Designing a low-cost underground sensor system to monitor forestries
Client: GreenDMS, Tree-o-logic
Industry: AgriTech / Smart City
Service: Hardware Design, Embedded Software, Sensor Engineering
Municipalities of the Netherlands face the problem of one out of three trees dying in an urban environment.
Our engineers designed and developed a low-cost sensor system combined with software algorithms to monitor the gas, water, CO2, methane, and oxygen content of the soil at regular intervals to ensure the long-lasting health of the tree patches.
Client and Goal
GreenDMS is a Dutch tech company that has been providing soil monitoring sensor technology to municipalities and green space managers since 2018. Their SoilDash platform displays soil quality data from grounded sensors and translates it into tailored advice on soil condition improvement. Tree-o-logic is their partner organisation specialising in urban forestry management, applying that data in practice to extend the lifespan of city trees. Together, they are tackling one of the more persistent problems facing Dutch municipalities: one in three trees planted in an urban environment dies prematurely.
The causes are largely invisible above ground. Poor soil conditions, compaction, inadequate aeration, waterlogging, toxic gas buildup, are among the leading drivers of urban tree failure, and by the time a tree shows symptoms, the damage is often already done. GreenDMS and Tree-o-logic in collaboration with SPINNOV designed and developed a low-cost underground sensor system that would give municipalities the soil data they needed to spot deteriorating conditions early and intervene before trees were lost.
Challenges
Soil monitoring in an urban environment is harder than it sounds. The sensors have to survive underground, in wet, compressed soil, subject to temperature extremes and the kind of mechanical disturbance that comes with road maintenance and construction activity nearby. An IP65-rated enclosure is a baseline requirement, not a differentiator.
The more demanding challenge was cost. Municipal budgets don't allow for expensive, high-maintenance monitoring equipment at every tree patch in a city. The sensor system had to be low-cost enough to deploy at meaningful scale, which meant careful hardware design, selecting components that were accurate and durable without being overspecified, and engineering a system that could be installed and left to operate autonomously without regular servicing.
The soil parameters that matter for tree health, gas composition, water content, CO2 levels, methane, and oxygen, each required their own sensing approach, and the system had to measure them reliably at regular intervals and make the data available for analysis.
With Bluetooth as the communication method, the firmware had to manage the measurement schedule, data storage, and transmission efficiently within the power constraints of a device that couldn't easily be recharged once in the ground.
SPINNOV’s Solution
Our team designed and developed the GreenDMS sensor hardware and the embedded software that drives it, a complete underground monitoring unit that municipalities can deploy at tree patches and leave to do its job. Specifically, we:
Designed the sensor hardware integrating temperature and EC microsensors alongside gas measurement capabilities into a compact, deployable unit
Engineered the IP65-rated enclosure to protect the electronics against the moisture, soil pressure, and temperature variation of a permanent underground installation
Developed the embedded software managing the measurement schedule, multi-parameter data collection, local data storage, and Bluetooth transmission
Implemented software algorithms for processing the raw sensor readings (gas levels, water content, CO2, methane, and oxygen) into meaningful soil health data
Optimised the system for autonomous, low-maintenance operation suitable for deployment across a large number of tree patches without regular servicing
