Estimating Forage Mass with a Commercial Capacitance Meter, Rising Plate Meter, and Pasture Ruler

tronic capacitance meter, rising plate meter, and simple pasture ruler. Accurate assessment of forage mass in pastures is key to budgeting The electronic capacitance meter relies on differences forage in grazing systems. Our objective was to determine the accuracy of an electronic capacitance meter, a rising plate meter, and a pasture in dielectric constants between air and herbage. The meruler in measuring forage mass and to determine the cost of measure- ter measures the capacitance of the air–herbage mixture ment inaccuracy. Forage mass was estimated in grazed pastures on (Curie et al., 1987) and responds mainly to the surface farms in Pennsylvania, Maryland, and West Virginia in 1998 and 1999. area of the foliage (Vickery and Nicol, 1982). The rising Forage mass estimated by each method was compared with forage plate meter integrates sward height and density into one mass estimated by hand-clipped samples. None of these indirect meth- measure, often called bulk height or bulk density (Miods were accurate or precise, and error levels ranged from 26 to 33% chalk and Herbert, 1977). Pasture rulers rely on a positive of the mean forage mass measured on the pastures. The computer relationship between forage yield and canopy height. model DAFOSYM (Dairy Forage System Model) was used to simuCommercially available meters come with factory late farm performance and the resulting effects of inaccuracies in calibrations; however, the accuracy and precision of estimating forage mass on pasture. A representative grazing dairy farm was developed, and the costs and returns from low-input and these equations have not been evaluated for Northeast conventional managements were calculated. Different scenarios were pasture conditions. Many studies of double-sampling then simulated, including under- or overestimating forage yield on techniques have shown that these techniques require pastures by 10 or 20%. All scenarios simulated resulted in lower frequent calibration and that universal equations for returns compared with the optimum farm, with decreases in net return estimating pasture mass may be unreliable (Frame, ranging from $8 to $198 ha 1 yr 1 . Underestimating forage mass re- 1993).