FORAGE QUALITY AND ECONOMIC-IMPLICATIONS OF SYSTEMS TO MANAGE GIANT FOXTAIL AND OAT DURING ALFALFA ESTABLISHMENT

Companion crops and weeds compete with alfalfa (Medicago sativa L.) du ring establishment and affect forage yield, composition, quality, popu lation density, and net income. We compared four establishment systems seeded in April and again in May. The four systems were (i) oat (Aven a sativa L. var, 'Starter') mulch with a postemergence herbicide on oa t leaving residue, (ii) oat companion crop harvested at boot stage, (i ii) solo seeding with a herbicide, and (iv) solo seeding without a her bicide, Field studies were conducted for 2 yr on a Waukegan silt loam (mixed, mesic Typic Hapludoll), The highest season total forage yields mere obtained with solo seeding without herbicide and with oat compan ion crop systems. The highest season total alfalfa yields and lowest p ercentage oat or giant foxtail (Setaria faberi Herrm.) composition in forage were obtained when solo seeding with herbicide. Forage usually contained significant levels of oat or giant foxtail when managed with out herbicides, Forage relative feed value (RFV) was highest with alfa lfa solo seeding with herbicide, and lowest with companion crop or sol o seeding without herbicide systems. Use of herbicides to establish al falfa consistently resulted in forage of highest quality and value, bu t not always the highest net income after yield and production costs w ere considered. April plantings resulted in higher net income than May plantings. When soil moisture was adequate and the date of seeding co nducive for alfalfa growth, the most profitable method of establishing alfalfa was with oaf: mulch systems, or when solo seeding with herbic ide. If alfalfa planting was delayed or soil moisture limiting, herbic ide systems mere similar to, or less profitable than the oat companion crop or solo seeding without herbicide systems. Oat companion crop or giant foxtail did not decrease alfalfa population density the year fo llowing establishment, and decreased residual alfalfa yield in only on e of four seeding dates.