Barley vs. Oat Companion Crops. I. Forage Yield and Quality Response during Alfalfa Establishment1

Abstract

Oats (Avena sativa L.) is often chosen as a companion crop during the establishment of alfalfa (Medicago sativa L.). Recent research has shown barley (Hordeum vulgare L.) forage to have superior nutrient duality compared to that of oats. Our primary objective was to determine the forage quality and yield potential of representative barley and oat cultivars harvested at various maturity stages as companion crops during alfalfa establishment. Four cultivars each of barley and oats were established with alfalfa at each of two locations during each of 2 yr and harvested initially as forage at each of three small grain crop maturation stages. Alfalfa was also established alone (solo‐seeded) with and without herbicides, and was harvested at first flower. In vitro digestible dry matter (IVDDM) concentration of small grain‐alfalfa mixtures declined from 83 to 55 dag kg−1 (%) dry wt as companion crop maturation increased from five leaf to dough stage, whereas crude protein (CP) concentration declined from 29 to 9 dag kg−1 dry wt. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations increased with maturation until flag leaf stage, and then stabilized through dough stage. Average IVDDM concentration of mixtures of alfalfa and ‘Morex’ barley or ‘Lyon’ oats harvested initially at flag leaf stage was equivalent to or greater than that of solo‐seeded alfalfa established with or without herbicides. However, the average NDF and ADF concentrations of solo‐seeded alfalfa were lower than those of small grain‐alfalfa mixtures. Nutritive value and nutrient yield did not differ between soloseeded alfalfa established with and without herbicides. When barley and oat cultivars were used as companion crops for spring‐seeded alfalfa, barley mixtures harvested initially at the five leaf, flag leaf, or dough stage usually provided superior quality forage in the seeding year than did oat mixtures. However, annual IVDDM and CP yields were more influenced by location and year than by small grain species or cultivar.