Enhancing NPK Detection in Agriculture through Electrochemical Sensors Utilizing 2D Nanomaterials
Authors: Pavlovic Zoran Miroslav , Kupresanin Ana Miodrag 
Published: December 2024

NPK electrochemical soil sensors are essential tools for sustainable agriculture, enabling farmers to optimize nutrient management practices, improve crop productivity, and protect the environment for future generations. Those sensors are designed to primarily measure the levels of nitrogen (N), phosphorus (P), and potassium (K) in the soil. These are essential nutrients for plant growth and health, and monitoring their levels can help optimize fertilizer application and improve crop yield, while minimizing environmental impact, effectively supporting precision agriculture practices.
Novel 2D nanomaterials can enhance the electrochemical properties of the sensors, enabling them to detect trace levels of nutrients with high precision. The operation principle of the sensors is based on the electrochemical reactions occurring at the surface of 2D nanomaterials when they come into contact with target ions in the soil solution through an ion-selective membrane. The presence and concentration of these ions cause changes in the electrical properties of the nanomaterial, which are then measured and correlated with the nutrient levels. By applying specially designed composite nanomaterials made of transition metal dichalcogenides, Mxenes, Graphene-based materials, conjugated conducting polymers, and ion-selective membranes, it is possible to precisely and stably measure soil ion content as batch, or continuous readout. These materials offer high surface area-to-volume ratios, excellent electrical conductivity, and sensitivity to changes in the chemical environment, making them ideal candidates for sensing applications. The laboratory experiments show that various combinations of nanomaterials in composites at the sensor working electrode have a high impact in increasing the selectivity of the ISM towards omitting ions in soil, repeatability of measurements, and durability of the sensor, compared to the electrodes with only ISM on top. Several nitrate ionophores and ISM cocktails are tested and compared toward ionic selectivity.
The electrochemical sensors are controlled by the electronic circuitry, designed to give input and readout of the data from the sensing elements, as well as for sensor conditioning and calibration, data storage, and wireless communication. Various electrochemical methods through controlling electronics, like Open circuit potentiometry, Chronopotentiometry, and Chronoamperometry are employed for sensor control and data collection. Those methods were tested and compared in terms of the response time and durability of the sensor.
Overall, the integration of electrochemical sensors with 2D nanomaterials represents a significant advancement in precision agriculture, offering farmers the tools they need to efficiently manage nutrient levels in soil and improve crop productivity, contributing to traceability and quality assurance in food production.
*This work is supported through the ANTARES project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement SGA-CSA. No. 739570 under FPA No. 664387. https://doi.org/10.3030/739570

Figure 1