Keen's box is used to determine which of the following properties?

Correct option is A

The correct answer is (A) Water holding capacity

Explanation:
• The Keen-Raczkowski box (commonly known as Keen's box) is a laboratory apparatus used for physical analysis of soil.
• It is specifically designed to determine the Maximum Water Holding Capacity (MWHC) of a soil sample.
• It consists of a small circular brass box with a perforated bottom. Soil is packed into the box, saturated with water by capillarity, and then weighed.
• This method also allows for the simultaneous measurement of other physical properties like bulk density, particle density, and pore space, but its primary and most famous use is for water holding capacity.

Information Booster:
• Maximum Water Holding Capacity is the amount of water a soil can hold when all its pores are filled with water (saturation), expressed as a percentage of the dry weight of the soil.
• It is different from "Field Capacity," which is the water held after excess water has drained away due to gravity.

Additional Knowledge:
• Soil temperature (Option B): Measured using soil thermometers or thermistors.
• Soil permeability (Option C): Usually determined using a permeameter (constant head or falling head methods).
• Soil moisture tension (Option D): Measured using a Tensiometer (for low tension) or a Pressure Plate Apparatus (for high tension).