Delta-T HH2, User Manual

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Field Water Capacity Values Moisture Meter User Manual 4.0
Field Water Capacity Values
Field Water Capacity values are given for several soil types. These values can be
entered in the ‘Field Capacity’ option of the Data menu. This is needed if you want the
meter to display mm deficit.
You will also need to enter a value for Root Depth.
Standard Soil Types
The following are tables of Field Water Capacity values for standard soil types:
WARNING: USE EXPERIMENTALLY DETERMINED FIELD CAPACITY VALUES
WHEREVER POSSIBLE - see Calculating Field Capacity.
Volumetric Field Capacity
Defined at a tensiometer reading of: 0.05 bar 0.15 bar
Commonly used in : UK & Europe USA
CLAY 43.4% 42.2%
SILTY CLAY 40.5% 39.0%
SILTY CLAY LOAM 38.0% 36.0%
CLAY LOAM 35.9% 34.0%
SANDY CLAY LOAM 34.0% 31.0%
SANDY SILT LOAM 33.5% 29.9%
SILT LOAM 34.5% 31.0%
SANDY LOAM 27.5% 23.2%
LOAMY SAND 22.0% 17.0%
SAND 13.9% 8.2%
Table by courtesy of Justin Smith of Turftrax Group Ltd
Enter the Field Capacity of the soil closest to your soil.
Note: These are average values. Individual soils will vary dependent on particle
size, organic matter and compaction.
If you do not know what soil type to use - see Identifying Soil Types, page 107 - or
better still, determine the Field Capacity experimentally - see Calculating Field
Capacity on page 108.
Owing to the variable nature of
organic soils we are unable to recommend even a
"standard" value for Field Capacity. Some irrigation consultants will advise you not
to record mm deficit unless you can confidently measure and interpret your
own soil's Field Capacity .