New soil sensor technology developed in Ireland could help reduce the use of chemical fertilisers on farms in the short and medium terms and improve water quality in Ireland’s rivers and estuaries.

The sensors have been developed by Tyndall as part of an international project to measure levels of nitrates in soils more accurately. Tyndall is part of the network of organisations and companies that host the VistaMilk SFI Research Centre.

Buried in the ground at a depth of 20cm, the tiny sensors – which measure around half the diameter of a human hair and are in packaging about 1cm across – communicate data about nitrates in soil wirelessly (bluetooth and the internet of things) and in real time. Tiny though the sensors are, initial results indicate that, per hectare of land, only a small number will be required.

Affects water quality and biodiversity

Nitrates – compounds comprising nitrogen and oxygen atoms – are essential for plant growth; however, too much of it is a pollutant and when it runs off the land into lakes, rivers, and the sea, it affects water quality and biodiversity.

Traditionally, soil testing for nitrates has been done in laboratories, in test tubes, and the results give a picture of a single point in time. As a result, farmers tend to spread fertiliser in the places and quantities that they always have. 

Testing the new sensors in Romania has shown that soil nitrate levels fluctuate considerably more than previously thought. This means the measurements the sensors provide could have a significant impact on when, where, and how much fertiliser is spread on farms.

A recent report from the Environmental Protection Agency (EPA) pointed to a continuing reduction in water quality across the island of Ireland – particularly in estuaries and coastal waters. Dr Alan O’Riordan, senior research fellow at Tyndall and principal investigator at VistaMilk SFI research centre, said the sensors represent a real opportunity for farming in Ireland, both in terms of cost savings and environmental impact. 

“No beating about the bush – this is complicated tech, developed here in Ireland. We had to deliver a new material for the sensor, we had to make it pH adjustable for better results and we had to stabilise it to prevent ‘drift’ – all while working with something that’s genuinely tiny.

“We needed to ensure that it could communicate the data it needed to and – as we were going to bury it – it needed to have a decent enough lifespan. I’m pleased to say that our test chips are still reporting back and that means they’ve survived a full growing season.

Fluctuations in soil nitrate content

“Of course, it’s the results that are really important. What we’re seeing is real fluctuations in soil nitrate content, against the baseline of traditional testing. It implies that traditional fertiliser use – field x has always needed fertiliser, so we’ll keep spreading – can be challenged. 

“Fertiliser is expensive and, while we’re still using it and waiting for fertiliser reduction initiatives to gain traction, our research will save farmers money. Clearly – less fertiliser means less run-off, means less impact on Ireland’s water quality.”

Nicholas Cooney, a dairy farmer from Co Louth and National Dairy Council farmer ambassador, welcomed the news of the innovation and the positive results of the trial: “There’s no doubt that advances in technology are going to help our industry address the environmental challenges that we face and it’s great news that these advances are being made here in Ireland.

"Real-time data on nitrates in soil would certainly assist our current decision-making when it comes to fertiliser use and slurry spreading and would have a positive impact on our costs and on our environmental impact. I look forward to seeing results from trials here in Ireland.”