Soil Moisture Sensors for Irrigation Scheduling

Tension, oxygen and temperature from the root zone, on one station and one dashboard. Tensiometers for wet-range precision, the maintenance-free Watermark 200SS for scale, and the sensors that catch what a moisture reading alone misses.

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Three Ways to Read Soil Water

Two of them measure tension, the force roots actually work against, and need no soil-specific calibration. The third measures water content and does.

Tensiometer

A water-filled tube reads tension directly and precisely in the wet range where most irrigation decisions are made: 0-80 cb at ±1 cb. The tradeoff is periodic refilling. The choice for high-value crops managed close to field capacity.

Three tube lengths: SR, MLT and LT.

Granular Matrix

The Watermark 200SS reads tension through a granular matrix: 0-200 cb, ±15% of reading between 10 and 100 cb, no calibration, no refilling, 5+ years in the ground.

The choice when you want many stations, a wide dry range, and nothing to maintain.

Capacitive and TDR

Volumetric sensors report water content as a percentage. The number is only as good as the soil-specific calibration behind it, which is why they earn their place in uniform soils where water-content data is the goal.

Not in our range. See how they compare in our two-sided product comparisons.

The Agrinovo Soil Sensor Range

Four tension sensors, one oxygen sensor, one temperature probe. Any of them connects to the same controller.

Granular matrix, maintenance-free

Watermark 200SS

Measures
Soil water tension
Range
0-200 cb (kPa)
Accuracy
±15% of reading (10-100 cb)

Orchards, vineyards and row crops where a wide range and a 5+ year life matter more than wet-range precision. No calibration, no refilling.

View Watermark 200SS
Tensiometer, 15-30 cm

Irrometer SR

Measures
Soil water tension
Range
0-80 cb (kPa)
Accuracy
±1 cb at field capacity

Vegetables, flowers, turf and greenhouse beds with a shallow active root zone.

View Irrometer SR
Tensiometer, 45-60 cm

Irrometer MLT

Measures
Soil water tension
Range
0-80 cb (kPa)
Accuracy
±1 cb at field capacity

Field crops, orchards and vineyards at the standard mid root-zone depth.

View Irrometer MLT
Tensiometer, 90-120 cm

Irrometer LT

Measures
Soil water tension
Range
0-80 cb (kPa)
Accuracy
±1 cb at field capacity

Deep-rooted orchards and vineyards, and percolation checks below the root zone.

View Irrometer LT
Soil oxygen

O2-100

Measures
Root-zone oxygen
Range
0-25 %VOL
Accuracy
±2% FS at 25°C

Waterlogging and compaction: heavy soils, high-frequency drip, and substrate beds where roots suffocate before the moisture reading looks wrong. RS485 Modbus RTU.

View O2-100
Digital, 1-Wire

Soil temperature probe

Measures
Soil temperature
Range
-55°C to +125°C
Accuracy
±0.5°C (-10°C to +85°C)

Germination and planting timing, frost risk in the root zone, and temperature context for every moisture reading.

View Soil temperature probe

Comparing the three tensiometer lengths in detail? See the tensiometer range page. Want the theory first? Read the soil moisture sensor buyer's guide and the granular matrix sensor guide.

Sensor Types Side by Side

What each sensor measures, what it asks of you, and where it fits.

Sensor Measures Range Maintenance Best for
Tensiometer (SR, MLT, LT) Tension, direct 0-80 cb Refill the tube seasonally; keep the ceramic tip wet Precise irrigation close to field capacity; high-value crops
Watermark 200SS Tension, via granular matrix 0-200 cb None; 5+ year life Wide dry range, many stations, low upkeep
Capacitive or TDR (not in our range) Volumetric water content Per probe Soil-specific calibration to be accurate Uniform soils where water-content data is the goal
O2-100 soil oxygen Oxygen in the root zone 0-25 %VOL Electrochemical cell, periodic check Catching waterlogging that a moisture reading hides
Soil temperature probe Temperature -55°C to +125°C None Planting windows, frost, reading context

Which Sensor for Which Situation?

