Page 29 - soil-plant-water relationship and water requirement

SOIL-PLANT-WATER RELATIONSHIP AND WATER REQUIREMENT

EXERCISE 2

1. An evaporation pan filled with 25°C of water surface temperature. The average
temperature and relative humidity in the elevation of 7.6 m from the surface are 30°C
o
and 65% respectively, and the wind speed is 12km/h. (If es at 25 C = 24 mmHg and es
at 30 C = 32 mmHg )
o

i. The real water vapor pressure ed is ……..

=A= 17.6 mmHg
=B= 15.6 mmHg
=C= 20.8 mmHg
=D= 22.4 mmHg

ii. Variable, C based on information above is …….

=A= 26.16
=B= 19.16
=C= 22.07
=D= 16.16

2. Kostiakov equation is one of the equation to determine infiltration rates. The equation
derived below is from experimental results in the field;

i  6 . 0
5 . 0 t

Based on the above equation, calculate the depth and infiltration rate after 3.5 hour.

3. Elaborate the relationship between precipitation, infiltration and run-off with the aid of
related graph.

4. Relationship between time and depth of water infiltration into the soil obtained from
double-ring infiltrometer experiment are:

Time, t (min) 60 180
Infiltration, i (cm) 3.5 8.0

Determine;

i. Value for the constants of c and α
ii. The time required for the 12cm of irrigation depth
iii. Infiltration rate at the time above.

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