Field Capacity & Wilting Point Set — pF Determination with Ceramic Plates

This set determines soil moisture characteristics via ceramic plates, measuring pF curves in the range pF 2.0–4.2 (0.1–15 bar suction).

Working Principle

Soil moisture is removed from a soil sample by raising the air pressure in an extractor. A porous ceramic plate serves as a hydraulic link that "pushes" water out of the soil. Since the ceramic plate's pores are saturated with water, they allow water through but block air flow. As pressure increases, soil moisture equilibrates around each particle and exits through the ceramic plate and outflow tube; equilibrium is reached once no more water emerges from the outflow tube.

The method is relatively simple, applicable to prepared samples or undisturbed soil cores, and provides a reliable way of removing moisture from a sample without disturbing the soil structure. Double regulators on the pressure control panel help ensure measurement accuracy.

Set Contents

• Two extractors (5 and 15 bar)
• 4 ceramic plates, 1 bar
• 4 ceramic plates, 15 bar
• Pressure control panel
• 20 bar compressor with reducing valve
• 144 soil sample rings
• Coupling hoses

Applications

• Calculating soil pore volume and pore-size distribution
• Calculating capillary-rise capacity
• Calculating air and moisture content at a given groundwater level
• Determining field capacity and available soil moisture
• Soil suction research related to seed germination time
• Calibrating soil moisture blocks or measurement equipment