AI soil sensors to help farmers curb fertiliser use

Funded by EPSRC, Innovate UK and Cytiva, the research could help growers work out the best time to use fertiliser on their crops and how much is needed based on factors including weather and soil condition.

This could reduce expensive and damaging effects of over-fertilising soil, which releases the greenhouse gas nitrous oxide and can pollute soil and waterways.

Over-fertilisation has so far rendered 12 per cent of once-arable land worldwide unusable and the use of nitrogen-based fertiliser has risen by 600 per cent in the last 50 years. However, it is difficult for crop growers to precisely tailor their fertiliser use: too much and they risk environmental damage and money wastage, too little and they risk poor crop yields.

Named ‘Chemically functionalised paper-based electrical gas sensor (chemPEGS)’, the team’s sensor measures levels of ammonium in soil, the compound that is converted to nitrites and nitrates by soil bacteria.

Using machine learning, it combines this with weather data, time since fertilisation, pH and soil conductivity measurements. It uses this to predict how much total nitrogen the soil has now and how much it will have up to 12 days in the future to predict optimum time for fertilisation.