Soil Sensors

The GroPoint™ Sensor Suite

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Product

Summary

Measure soil moisture at multiple depths with a single probe and cable. Installs quickly and easily without excavating. Analog or digital soil moisture and temperature. Exceptional accuracy and fully-potted electronics for long-term durability. SDI-12 sensor measures moisture, salinity (electrical conductivity) and temperature. Exceptional accuracy and fully-potted electronics for long-term durability. Legendary ruggedness and dependability. Exceptional accuracy and large sphere of influence.
Why choose this sensor? When you want to measure soil moisture and temperature with extreme accuracy at multiple depths to analyze water penetration through the soil. When you need an extremely accurate and durable single-point soil sensor to measure moisture content and temperature. When you need the accuracy and durability of GroPoint Lite, but also need to measure electrical conductivity (salinity) and would like a simple way to measure the wetting front. When you need a 4-20mA analog solution and/or want a large area of influence surrounding the sensor.
Moisture
Temperature (Digital only)
Electrical conductivity (salinity or EC)
Wetting front
Technology

TDT5
Multiples of 15cm segments.

TDT5 TDT5 TDT
Analog

0-5mA

4-20mA

Digital

SDI-12

RS-485

Measurement range

Moisture

0% to 100% of VMC 0% to 100% of VMC 0% to 100% of VMC 0% to 100% of VMC

Temperature

-20°C to +70°C (-4°F to 158°F) -20°C to +70°C (-4°F to 158°F) (digital only) -20°C to +70°C (-4°F to 158°F) n/a

EC

n/a n/a 0 to 4 dS/m n/a
Accuracy

Moisture

±2.0% * ±2.0% * ±2.0% * ±2.0% *

Temperature

±0.5°C ±0.5 °C (digital only) ±0.5 °C n/a

EC

n/a n/a ±3% n/a
Precision

Moisture

< 0.2% < 0.2% < 0.2% < 0.2%
Current consumption

Quiescent

< 0.5mA < 0.1 mA (digital) < 0.1 mA n/a

Active

15-20 mA (depending on number of segments) for 100 mS 0-5 mA: 18 mA nominal, 25mA max
4-20 mA: 30mA (nominal), 50 mA (max)
SDI-12/RS-485: 15-35 mA
15-35 mA 0-5 mA: 15 mA nominal, 20mA max
4-20 mA: 30 mA nominal, 50 mA max

* 8% to 42% VMC, in controlled laboratory conditions; factory calibrated for most agricultural soils. In field applications, accuracy may slightly decrease due to the inevitable heterogeneity of soil texture, soil compaction, moisture and fluctuation in soil temperature. The accuracy may also decrease in difficult soil conditions (higher clay and salinity content). In normal conditions, GroPoint sensors will maintain their accuracy from permanent wilting through field capacity in sandy loam through clay soils with less than 60% clay particles. Under moderately saline conditions. GroPoint sensors will maintain their accuracy up to 6 ds/m.

  • All products can be ordered online, or by contacting a local dealer.
  • See our ordering and returns policy.
  • All sensors come standard with 5m cable, 3xAWG22 (analog) or 4xAWG22 dual-shielded, twisted pair, rated for direct burial.
  • Cables terminate in bare wire, but can be ordered with an optional EN3 IP66/IP68 rated environmental connector.
  • Custom cable lengths can be ordered.
  • All sensors come with a 1-year limited parts and labour warranty.

GroPoint's patented technique for soil moisture measurement

Our proprietary TDT5 technology delivers an exceptional price:performance ratio, with performance as good (in most cases better) as sensors costing much more.

 

How does it work?

GroPoint™ sensors are based on the field-proven Time Domain Transmission (TDT) method of reliably measuring soil moisture, which is a refined version of Time Domain Reflectometry (TDR). TDT-based sensors do not need to be calibrated to each type of soil they will be buried in to deliver excellent accuracy and stability, however we do calibrate for 3 specific soil types for even greater accuracy.

TDT5 enhances TDT in 5 key ways:

Antenna length per
segment: 15cm,
effective length (if
stretched out): 75cm

Accurate Measurement Across Entire Length

Our patented design weaves the antenna through the circuit board 20 times per centimetre, and much like a coiled spring the effective length of the antenna is 5 times the physical length it consumes. It’s like having a 75cm long antenna in a single 15cm sensor. A larger antenna increases the resolution and sample area of each sample, allowing more noise to be filtered out. This gives highly accurate tracking of moisture changes with no “dead spots”.

Reduced manufacturing cost

Unlike other moisture probes, Gropoint sensors do not have separate components for electronics and bulky metal antennas. By integrating the antenna and all electronics into the same circuit board (possible thanks to the patented antenna design), manufacturing costs are dramatically reduced.

pulses filtered per measurement

Repeatable accuracy

Each time a measurement is taken, GroPoint sends 400,000 pulses through the sensing element to generate data for the measurement, then employs advanced filtering to eliminate outlying readings (noise) before averaging the data and sending the measurement as SDI-12 output. This ensures that the same accuracy (±1%) is obtained each and every time moisture is measured.

Low power consumption

Even with 400,000 pulses for each measurement, the total time to take the measurement is less than 100 ms. This means that power consumption is minimal, and that permits GroPoint sensors to be operated for many months with small 9V battery-powered data loggers.

Drag me!

Polycarbonate housing
Epoxy Sealant + Circuitboard

Maximum durability

Unlike typical sensors, the antenna is not exposed to the soil, so there’s nothing to bend or break. The entire sensor circuit board is sealed in epoxy then encased in a polycarbonate housing.

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