World-class satellite grass innovations to go online

The Spatial Analysis lab in Teagasc, with partners in the Department of Geography in University College Cork, are developing new tools to estimate grass growth in Ireland using satellite imaging, many of which will be online.

This is according to Teagasc’s Stuart Green who was speaking at today’s Future Weather, Future Farming Teagasc conference in Ashtown, Co Dublin.

“Along with colleagues in the Teagasc Grass Programme, the aim is to be able in a short number of years to give very local measurements of grass growth rates and more importantly predictions for growth over the coming few days or even weeks,” Green outlined in his presentation this afternoon.

The world-class research allows Teagasc to produce maps on a weekly basis to show how the grass growth at the scale of townlands can be compared to the 10-year average for that period.

He also outlined the latest on satellite imaging developments of grass growth.

“Satellite imaging is increasingly familiar through online mapping tools such as Google Earth. However, the satellites used in this project have a wider application than just simple imaging.

He continued: “The NASA Aqua and Terra satellites each carry a version of the Moderate Resolution Imaging Spectroradiometer (MODIS). For the purposes of monitoring grass-level MODIS can take images in the Near Infra Red (NIR). This is light that is just beyond the red wavelengths of visible light that we can see, and is important because it is strongly reflected by plants. This bright signal is directly related to the amount of plant material and how well it is growing.”

Using maps of this type, Teagasc can now compare grass performance past and present.

“To look at how performance this year compares with the average, a 10-year rolling archive of weekly satellite data has been created,” Green explained.

“With this archive we have been able to track grass growth over the spring of 2013 as the Fodder Crisis unfolded. However research has shown that information needs to be re-figured into a common language to be used fully.

“When discussing the effect of weather on farming, talk revolves around ‘slow growth’ or ‘we’re two weeks behind’. To re-interpret our trend data into this ‘time domain’, we created phenological growth models for every pixel, showing how, on average, the vegetation grows as a function of time.”

The Teagasc experts says this allows it to compare current growth as seen by the satellite on a particular day with the model and calculate whether the growth is on target or lagging behind where it would normally be. This difference can also be expressed in days or weeks, he added.

“Moving beyond trend mapping, the next stage is to estimate actual grassland yield using satellites. Using historical grass growth data from Moorpark, contained within the PastureBase service, Walsh Fellow Iftikhar Ali has been creating models of biomass (DM Kg/Ha) as a function of vegetation index.”

He explained that these models are currently in early devolvement and are proving successful.

“In the coming two years this model will be refined and combined with RADAR data to produce reliable, parcel scale estimates of standing biomass,” he concluded.

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