Grass-legume mixtures are considered viable alternatives to nitrogen (N)-fertilized grass pastures, but there is a dearth of information on effects of seed mass ratios on productivity and economic returns. We evaluated the effects of grass-legume seed mass ratios and N fertilizer rates on forage accumulation, nutritive value, and profitability. There were 15 treatments arranged in randomized complete blocks with four replicates. The treatments included four species (meadow bromegrass [Bromus biebersteinii Roem. & Schult] and three legumes— alfalfa [Medicago sativa L.], sainfoin [Onobrychis viciifolia Scop.], and birdsfoot trefoil [Lotus cor-niculatus L.]), various seed mass ratios (100:0, 50:50, 70:30, 50:25:25, and 50:16.7:16.7:16.7), and three rates of N (0, 56, and 112 kg N ha−1) applied only to meadow bromegrass monocul-tures. The 2-yr average annual forage accumulation of meadow bromegrass receiving 112 kg N ha−1 was 6.89 Mg ha−1 yr−1, which was similar to the 30% alfalfa + 70% meadow bromegrass, 30% birdsfoot trefoil + 70% meadow bromegrass, 25% alfalfa + 25% birdsfoot trefoil + 50% meadow bromegrass, and 50:16.7:16.7:16.7 mixture treatments. Mixtures had greater nutritive value than N-fertilized meadow bromegrass. All treatments except 100% sainfoin and 50% sainfoin + 50% meadow bromegrass treatments were profitable. On the basis of forage accumulation, nutritive value, and profitability, the 30% alfalfa + 70% meadow bromegrass and 30% birdsfoot trefoil + 70% meadow bromegrass seed mass ratios are simple mixtures that may be viable alternatives to 100% alfalfa and N-fertilized meadow bromegrass monocultures.
Bibliographical noteFunding Information:
This study was funded by ShREC competitive graduate assistantship and Western SARE. Authors also thank Mr. Dan Smith and the staff of ShREC for their help in establishment and management of the research plots.
© Crop Science Society of America.