Welcome to Twin Cities Engineering's project on soil health monitoring through gas-based measurement! Soil health plays a critical role in agriculture and environmental sustainability. Measuring gases in soil pore spaces is an effective way to monitor soil health, providing valuable information about the soil's nutrient content and microorganism activity. However, commercially available gas-based soil health measurement devices are prohibitively expensive, limiting their accessibility to farmers and soil scientists. To address this issue, our engineering project team is developing a low-cost DIY soil gas sensing unit capable of measuring oxygen, carbon dioxide, and methane concentrations at four soil depths every hour. Our goal is to create a prototype that is affordable, portable, and easy to use, empowering more people to measure and monitor soil health.
Our project is centered around a device that attaches to four soil probes of varying lengths (0.25, 0.5, 0.75, and 1 meter) to extract soil gases. These probes are placed in a 1-meter squared area of soil, assuming that the soil gas concentrations will remain constant. The device has four ports for tubes that connect from the probes to the device, and each port connects to a solenoid valve inside the device. These valves can be opened and closed by a Mayfly microcontroller, allowing the device to be exposed to one probe at a time. A sensor chamber houses four sensors, including an Alphasense IRC-AT carbon dioxide sensor, Alphasense O2-A3 oxygen sensor, and TGS2611-E00 methane sensor, along with a bme280 temperature, pressure, and humidity sensor. The final component in the sensor chamber is a heating element, which is designed to prevent condensation from forming and potentially damaging the sensors. If the bme280 detects a dew point, the heating element is activated.
All work accomplished can be found in the Final Design Document and more discussion about the project. A poster has been developed for this project and is also uploaded in the repository. Lastly STL files for the sensor chamber and the program to control the device are included.