ICT MP306 Operation Manual

DocRef: Ver1.3

MP306 Moisture Probe

Operation Manual

ICT International Pty Ltd

PO Box 503

Armidale NSW 2350

AUSTRALIA

Phone: [61] 2-6772-6770

Fax: [61] 2-6772-7616

Email: [e-mail]

Web: www.ictinternational.com

MP306 Moisture Probe Operation Manual

TABLE OF CONTENTS PAGE

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.1 Hand Held Moisture Probe Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.2 Data Logging or Irrigation Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.2.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.2.3 Cable Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2.2.4 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2.3 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2.3.1 Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2.3.2 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

 2.3.3Denitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

2.4 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.4.2 Linear Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.4.3 Polynomial Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.4.4 Polynomial Lookup Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2.5 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2.6 TechnicalSpecications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

2.6.1 Mechanical Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

 2.6.2ElectricalandMechanicalSpecications . . . . . . . . . . . . . . . . . . . . . . .9

LIST OF FIGURES PAGE

1. MP306 Measurement of Absolute Volumetric Soil Water Percent. .

. . . . . . . . . . 5

2. MP306 in comparison to TDR Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

3. Mechanical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

MP306 Moisture Probe Operation Manual

1. Introduction

The MP306 Moisture Probe can be used to measure the moisture content in many materials such as soil,
food and materials used in roadway and building construction.

The MP306 can be used to measure the soil moisture for scientific research or irrigation management. In
either situation the MP306 can:

- rapidly measure the soil moisture by pushing the needles of the sensor into the soil surface or soil profile;

- make measurements over time by permanently burying the MP306 and connecting it to a data logger;

- control irrigation by permanently burying the MP306 and connecting it into an irrigation controller.

2. Operation

2.1 Hand Held Moisture Probe Meter

The MP306 has a connector which plugs directly into the MPM-160 hand held meter for direct readout.

The meter provides the power to the MP306 for the reading, display and storage of measurements. The
returned mV signal is displayed directly as mV and is also converted and displayed as Volumetric Water
Content (VSW%). Refer to section 2.4.4 for the conversion table.

When being used with a hand held meter the MP306 is usually connected to a set of chrome extension rods
which have a T handle on the end.

The extension rods enable the operator to insert the needles of the MP306 into the soil surface without
bending over, and then more conveniently read the MPM-160 meter.

2.2 Data Logging or Irrigation Control

2.2.1 General

The MP306 exterior is made from extremely durable ABS plastic formed into a custom designed tube. The
electronics is totally sealed within this tube. The needles are made from high quality stainless steel. Then the
MP306 can be buried permanently at a location as part of either an input to a data logging system or for an
input to an irrigation controller or environmental monitoring system.

2.2.2 Installation

The MP306 can be installed by drilling a close fitting hole into the soil profile, either at an angle or
vertically or it can be installed horizontally from a larger augered hole or soil pit. In all situations care must
be taken to ensure the needles are in contact with soil profile after installation. It is usual practice to install
the MP306 with the 3 needles in a horizontal plane in order to maximise the measurement of soil spatial
variability. The MPM-160 meter should be used during the installation process to ensure good contact of the
needles and the soil is maintained during back filling of the hole.