Evaluation of Alfalfa and Grass Species in Binary and Complex Mixtures on Performance under Soil Salinity Conditions

The effect of synergies between saline-tolerant grass and legume species grown in saline soil, on yield, quality, composition, persistence, and weed suppression was studied in 2019&ndash:2021 in a moderately saline soil located in the dark brown soil zone near Saskatoon, Saskatchewan, Canada. &lsquo:Halo&rsquo: alfalfa (ALF), a salt-tolerant cultivar of alfalfa, was seeded in binary mixtures with &lsquo:Revenue&rsquo: slender wheatgrass (ALF-SWG), &lsquo:Garrison&rsquo: creeping meadow foxtail (ALF-CMF), and &lsquo:Radisson&rsquo: smooth bromegrass (ALF-SBG). A complex mixture (quaternary) with all three grasses was also included. Four replicated treatments (n = 4) were randomly allocated to 6.2 &times: 1.2 m plots in spring 2019. The binary mixtures had similar or slightly better stand establishment compared to the quaternary mixture over the two years (83.3 vs. 76.9%), the quaternary stand showed greater (p = 0.01) establishment in Yr 2 than in Yr 1 (85 vs. 68.8%). There was high weed infestation in all the stands, but ALF-SWG had less weed infestation (23.8 vs. 44.1%) than ALF-CMF, especially in Yr 2 (p = 0.05). There were no significant differences among mixtures in yield, nutritional composition, and nutrient uptake. The ALF-CMF and ALF-SWG binary mixtures had 9 to 23% greater mean total DMY than the other mixtures in the moderately saline soil. The cost of establishing forage mixtures on unproductive saline land can be up to 89% recovered after only two years. The results suggested that binary mixtures of &lsquo:Halo&rsquo: alfalfa with &lsquo:Revenue&rsquo: slender wheatgrass or &lsquo:Garrison&rsquo: creeping meadow foxtail could be reasonable alternatives for adequate forage production and quality, high N-use efficiency, and ultimately livestock gain per hectare, as well as for controlling soil salinity and improving soil fertility in this saline area in the dark brown soil zone.