Practical use of the rising plate meter (RPM) on New Zealand dairy farms

Abstract

Herbage mass and rising plate meter (RPM) height was estimated using the RPM as part of a farmlet trial, at No. 2 Dairy, Dexcel Hamilton. Herbage mass estimations were collected over a 3-year period, from pre- and post-grazing and weekly farm walk estimates. The aim of the study was to determine how appropriate the RPM was for use on New Zealand dairy farms. The RPM gives reliable information using 50 readings per paddock for paddock selection, grazing residual, and average herbage mass between 1000 and 4000 kg DM/ha. There was a tendency however, for the RPM to underestimate herbage mass when compared with visual estimates. The RPM is limited in its estimation of herbage mass above 4000 kg DM/ha and cannot be relied upon to give useful results for dry matter intake and net herbage accumulation (particularly with weekly farm walk data). As long as RPM limits are observed, overall results show that the RPM is an inexpensive tool to aid in farm monitoring and decision making. Keywords: dairy farming, grazing residual, herbage mass, rising plate meter, RPM height