Using A Plate Meter

Using a Plate Meter is straight forward but accuracy and technique is very important when measuring with a grass plate meter. Not using the plate meter correctly can lead to a variation of up to 300kg DM/ha. This can lead you to believing you have adequate covers or surplus when the reverse maybe true.

When using a Jenquip plate meter take a minimum of thirty readings (plonks) with the Plate Meter as you walk across a representative part of the field. This will take into account the better and worst areas giving you a much more accurate cover assessment. 

It is advisable to take the same route across the field week after week so that you have comparable data. If there is more than one person walking the farm then it is advisable to put markers on posts and this makes it easier to follow the same route each time.

Do not choose where to place the plate meter as it must be random so that you get a good representation of covers in the field. Also it is important to place the plate meter rather than use a walking stick motion or push down.

The reason you need to take a minimum of thirty plonks is to even out the extremes of growth you may encounter. The key is to take as many as possible i.e. 50 is more accurate than 30, also 100 is more accurate than 50.

Plate meters are designed for grass clover swards and they are most accurate between 1800 and 3000kg DM/ha.

Unexpected Readings

If the plate meter is not reading as you expect then check:

There is no grass wound around the bottom of the plate.

That you are placing the plate meter vertically in the pasture and not rocking it like you would with a walking stick.

The density of the pasture at the base; if the sward is really thick and dense at the base of the sward the reading may be correct as the density has a large affect on the plate meter reading.

Using the correct technique there is no difference in readings between the electronic and mechanical plate meters.

Measuring during or immediately after heavy rain will give lower readings

Measuring with heavy frost will give higher readings