The SOILMONITOR proposes a highly miniaturized sensor system for continuous monitoring of soil nutrients. Through time series monitoring of nitrate, phosphate, and ammonium, the SOILMONITOR is aimed at contributing to a balance in the supply of soil nutrients. The sensor is intended to spend one year maintenance-free in the soil, where it takes nutrient concentration measurements in soil water at regular intervals when there is sufficient soil moisture. For this, soil water is drawn into a microfluidic through the ceramic of the inlet. In the microfluidic system, the solution is stained with a nutrient-specific assay and its concentration is determined by photometry using an organic light-emitting diode - organic photodetector (OLED-OPD) pair. Once the concentrations have been determined, the mixture will be pumped into a waste reservoir. The determined concentrations are to be sent to a station via a Lo-Ra WAN network. In the first development phase, nitrate will be measured; the measurements will then be extended to ammonium and phosphate.
The project is intended to deliver seven complementary and synergistic benefits: quick and informed decisions on fertilization, higher fertilizer efficiency, soil-quality improvements, easier compliance with environmental standards, reduced management efforts, less nutrient leaching, and reduced N2O-emis-sions. The SOILMONITOR project is divided into six work packages aimed at the following main achievements:
• Development and optimization of a prototype to ensure the broadest possible applicability of accurate soil nutrient measurement, and test for these results.
• Development, test and optimization of water extraction and demonstration that the average sensor water extraction radius is equivalent to plant root water extraction radius.
• Demonstration of a maintenance-free sensor lifetime of at least one year.
• Preparation of private investment and/or funding to transition and progress the sensor along the commercialization roadmap.
