Water contained in soil is called soil moisture. The water is held within the soil pores. Soil water is the major component of the soil in relation to plant growth. If the moisture content of a soil is optimum for plant growth, plants can readily absorb soil water. Not all the water, held in soil, is available to plants. Much of water remains in the soil as a thin film. Soil water dissolves salts and makes up the soil solution, which is important as medium for supply of nutrients to growing plants.
Importance of Soil Water
Soil water serves as a solvent and carrier of food nutrients for plant growth
Yield of crop is more often determined by the amount of water available rather than the deficiency of other food nutrients
Soil water acts as a nutrient itself
Soil water regulates soil temperature
Soil forming processes and weathering depend on water
Microorganisms require water for their metabolic activities
Soil water helps in chemical and biological activities of soil
It is a principal constituent of the growing plant
Water is essential for photosynthesis
Retention of Water by Soil: The soils hold water (moisture) due to their colloidal properties and aggregation qualities. The water is held on the surface of the colloids and other particles and in the pores. The forces responsible for retention of water in the soil after the drainage has stopped are due to surface tension and surface attraction and are called surface moisture tension. This refers to the energy concept in moisture retention relationships. The force with which water is held is also termed as suction.