Herbage Quality of Fertilized Cool-Season Grass-Legume Mixtures in Western Nebraska

Abstract

Herbage quality of meadow bromegrass [Bromus biebersteinii Roem and Schult.], smooth bromegrass [Bromus inermis Leyss.], intermediate wheatgrass [Agropyron intermedium (Host) Beauv.], Russian wildrye [Elymus junceus Fisch.], crested wheatgrass [Agropyron cristatum (L.) Gaertn.] in mixtures with alfalfa [Medicago sativa L.] or cicer milkvetch [Astragalus cicer L.] and with the 2 legumes in pure stands at 2 dates of harvest (June 5, June 26) and with 4 rates of fertilizer (0 kg N/ha-0 kg P/ha, O kg N/ha-22 kg P/ha, 45 kg N/ha-0 kg P/ha, 45 kg N/ha-22 kg P/ha) was studied in western Nebraska in 1977 and 1978. Soil at the study site was a loam (Typic Argiustoll) and average annual precipitation is 386 mm. Alfalfa-grass mixtures maintained a higher percentage crude protein than the respective cicer milkvetch-grass mixtures, with the alfalfa-Russian wildrye mixture producing the highest percentage crude protein. Percentage in vitro dry matter digestibility (IVDMD) of the cicer milkvetch-Russian wildrye mixture was the highest of all mixtures, and the percentage IVDMD of the cicer milkvetch-crested wheatgrass mixture the lowest. Herbage quality was higher for the June 5 harvest than the June 26 harvest. Percentage IVDMD of regrowth, which developed after the June harvests, was higher for plots harvested on June 26 than on June 5. Fertilizer rates had a variable effect on herbage quality. Russian wildrye-legume mixtures generally maintained the highest level of herbage quality.