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Waterscout SMEC 300 Soil Product Manual

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 Waterscout SMEC 300 Soil

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

  • Page 2: Table Of Contents

    Volumetric Water Content Specifications 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 3: 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 4: 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 5 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 6: 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 7 Upgrading older weather stations Older WatchDog mini-stations can be upgraded with a new micro-controller chip (3300WD2). Full weather sta- tions can be upgraded with a replacement micro-controller with integrated clock board (item 3300CBWM). Micro stations can be upgraded through SpecWare software. Contact Spectrum Technologies for details.

  • Page 8: Calibrating The Ec Sensor

    Calibrating the EC Sensor The EC sensor can be calibrated with the Soil Sensor Reader or with the EC Calibration Device (item 6470CAL3V). The calibration procedures are included in the product manuals for each device. With both devices, calibration is done with a 1.41 mS/cm calibration stand- ard.

  • Page 9: 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. 8). 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 10: 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 11 native soil, especially in dry, high-clay or gravel/stone- laden soil. Instead, it is best to return some crumbled na- tive soil from the bottom of the access hole, tamp it suffi- ciently and use the insertion device to push the SMEC 300 into the packed soil.
  • Page 12 cause the sensor board is flexi- ble, care should be taken to avoid snapping it during instal- lation. To limit the effect of water moving vertically through the soil profile, the sensors should be installed so the flat face is perpendicular to the soil surface.

  • Page 13: 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 actu- al volumetric water content (VWC).
  • Page 14 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. 4.
  • Page 15 The volumetric water content at each data point is calcu- lated as follows:    = mass of soil at a given point during drydown (grams) = mass oven-dry dry soil (grams) = total soil volume (ml)  = density of water (1g/ml) These calculations can easily be set up in a spreadsheet.
  • Page 16 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 ide- al method for collecting data for a media-specific calibra- tion.
  • Page 17 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 18 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 19: 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 20: Volumetric Water Content

    Volumetric Water Content The SMEC 300 measures volumetric water content. The volumetric water content (VWC) is the ratio of the volume of water in a given volume of soil to the total soil volume. At saturation, the volumetric water content (expressed as a percentage) will equal the percent pore space of the soil.
  • Page 21 Figure 1.

  • Page 22: Specifications

    Specifications Standard WatchDog weather station, Interfaces FieldScout Soil Sensor Reader Connector 2.5mm stereo pin Range VWC 0% to saturation EC 0 to 10 mS/cm Temp -60 to 185°F (-50 to 85°C) Resolution VWC 0.1% EC 0.01 mS/cm Temp 0.1 F (0.1°C) Power 3V @ 6 to 10mA Output...
  • Page 23 Warranty This product is warranted to be free from defects in mate- rial or workmanship for one year from the date of pur- chase. During the warranty period Spectrum will, at its option, either repair or replace products that prove to be defective.
  • 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 2/18...

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