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Winter Tall Fescue Yield and Quality with Different Accumulation Periods and N Rates

Rayburn, E. B., Blaser, R. E., Wolf, D. D.
Agronomy journal 1979 v.71 no.6 pp. 959-963
Festuca arundinacea, Hapludults, application rate, canopy, carbohydrates, chlorophyll, crude protein, grazing, hay, leaves, nutritive value, pastures, regrowth, summer, winter
Tall fescue (Festuca arundinacea shreb.) is used extensively for pasture, hay, and accumulated after midsummer (stockpiled) for winter grazing. The stockpiled canopies are suitable for winter grazing because of high yield, and the erect leaves remain green after several freezes, causing rather high protein contents and feeding values. More information is needed on yield and quality; hence, this investigation was planned to measure the quality [crude protein (CP) and total nonstructural carbohydrates (TNC)] and yield of stockpiled growth as influenced by June, July, August, and September dates of applying N and stockpiling the growth. Winter influence on the quality and yield of the stockpiled forage was also measured by sampling the accumulated canopies in early (December) and late winter (February). Summer regrowth yields were also measured and the soil is classified as Groseclose loam (Typic Hapludults, clayey mixed, mesic). As the age of the tall fescue stockpiled canopies harvested in December decreased from the June to September, stockpiling dates (SD), the dry matter (DM) yields decreased from 3,920 to 840 kg/ha, TNC increased from 15.6 to 23.0%, CP increased from 9.4 to 11.3%, and the chlorophyl index (CI) increased from 32 to 45. When N application was delayed from the June to the September dates, the DM decreased from 3,990 to 3,350 kg/ha, TNC increased from 17.4 to 23.8%, CP increased from 9.0 to 13.2%, and CI increased from 31 to 61. However, a stockpiling date ✕ N interaction occurred because the stock-piled yields tended to decrease with delayed N applications for the June and July SD but increased for the August and September SD. Total DM yields (stockpiled plus summer growth) were highest for the earliest N applications. Dates of starting stockpiling affected the distribution of grazable forage with the highest summer production being 2,880 kg/ha with the September SD. The early June SD does not provide summer pasture, but would reduce the area needed for winter grazing because of the highest yield. The quality and yields of stockpiled tall fescue declined as the winter season advanced. DM, CP, and TNC values of stockpiled tall fescue in February were lower than in December, but highly, and positively correlated to the December values: DM (r = 0.95), TNCO% (r = 0.88), TNC yield (r = 0.92), CP% (r = 0.99), CP yield (r =0.95), and CI (r = 0.89). As compared to no N, and N fertilized forage lost more yield and quality in absolute terms, but continued to be higher in DM and quality in February due to high initial levels.