Soil moisture measurement

pF determination

The pF curve illustrates the correlation between soil moisture contents and suction, with variations according to soil type. With appropriate equipment, the pF curve can be determined for each soil type, elucidating water availability. We present three laboratory devices for comprehensive pF determination.

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Sandbox for pF determination (pF 0 - 2.0)

Sandbox for pF Determination (pF 0 - 2.0)

  • Suitable for the wettest pF curve segment
  • Utilizes undisturbed 53mm or 60mm diameter samples
  • Accommodates 40 sample holders for extensive research
Sand/kaolin box for pF determination (pF 2.0 - 2.7)

Sand/Kaolin Box for pF Determination (pF 2.0 - 2.7)

  • Covers a significant pF curve range
  • Holds 40 samples, facilitating large-scale research
  • Reusable set-up for long-term use
Membrane apparatus for pF determination (pF 3.0 - 4.2)

Membrane Apparatus for pF Determination (pF 3.0 - 4.2)

  • Focuses on the driest pF curve range
  • Applies overpressure on disturbed samples
  • Efficient and effective configuration
Ceramic plates set for pF determination (pF 2.0 - 4.2)

Ceramic Plates Set for pF Determination (pF 2.0 - 4.2)

  • Relatively straightforward method
  • Applicable to prepared samples or undisturbed soil cores
  • Non-disruptive moisture removal from samples
Complete set for pF determination, sandbox & pressure method (pF 0 - 4.2)

Complete Set for pF Determination, Sandbox & Pressure Method (pF 0 - 4.2)

  • Comprehensive pF determination kit
  • Incorporates sandbox, sand/kaolin box, and membrane apparatus
  • Enables pF curve assessment across the full range of pF 0 - 4.2

pF determination

The relationship between soil water retention and moisture content significantly shapes soil suitability for agriculture. Grasping this concept contributes to effective irrigation practices..

Various methods exist to comprehend soil moisture content at different suction pressures. United Empire Ltd. offers the following laboratory equipment for this purpose.

Sandbox for pF Determination in the Range 0 - 2.0
  • Focuses on the wettest curve portion
  • Utilizes undisturbed samples of 53mm or 60mm diameter
  • Accommodates up to 40 sample rings
Sandbox/Kaolin Method

Covers the substantial curve range of pF 2.0 to 2.7

Membrane Apparatus

Suitable for the pF range of 2.0 to 4.2, and also for soil moisture block calibration or soil moisture measurement equipment.

Ceramic Plates

Suitable for the pF range of 2.0 to 4.2, and also for soil moisture block calibration or soil moisture measurement equipment.

The Soil Moisture Retention Curve

Known as the soil suction curve or pF curve, this graph depicts moisture content at varying suction pressures. While a soil may hold ample moisture, if it retains moisture at low suction pressures, it may remain inaccessible to plants, hampering growth.

Typically, sandy soils have limited water at low suctions, while clay soils retain significant water even at higher suctions, which may still be unavailable. With the soil moisture retention curve for a specific soil, you can determine whether watering is required using a soil moisture sensor or a tensiometer.