PSXII-11 - Evaluation of Yellow-flowered Subspecies Falcata Alfalfa to Purple Flowered Medicago Sativa for Northern Plains: Productivity, Nutrient Profile, and in vitro True Dry Matter Digestibility

Abstract: The protein content and nitrogen fixation capabilities of alfalfa (Medicago sativa L.) make it valuable in cropland and rangelands. However, the semi-arid Northern Great Plains climate negatively affects stand establishment and persistence. Falcata alfalfa (Medicago sativa subs. Falcata) produces adventitious shoots from roots, improving stress and drought resistance. This study compared production and forage quality for yellow- flowered falcata alfalfa (FAL) to a conventional alfalfa (var. Vernal [MSP]). Plots were established as randomized complete block design with four replications. Each cultivar was seeded in 2019 as a monoculture. In 2020, two harvests were made and sampled. Dry matter yield (DMY) and nutritive value of alfalfa were determined. Results showed first cut DMY was 4,228±361 and 3,442±720 kg/ha for the FAL and MSP, respectively. Results for forage quality for first harvest indicate that FAL alfalfa had greater (P < 0.05) ash (10.36 vs. 9.85 %), lignin (7. 86 vs. 7. 14 %), acid detergent fiber (ADF: 38.4 vs. 33.4%), neutral detergent fiber (NDF: 45.4 vs. 39.0 %) but less crude protein (CP; 18.7 vs. 21.2 %, DM basis), total digestible nutrients (TDN: 59.2 vs. 55.5%), non- fiber carbohydrates (NFC; 186 vs. 164), sugar (8.4 vs. 7.0 %), in vitro true dry matter digestibility after a 48-h incubation (IVTDMD48: 58.6 vs. 55.8%), compared with FAL. However, for the second harvest, DMY was 2,837±361 kg/ha for FAL, which had greater CP (20.4 vs. 19.4%), similar ADF (35.4 vs. 35.0), NDF (42.7 vs. 41.8 %), and IVTDMD48 (65.6 vs. 64.0%), but lower lignin (7.68 vs. 7.84%) and TDN (58.1 vs 58.9%) than MSP which yielded 2546 ±515 kg/ha. Falcata had greater nutritive value at second cutting and greater yield compared with Medicago but generally differed little for quality, suggesting falcata can be a viable alternative legume for Northern Plains.