Farmers have been relying on experience
Lab tests, even though very reliable are time consuming and expensive. Therefore, farmers have relied more on their experience than on regular testing when it comes to fertilising their crops. This is why they have been traditionally overfertilising in order to ensure that their plants are supplied with nitrate in sufficient quantities, which they require to make proteins.
Fertiliser contaminates groundwater
"Not only does fertiliser cost a lot of money, but it also gets into groundwater if it is not absorbed by the plants," explains Nicolas Plumeré, member of the cluster of excellence Ruhr explores solvation (Resolv). As nitrate is converted to harmful nitrite by bacteria, it must be removed from drinking water. This, in turn, leads to additional costs borne by the public purse.
A drop of plant juice is enough
Under the umbrella of the ERC Starting Grant, Plumeré, together with Tobias Vöpel, developed the nitrate sensor, which is only marginally bigger than a Cent coin and on which disposable electrodes have been printed. It determines the nitrate concentration in soil by analysing one drop of plant juice within seconds and sends the result to the farmers' smartphones. "Thus, the user is able to determine then and there how much fertiliser his crop requires," explains Tobias Vöpel. By applying fertiliser in the optimal quantities at the right time, the plants' protein concentration is improved, which in turns means that they can be sold at a higher price. In addition, significantly more plants can be harvested.
Estimating the demand
In future, a dedicated software will be generating local and regional nitrate maps based on the nitrate concentrations determined by numerous sensors in different locations, sending the information from the sensor to the cloud. Linked to weather data, simulations and satellite images, the system will be indicating trends in nitrate supply and will help estimate the overall fertiliser demand in the long-term.
Spin-off for commercialisation
Funded by the grant, the researchers are going to perform a market analysis, launch series production, and develop a business plan for a spin-off enterprise that will be in charge of marketing the sensor.
Detailed article in Rubin
You can find a detailed article on the nitrate sensor in the science magazine Rubin . Texts on the website and images in the download page are free to use for editorial purposes, provided the relevant copyright notice is included.