In App Formulas

Did you know the Platemeters app can automatically adjust the changes in your dry matter for seasonal and regional variations?

Instead of calculating formulas and entering them yourself, the Platemeters app lets you select the inbuilt formula that best applies to your farm. This is important in spring when pasture growth rates vary significantly from week to week and the demand is constantly changing with the numbers of stock.

The app also lets you adjust the feed wedge for the feed demand with just a few key inputs and breaks down your walk data into metrics that are easy to read and understand. Once you receive the data, the app lets you view, edit and share it instantly.

How Platemeters work

Platemeters convert compressed pasture height to an estimate of dry matter in the pasture via a standard formula termed The RPM calculation.

The formula is relatively simple consisting of three components:

  1. the Pasture height measurement 
  2. a Multiplier 
  3. an Adder.

The RPM Calculation

The RPM calculation

The Multiplier can be considered as the slope of the relationship between height of grass and dry matter, the bigger the multiplier the more dry matter per unit of pasture height. A high number would be used if the pasture is growing slowly but has high dry matter. 

The Adder can be considered as the amount of dry matter at a zero height reading – generally, a correction factor.

Platemeters have traditionally come with the pre-set formula which DairyNZ have said most accurately reflects the average this has been the Waikato Winter formula of *140 +500 .

However, as farmer you’ll notice during the flush or in warm wet conditions the grass has little ’grunt’ and research supports that seasonal variation can range and that this also varies with your region with variations in Waikato from a multiplier of 185 (dry conditions) through to 115 (wet conditions), and they follow a seasonal cycle as shown in the graph below.

RPM Waikato

How to select the in app formula

Platemeter App

More information about these formulas can be found on the DairyNZ website.