Barley vs. Oat Companion Crops. II. Influence on Alfalfa Persistence and Yield1

Abstract

Recent evidence has indicated the superior quality of barley (Hordeum vulgare L.) forage compared to that of oats (Arena saliva L.). Evaluations of alfalfa (Medicago saliva L.) persistence following the seeding year are needed to determine the potential of barley vs. oats as a companion crop during alfalfa establishment. Our primary objective was to determine the influence of establishment with barley or oat companion crops harvested at four small grain crop maturation stages on alfalfa persistence overwinter and first crop yield the following spring. Four cultivars each of barley and oats were established with alfalfa at each of two locations during each of 2 yr and harvested initially at each of four small grain crop maturation stages. Alfalfa was also established alone (solo‐seeded) with and without herbicides and was harvested at first flower. Alfalfa persistence (proportion of complete ground cover) and subsequent yield of all treatments were determined in the spring following the seeding year. Alfalfa persistence and subsequent spring yield were usually not affected by harvest stage or small grain crop cultivar when the companion crop was harvested initially at the five leaf, flag leaf, or dough stages, even though barley cultivars frequently had greater potential for competition with the alfalfa at each stage than oat cultivars as measured by ground photography, leaf area index, and seedling alfalfa yield. Barley cultivars also lodged more frequently than oat cultivars. When the first establishment year harvest of the companion crops occurred at grain stage, alfalfa stands were often reduced more than when harvest occurred at immature stages. Persistence of alfalfa established when ‘Morex’ barley or ‘Lyon’ oats and harvested initially at flag leaf stage and then at first alfalfa flower was not different from that of solo‐seeded alfalfa established with or without herbicides and harvested twice at first flower. However, under the same management (but with a greater interval between seeding year harvests), the subsequent spring yield of solo‐seeded alfalfa was greater than that of alfalfa sown with Morex barley or Lyon oats in one year at both locations. We conclude that the barley cultivars tested in this study were as successfully utilized as oat cultivars during alfalfa establishment when the companion crop was harvested at immature stages. Although risk of alfalfa stand loss was greater following harvest of the companion crops at grain stage, the influence of barley and oat cultivars on alfalfa persistence at this stage was inconclusive and varied with the location and year.