Effect of fertilization and harvest frequency on yield and quality of tall fescue and smooth bromegrass

Abstract

The effects of fertilization and frequent harvesting on yield and quality of tall fescue (F. arundinacea Schreb.) and smooth bromegrass (B. inermis Leyss.) and the efficiency of N in animal waste as compared to inorganic N fertilizer for forage production of these cool season grasses were determined. ''Fawn'' tall fescue and ''Southland'' smooth bromegrass were grown in the greenhouse on Pullman clay loam topsoil (fine, mixed thermic Torrertic (Paleustoll) under 11 fertilizer treatments and 2 harvest regimes. N fertilizer increased yields, N and K concentrations and K/(Ca + Mg) ratios, and decreased P, Ca and Mg concentrations. P and K fertilizers did not affect yields but applied P increased P and tended to decrease N and Ca concentrations. Applied K tended to increase Ca concentrations. Recovery of N from feedlot manure ranged 0.8-14%, whereas recovery from NH4NO3 averaged 64%. Harvesting at 3-wk rather than at 6-wk intervals reduced yields 25%; however, N and P removal were higher under the 3-wk harvest regime. Even though forage production was reduced under heavy utilization, the grasses required more N fertilizer under heavy than under ligher utilization. The 2 grasses produced similar yields under the 3-wk cutting regime and at N rates through 340 kg/ha under the 6-wk cutting regime. Tall fescue yields were higher with the higher N rates under the 6-wk cutting regime. Smooth bromegrass forage was higher than tall fescue forage in N, K, and Ca, whereas tall fescue forage was higher in P and Mg.