Sand/kaolin box for pF determination

When researching the quantity of moisture available in the soil for plants and trees to grow, it's essential to determine the moisture characteristic (or pF-curve). The sand/kaolin box is suitable for a maximum of 40 soil sample rings and uses undisturbed samples of 53 or 60 mm in diameter.

The standard set for pF determinations of pF 2.0 - 2.7 (0.1 - 1 bar) contains:

• Sand/kaolin box with control panel
  

• Electronical suction level control system (pressure range 0 - 600 hPa)

• Pressure sensor

• 10 litre tank

• Containers with synthetic sand

• Container with kaolin clay

• Various accessories

Method:

The test is done on undisturbed soil samples, which can be taken with a soil sample ring kit (07.53.SC).

Firstly, the samples are fully saturated and subsequently weighed with respect to the increasing values of the moisture tension. These moisture tensions are obtained by creating a series of under- and overpressure. Weighing of the samples after each adjustment yields the moisture content for each moisture tension.

Additional requirements

Correct use of this instrument also requires a soil sample ring kit, cases with soil sample rings and aluminium soil sample boxes. A balance and a drying oven are part of the minimum equipment for preparation of the samples. The laboratory table on which the measuring instrument is placed should be level and isolated against vibration.

Applications

• Soil physical laboratory research
  

• pF determination in the lab

• Irrigation research

The sandbox and the sand/kaolin box can be used together to cover a larger pF-range (0 - 2.7). A filled box will last several years, if it is inundated with water after each test. A copper ring prevents algal growth in the instrument.