DETERMINATION OF PASTURE BIOMASS USING 4 INDIRECT METHODS

The most accurate method for determining canopy biomass of pastures Fo r forage availability is by cutting and weighing forage from known are as, Faster methods that require less time and labor would help produce rs to monitor forage availability in pastures on a daily or weekly bas is. Indirect methods rely on calibrations performed on pure or evenly distributed plant compositions to determine forage biomass. However, m icroclimates developed by varying landscape positions and soil morphol ogical characteristics of pastures may cause uneven plant and species distributions, This study was performed to compare the ability of a mo dified Rebel pole, rising plate meter, canopy height stick, and Li-Cor LAI 2000 leaf canopy analy:rer to determine forage availability in pa stures with varying species composition from four areas, Swards consis ted of pure warm-season grass stands, cool-season grass stands, legume stands, and grass-legume mixtures, Instrument readings were compared with forage availability determined by clipping and were measured for accuracy, or closeness to clipped weight, For all observations, coeffi cients of determination (r(2)), were 0.63, 0.59, 0.55, and 0.32 for th e modified Rebel pole, rising plate meter, canopy height stick, and le af canopy analyzer, respectively, For modified Rebel pole readings, r( 2) was highest for observations in red clover (Trifolium pratense L.) (r(2) = 0.83), smooth bromegrass (Bromus inermis Leyss.) (r(2) = 0.82) , and alfalfa (Medicago sativa L.) (r(2) = 0.76) swards, whereas the r ising plate meter r(2) values were highest for observations in tall fe scue (Festuca arundinacea Schreb,) (r(2) = 0.85), alfalfa (r(2) = 0.84 ), and red clover (r(2) = 0.73) swards, Grass observations also had th eir highest r(2) values with the modified Rebel pole and rising plate meter at 0.63 and 0.59, respectively, The modified Rebel pole proved t o be the most acl:urate method used over a variety of species.