W.R in lit /day/plant= crop area X PE XPCX KC X wetted area.
Where,
Crop area (m2)= Row to row spacing X Plant to plant spacing in m.
PE= Per evaporation mm/day.
PC= Pan evaporation 0.7 (ave)
KC= Crop efficient of crop factor.
The value of crop factor for any crop depends on foliage characteristics, stage of growth, environment and geographical location.
The values of KC ranges from 0.4 to 1.0 and average value of KC is about 0.7.
Example:
1. Find out water requirement of mango crop (5mX 5m) having pan evaporation of the region is 8 mm / day and % wetted area is 40. Assume crop factor and pan coefficient.
Solution:
W.R= Crop area X PE X PC X KC X % wetted area
= 5m X 5m X 8 x 0.7X 0.7 X 0.4
= 39.2 lit/day/plant
2. Find out water requirement of banana crop ( 5ftX 5ft) having pan evaporation of the region is 8 mm / day/ and % wetted area is i80. Assume crop factor and pan factor.
Solution:
W.R = Crop area X PC X PC X KC X % of wetted area
= (5 X 0.3058 X 5 X X 0.3048) X 8X 0.7 X 0.75 X 0.80
