Tensiometer Irrigation & Irrigate Now or Hold?
Reads soil tension
Enter your tensiometer reading in kPa and pick your soil texture to get the irrigate-at threshold, an irrigate-or-hold verdict and the margin to the trigger.
Tensiometer irrigation trigger
Next: hold off — there is still 10 kPa of available moisture before the loam trigger of 50 kPa; recheck in a day or two.
Higher suction (kPa) means drier soil. Sandy soils trigger sooner (~30 kPa) because they hold less water; clays can wait longer (~70 kPa).
Tensiometer irrigation — key facts
- Unit
- kPa (≈ centibars)
- Reads
- soil moisture tension
- Sandy soil
- irrigate ≈ 10–30 kPa
- Loam soil
- irrigate ≈ 30–50 kPa
- Clay soil
- irrigate ≈ 50–70 kPa
- Low reading
- wet soil, water freely available
- Verdict
- reading vs soil threshold
- Privacy
- Runs in your browser; nothing uploaded
Let the soil tell you when it's thirsty
Irrigating by the calendar wastes water when the soil is still moist and stresses the crop when it has dried faster than expected. A tensiometer ends the guessing: it reads the suction roots feel, in kPa, so you irrigate on the soil's actual demand. The catch is that the same number means different things in sand and in clay — a reading that's bone-dry for a sandy soil is comfortable for a clay. That's why the right threshold depends on texture.
This tool takes your reading and your soil texture and returns the irrigate-at threshold, an irrigate-or-hold verdict, the margin to the trigger, and the moisture status. Use it for the daily call of whether to switch the pump on. Pair it with the Irrigation Scheduling, Soil Water Holding Capacity, Soil Infiltration and Drip Emitter Spacing tools to manage both timing and amount.
Irrigate on demand
Water when the soil is actually thirsty, not by date.
Texture-aware trigger
The right kPa threshold for sand, loam or clay.
Clear go / wait call
An instant irrigate-or-hold answer from one reading.
See how close you are
The margin shows kPa left before watering is due.
Frequently Asked Questions
What does a tensiometer measure?+
A tensiometer measures soil moisture tension — the suction, in kilopascals (kPa) or centibars, that roots must overcome to pull water from the soil. A low reading means the soil is wet and water is freely available; a high reading means the soil is drying and water is harder to extract. It reads how thirsty the soil is, not how much water it holds.
At what reading should I irrigate?+
It depends on soil texture. Sandy soils release water at low tension and dry quickly, so you irrigate at a low threshold (around 10–30 kPa); loams sit in the middle (around 30–50 kPa); clays hold water more tightly and can wait for higher tension (around 50–70 kPa). The tool picks the right irrigate-at threshold for your soil.
How does the tool decide irrigate or hold?+
It compares your reading to the irrigate-at threshold for your soil texture. If the reading has reached or passed the threshold, it says irrigate; if it's still below, it says hold and shows the margin — how many kPa of drying are left before you need to water.
Why does soil texture change the threshold?+
The same tension represents different amounts of available water in different soils. Sandy soils have little buffer and most of their water leaves at low tension, so waiting risks stress; clays hold a large reserve that only releases as tension climbs, so they can safely dry further before irrigation is needed.
What does the margin tell me?+
The margin is the gap between your current reading and the irrigate-at threshold. A large positive margin means the soil is still comfortably moist and you can wait; a small margin means irrigation is due soon; a negative margin (past the threshold) means you're already in the irrigate zone and the crop may be drawing on its reserves.
Where should the tensiometer be installed?+
Place it in the active root zone, in a representative part of the field, away from the edge of the wetted pattern of drippers or sprinklers. Many growers use two depths — a shallow one to time irrigation and a deeper one to confirm water reached the lower roots. Keep the ceramic tip in good contact with the soil.
Does a high reading mean the crop is stressed?+
Not always immediately, but a reading well past the irrigate-at threshold means roots are working hard for water and yield can suffer if it continues. Different crops tolerate different tensions; sensitive crops and shallow-rooted vegetables want irrigation at lower tension than deep-rooted, drought-tolerant field crops.
Can I use this with soil moisture sensors instead?+
Yes — many electronic soil moisture sensors report in kPa or centibars, the same units as a tensiometer, so you can enter their reading the same way. Capacitance probes often report volumetric percent instead; for those, use the Soil Water Holding Capacity tool to relate moisture to the refill point.
Is this a substitute for a full schedule?+
It tells you whether to irrigate now from a single reading, which is the everyday decision. For planning how much to apply and how long between irrigations across the season, combine it with the Irrigation Scheduling and Soil Infiltration tools so you know both when to water and how much.