YARA is more known in Ireland for its fertiliser products but it also has a piece of technology that makes fertiliser spreading smarter. Akin to a savvy dairy farmer feeding his best-producing cows more grass or ration to produce more milk, the YARA N sensor works by continuously adjusting the rate of nitrogen through manipulating the spreader.

The cab-mounted sensor scans the crop canopy on either side of the cab and measures the crop’s light reflectance at specific wave bands related to the crop’s chlorophyll content and biomass. This measurement is then fed back to the YARA N controller, which adjusts the application rate accordingly. Once an upper limit has been set for target kg/ha, the spreader works within this range. Measurements are taken every second on the go and the area covered is 50m2.

John Collins of Tourin Farm, Lismore, Co Waterford, has this technology fitted to his Deutz Fahr-Amazone spreader combination. On the day John met the Irish Farmers Journal, he was spreading ASN on to winter oilseed rape.

Adjusting continuously

When asked what he thought of the YARA N sensor, John said: “It definitely works well and you can see it adjusting the spreader continuously by opening and closing the shutter at the base of the machine when spreading. If I’m spreading in a field and there’s a bare patch from pests or weather damage, the spreader will reduce the rate immediately.

“We’re definitely saving on fertiliser as we’re not spreading too much on thinner crops and stronger crops are getting more targeted rates.”

We also spoke to Clive Blacker of Precision Decisions, which imports the units to Ireland. Clive pointed out the technology is unlike other sensors out there as it is calibrated to measure nitrogen uptake and not crop thickness, which Clive says can be misguiding as a thick crop does not mean it needs less nitrogen.

Also, the sensor can be calibrated for each individual crop based on growth stages and timing. This degree of variance is calculated from extensive agronomic trials run by YARA.

When asked if the technology is accurate on grass, Clive said: “It definitely does work but we are working on making this more accurate. In a grass species such as perennial ryegrass, the reflectiveness of the grass surface interferes with the accuracy and this is where the machine needs more refinement.”