Reevaluation of row spacing/plant density of seeded pasture grasses for the semiarid prairie

Abstract

Previous research in the semiarid prairie at Swift Current, Saskatchewan, indicated that optimum row spacing for forage production was 60 or 90 cm for crested wheatgrass (Agropyron cristatum [L.] Gaertner) and Russian wild ryegrass (Psathyrostachys juncea [Fisch.] Nevski). However, recent research suggested that harvest method affects forage yield estimates from row spacing experiments. An experiment with three row spacings of mixtures of alfalfa (Medicago sativa L.) with crested wheatgrass and Russian wild ryegrass was harvested mechanically and by hand. Yield differences between methods of harvesting were affected by row spacing; larger differences were observed at 15 cm than at 60 cm spacing, particularly for Russian wild ryegrass. The highest hand-harvested forage yield estimates were observed in the narrowest row spacing. In a second experiment, plant density was evaluated for the same grasses using square grid spacings of 30, 45, 60, 75 and 90 cm. Decreasing plant density was associated with decreased hand-harvested forage yield in both species. In a third experiment, 60- and 90-cm row spacing resulted in more seed heads and lower leaf content than 30-cm row spacing. Leaf digestibility increased slightly with increased row spacing. These results suggest that 30-cm row spacing should be recommended to producers for sustainable pastures in the semiarid prairie region. Key words: Forage yield, forage quality, leaf:stem ratio, plot technique