Plate meter the ‘go-to’ for grass data accuracy but trial shows satellite imagery is closing the gap

A Ceredigion dairy farm is using satellite-derived data to inform grassland management decisions and is trialling its accuracy against a plate meter.

Ffosygravel, a Farming Connect focus site near Borth, produces over half its milk output from forage.

Grass quality and quantity is therefore key to the system at the 102-hectare (ha) holding and good grassland management allows the Griffiths family to achieve this from its herd of 183 Holstein and Friesian cows.

“We have always been a grazing farm, the cows are out as early as possible and for as long as possible,” said Martin Griffiths. “Our system revolves around quality pasture and silage and it pays dividends.”

He is working with Farming Connect to evaluate the potential of satellite pasture measurement technology in a managed grazing system with support from Sarah Morgan of Precision Grazing.

Ms Morgan told farmers listening in to a recent Farming Connect webinar that measuring with a plate meter was the ‘go to’ for most farmers who measure grass and that it is widely recognised as a reliable method for doing this.

Walking the fields gave farmers the opportunity to not only visually assess grass quality but to check on water troughs and fence lines and to monitor leys for weeds, she said.

But where satellite systems score is through the provision of daily data without the time commitment of physically measuring grass, Ms Morgan added.

As the technology is still relatively new, the project at Ffosygravel has shown that the accuracy of data is currently within the ball park of the plate meter and is being improved weekly with feedback from Mr Griffiths and other trial farms.

“If time to physically measure grass is a limiting factor for a farmer, satellite systems can provide an alternative option,” said Ms Morgan.

The annual costs of each are comparable.

Based on the requirements of a 150-ha dairy farm, and assuming measuring with for three hours a week for 40 weeks at a labour cost of £15/hour, gathering data with a plate meter works out at £1,900 a year inclusive of a £100 subscription fee for the grass management programme Agrinet.

The annual cost associated with the satellite system provided by ruumi on that same holding and based on its current pricing structure would be £1,800.

ruumi engineering lead Britta Weber told the webinar attendees that one of the current limitations with satellite imagery – its inability to gather data through cloud – is being addressed by ruumi by integrating radar satellite.

“Measuring with a plate meter is more reliable at the moment but I am sure that satellite will be catching up quickly especially after introducing radar satellite,” Ms Morgan predicted.

Mr Griffiths said he was impressed with the speed at which the technology was developing.

“The accuracy at the present time on grass dry matter data for making decisions on a dairy farm is improving and the way the technology is being brought forward is very impressive,” he said. “The satellite image if very accurate and I could tell you which day the satellite went over; being able to point out where paddocks are split by fence.”

Satellite imagery is continuously progressing and Farming Connect look forward to sharing the project progress later in the season.

Farming Connect, which is delivered by Menter a Busnes and Lantra, has received funding through the Welsh Government Rural Communities – Rural Development Programme 2014-2020, which is funded by the European Agricultural Fund for Rural Development and the Welsh Government.