The time and effort required with traditional quadrat clipping often makes collection of adequate samples impractical and limits the utility of the information for making timely decisions. For that reason, alternative methods are sought to estimate mass. We choose forage sticks (forage height), rising plate meter, and forage sled methods as potential alternative for estimating mass and compared these estimates with hand clipped measurements on rangeland, switchgrass, bermudagrass and winter wheat. These data are from the first year of a 2-year study. We measured biomass in each vegetation type on several occasions during its respective growing season at several sites. For each site/date combination, we made measurements in 3 plots (30.5m by 3.7m). Each plot had 2 strips (30.5m by 1.8m), and each strip had 4 quadrats (0.145m2) that were averaged. One strip was randomly chosen for calibration and the other strip for validation. We calibrated the forage stick, plate meter, and sled to the clipping measurements. Limits-of-agreement analysis was used to compare the methods. For example in rangeland sites, there were 14 date/site combinations and 42 forage mass measurements by clipping that ranged from 495 to 6,319 kg/ha. The repeatability of clipping estimates was -2,965 to 2,965 kg/ha. Ocular estimates, based on a 4 quadrat mean, were on average 953 kg/ha smaller than clipping measurements and the limit-of-agreement was -3,399 to 1,493. Ocular estimates, based on one estimate considering the entire strip, were on average 163 kg/ha smaller than clipping measurements and the limit-of-agreement was -2,683 to 2,357 kg/ha. The plate meter estimates, based on the 4 quadrat mean, were 329 kg/ha smaller than clipping measurements and the limit-of-agreement was -2,624 to 1,965 kg/ha. In this poster, we present the results for the other vegetation types.
FORAGE MASS MEASUREMENT: A METHOD COMPARISON
Society for Range Management
SRM Orlando, FL