A comparison of quadrat, capacitance meter, HFRO sward stick, and rising plate for estimating herbage mass in a smooth-stalked, meadowgrass-dominant white clover sward


W. M. Murphy, Department of Plant and Soil Science, Hills Building, Burlington, Vermont 05405-0082, USA.


A single-probe capacitance meter (Pasture Probe), the Hill Farm Research Organization (HFRO) sward stick, a rising-plate meter, and cut quadrats were used to estimate herbage mass of swards that were rotationally grazed by cattle, cattle followed by topping, cattle followed by sheep, or sheep alone during 1989 and 1990 grazing seasons. Mean target pre- and post-grazing herbage masses were 2200 and 1100 kg dry matter (DM) ha−1 respectively. Linear regressions, correlations and scatterplots were calculated relating meter and sward stick readings to herbage mass on an ash-free organic matter basis measured by cutting quadrats of herbage at ground level.

Mean coefficients of variation for quadrat, capacitance meter, sward stick and rising plate were 28·8, 15·5, 27·2 and 27·9% respectively for pre-grazing herbage mass measurements, and 20·2, 10·1, 21·4, and 18·4% respectively for post-grazing measurements. These coefficients indicate that the capacitance meter varied less in estimating pre- and postgrazing herbage mass than the other three methods.

Correlation coefficients relating cut quadrats to capacitance meter, sward stick and rising plate readings were 0·65, 0·70 and 0·72 for pre-grazing, and 0·36, 0·31 and 0·05 for post-grazing herbage mass measurements respectively.

The non-destructive methods provided quick herbage mass estimates at a level of precision adequate for making day-to-day grazing management decisions on farms.