Irrigation Management Under Limited Water Supply


Integration of all water resources like surface, ground water, wastewater, snow, dew etc., is most important to achieve maximum food production per unit quantity of water used to meet the demand from 1 billion population present. In this juncture, water resources itself become a constraint due to abnormality in distribution and uncertainty it in the occurrence of rainfall. Hence, at present frequent droughts are very common.

Under these circumstances, a new water saving strategy has to be adopted in irrigation management and in crop production activities. This part of the chapter discusses about water scarce conditions and the ways to overcome it with some drought alleviating methods.

Water Scarcity Conditions

Water scarcity is the term used for poor storage or non-availability of required quantity of water for the purpose of crop production and otherwise due to failure of monsoons. The scarcity will lead to inadequate supply of water to the cropped fields, which in turn create a stress in plant community. This degree of stress varies depending upon the frequency of irrigation, nature of the crop, type of soil etc. In this situation our primary aim is to produce the maximum possible yield per unit quantity of water. The following are some management techniques under stress periods.

Assess resource potential – Based on the water potential, optimize the water use by linear programming techniques. This type of exercise should be done by the concerned department especially irrigation and agriculture.

Farmer’s attitude – Farmer or user’s behaviours need considerable reorientation to enable them to realize that water is an economic input and conservation of water is their prime responsibility.

Improvement in conveyance structure – A large quantity is lost through conveyance from source to field. It is estimated that about 30-40% of water is lost in conveyance systems. Reducing or totally preventing such losses of water can be made by proper maintenance, lining the channels etc. Conveyance by pipes is often adopted for ground water resource. Such conveyance may be made even at small sluice level in command areas.

Conjunctive use of water – Integrating all water resources with water conservation methods is termed as conjunctive use. Optimum use of water from different source is the main aim of conjunctive use. For example, in canal irrigation system the utilization of rainfall and well water optimally to protect the crop without eroding a single resource of water is termed as conjunctive use of water.

Contingent plant for rice – Rice is a semi-aquatic plant, which needs submergence of water for its establishment and better yield. The experimental evidences clearly indicated that 5 cm depth of ponding one day after disappearance of previously provided water is superior to higher depths. This was attributed to better aeration and consequently improved root activities.

This finding is helpful not only for micro level alone but also to change the water release pattern at macro level too and a turn system can be adopted in canal operation system. Further investigation reveals that 2 days dry spell in light textured soil and 2–3 days dry spell in heavy textured soil can be advocated without much yield reduction.

If further scarcity arises, the next management techniques to save the rice crop is to adopt irrigation at critical stages. Different crop growth stages have different response to water stress. In rice crop the most sensitive periods for water stress are active tillering (AT), primordial initiation (PI), and flowering and milky stages. Dry spell during these periods will drastically reduce the yield.

Other Management Techniques

• Summer ploughing reduces runoff by increasing the infiltration and thereby reduces water needed for land preparation.

• Dry nursery with seed hardening technique (1% KCl) can be made which in turn will enhance the drought tolerance capacity.

• The short duration varieties like ADT 36, IR 36 and IR 50 can be chosen.

• During transplanting, it is enough to irrigate to a depth of 2 cm of water in the field. After that, maintaining 2.5 cm of water up to 12 days is sufficient.

• Application of herbicide within 3–5 days reduces the weed competition for water which in turn saves water considerably.

• After 12 days of transplanting, irrigating 5 cm of water one day after the disappearance of ponded water can be adopted not only to save water but also to increase the yield to some extent.

• Plastering field bunds and plugging of all crevices, rat and crab holes to avoid water loss through seepage.

• Proper levelling of the field.

• Water should be stopped 10–15 days before harvesting.

• Semidry rice (direct down) saves 30–40% water.

• Application of potassium in 3 split doses as 50% basal 25% at tillering and 25% at panicle initiation.

• Application of cycocel at the rate of 1000 ppm.


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