OMAFRA report: calibrating rising plate meter

A weekly report prepared by the staff of the Ministry of Agriculture, Food and Rural Affairs (OMAFRA).  If you require further information, regarding this report, call the Elora Resource Centre at 519-846-0941. For technical information call the Agricultural Information Contact Centre at 1-877-424-1300 or visit the website:

Grazing pasture is a great way to save on feed costs and utilize marginal land.

One tool to maximize the profitability of pasture land is the rising plate meter, providing producers an estimate of dry matter cover in a paddock, while also being more user-friendly compared to the falling plate meter.

And knowing dry matter cover of a paddock can help determine when to move livestock based on the amount of available feed and how much animals eat.

This can lead to longer grazing seasons, resulting in a greater profit from pasture for producers.

Knowing the amount of available pasture can help to determine proper stocking rates and improve pasture utilization with before and after measurements from grazing.

Knowing the amount of cover the livestock have consumed while in a paddock gives the percent of pasture usage, or pasture utilization.

What is a rising plate meter?

A rising plate meter has a round plate, rising and lowering on a shaft, and counts the number of half-centimetre notches on the shaft the plate moves when placed on the ground, depending on the height of the forage beneath it.

Placing the rising plate meter straight down on pasture results in the plate being supported by the grass below it—called a plonk.

Recording the initial number on the counter, then subtracting by the final number on the counter after plonking and dividing by two gets the bulk height in centimeters of the sample.

The bulk height is a more accurate measurement than height as it takes density into account.

For practical use, walk in a zig zag pattern across pasture, taking 30 to 50 plonks depending on the size of the paddock.

Record the initial number on the counter before starting, and after 30 to 50 plonks, record the final number. Then subtract the initial from the final number off the counter and divide by the amount of plonks taken, divided by two. This will give the average bulk height of the paddock, which can then be used to find the dry matter yield in that paddock.

The rising plate meter needs to be calibrated to Ontario pastures so that producers can look up accurate estimates of available forage.

Calibration needs to be done over several years to ensure accuracy.

What we did…

Bulk height measurements and corresponding pasture samples were taken using the rising plate meter and a quadrat that is the same area as the plate.

The grass in the quadrat was clipped at 5 cm as livestock shouldn’t graze below that height.

Samples were dried and weighed to find dry weight. This was used to calculate the dry matter yield using the equation: kg DM/ha = dry mass of the samples x (100,000/area of the plate). Results were graphed on the ‘y’ axis against the corresponding bulk height measurement on the ‘x’ axis.

The switch date

Grass growth rates change with rates slowing in summer and require different calibrations.

The switch date is when the spring calibration is no longer accurate and the date can be a useful indicator of the “summer slump.”

It is common to run out of feed on pasture with dried stems due to grasses being in the reproductive stage.

The switch date can indicate when the slump starts, which helps producers to take action ahead of the slump.

The switch date for this year was between the last week of June and the first week of July.

In the future

In years ahead, more samples will be taken across Ontario over grazing seasons to produce different equations depending on factors like region and time of year.

An accurate equation depending on area and season would allow producers to take measurements of their own pastures and estimate dry matter yield in their paddocks helping with management decisions to optimize performance of livestock on pasture.

Jessica Brasier