Know your Soils #9: The plate meter

470 351 Sectormentor for Soils

Welcome to the ninth instalment of our Know your Soils series sharing practical tips for monitoring the soil health on your land. Keep an eye out for our bitesize videos and fact sheets on simple tests you can do yourself on farm.

“If you can’t measure it, you can’t improve it.


How to maintain productive grassland

Insights from Alex Heffron, Welsh farmer and regenerative agriculture enthusiast

Plate meters allow farmers to measure and monitor the volume of forage they have across their fields and farm. This is a very important tool for understanding how to maintain productive grassland and extend the grazing season.

We travel to Wales, to meet Alex Heffron, from Mountain Hall Farm, who produces Jersey raw milk and beef. He’s a first generation farmer, managing 13.5 acres of grazing and 100% pasture fed livestock. So you could say grass is his bread and butter!

Calculating forage volume is an essential tool for Alex to manage food supply for his animals while maintaining and improving grass and soil health. He regularly moves his cattle to new pasture using a Holistic Planned Grazing framework and mob grazing.

It’s time for you to meet Alex’s good friend, the plate meter:

Every time Alex moves animals to new pasture he takes a plate meter reading for that field so he can calculate how much grass is there, and when he should move them again to ensure optimum regrowth of the grass.

Plate meters measure the height and density of the sward. It takes the average height in compressed centimetres and converts it to kilos of dry matter per hectare using this equation: [average sward height] x 125 + 640 = [forage volume] kg DM/ha.

For example: if there’s 4000 kg DM/ha in Alex’s field and he aims to leave 2500 kg DM/ha to ensure grass regrowth, then there’s 1500 kg DM/ha to graze. If the field is 1 ha and there are 10 steers each weighing 400 kg which need to graze 80 kg DM/ha per day, they will last 5 days in that field.

How to take a plate meter reading

The same calculation could be worked out with a sward stick (a sort of paper ruler), but Alex finds using a plate meter less time consuming and more accurate. Manual and electronic plate meters go by a many names: PLATE meters, pasture meters, rising plate meters, falling plate meters. They are all in fact measuring pretty much the same thing.

By plate metering and moving his livestock around different grazing areas Alex maintains a good supply of grass, giving it time to regrow. He uses the Sectormentor For Soils app to record plate meter readings and observations, tracking how his forage and fields change and develop with different farm management practises.

“The advantage of using Sectormentor is that it’s an easy and convenient way to record and keep that information handy. It will be interesting to analyse each year the levels of growth and speed of re-growth. It’s another way that I can assess if our management is improving our grazing.”

Even better, taking a plate meter out is another good reason to walk around the fields and visually assess grassland. Alex observes forage diversity, grass condition, trampling, manure quality (indication of rumen health), and how wet or dry the ground is. This observational library is central to continued learning and the evolution of Alex’s farming practises.

Plate metering can be used in different pasture management contexts other than 100% grass fed too. Taking readings across a whole farm gives an overall picture of forage volumes and if there is any grassland underperforming. It’s important not to let the volume drop too much as winter approaches, otherwise grass growth rates will be low in the spring.

 

Resources

Using a plate meter – AHDB Dairy

Expert Guidance on using a plate meter – Farmers Weekly


See our free online soils guide for soil tests you can do at home and find out how our app Sectormentor for Soils helps you record & learn how your soil is changing.