Question

The water characteristic curve is important because:

a) It is used to obtain the available water content of a soil

b) All organisms including roots respond to water content rather than water potential

c) It relates soil water content to the energy with which the water is held in the soil

d) b) and c) only

e) a) and b) only

Answer 1

Ans-- Option [c] It relates soil water content to the energy with which the water is held in the soil.

Water characteristic curve is the relationship between the water content and the soil water potential. This curve is characteristic for different types of soils as the water holding capacity of any soil is due to its porosity and the nature of the bonding in the soil.

Due to the hysteretic effect of water filling the pores as well as draining from the pores, adsorption and desorption curves are graphed. If the soil water potential is equal to zero, the degree of saturation of the soil is close to 100% and water is held in the soil primarily by capillary forces.

As the volumetric water content of the soil reduces, the water binds together creating suction within the soil. In a sandy soil the reduction in the volumetric water content will occur at much higher potentials than clayey soil. The amount of water a soil can retain is directly related to its porosity.