Autumn-Winter Yield and Quality of Tall Fescue1
- William R. Ocumpaugh and
- A. G. Matches2
Stockpiling, an agricultural practice that extends the grazing season into the winter by accumulating growth of standing forage during the growing season, is practiced successfully in numerous regions of the world. The objectives of this 2-year experiment were to determine, for tall fescue (Festuca arundinacea Schreb.), the effects of spring-summer defoliation and autumn-winter environmental conditions on the quantity and quality of forage available during the autumn and winter. Three sets of plots were defoliated during the spring and summer at 4, 8, and 10-week intervals so that the last defoliation occurred on 9 August of each year. A different subplot of each set of preconditioned plots was then harvested at approximately weekly intervals through November. An additional set of preconditioned plots (8-week defoliation treatment) were harvested at approximately weekly intervals from the end of November into February. The soil was a fine, montmorillonitic, mesic Udollic Ochraqualfs. More frequent defoliations (4 weeks vs. 8 to 10 weeks) reduced the yield of dry matter in the springsummer period by 30 to 40%, but had no effect on autumn yields. Forage from frequently defoliated plots was of higher quality during the spring and summer than less frequently harvested plots, but frequency of defoliation did not affect the quality of autumn stockpiled rescue and had little effect on autumn yields. Dry matter production in the autumn was directly related to the autumn-accumulated rainfall (Y = 52.7 + 62.1 X, r = 0.988 for 1971 and Y = −1068 + 163.6 X, r = 0.934 for 1972). Freezing temperatures in early November stopped autumn growth at about 1,000 kg/ha in 1971 and 1,800 kg/ha in 1972. After freezing temperatures, there was a 25 kg/ha/week decrease in harvestable dry matter. The crude protein content decreased steadily throughout the autumn-winter period, and after growth stopped the rate of decrease averaged about 0.1 percentage unit/week. The in vitro dry matter digestibility of stockpiled fescue remained fairly constant (63 to 68%) from September to early November. After growth was stopped by freezing temperatures in November, digestibility decreased about 1.0 percentage unit/week. The potassium content of the autumn-grown forage decreased at a linear rate of about 0.1 percentage unit/week throughout most of the autumn-winter period and, in 1971–72, decreased to levels considered below the minimum requirements of ruminants.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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