The system uses remote sensing technology to determine the crop’s N demand by measuring light reflectance but has not so far been used on grassland.
The main constraint on grassland is the uniformity of sward. Normal swards tend to be a mixture of different grasses or grass and clover mixes, all of which have different natural colours. This makes calibrating for average conditions difficult.
On 13 February an N Sensor was fitted to the Agribuggy used to fertilise the Grassland and Muck 2008 event fields at Stoneleigh Park and a scan of the biomass from one of the fields was taken. With no specific grassland calibration, the only relevant information was the crop biomass.
Yara will be revisiting the site regularly in the run-up to the event to measure the grass. To get useful data from the readings, it plans to calibrate them by also measuring the biomass using a quadrant and then analysing the leaves to measure nitrogen content. This will be carried out on known areas of the field with different biomass levels.