Low-cost open-source in-situ nitrate sensor system for precision agriculture

Overview

This research proposes a low-cost, open-source nitrate sensing system designed to measure soil nitrate concentrations in real time directly in the field. Current in-situ nitrate probes are scarce and expensive, making them impractical for commercial farm use. By leveraging open-source hardware principles, the proposed system aims to deliver an affordable monitoring solution at approximately $500 per unit, enabling farmers to match nitrogen fertilizer applications precisely to crop needs.

The core value proposition is improved agronomic performance: higher crop yields achieved with less water and fewer nutrient inputs, while reducing adverse environmental effects such as fertilizer pollution of surface water and groundwater. The system is initially targeted at commercial processing tomato operations but has broad applicability across row crops and irrigated agriculture.

Technical specifications

System components:

• Spectrophotometer core: Hamamatsu C12880MA miniature spectrometer, recently validated as appropriate hardware for portable low-cost open-source spectrophotometry
• Sample collection: Suction cups installed at three depths within the root zone to extract pore water samples
• Sample conveyance: Low-cost vacuum pump that transports pore water from suction cups into a measurement cuvette
• Data transmission: Wireless communication protocol previously validated by the research lab for remote data delivery to farmers

Key features:

• Open-source design allowing free replication and modification
• In-situ measurement capability eliminating the need for laboratory sample transport
• Multi-depth sampling providing a profile of nitrate availability through the root zone
• Wireless data transmission enabling remote monitoring and decision support

Technology readiness level

The underlying spectrophotometer hardware has been validated in prior work as a portable low-cost open-source instrument, but has not yet been applied directly to nitrate measurement in soil or under field conditions. The research team has prior experience developing open-source systems for monitoring related soil parameters including water content, dissolved oxygen, and carbon dioxide, which provides a strong foundation for this development effort.

The proposed one-year project will first validate the system under controlled laboratory conditions, then duplicate and deploy multiple units across commercial processing tomato sites. This staged validation approach moves the technology from laboratory proof-of-concept toward field-ready deployment, with the goal of producing a practical, scalable sensing platform for precision agriculture.