Abstract

During 1962 and 1963 we obtained estimates of herbage yield before grazing from mower-strips in orchardgrass and Kentucky bluegrass pastures. Mower-strips were 13 inches wide and ranged from 1 to 10 sample units (4 to 40 feet) in length. A maximum of 10 mower-strips were harvested within 0.83 acre paddocks of each grass.

Since estimates of 3 strips and d units in strips varied from year to year, it is suggested that the optimum size of sample for mower-strip sampling of pastures should be determined each season.

The .95 confidence intervals for herbage yield tended to decrease with an increase in sample size. Confidence intervals and estimates of the variance of an over-all mean were reduced more by increasing the number of mower-strips per paddock than from an equivalent increase in number of sample units per strip. If estimates of herbage yield are to be obtained for the purpose of adjusting grazing pressures on pastures, there appears little practical advantage in harvesting more than 7 mower-strips 16 to 40 feet long.

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