Soil Water water in the soil pores and adsorbed on soil particle. The soil has solid, liquid, and gaseous phases. The liquid phase consists of soil water, which contains dissolved substances. Hence, soil water is also termed soil solution.
Water, a vital need for plant growth, comes from the soil through roots into the plant. Soil water thus plays an important role in agricultural production. It also plays a significant role in several natural processes that influence energy balance on the earth surface. The ability of soil to supply water to plants depends on soil water replenishment from precipitation and/or irrigation. Water enters into the soil through the surface and then redistributes itself along the soil depth through both macro and micro pores.
The quantity of water in soil is expressed as water content by volume or by mass. Soil water content by mass is generally measured by weighing the soil sample, drying it at 105'C for 24 hours and re-weighing it.
The maximum amount of water which can be stored in the upper 60 cm of silt loam soils in Tista and Old Himalayan Piedmont Plain alluvium is about 24 cm. These soils have the highest moisture holding capacity found in bangladesh soils. A short-term dryland crop grown in the winter months is estimated to require about 30 cm of water. Therefore, the satisfactory cultivation of dryland rabi crops on these soils without irrigation depends on the recharge of consumed water by capillary rise from deeper soil horizons and by occasional winter rainfall. [Md Akhter Hossain Khan]