Page 16 - soil-plant-water relationship and water requirement

SOIL-PLANT-WATER RELATIONSHIP AND WATER REQUIREMENT

2.1.2 Measurement of Evaporation

Estimation or measurement of Evaporation is done by the following methods

 Using evaporimeters
 Using empirical equations
 By analytical methods

Using Evaporimeter

These are water-filled pans that are exposed to the atmosphere. Evaporation
losses from these pans are recorded at regular intervals (daily). In addition to
evaporation, meteorological variables such as humidity, wind velocity, air and
water temperatures, and precipitation are observed and recorded.

i. Class A Evaporation Pan
o A pan of diameter 1210mm and depth 255mm
o Depth of water is maintained between 18 and 20cm
o The pan is made of unpainted GI sheet
o The pan is placed on a wooden platform of height 15cm above ground
level to allow free air circulation below the pan
o Evaporation is measured by measuring the depth of water in a stilling
well with a hook gauge

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