ESTIMATION OF HERBAGE MASS IN RYEGRASS/WHITE CLOVER DAIRY PASTURES

Abstract

The pasture probe, rising plate meter (RPM), ward height and visual assessment methods were compared for the estimation of the herbage mass of dairy pastures. The pasture probe and calibrated visual assessment were slightly more accurate than others. Visual assessment without calibration was less accurate than all other methods. There was little difference between operators of the pasture probe and RPM, but operator variation was large with visual assessment. Variation between calibrations from different days, seasons, and sites was large. Only dead material content was identified to influence this variation. Pooling of calibrations, double sampling procedures, and derivation of different calibration slopes for each day from an equation fitted to calibration data are procedures discussed for the estimation of herbage mass by farmers, advisors and researchers. Wide adoption of methods such as the pasture probe or RPM with "universal" calibrations could reduce inconsistent advice offered to farmers, and can be used with confidence. Keywords: capacitance probe, rising plate meter, visual assessment, ward height, grassland management, pasture composition, pasture assessment.