Page 12 - soil-plant-water relationship and water requirement

SOIL-PLANT-WATER RELATIONSHIP AND WATER REQUIREMENT

Anywhere in the world, a portion of the water that falls as rain and snow infiltrates into the
subsurface soil and rock. How much infiltrates depends greatly on a number of factors.

Infiltrate water is the only source of moisture in the soil that helps continue the growth of
trees.

Evaporation, the process by which water transforms from a liquid to a gas, moves water from
the surface to the atmosphere. The oceans contribute for about 80% of overall evaporation,
with the remaining 20% coming from inland water and vegetation. Winds distribute
evaporated water around the world, affecting the humidity of the air wherever.
Transpiration is the evaporation of water into the atmosphere from the leaves and stems of
plants.

Plants absorb soil water through their roots and this water can originate from deep in the
soil.

Plants pump the water up from the soil to deliver nutrients to their leaves. Transpiration
accounts for approximately 10% of all evaporating water. Plants root draw water and
nutrients up into the stems and leaves.

Some of this water is returned to the air by transpiration. Transpiration rates vary widely
depending on weather conditions, such as temperature, humidity, sunlight availability and
intensity, precipitation, soil type and saturation, wind, and land slope.

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