GROWTH OF FOUR GRASS SPECIES AS AFFECTED BY RATE OF NITROGEN APPLICATION AND YEAR OF ESTABLISHMENT ON TWO SOIL TYPES

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Abstract
In an experiment to investigate the relationship between nitrogen fertilization and forage yield, four grass species, bromegrass (Bromus inermis Leyss.), intermediate wheatgrass (Agropyron intermedium (Host) Beauv.), crested wheatgrass (A. cristatum (L.) Gaertn.) and Russian wild ryegrass (Elymus junceus Fisch.), were sown in each of 3 yr on two soil types, a clay loam and a sandy loam. Five N treatments up to 252 kg N∙ha−1∙year−1 were imposed and data were collected for each of the 3 yr following the seeding year on each plot. There was considerable variation in the dry matter yields between seeding years and postseeding years. On the clay loam soil, the first year after seeding was generally the most productive whereas on the sandy loam the second harvest year produced the most. Intermediate wheatgrass was the most productive grass on the clay loam soil, crested wheatgrass on the sandy loam soil. Bromegrass produced well on both types while Russian wild ryegrass was the least productive on both soils. All species responded well to additional N. There was no advantage to split N application. The N content of forage was similar in all four species and on both soil types but was increased by fertilizer N.Key words: Bromegrass, wheatgrass, Russian wild ryegrass, nitrogen, forage yield, establishment year.