predominant forage production system used is monocultures of alfalfa (Medicago sativa L.), orchardgrass (Dactylis glomerata L.), and timothy (Phleum pratense L.) hay crops because of market demand. However, in water-scarce environments, single species cultivation of forage crops may pose a threat to the longevity of crop stand, and thus, forage species mixtures are deemed a more reliable choice [37]. Cultivating mixtures of forage species have been shown to increase overall forage biomass production and nutrient content compared to monocultures [38][39][40] as a result of niche complementarity [41].…”

Interseeding alfalfa into native grassland for enhanced yield and water use efficiency

“…The alfalfa‐induced N input can prime the process of plant growth and recovery of grasses in spring and optimize total niche complementarity for water, light, and other nutrients (Nyfeler et al., 2009). Many studies have reported alfalfa–grass yield advantages of 15–45% over N‐fertilized grass monocultures (Aponte, Samarappuli, & Berti, 2019; Sanderson, Brink, Stout, & Ruth, 2013; Sleugh et al., 2000) or up to 143% over rangeland grass stands (Mortenson, Schuman, Ingram, Nayigihugu, & Hess, 2005). Nyfeler et al.…”