Reaction of Tall Fescue to Frequent Summer Nitrogen Applications1

The postulation that tall fescue (Festuca arundinacea L. var. ‘Ky. 31’) might tolerate and respond more favorably to higher rates of N in summer if applied frequently in small increments was studied at Holland, Va. from 1966 to 1970. Weekly N applications of up to 56 kg/ha, May through August each year, and one application of 168 kg/ha each March, totalling 1,120 kg/ha by September 1, thinned stands of tall rescue by only 30%. Rates of N up to 22.4 kg/ha per week increased density of stands. Annual dry matter yields increased from 41 to 110 q/ha as N rates increased up to 39.2 kg/ha per week. Yields from the May harvests were highest with generally lower yields in successive cuttings taken every 4 to 6 weeks through September. Nitrogen content was lower in the May cuttings than in succeeding cuttings. Generally, protein concentrations increased in the summer cuttings as the rate of N increased to 22.4 kg/ha per week, above which no increase occurred. Nitrogen uptake by fescue increased from 90 to 375 kg/ha as weekly N rates increased from 0 to 56 kg/ha. The proportion of N removed in rescue forage relative to that applied was highest (61%) from 5.6 kg/ha per week of N and lowest (33%) from 56.0 kg/ha per week of N. Use of tall rescue may be feasible as a vegetative cover for disposal of high N waste if applied frequently in small increments. Soluble carbohydrate concentrations in the stubble probably were not low enough (7%) to influence regrowth and stand survival appreciably.