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Spectrum WaterScout SMEC 300 Product Manual

Soil moisture sensor
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SMEC 300 Soil
Moisture Sensor
PRODUCT MANUAL
Item # 6470-6, 6470-20

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Summary of Contents for Spectrum WaterScout SMEC 300

  • Page 1 SMEC 300 Soil Moisture Sensor PRODUCT MANUAL Item # 6470-6, 6470-20...

  • Page 3: Table Of Contents

    Volumetric Water Content Electrical Conductivity This manual will familiarize you with the features and operation of your new WaterScout SMEC 300 Soil Moisture Sensor. Please read this manual thoroughly before using your instrument. For customer support, or to place an order, call Spectrum Technologies, Inc.

  • Page 4: General Overview

    General Overview Thank you for purchasing a WaterScout SMEC 300 Soil Mois- ture Sensor. The moisture and nutrient status of your soil or container substrate are key pieces of information. They allow you to tailor your irrigation and fertilization program to suit your crop's needs.

  • Page 5: Specifications

    Specifications Standard WatchDog weather station, Interfaces FieldScout Soil Sensor Reader 2.5mm stereo pin Connector Range VWC 0% to saturation EC 0 to 10 mS/cm Temp 33 to 175°F (0.5 to 80°C) VWC 0.1% Resolution EC 0.01 mS/cm Temp 0.1 F (0.1°C) 3V @ 6 to 10mA Power Analog voltage, time division...

  • Page 6: Sensor Placement

    Sensor Placement The sensors should be located in the effective root zone and at locations that will give a representative picture of the salinity and soil water status of the area being meas- ured. For outdoor appli- cations, consider areas of the field planted to different types of vege- tation.
  • Page 7 The SMEC 300 is most sensitive to the soil adjacent to the sensor. Therefore, good contact between the soil and sen- sor is important. Stones and air pockets next to the sensor will affect the accuracy of the readings. Because it is sen- sitive to differences in dielectric permittivity, care should be taken not to install the sensor in or near metal.

  • Page 8: Hardware/Software Compatibility

    Hardware /Software Compatibility There are some restrictions on which equipment is compatible with the SMEC 300 and how many sensors can be connected to a single unit. These are outlined below. Soil moisture sensor reader • Requires firmware version 4.4 or greater. Specware software Weather stations require Specware version 9.04 or greater.

  • Page 9: Calibrating The Ec Sensor

    (item 3300CBWM). Micro stations can be upgraded through SpecWare software. Contact Spectrum Technologies for details. Original WatchDog weather stations (models 525, 550, 600, 700, and 900), 200- and 400- series purple loggers, and A-series loggers are incompatible with the SMEC 300.

  • Page 10: Checking The Sensor

    Checking the Sensor The EC sensor can be checked with the 1.41 mS/cm cali- bration standard (see Calibrating the EC Sensor p. 9). The soil moisture calibrations were developed using min- eral soils and a soilless material (peat moss). Therefore the sensor will not give a value of 100% in water.

  • Page 11: Installation

    Installation The most important consideration for installing the sen- sors is maintaining good contact between the sensor and the soil. This ensures optimum performance. Before any installation, be sure that the EC electrode has been cleaned with alcohol and is recently calibrated (see Calibrating the EC Sensor p.
  • Page 12 ½” Schedule 40 PVC works well as an insertion device because the sensor molding has a width of 7/8”. In gen- eral, it is not recommended to push the sensor directly into native soil, especially in dry, high-clay or gravel/stone- laden soil.
  • Page 13 Horizontal Orientation Digging a small hole or trench in the soil allows the sensors to be installed horizontally. The sensors are pushed directly into the exposed face of undis- turbed soil. Because the sensor board is flexible, care should be taken to avoid snapping it during installation.

  • Page 14: Soil Moisture Calibrations

    soil moisture Calibrations In some instances, greater accuracy is desired than can be obtained from a general soil moisture calibration equation. In this case, it is necessary to perform a calibration on your unique soil. Essentially, a relation needs to be devel- oped that relates the meter’s electronic reading to the ac- tual volumetric water content (VWC).
  • Page 15 ing without allowing soil to spill or leak out. Drilling the holes at a slight downward angle will minimize spillage. 2. Measure the mass of the empty container and the sensor or sensors being used in the calibration. 3. Determine the volume of the container. This can be done geometrically or by measuring the volume of sand needed to completely fill the container.
  • Page 16 The volumetric water content at each data point is calcu- lated as follows: − ρ = mass of soil at a given point during drydown (grams) = mass oven-dry dry soil (grams) = total soil volume (ml) ρ = density of water (1g/ml) These calculations can easily be set up in a spreadsheet.
  • Page 17 Soilless Media Because soilless media tend to be hydrophobic and have a tendency to shrink dramatically when very dry, wetting the material and allowing it to dry over time is not the ideal method for collecting data for a media-specific cali- bration.
  • Page 18 Calibration procedure 1. Acquire 18 containers with a diameter of 4 to 6 inches and a height slightly greater than SMEC 300 sensor (2.8 inches). This allows for 3 replicates at 6 different water contents. Commercially available pots should suffice. Containers can also be built from PVC.
  • Page 19 7. Weigh each of the filled containers. 8. For each container, take three SMEC 300 readings. Take care not to take readings too near the edge of the container. It is rec- ommended to take readings per- pendicular to the sides of the con- tainer.

  • Page 20: Volumetric Water Content

    Water draining from a soil profile can- not, in general, be taken up by plant roots. On the oppo- site end of the spectrum, permanent wilting point is the highest moisture level at which an indicator plant cannot recover turgor after being placed in a humid environment.
  • Page 21 Figure 1.

  • Page 22: Electrical Conductivity

    Electrical Conductivity Electrical conductivity (EC) is a measure of how well a solution conducts electrons. Pure water does not conduct electricity at all. However, as the concentration of dissolved ions increases, the electrical charged carried by those ions of the solution will increase as well. This is reflected in a higher EC measurement for that solution.
  • Page 23 Before returning a failed unit, you must obtain a Re- turned Materials Authorization (RMA) from Spec- trum. Spectrum is not responsible for any package that is returned without a valid RMA number or for the loss of the package by any shipping company.
  • Page 24 3600 Thayer Court Aurora IL 60504 (800) 248-8873 or (815) 436-4440 Fax (815) 436-4460 E-Mail: info@specmeters.com www.specmeters.com R 3/14...

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