 The "Soil Analysis Sensor" (Digital) as well as the "Analog Soil Sensor" (including a soil moisture sensor) are one of the most modern sensor elements / probes for the accurate monitoring, recording and analysis of moisture, electrical conductivity and surrounding temperature in soils and other granular media.
The completely digital "Soil Analysis Sensor" has been developed as a versatile Universal Sensor (extension element) for the direct connection to our flexible data logger systems (e.g. Thermofox Universal, Universal HUB, Materialfox,...). It allows the easy analysis of different granular substances like mineral soils or similar media.
The "Analog Soil Sensor" supports the same functions and features as its digital counterpart. In addition, it offers 3 x precise and flexibly configurable analog signal outputs. Via these outputs, the current measurement value can easily be passed on as a voltage signal (0V - 2.5V) to other measuring devices, control and regulation systems, data loggers and many more.
The measuring probe of both sensor versions offers three highly-sophisticated sensing elements:
The moisture content of the soil (VWC = Volumetric Water Content in %) is determined by measuring the dielectric permittivity / dielectric constant ε = 1 (air) to ε = 80 (water) with a soil moisture sensor. This physical property of the soil varies greatly depending on the water content and is recognised worldwide as the standard for measuring the moisture in the soil and in other materials. The dielectric permittivity is measured using capacitive frequency domain technology at a frequency of 80 MHz.
This high frequency was specifically selected in order to reduce influences by the salt content and the structure of the medium to be examined. This also makes the sensor very accurate and suitable for different types of soil. In mineral soil types, the conversion of the permittivity into volumetric water content (VWC in %) takes place fully automatic directly in the sensor by means of the widely used and validated "Topp equation". Custom-made calibrations can of course also be carried out on request. For this purpose, the soil moisture sensor provides access to all digital raw data, making it even more flexible. The electrical conductivity of the soil (Electrical Conductivity = EC, measured in uS/cm or cs/m) is measured directly at the sensor using two high-quality and very robust V4A stainless steel electrodes. To achieve good results, a reliable and firm contact between the measuring substrate and the electrodes is important. The measurement range of the sensor is between 0 and 20,000 uS/cm (or 0 and 200 cS/m), thus enabling monitoring the influence of salts or fertiliser on the conductivity of the soil, for example. On request, the sensor also performs a fully automatic temperature compensation of the measured conductivity. The user can choose between the following three options: either a linear temperature compensation with adjustable compensation coefficient, a special temperature compensation matched to soil analysis based on the recommendations of the "US Salinity Handbook 60" or no temperature compensation.
As a third analysis element, the waterproof Soil Analysis Sensor as well as the Analog Soil Sensor include a high-precision NTC temperature sensor to measure the exact temperature in the soil (measured in °C or °F). The measurement range of the sensor is between -30°C and +80°C with a resolution of 0.1°C. The sensor is already pre-calibrated. In addition to that, the user has flexible access to the internal adjustment offset.
The compact Soil Analysis Sensor as well as the Analog Soil Sensor can be easily installed at any time. The waterproof sensor element is simply pushed directly and firmly into the unaffected soil. This provides good contact between the sensor and the soil and maximises the accuracy of the system.
More information about the "Soil Analysis Sensor" (Digital):
In many cases, the Soil Analysis Sensor is combined with our convenient data logger Thermofox Universal. Its large, clear display, memory for up to 64,000 readings, an additional internal temperature sensor and two external temperature sensor inputs for NTC thermistors (measuring range: -30°C to +120°C, wired sensors or wireless sensors) as well as its Universal Sensor® bus for numerous extensions like the Soil Analysis Sensor make this data logger especially versatile.
Depending on the particular application, the Soil Analysis Sensor can either be connected directly, as stand-alone sensor, to one of our flexible data logger systems (e.g. Thermofox Universal):
Or, as an alternative, the Universal HUB enables you to simultaneously process up to four Soil Analysis Sensors with one of our data logger systems (e.g. Thermofox Universal):
If you do not want to read out the Soil Analysis Sensor - System (incl. soil moisture sensor) and the associated data logger (e.g. Thermofox Universal) manually on site, you can also easily connect the measuring system with our mobile Remotefox - Remote Data Transmission System. This way, you regularly get all measurement data via mobile service, internet and email even if you are hundreds of kilometers away from the measurement site. As all our data loggers, the Remotefox also operates completely battery-powered and does not require any access to the power grid. This allows effortless stand-alone use, also for several months or even years!
This way, even very extensive and geographically dispersed long-term recordings can easily be performed.
The fields of application for the Soil Analysis Sensor in combination with our data logger systems are almost unlimited and range from irrigation planning and control, over the use in greenhouses, the prognosis of plant diseases, soil respiration, watershed characterization through to fertilization management, plant ecology and many more...
 If you also need reliable alerting in addition to the analysis and recording of measurement data, this is also easily possible with the Soil Analysis Sensor. Just combine the measurement system with our flexible Universal Alarm. This optional alarm module can be individually configured and features a highly flexible and independent alarm output. There are different alarm functions for e.g. exceeding or falling below a user-defined alarm threshold, but also for the entry or exit of an alarm range. The freely programmable alarm delay completes the range of alarm functions. Alarm systems include our SMS-Alarm-System for the mobile sending of SMS alarm messages to one or more recipients, our SMS-Power-Pack or our flexible Acoustic-Alarm.
The independent power supply to the Soil Analysis Sensor is provided by a high-quality, durable and replaceable standard 3.6V lithium battery, supplied as part of the Power-/Setup-Module included in the delivery. The sensor can also be configured as desired using this module. Depending on the selected measuring rhythm, the battery life is up to 2 years.
The programming of the Soil Analysis Sensor - System and the used data logger (logger type depending on the application) as well as the data evaluation is done via the SoftFOX - Universal Analysis Software under Microsoft Windows® XP, 7 ,8, 10 or 11.  Newer operating systems are naturally also supported. After the sensor or the corresponding data logger is connected to the computer via a PC interface cable, the system can be read out or configured immediately. The software offers numerous general functions like for example dynamic project management, graphic data analysis, guide lines, overlay function for curves originating from different data loggers, mathematical curve calculation, statistical curve analysis, export function, auto backup, flexible zoom and many more. Besides that the Soil Analysis Sensor as well as the used data logger system itself can be configured arbitrarily. Functions like setting the measuring rhythm, min./max. monitoring for extreme value recording without interruption for even slow measuring rhythms, configuration of the real time clock, reading out the measurement data, test of the memory fill level, digital serial number and many more are available here.
More information about the "Analog Soil Sensor":
The Analog Soil Sensor is supplied with power using the two power connectors VIN+ and GND. The applied supply voltage can range from 3V DC to 12V DC. Within approximately 1 second after applying the supply voltage, the measurement values for the soil moisture (SM), the electrical conductivity of the soil (EC) as well as the soil temperature (TP) are available as analog voltage signal at the three outputs Ax. The measurement value of each sensor channel is mapped proportionally and with high precision to the output voltage range between 0V DC and 2.5V DC. The analog output signals are updated every 5 seconds by default (freely configurable).
The sensor can also be addressed digitally (RS-232 / UART / USB / Universal Bus®) via the DIGI interface connector. Simply use our optionally available Power-/Setup-Module for this purpose. By this means, you can easily adjust all settings of the sensor and thus flexibly configure, for example, the measurement rhythm or the mapping range of the measurement values to the analog 0 - 2.5V output signal. For all questions regarding the configuration or installation of the Analog Soil Sensor, our support team is, of course, always at your disposal.
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