Yield and Nutritive Value of Irrigated Winter Cereal Forage Grass–Legume Intercrops in the Southern High Plains, USA

Abstract

With dwindling water supplies, alfalfa ( Medicago sativa L.) and corn ( Zea mays L.) producers in the Southern High Plains (USA) seek alternative forages for the dairy industry. At New Mexico State University's Agricultural Science Center at Tucumcari, cereal forage monocultures and intercrops with legumes were subjected to two irrigation treatments during two growing seasons in a Canez fine sandy loam (fine‐loamy, mixed, thermic Ustollic Haplargid). Dry matter (DM) yield of monocultures averaged 3.76, 3.90, 5.55, 5.59, and 3.17 Mg ha −1 for rye ( Secale cereale L.), barley ( Hordeum vulgare L.), wheat ( Triticum aestivum L.), triticale (× Triticosecale rimpaui Wittm.), and oat ( Avena sativa L.), respectively. Cereal forages irrigated once in a growing season yielded equally to those watered twice with average precipitation (2000–2001, 408 mm), but not in a dry growing season (2001–2002, 245 mm) (6.15, 5.41, 1.90, and 3.21 Mg ha −1 for cereal forages irrigated once or twice in 2000–2001 or 2001–2002, respectively). Also, levels of forage nutritive components were greatest when irrigated once in 2001–2002. Intercropping with winter pea [ Pisum sativum subsp. arvense (L.) Poir] or hairy vetch ( Vicia villosa Roth.) reduced yield of wheat and triticale compared with monocultures, but these yields were still greater than those of the other cereal forages and winter pea improved quality indicators when intercropped with wheat or triticale. Water can be conserved in the Southern High Plains by irrigating cereals only as needed for germination or to promote fall growth.