Water Management in Horticultural Crops (1+1)

Biosphere in relation to hydrosphere, atmosphere and lithosphere

Hydrological cycle

• Life is influenced by the earth’s unending moisture cycle known as the hydrological cycle. Moisture is constantly circulating among the land, the ocean and the atmosphere. The cycle has neither a beginning nor an end. But the concept of the hydrological cycle commonly begins with the water of the oceans. Radiation from the sun evaporates water from the oceans into the atmosphere. The water vapour rises and collects to form clouds. When the air rises, it gets cooled and precipitation (Rain, hail, sleet or snow etc.) occurs.
• Precipitation, on reaching earth’s surface, is intercepted by vegetation, may infiltrate, flow over or evaporate. Evaporation may be from the surface of leaves, soil or free water bodies. A part of the precipitation runs off over the land to streams. Another part soaks into the soil and retained in the root zone. This water may rise by plants by capillary action or percolates down due to gravity.
• In the hydrological cycle, soil acts as a reservoir; water is always in transitory storage in the soil. Considerable time may elapse before this stored water flows underground to the stream or is returned to the atmosphere by evaporation. Eventually, however, all water temporarily stored in the soil must cover the transitory part of the hydrological cycle. There are many opportunities to influence the hydrological cycle and affect water conservation in agriculture.
• The hydrological cycle is not systematic and causes the problems of drought and flood affecting food production.