CLIPPING FREQUENCY AND FERTILIZER EFFECTS ON PRODUCTIVITY AND LONGEVITY OF FIVE GRASSES

Agropyron cristatum, Agropyron intermedium, Agropyron riparium, Elymus junceus and Stipa viridula were studied in relation to clipping effects on productivity and longevity. All species, except Elymus junceus, produced progressively less as number of clippings increased. Agropyron intermedium yielded the most forage, especially when harvested only once per season, followed closely by Agropyron cristatum. Crude protein yield was less variable under various frequencies of clipping than forage yield, and differences between species were also smaller. Elymus junceus and Agropyron cristatum displayed the strongest competitive ability, especially under frequent clipping and Stipa viridula the lowest. The amount of root produced varied significantly between species. Agropyron cristatum and Elymus junceus produced the most root and Stipa viridula the least. Fertilizer applied in the fourth and fifth crop years increased the yield by 30 to 200 per cent. It was concluded that Agropyron cristatum and Elymus junceus were about equally persistent under frequent clipping and should be more useful long-term pasture grasses than the other three in dry cold climates.