Vegetation dynamics in nitrogen‐fertilized versus mixed legume‐smooth bromegrass pastures interseeded with sorghum‐sudangrass

Interseeding annual warm-season grasses may increase forage and pasture productivity. From 2017 to 2019, we conducted a grazing experiment that examined smooth bromegrass (Bromus inermis Leyss.) responses interseeding sorghum-sudangrass [Sorghum bicolor (L.) Moench × S. ssp. drummondii (Nees ex Steud.) de Wet & Harlan]. The had split-plot design with six main plots each containing two, 0.60-ha subplots (i.e., 12 total subplots). included three replications of two types: (A) nitrogen (N)-fertilized (FERT) (B) mixed legume-smooth [LEG; alfalfa (Medicago sativa L.), red clover (Trifolium repens birdsfoot trefoil (Lotus corniculatus L.)]. interseeded unseeded control treatments. Each subplot, which supported steers (Bos taurus) from spring through summer, contained six, 0.10-ha sub-subplots for rotational stocking. Sorghum-sudangrass was after stocking cycle 2 in the subplot year. Vegetation were evaluated these adjacent subplot. Across years, sampling dates, treatments, LEG 7% greater biomass (2743 ± 102 kg ha−1) more days than FERT (2552 111 ha−1). sub-subplots, however, 36% pre-grazing 5. To optimize biomass, producers should fertilize early or maintain legumes pastures. provides an option late-summer biomass.