Measurements · Agriculture
Soil Temperature
Also known as ground temperature
Soil temperature.
What it is
What is soil temperature?
Soil temperature is the temperature of the ground at a stated depth, reported in degrees Celsius (°C). Unlike air temperature, it changes slowly and lags behind the atmosphere. The surface warms and cools quickly with sun and night, but a few centimeters down the swings are muted and delayed. Deeper still, the soil holds an almost steady temperature that tracks the season rather than the day. Because of this, soil temperature is always tied to a depth: a reading at seed depth is a different quantity from one in the root zone or below. It reflects the balance of solar heating, evaporation, soil moisture, and cover.
This is the temperature that seeds, roots, and soil organisms actually experience, which is why it, rather than air temperature, governs so much of what happens below ground.
Germination is triggered by soil temperature, and every crop has a threshold below which seed will not reliably sprout and above which it does best, so growers use soil temperature at seed depth to decide when to plant. In the root zone, temperature controls the rate of root growth and nutrient uptake. It also governs the activity of the microbes that cycle nitrogen and break down organic matter, biology that all but stops when the soil is cold. Soil temperature also indicates frost penetration and the risk to overwintering crops and buried infrastructure.
For growers and agronomists it is therefore a practical scheduling tool: the number that says whether the ground is ready to plant and how vigorously the soil below is working.
How it is measured
How Soil Temperature Is Measured
Soil temperature is measured with a buried probe: a thermistor, platinum-resistance (PT100), or thermocouple sensor sealed for burial and inserted to a defined depth in undisturbed soil. As a professional field sensor rather than a built-in reading, it is connected to a Thiamis gateway for continuous logging, often with several probes at different depths on the same logger to capture the profile from surface to root zone. Good thermal contact with the soil and accurate placement of the measuring depth are what make readings reliable and comparable between sites.
An instrument on Thiamis1
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing soil temperature sensors
Probes are buried at the depths that matter for the decision at hand (seed depth for planting, and one or more root-zone depths for crop management), in soil that represents the field rather than a compacted, disturbed, or unusually shaded spot. The cable trench is backfilled and firmed so the probe sits in natural, undisturbed soil, and the site is chosen away from irrigation lines or tracks that would bias it. Measuring at more than one depth is useful because the daily swing and the lag both grow with depth, and different processes live at different levels.
Every device and option that measures Soil Temperature 1
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
 Davis · Davis Wizard III, Davis Wizard II, Davis Monitor… | Weather Stations | Thiamis |
Where it is monitored
Solutions That Monitor Soil Temperature
Each one links to the solution page showing what that industry measures it for.
Agriculture & Irrigation
Core parameterSoil temperature governs seed germination, root growth, and microbial activity, so it is a key parameter for planting decisions and crop management.
Related
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Questions
Soil Temperature FAQ
Why does the measurement depth matter?
Soil temperature changes with depth. Shallow soil swings widely between day and night, while deeper soil is steadier and follows the season. A germination decision depends on the temperature at seed depth, while root and microbial activity depend on root-zone temperature, so a reading is only meaningful when its depth is stated.
How is soil temperature different from air temperature?
Soil temperature changes more slowly and lags the air, because the ground stores and releases heat gradually and is buffered by its moisture. On a cold morning the air can be well below the soil, and in a heatwave a shaded, moist soil stays far cooler than the air, so one cannot substitute for the other.
Why measure at several depths?
Different processes occur at different levels (germination at seed depth, root growth and nutrient uptake deeper, frost penetration deeper still), and the daily swing shrinks with depth. A profile of several probes shows the whole picture rather than a single point that may not represent the root zone.
How do I monitor soil temperature?
Pair a Thiamis gateway with buried temperature probes at the depths your crop and decisions require for continuous logging of the soil profile. Use the configurator to combine soil temperature with soil moisture and above-ground weather parameters for a complete agronomic picture.
Monitor Soil Temperature on the Record
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