Effects of N, P, and K Fertilization on Yield and Quality of Tall Fescue Forage in Winter1

Abstract

AbstractUse of tall fescue (Festuca arundinacea Schreb.) regrowth to extend the grazing season into late fall and winter is becoming increasingly popular in middle‐latitude regions of the USA. Few studies have been reported, however, that deal with factors influencing yield and quality of regrowth forage in winter. A field study was begun in October of 1971 to measure the effects of N, P, and K fertilization on yield and quality of tall fescue regrowth in late fall and winter. Eight fertility regimes were established in each of four replications. These were: 1) N applied at 60 kg/ha in spring and after each of three summer harvests, 2) P applied at 30 kg/ha in spring and in late summer, 3) K applied at 60 kg/ha in spring and in late summer, 4) to 7) the four possible combinations of the above three treatments, and 8) no fertilizer treatment. Forage from all plots was harvested in mid‐May, early July, and mid‐August and then in either mid‐December or mid‐January. In 1971 when the experiment began, all plots were harvested on 9 October rather than mid‐August and then in either mid‐December or mid‐January. Nitrogen fertilization increased yield and concentrations of in vitro digestible dry matter, total nonstructural carbohydrate, K, Mg, and N in the late fall and winter harvested forage and decreased concentrations of dry matter and Ca. Yield and concentration of quality components decreased less in N fertilized forage than in unfertilized and P and K fertilized forage as harvest was delayed from December to January. Phosphorus fertilization had little effect upon yield and quality components. Potassium fertilization decreased both Ca and Mg concentrations. Results suggest that winter forages of sufficient quality to meet most of the nutritional needs of many classes of livestock in mid‐latitude regions of the U.S. may be obtained by manipulating summer and/or fall harvest dates and fertilization rates. Supplementation of regrowth forage with Na and Mg and possibly with P during late winter months would be required.