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Logging Soil Salinity

Field station for logging soil salinity

Salinity measurements are an important aspect of soil, crop and environmental protection, research and management. ICT International can provide scientists and managers with a highly accurate, low cost, plug and play solution to logging salinity in the field.

The Field Station consists of a Smart Logger with LCD display and logger housing with mast and freestanding base. The system has a maximum capacity of 250 sensors, but for most applications 3-30 salinity sensors are common. The station can accommodate additional environmental sensors to measure other variables in association with salinity.

Applications

The Salinity Station is ideal for efficient monitoring of soil salinity. Used in conjunction with the soil salinity sensor, dynamic changes in soil salinity can be measured without continuous disruption to the soil.

Smart logging

A feature of the field station is plug and play, or smart logging. Using the Smart Logger does not require any knowledge of electronics or computer programming.

The station is operated simply by plugging in a sensor and pressing both buttons on the front panel. The Smart Logger will then search the DataBus, automatically identify the number of salinity sensors connected, and begin logging at hourly intervals.

For custom configuration of the Smart Logger or salinity sensors a simple menu system can be accessed through a HyperTerminal that provides complete control over each individual sensor's set-up. Instantaneous readings from sensors can be viewed on the logger's display directly in the field.

Smart interface

Each salinity sensor is fitted with an external smart interface that consists of an integrated microprocessor. This interface contains all the required information to allow autonomous operation of the sensor, including power requirements and logging interval. The smart interface resolution is 16 Bit, which offers highly precise and accurate recording of the salinity sensor.

Each interface is fitted with a standard cable length of 5 m but extension cables of any length can be interchanged as different situations demand. This length when added to the sensor cable of 4.6 m gives about 10 m cable length from the Smart Logger DataBus to the salinity sensor. However, extension cables of any length can be connected with the smart interface as different situations demand.

Salinity Sensor

The soil salinity sensor consists of a pair of platinum electrodes embedded in a fine-textured (15 bar) ceramic electrolytic element, with a thermistor behind the element. The sensor is spring loaded with a stainless-steel spring to ensure good hydraulic contact between the sensor and the soil.

Moisture saturating the ceramic element comes to equilibrium with the soil water to give constant salinity measurements.

The sensors are designed to fit crosswise into a 3.2 cm diameter cored hole. After the sensor is placed in position a stainless-steel release pin is removed to activate the spring. Once the ceramic element contacts the soil and the soil water saturates the element, a reading can be made.

An outside housing covers the unit apart from the ceramic sensing surface of the electrolytic element in the end of the unit. All sensor elements are solidly potted in place.

A four-conductor electrical cable encased in heavy polythene leads from the sensor to the Smart Interface and then the DataBus and Smart Logger.

The unit is exceptionally weather and corrosion proof.

Calibration and installation

Smart Loggers are supplied completely assembled, with the soil salinity sensors calibrated and ready for installation. An individual data sheet is supplied with each sensor.

Notes on soil salinity

The level of soluble salts above 4 dS/m in soil moisture inhibits the seed germination and growth of most commercial crops. This adversely affects the biomass production and economic yield. The following table illustrates the various saline conditions and categories of crop tolerance.

Units of salinity measurements

Ordering information

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