Above Ground and Sub Surface Profiling Soil Moisture Probes



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What it is


The Otto family of soil moisture probes offer features and flexibility that are not available in any competing products. The Otto probes are available in both above ground and sub-surface version. The latest sensor firmware improves sensor  resolution and reduces noise.. And if you only need one reason for buying the Otto compared to competing capacitance probes, think about this: have you ever watched the indicated soil moisture rise without any apparent reason? Short term variations have often been written off as “Capillary Rise” and longer term variations simply put up with: have you seen graphs where the moisture slowly rises, even though there has been no rain? Well, the cause is temperature change in the soil, which changes its dielectric properties hence its indicated moisture. The Otto is the first product with on-board, user programmable temperature compensation to both recognise and remove this effect. The Otto probes are also the first profiling capacitance probes to be offered with an integrated LoRaWAN module. See the Otto-Lo page for more details.


Flexible Configuration


The probes may be built in lengths of 30cm to 200cm and can be fitted with from 2 to 15 sensors. The sensor elements can be installed at 10cm increments along the probe body and, to save cost, depths can be skipped by inserting spacer boards of 10, 20 or 30cm length.


Form Factor


Rather than the 50mm format of the original capacitance  sensors, the Otto probes are built on a 32mm slimline design. This means a faster installation process (and easy removal).


Data Logging


The Otto’s SDI-12 interface allows the probes to be connected to any SDI-12 compatible logging device. Each sensor element returns Soil Moisture (%) and soil temperature (degrees C).




The Otto  sensors come with a default air-water calibration and users can select  generic soil calibrations for sand, potting mix and clay. Users can perform their own soil specific calibration and save the obtained calibration coefficients on to  the probe. The Otto probes are the first capacitance probe to include soil temperature compensation: allowing users to remove the changes in indicated moisture caused by variations in the dielectric properties of the soil with temperature.


Maintenance Free Sub Surface


The sub-surface Otto probes are fully sealed and the internal electronics potted to protect against moisture ingress. The sub-surface probes require no ongoing maintenance and can be buried below the soil  surface. This makes them ideal for broadacre farming and for turf and pasture.


More Details