EFFECTS OF NITROGEN-FERTILIZER ON DRY-MATTER AND NITROGEN YIELDS OF HERBACEOUS LEGUMES IN INTERIOR ALASKA

Birdsfoot trefoil (Lotus corniculatus L.), arrowleaf clover (Trifolium vesiculosum Savi.), berseem clover (Trifolium alexandrinum L.), crims on clover (Trifolium incarnatum L.), barrel medic (Medicago truncatula Gaertn.), winter vetch (Vicia villosa subsp. varia L.), flatpea (Lath yrus tingitanus L.), red clover (Trifolium pratense L.), alfalfa (Medi cago sativa L.), sweetclover (Melilotus officinalis Lam.), fababean (V icia faba L.), field pea (Pisum sativum subsp. arvense L.) and white l upin (Lupinus alba L.) were grown for 2 yr in interior Alaska to asses s their potential as forage and green manure crops and to evaluate the effects of N fertilizer on legume performance. Herbage yield, crude p rotein, and total N yield were the criteria used. In addition to previ ously identified promising species, berseem clover, arrowleaf clover, winter vetch and flatpea consistently produced over 3 t ha(-1) of herb age and accumulated over 67 kg N ha(-1). Nitrogen fertilizer (90 kg N ha(-1)) improved yields of arrowleaf clover and winter vetch at Fairba nks (5344 vs. 3685 kg ha(-1)), but N fertilization depressed yields at Delta Junction. Forage crude protein for the promising species ranged from 120 to 220 g kg(-1). Several species exhibited adequate toleranc e of low soil pH to be grown on acid soils without liming.