Question

At field capacity the soil contains
A) Capillary and gravitational water
B) Capillary and runaway water
C) Capillary and hygroscopic water
D) Capillary, hygroscopic and bound water

Answer 1

Field capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture.

Complete answer:
At field capacity, the soil contains capillary, hygroscopic and bound water. Runaway water isn't included within the field capacity since it is the intemperate water which exits or gets depleted out from the soil after greatest retention.

Capillary, hygroscopic and bound water is shown within the soil so it can be included in field capacity. Bound water is a greatly lean layer of water encompassing mineral surfaces. Hygroscopic water is the water which is firmly connected to the colloidal molecule of the soil. It is inaccessible to the plants but shows within the soil. Capillary water is held within the soil against the pull of gravity. The water rises within the xylem due to the cohesion drive between the water molecules.

Hence the correct answer is option ‘C’.

Note: Water holding capacity is the full sum of water a soil can hold at field capacity. Sandy soils tend to have moo water capacity. Sub-soil imperatives (sharpness, hardpans etc.) can anticipate crops from getting to water within the subsoil.