Critical Nitrate-N Concentrations for Growth of Two Strains of Idaho Fescue

Abstract

Nitrate-N in shoots of different strains of Idaho fescue, Festuca idahoensis, can be used for an adequate diagnosis of their respective N statuses at the late vegetative growth stage. The suggested critical nitrate-N concentration for growth of Elmer Idaho fescue, the improved strain used in this study, is 500 ppm of nitrate-N in the shoots, dry basis. The suggested critical nitrate-N concentration for growth of the nonimproved strain is 140 ppm of nitrate-N, dry basis. These critical concentrations are guides that can be used to determine the N status of Idaho fescue on rangelands. Nitrate-N in shoots of Idaho fescue should be above 500 ppm, dry basis, during active vegetative growth, if maximum forage production is desirable.