Restoring ecological function to saline-sodic soils in South Dakota with perennial grass mixtures

Revegetation of saline-sodic soils is challenging. Over 10 million saline-sodic hectares are intertwined with highly productive soils in the Northern Great Plains, with 3.4 million ha in South Dakota. Establishing salt-tolerant perennial plants provides soil cover and remediates barren areas. Two perennial salt-tolerant grass mixes [Mix 1: slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners) + beardless wildrye (Leymus triticoides [Buckley] Pilg.); Mix 2: slender wheatgrass + creeping foxtail (Alopercurus arundinaceus Poir.) + western wheatgrass (Pascopyrum smithii [Rydb.] a. Love) + 'AC Saltlander' green wheatgrass (Elymus hoffmannii K.B. Jensen & K.H. Asay)] were dormant-planted in 2018 and 2019 along a soil catena with high [electrical conductivity (EC1:1) = 0.39 dS m(-l); 72 mg kg(-1) Na+], moderate (EC1:1 = 1.64 dS m(-l); 343 mg kg(-1) Na+), and low (EC1:1 = 3.87 dS m(-l); 1,680 mg kg(-1) Na+) productivity zones. Vegetative biomass was measured after seeding (2018, 2019) and during growth (2020, 2021), and compared with areas seeded to maize (Zea mays L.) and a nonplanted area. Biomass varied with year and productivity zone. Except in 2018, grasses had greater biomass in the moderate and low productivity zones than maize. The sodium content of grass biomass in 2020 and 2021 was 10x greater in the low than in the high and moderate productive zones (0.25 vs. 0.02%, respectively) but could be suitable for livestock feed. By 2021, grass biomass was similar for both mixes in all zones, and the grasses spread into nonplanted areas.