Interseeding annual warm‐season grasses into pastures: Forage nutritive value and yields

Abstract

AbstractInterseeding annual warm‐season grasses into pastures often increases forage accumulation. Yet, impacts on nutritive value and yields remain unreported. We analyzed forage collected from five Nebraska and Kansas experiments in 2015–2016 (eight environments) for crude protein (CP), neutral detergent fiber (NDF), and in vitro organic matter digestibility (IVOMD) concentrations and yields. Each experiment subjected perennial cool‐season grasses to two harvest frequencies (once at 90 d and twice at 45 and 90 d after interseeding) and four interseeded annual warm‐season grass types–pearl millet [Pennisetum glaucum (L.) R. Br.], sudangrass [Sorghum bicolor (L.) Moench ssp. drummondii (Nees ex Steud) de Wet & Harlan], a sorghum–sudangrass hybrid (S. bicolor × S. bicolor var. sudanense), and an unseeded control. Across environments, 90‐d CP and IVOMD concentrations increased while CP and IVOMD yields decreased in interseeded pastures when harvested twice, indicating presence of nutritive value‐yield tradeoffs. Pastures interseeded with sorghum–sudangrass had greater 90‐d IVOMD concentrations and CP and IVOMD yields when harvested once but only greater 90‐d IVOMD concentrations when harvested twice compared to unseeded pastures. Interseeding sorghum–sudangrass provided an effective strategy to increase CP and IVOMD yields in late summer in humid environments with tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] and in mid‐ and late summer in humid environments with smooth bromegrass (Bromus inermis Leyss.) and semiarid environments with western wheatgrass [Pascopyrum smithii (Rydb.) Á. Löve]. Interseeding annual warm‐season grasses did not consistently increase CP and IVOMD yields in semiarid environments with smooth bromegrass and crested wheatgrass [Agropyrum cristatum (L.) Gaertn.].