The usual match for common crops and soils. Many stations combine two of these.

Situation Recommended
Vegetables, flowers, greenhouse and nursery beds Irrometer SR at 15-30 cm
Field crops, vineyards and orchards, mid root zone Irrometer MLT at 45-60 cm, or Watermark at two depths
Olives, avocado, citrus and other deep-rooted trees Irrometer LT at 90-120 cm, plus Watermark higher up
Many stations across a large plot, minimal upkeep Watermark 200SS at each depth
Heavy soil, frequent drip, or beds that stay wet Watermark or tensiometer plus the O2-100 soil oxygen sensor
Planting and germination timing, frost-prone ground Soil temperature probe alongside the moisture sensor

Not sure? Send us your crop, soil type and plot layout through the contact form and we will recommend an exact configuration.

One Station, Continuous Readings, Automated Irrigation

Every sensor on this page connects to an Agrinovo Genesis controller: tension at two depths, root-zone oxygen and soil temperature logged together, alerts when a zone dries past your threshold, and valves that open and close on the reading. It all runs through the IoT soil monitoring platform, as part of a complete precision agriculture setup.

Request a soil sensor quote

Soil Moisture Sensor Questions, Answered

Choosing, installing, and automating soil sensors

Which soil moisture sensor should I choose for my crop?
Start from the root zone and the maintenance you can live with. Shallow crops (vegetables, flowers, turf, greenhouse beds) suit the Irrometer SR at 15-30 cm. Field crops and mid-depth orchards suit the MLT, deep-rooted trees the LT. When you want many stations with no refilling, the Watermark 200SS covers the same job with a wider 0-200 cb range and a 5+ year life.

What is the difference between a tensiometer and a Watermark sensor?
Both read soil water tension, the force roots work against, which is why both schedule irrigation without soil-specific calibration. A tensiometer measures it directly through a water-filled tube: ±1 cb accuracy at field capacity in the wet range, but the tube needs periodic refilling. The Watermark 200SS reads tension through a granular matrix: coarser (±15% of reading between 10 and 100 cb), but maintenance-free, 0-200 cb, and it lasts multiple seasons in the ground.

Do soil moisture sensors need calibration?
Tension sensors do not. A tensiometer and a Watermark 200SS read the same physical quantity in any soil, so the irrigation thresholds you set transfer between fields. Volumetric sensors (capacitive, TDR) report water content, which means a soil-specific calibration if the number has to be accurate rather than relative. That difference is the main reason tension sensors are the practical default for irrigation scheduling.

How deep should I install a soil moisture sensor?
At the depth where the crop takes most of its water, and usually at a second, deeper point to confirm water reaches the bottom of the root zone without passing below it. Shallow vegetables and turf: 15-30 cm. Field crops and mid-depth orchards: 45-60 cm. Deep-rooted trees and vines: 90-120 cm. Watermark sensors are often installed at two or three depths on the same station.

How many sensors do I need per plot?
One station per homogeneous irrigation zone (same crop, same soil, same drip line), usually with two depths per station. Start with one or two stations in the most representative zones and expand after a season, once you can see where the real variability is. The system is modular, so later stations join the same controller and dashboard.

Why add a soil oxygen sensor to a moisture station?
Roots need air as much as water. In heavy soils, on high-frequency drip, and in substrate beds, the root zone can stay wet enough to suffocate roots while the moisture reading still looks fine. The O2-100 reads oxygen in the root zone directly (0-25 %VOL), which catches waterlogging and compaction before yield does.

Can these sensors automate irrigation?
Yes. Every sensor here connects to an Agrinovo Genesis controller, which logs the readings to the cloud, sends alerts when a zone dries past your threshold, and can open and close valves on the tension reading. It all runs through the IoT soil monitoring platform.

How much does a soil moisture monitoring system cost?
It depends on the sensor type, the number of stations and depths, and whether you read a gauge on field rounds or connect everything to a controller for continuous logging and alerts. Our pricing is by tailored quotation, so you pay for the configuration that fits the plot. Request a quote with your crop, soil type and plot layout and we will come back with a concrete recommendation.