Row Spacing and Fertilization Influences on Forage and Seed Yields of Intermediate Wheatgrass, Russian Wildrye, and Green Needlegrass on Dryland1

Abstract

AbstractThe effects of contour row spacings of 76, 107, and 152 cm and N and N‐P fertilization on forage and seed production of intermediate wheatgrass (Agropyron intermedium [Host] Beauv.), Russian wildrye (Elymus junceus Fisch.), and green needlegrass (Stipa viridula Trin.) were evaluated over a 5‐year period.With 45 or 67 kg/ha of N applied annually, forage and seed yields of all species increased 1.5‐ to 2.0‐fold regardless of row spacing, independent of added P. The need for N and N‐P fertilization increased with age of stand regardless of row spacing. Without N or N‐P fertilization, row spacings had no significant influence on forage or seed production of intermediate wheatgrass or Russian wildrye. Forage and seed yields of green needlegrass decreased progressively as row spacing increased regardless of N or N‐P fertilization.Nitrogen recoveries by the three grasses ranged from about 20 to over 50%. In general, N fertilizer recovery was highest from plots with the highest yields and greatest water‐use efficiencies. Russian wildrye grown in 76‐ or 107‐cm rows recovered more than 50% of the N fertilizer applied.Considering all factors involved—forage and seed yields, water‐use efficiencies, and plant N and P uptake—intermediate wheatgrass, Russian wildrye, and green needlegrass should be grown in 107‐ 76‐, and 76‐cm row spacings, respectively, with annual applications of 40 to 60 kg/ha of N with P added.