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Slightly loamy Sand (Sl2)
Site: UMS, soil type: slightly loamy sand (S: 1%, U: 82%, T: 17%), measurements at UMS Soillab, Evapo-
ration: 5.7 mm/d, temperature: 23°C
Description of the measuring process
The measurement process is typical of sand with low fines
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The water tensions rise spontaneously immediately after the start of measu-
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rement, until they reach a level that corresponds to the bubble point. In this
case it is about 30 cm (pF 1.5).
Small "spikes" at the beginning of the measurements indicate that the air is not
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uniform but occur in the system in jerks. This will be shown in the evaluation of
the retention curve.
The tensio shafts run for a long time completely in parallel, and differ only
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around a hydrostatic pressure difference of 2.5 hPa .
Only after the main pores are being drained, the upper tensio shaft value
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initially rises exponentially. The tensio shaft failed very quickly, and the air entry
point of the ceramic tip is reached shortly, while the lower tensio shaft is still in
the regular measuring range.
The difference of the tensions is suitable only after reaching the exponential
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rise, that hydraulic conductivities can be calculated.
The measurement is completed due to the failure of the upper tensio shaft
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after a loss of almost 30% water.
87 | Addendum
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