Design and Qualification of a Robust, Autonomous Probe for Nitrate Measurement in Extended Operational Field Environments

Nitrates are one of the main contaminants of drinking water, and come mainly from the application of fertilizers in agriculture. Nitrogen is an essential nutrient for plant growth, and is used worldwide as a fertilizer in agriculture to improve productivity. When fertilizer application exceeds demand and the capacity of soil and plants to assimilate it, excess nitrogen can migrate to the aquifer in the form of nitrate (NO₃-), contaminating it. The greenhouse gas (GHG) emissions generated by the denitrification of this nitrogen in the form of N^₂O make up the lion's share of agricultural GHG emissions. In addition, a Canadian standard has been established to protect the most sensitive populations from the negative impact of nitrates on neurological development.

Precise management of nitrogen fertilization requires continuous, real-time measurement of its availability in soils. The real-time measurement system must be highly specific to nitrates, and require no on-site calibration once factory-calibrated, in order to meet the autonomy requirements of agricultural producers. In addition, probe production must be homogeneous, and the probes reliable and robust for prolonged operation in a variety of soils. Real-time nitrate measurement aims to reduce pollution of the atmosphere, surface water and groundwater by reducing fertilizer applications, while improving yields.

The main aim of the project is to develop a robust, reliable and autonomous Hortau Nitrate Sensor (SNH) so that Hortau can prepare for commercial deployment of its new intelligent fertilization service. The aim will be to bring the new SNH to a stage of maturity enabling pre-commercial demonstration under full agricultural production conditions, with manufacturing capacity to produce at low production rates. The secondary objectives of the project are to 1- develop manufacturing production technologies to homogenize production, 2- improve the watertightness of probes by reworking their design, 3- ensure the validity of the universal equation for their calibration, 4- ensure the optomechanical, optoelectronic and optical integrity of probes in prolonged field operation, and 5- reduce the complexity of assembly and even automate certain parts.