Delta-T's ThetaProbe soil water content sensor

ThetaProbe type ML2x

± 1 % accuracy

Easy data logger connection (DC in DC out)

Excellent temperature and salinity stability

Dual purpose: either hand-held for spot readings or left in situ for data logging

The ThetaProbe type ML2x measures volumetric soil moisture content to within 1 %. The ML2x has decisive advantages over other technologies, offering precision and reliability at an affordable price

Simple to use

With the ThetaProbe type ML2x it's easy to make reliable, accurate soil moisture measurements. Simply insert the probe into the soil, connect to your data logger or meter, provide 5-15V DC at 20mA, and within seconds you can be measuring soil moisture.

Calibration

After a single two-point gravimetric calibration, ThetaProbes will meet their full 1% accuracy specification for your specific soil (or other medium).

The ML2x has a predictable saline response (which declines as salinity increases) it can typically be used even in very saline soils - up to 2000 mS.m^-1 .

Installation

ThetaProbes are robust, buriable and maintenance free. They can be placed in the soil by inserting them into augered holes or alternatively by positioning them in the wall of a trench (which is then carefully back-filled).

Optional Extension Tubes assist convenient placement and removal when burying at depth.

Data Logging

Most types of data logger can provide the 5 - 15V DC required to power the ThetaProbe, and will accept its 0 - 1V DC output signal. The DL3000 and DL2e Loggers from Delta-T are well suited to this application.

For instantaneous readout of ThetaProbes, the ThetaMeter provides a portable solution. A single ThetaMeter can be used to measure many ThetaProbes - by connection to each in turn.

For more details please see the "Data Loggers and Readout Units" page.

Independent Comparison of Performance

Recently found to be ".. consistently accurate under a variety of soil types." in the presented oral paper:

Evaluations Of Dielectric Soil Moisture Sensors For Irrigation Scheduling
presented as Topic 3 at: the International Symposium on Irrigation of Horticultural Crops, Estoril., Portugal 1999 by Hanson, B.; Douglas, P. and Serrarens, D.

For more information on the design and performance of the ML2x, please see the performance table.

		Delta-T's new catalogue: covering: Soil Water Content: ThetaProbe - introduction ; performance ; theory Soil Water Potential: Tensiometer ; Equitensiometer Pore water conductivity: Sigmaprobe theory Evapotranspiration: (Software and weather stations) Data loggers and readout units ; Application examples ;
A sowacs feature page			Back to Delta-T Feature Page Index	© Bruce Metelerkamp www.sowacs.com/feature/deltat/swc1.html last update : 14 August 1999