Page 60 - soil-plant-water relationship and water requirement

SOIL-PLANT-WATER RELATIONSHIP AND WATER REQUIREMENT

Normally, irrigation should be given at about 50 per cent and not over 60 per cent
depletion of the available moisture from the effective root zone in which most of the
roots are concentrated.

In designing irrigation system the irrigation frequency to be used, is the time (days)
between two irrigation in the period of highest consumptive use of crop
growth, i.e. peak consumptive use of crop.

Design frequency (days) = F C – MC of the root zone prior to starting irrigation
Peak period consumptive use rate of crop

6.3 IRRIGATION PERIOD

Irrigation period is the duration of irrigation (time required) that can be allowed for
applying one irrigation to a given design area during peak consumptive use period of
the crop.

Irrigation period = Net amount of moisture in soil at start of irrigation (FC-PWP)
Peak period consumptive use of the crop

6.4 IRRIGATION EFFICIENCIES

These irrigation efficiencies are brought about by the desire not to waste irrigation
water, no matter how cheap or abundant it is.

The objective of irrigation efficiency concept is to determine whether improvements
can be made in both the irrigation system and the management of the
operation programmes, which will lead to an efficient irrigation water use.

In general term, efficiency is a ratio of output to input expressed as percentage. Similarly
irrigation efficiency is also expressed as a percentage and is a ratio of irrigation water
utilized to the water supplied. The irrigation efficiency inversely depends on the extent
of water loss occurring in the system.

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