Grass SAT is powered by a sophisticated grass growth model that monitors over 20 different data sets including daily weather, soil, Earth observation (from satellites) and management activities (that users enter into the tool themselves). The model makes hundreds of complex calculations many times every day, from which valuable information can be derived about soil properties, grass characteristics and the grass growth rates (kg DM/ha).

Satellite imagery

Although satellites pass on a regular basis, we can only use a satellite image when there are no clouds or haze obscuring the view, so the frequency of satellite updates may vary. Don’t worry though, the satellite image is just one component. As long as you add activities, the grass growth model will continue to provide accurate grass cover values.

Adding Activities

Adding activities such as grazing or cutting is important as it assures accuracy of values in between satellite image updates. This is now easier with release of a mobile App. You can use the mobile App to add activities real-time in the field with the ability to cache data and automatically synchronise with Grass SAT when back in range. You can set default values for all your common tasks. Just select the relevant paddock (or multiple paddocks) and click ‘Add Activity’. The grass cover values will then be updated. The App is available for iPhone and Android users and can be downloaded from the Google Play Store or the Apple App Store by searching for ‘Grass Sat’.


Grass cover values are available real-time and dynamically updated from multiple data sources enabling dynamic decision making.


Andrew Williams
Rhadyr Farms ltd
The system is user friendly and visual. It has a lot of useful information
Michael Colwell
Glyn Crest Farm
I like using technology on the farm because it makes my life easier. Grass Sat is a bit of technology that does exactly that and has allowed me to become a bit more of an armchair farmer, managing the grass allocation from my armchair!
George Holmes
Dairy Farmer, UK Arla council member, Frampton, Dorset.
I think the real value in Rezatec’s grass management tool is to free up time spent on labour intensive activities such as grass measurement, while providing daily estimates of grass cover in an automated, easy-to-use wedge tool all served up in a digital format without the need to do anything. This enables farmers to be more efficient with their time and optimise grazing potential.
John Brocklehurst
Dairy Farmer, Hilltop Farm
Utilising as much grazed grass as possible is a top priority KPI for our business and I hope by using Grass SAT it will provide me with more frequent grass measurements of the whole farm without having to walk it. The data is already informing my day to day grazing management and moving forward I hope to identify areas of the farm that are less productive and improve them as well as allocating grass to the cows more efficiently.