Irrigation requirement (IR)

It refers to the quantity of water required to be applied for successful growth of crop exclusive of effective rainfall(ER) and soil profile contribution(S) including that from shallow water table.

IR = WR - (ER + S)

Three criteria for good irrigation management
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To supply right amount of water to the crop at right time and distribute it uniformly in the field one must know;-

(a) When to irrigate? Time/ Frequency of irrigation.
(b) How much to irrigate? Quantity of irrigation water/ Depth of irrigation water.
(c) How to irrigate? Method of irrigation.