Installation; Scientific Measure Ideas; Selecting The Measuring Site; Number Of Tensiometers Per Level - UMS T5 User Manual

3 Installation

3.1 Scientific measure ideas

3.1.1

Selecting the measuring site

The installation spot should be representative for the soil which
should be surveyed. For selection it might be necessary to take soil
samples. If the column is refilled care should be taken to achieve the
best possible homogenous distribution and evenly compaction. Bear
in mind a possible shrinking of backfilled columns when T5 are
installed through the cylinder.
On tillage sites (with plants) root spreading and growth during the
measuring period should be considered. Fine roots might develop
around the ceramic cup as it is a poor but assured water source.
Avoid the root zone if possible or replace the Tensiometer from time
to time.
3.1.2

Number of Tensiometers per level

The lower the level the less the variations of water potentials are. In
sandy or pebbly profundities one Tensiometer per depth is sufficient.
Close to the surface about 3 Tensiometers per level are
recommendable.
Guiding principle: More heterogeneous sites and soil structures
require a higher number of Tensiometers.
3.1.3

Extension of the site

Large distance along with high equidistance between the measuring
spots will reduce the influence of sectional heterogeneity.
To determine the water flow according to Darcy two Tensiometers
per horizon or required, one each in an upper and lower level of this
horizon.
Max. recommendable cable lengths for T5 and T5x are 20 meters:

Accuracy: long cables cause a reduction of the accuracy.

Lightning: cables act as antennas and should always be as short
as possible.
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