Drip Irrigation: Way towards conservation of water resources

Drip Irrigation

Drip Irrigation 

Way towards conservation of water resources 

-Dr. Arvind Singh 

Drip irrigation which is also known as ‘trickle irrigation’ is a slow application (2-20 litres/hour) of water drop by drop to the root zone of the crop from a system of small diameter plastic pipes fitted with outlets called emitters or drippers.

The method of drip irrigation was devised and initiated in Israel and is now being used in other countries of the world. In drip, irrigation water is used very economically, since losses due to deep percolation and surface evaporation are reduced to a minimum. This method is therefore very much suited to arid regions and is being followed by irrigating orchard crops at present. The successful growing of orchard even on saline soils has been made possible by the drip irrigation system. The system is also used for applying fertilizers in solution.

Drip irrigation is best suited to areas where water quality is marginal, the land is steeply sloping or undulating and of poor quality, where water or labour is expensive, or where high-value crops require frequent water applications.

What are the advantages of drip irrigation?

1. The water use efficiency in drip irrigation is as high as 95% as compared to only about 50% under the conventional irrigation system. So it has the potential to convert the non-productive areas such as deserts, hilly areas and other arid and semi-arid areas into fertile lands.
2. Drip irrigation delivers exact quantities of water and other nutrients, thereby cutting down wastages. So it not only solves the problems of water scarcity but also the input costs of fertilizers, pesticides, power and irrigation declines by approximately 30%. 

3. It leads to faster plant growth as it supplies controlled, uniform and exact quantities of water and other nutrients at the root zones. Thus leading to an increase in yield and also checks the growth of weeds. 

4. Drip irrigation is suitable to the area of acute water shortage. 

5. Deep percolation and surface runoff losses of water are non-existent in drip irrigation. 

6. Evaporation loss is reduced. 

7. Drip irrigation can be put to use even during the night. 

8. It provides the most ideal moisture level conditions for good plant growth. 

9. In drip irrigation fertilizers in the solution can be applied through dripper. 

10. Disease spread is less in drip irrigation especially those diseases which spread by irrigation water. 

11. Insecticides and fungicides are not washed away in drip irrigation. 

12. Saline water can be safely used in a drip irrigation system. 

13. There is less weed growth due to limited surface wetting. 

14. The drip irrigation increases the yield up to 150%. 

15. It saves water up to 70% compared to conventional irrigation. 

16. Drip irrigated crop grows consistently, healthier and matures fast. The early maturity of crops results in higher and faster returns on investment. 

17. The cost of fertilizers, inter-culturing and labour use gets reduced under drip irrigation. 

18. Undulating terrains, saline, waterlogged, sandy & hilly lands can also be successfully brought under cultivation by drip irrigation. 

19. Fertilizer and nutrient loss is minimized owing to localized application and reduced leaching. 

20. Water application efficiency is high in drip irrigation. 

21. Drip irrigation conserves soil by reducing the rate of soil erosion. 

22. Water distribution is highly uniform in drip irrigation. 

23. Labour cost is less than other irrigation methods. 

24. Variation in the supply of water can be regulated by regulating the valves and drippers. 

25. In drip-irrigated crops foliage remains dry, reducing the risk of disease. 

26. Drip irrigation is usually operated at a lower pressure than other types of pressurized irrigation, reducing energy costs.

What are the disadvantages of drip irrigation? 

1. Higher initial installation cost. 

2. Pipes are liable to rodent damage. 

3. Turbid water cannot be used as it clogs the emitters. 

4. Salt accumulation near plants due to lack of sufficient water for leaching. 

How does drip irrigation system works?

A typical drip irrigation system consists of the pump unit, control head, main and sub-main lines, laterals and emitters.

The pump unit takes water from the source and provides the right pressure for delivery into the pipe system. The control head consists of values to control the discharge and pressure in the entire system. It also has filters to clean the water. Some control head units contain a fertilizer or nutrient tank. These slowly add a measured dose of fertilizer into the water during irrigation. This, in fact, is one of the major advantages of drip irrigation over other methods.

The mainlines, sub-mains and laterals supply water from the control head into the fields. They are generally made of polyvinyl chloride (PVC) or polyethene hose and are buried below ground as they are vulnerable to damage by direct solar radiation. Lateral pipes are usually 13-32 mm in the diameter.

The emitters are devices used to control the discharge of water from the lateral to the plants. They are usually spaced more than 1 meter apart with one or more emitters used for single plant such as a tree, for row crops more closely spaced emitters are used to wet a strip of soil.

Which crops are suitable for drip irrigation?

Drip irrigation is most suitable for row crops (vegetables and fruit crops), tree and vine crops where one or more emitters can be provided for each plant. Generally, only high-value crops are considered because of the high capital costs of installing a drip system. Drip irrigation is used by farms, commercial greenhouses and residential gardeners.

Drip irrigation is most suitable for widely spaced crops. Fruit trees like apples (Malus sylvestris), grapes (Vitis vinifera), oranges (Citrus reticulata), lemon (Citrus lemon), banana (Musa paradisiaca), pomegranate (Punica granatum), Chinese date (Ziziphus mauritiana) and mangoes (Mangifera indica), and vegetable crops like tomato (Lycopersicon esculentum), brinjal (Solanum melongeana) and cucumber (Cucumis sativus) can be irrigated with drip irrigation system. The crops, other than fruits trees and vegetable crops, which can be irrigated with drip irrigation are cotton (Gossypium spp.), sugarcane (Saccharum officinarum) and maize (Zea mays).
 

What is the pattern of root development under drip irrigation?

The development of root system under drip irrigation is quite different compared to that in another irrigation system. Drip irrigation wets only a fraction of soil volume in the field. The limited wetted soil bulk results in a corresponding low root zone volume. However, the root system which is denser within the water boundaries compensates for the loss in spreading. There is no sign of poor anchoring of roots due to drip irrigation. Mature trees and bearing trees shifted to drip irrigation after using other irrigation methods, adapt readily to the new water regime.

Conclusion:

Conclusively it can be said that drip irrigation is a technique of irrigation in which water is used economically to irrigate the plants. This irrigation technique not only ensures the conservation of water and soil resources but it also leads to increased yield. Therefore, drip irrigation is necessary to achieve the goal of sustainable development.

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Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with an area of specialization in Ecology. He is a dedicated Researcher having more than four dozen of published Research Papers in the Journals of National and International repute. His main area of Research is Restoration of Mined Lands. However, he has also conducted research on the Vascular Flora of Banaras Hindu University-Main Campus, India.  

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