The water-holding capacity (WHC) is defined as the amount of water held in the soil after the excess gravitational water has drained away and after the rate of downward movement of water has materially ceased.

Apparatus

·         Oven,

·         Perforated circular soil boxes (5.6 cm diameter, 1.6 cm height bottom perforated with hales of 0.75 mm diameter),

·         Filter paper (whatman no.1),

·         Petridish

·         Analytical balance.

Procedures

·         Dry the crushed soil sample in an oven at 105⁰C.

·         Place a filter paper inside the perforated bottom of the circular soil box,

·         weight the box and fill it with dried soil sample.

·         Note the weight of box filled with dried soil.

·         Place the box in Petridish of 10 cm diameter containing water for about 12 hours. So that water enters the box and saturates the soil.

·         Take the box out of water wipe it dry on the outside and records its weight.

·         To get the water hold capacity use the formula below:

                                              Water holding capacity (%)= [(W₂-W₁) -(W₁-W₀)]/(W₁-W₀) *100

                     Where W₀: Initial weight of soil box (gm)

                                  W₁: Weight of soil box with soil (gm)

                                  W₂: Weight of soil box with soil after observing water (gm)

References

1. George E., Rolf S., John R.; Methods of Soil, plant and water analysis;3^rd ed; p65

2.Sadhan C. Anand Dev G.; Handbook of Water, air and soil analysis; international E publication;2014

3.Haluschak P. Laboratory Methods of Soil Analysis Canada-Manitoba Soil Survey, April 2006