Spectrum WaterScout SMEC 300 Product Manual
SMEC 300 Soil
Moisture Sensor
PRODUCT MANUAL
Item # 6470-6, 6470-20
2
CONTENTS
General Overview 4
Specifications 5
Sensor Placement 6
Hardware/Software Compatibility 8
Calibrating the EC Sensor 9
Checking the Sensor 10
Installation 11
Soil Moisture Calibrations 14
Volumetric Water Content 20
3
Electrical Conductivity 22
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. at (800)248-8873 or (815) 436-
4440 between 7:30 am and
5:30 p.m. CST, FAX at (815)436-4460, or E-Mail at
info@specmeters.com.
www.specmeters.com
Spectrum Technologies, Inc.
3600 Thayer Court
Aurora, IL 60504
4
General Overview
Thank you for purchasing a WaterScout SMEC 300 Soil Moisture 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. They also help identify if it is necessary to
leach salts from the profile. The SMEC 300 combines affordability and accuracy into a sensor that is easy to install.
The soil moisture sensor consists of two electrodes that function as a capacitor, with the surrounding soil serving as the dielectric. An 80 MHz oscillator drives the capacitor and a signal
proportional to the soil’s dielectric permittivity is converted to
the output signal. The dielectric permittivity of water is much
greater than air, soil minerals and organic matter. So, changes
in water content can be detected by the sensor circuitry and correlated to the soil’s moisture content.
The salinity of the soil solution, irrigation water or fertilizer
solution is an important parameter affecting the root zone environment. Any of these factors can have a significant effect on
plant growth and physiology. The easiest way to monitor salinity is by measuring the electrical conductivity (EC). EC is
strongly correlated to the salinity of the soil solution. EC measurement is also affected by temperature and, to a lesser degree,
by soil moisture content. The SMEC 300 measures EC with a
pair of carbon ink electrodes which provide a large contact surface with the soil solution. Temperature is measured with a
thermistor potted in the sensor molding.
The SMEC 300 is designed to be compatible with the Watch-
®
Dog
data loggers and weather stations as well as the Field
®
Scout
view your data in graphical and tabular form as well as run reports customized to your application.
soil sensor reader. SpecWareTM software enables you to
Specifications
5
Standard
Interfaces
Connector
Range
Resolution
Power
Output
Oscillator Frequency
Accuracy
WatchDog weather station,
FieldScout Soil Sensor Reader
2.5mm stereo pin
VWC 0% to saturation
EC 0 to 10 mS/cm
Temp 33 to 175°F (0.5 to 80°C)
VWC 0.1%
EC 0.01 mS/cm
Temp 0.1oF (0.1°C)
3V @ 6 to 10mA
Analog voltage, time division
multiplexed.
80 MHz
VWC 3%
EC ±2%
Temp ±1oF (0.6°C)
Sensor Dimensions
Cable length
2.8in. (7cm) x 1.2in (3cm)
6 and 20ft. extendable up to 50ft.
6
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 measured. For outdoor applications, consider areas
of the field planted to
different types of vegetation. This could be
fairways vs. greens or
landscaped areas planted
with trees as well as
those planted with flowers. Areas with significant differences in factors such as topography
or soil type should be
considered unique environments. For greenhouse applications, select one or
more representative containers. Selecting a site which receives the least amount of water from the irrigation system
will tell you when that area becomes critically dry and is
in need of attention. Sites that have the greatest fluctuation in soil moisture will exhibit the greatest level of EC
variability as well. Typically, one or two sensors should
be installed in the root zone. A single sensor should be
placed in the middle of the root zone. When two sensors
are installed at a single site, it is recommended to place
one sensor at the top of root zone and a second at the bottom. An advantage of installing multiple sensors is it allows you to see how well irrigation and rainwater is moving through the soil profile.
7
The SMEC 300 is most sensitive to the soil adjacent to the
sensor. Therefore, good contact between the soil and sensor is important. Stones and air pockets next to the sensor
will affect the accuracy of the readings. Because it is sensitive to differences in dielectric permittivity, care should
be taken not to install the sensor in or near metal.
8
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.
WatchDog weather stations
The table below outlines the compatibility of the sensor with the
various WatchDog weather products. All micro-stations and
mini-stations with firmware v. 3.8 or greater can read an SMEC
300 on any channel. Full stations and mini-stations with firmware v. 3.5 can only have SMEC 300 sensors connected to ports
A or D. Ports B and C (and/or E and F) become "virtual" software ports and are unavailable for other sensors.
Station #
1225, 1250 Micro N/A 0 Incompatible
1400, 1525,
1650
1200, 1425,
1450
2475 Mini 3.8 1 A
2450 Mini 3.8 2 A, B
2425 Mini 3.8
2400 Mini 3.8* 4 A, B, C, D *
2550, 2700 Full 6.9 2 A, D B/C, E/F
2800 Full 3.2 2 A, D B/C, E/F
2900ET Full 6.9 1 A B/C
Station
Type
Micro 2.0 2 A, D
Micro 2.0 1 D
Station
FW version
*
3 A, B, C *
Number
of
Sensors
Compatible
Channels
Potentially
unavailable
channels
*
Can accommodate 1 SMEC 300 with FW v. 3.5 using port A plus B/C as
virtual ports
Loading...