What is irrigation? Describe two methods of irrigation that conserve water.

AcademicBiologyNCERTClass 8

Irrigation 

Irrigation is the supply of water to crops at regular intervals. The frequency of irrigation is based on the type of crop, soil and season. 

For example, crops like paddy require more water. Sandy soils have less water retention capacity so need more water. Similarly, summers demand frequent watering of crops due to the increased rate of evaporation.


Irrigation is broadly categorized into two types:


1. Traditional Methods of Irrigation

The sources of irrigation are wells, tube-wells, ponds, rivers, lakes, dams, and canals. The ways to access these water sources and use it to water crops are called the methods of irrigation.


2. Modern Methods of Irrigation

The modern system of irrigation uses water more economically. 


The modern methods of irrigation are:

a. Sprinkler irrigation- It is a method of irrigation in which water is distributed similarly to rainfall. 

It conveys water evenly throughout the surface with the help of a sprinkler that has rotating nozzles on top which seems like rain falling on the surface.

It is the best method of irrigation for uneven land, as it does not need investment in leveling procedures.

This irrigation system is used to irrigate agricultural crops, lawns, landscapes, golf courses, and other areas. 


b. Drip irrigation- Drip irrigation is a technique in which water and nutrients are delivered directly to the plant's roots zone, in the right amounts, at the right time, through special drip pipes, with emitters located at different spacing, so that each plant gets exactly what it needs.  

This method of irrigation is the most efficient water and nutrient delivery system for growing crops because it saves water and increases yield.


Other types of modern irrigation methods are:

Tube-well irrigation- It is the method of irrigation in which a long, 3.9–7.9 inch wide, stainless steel tube or pipe is bored into the underground layer of water, and a pump lifts water for irrigation. 

The depth of the tube-well depends on the depth of the water table of the area.

This method is more reliable during periods of drought when surface water dries up.


River-lift irrigation- It is the method of irrigation in which water is lifted mostly from groundwater, river stream channels, and lakes with heavy capacity electric pumps, to the main delivery chamber, which is situated at the topmost point in the command area, and then distributed through the pipeline to the nearby fields within its area.

This method of irrigation made irrigation possible at a higher level.


Canal irrigation- It is the method of irrigation in which an artificial channel that is constructed to carry water to the fields either from the river and reservoir to perform irrigation.

The canals are constructed by using concrete, stone, and brick so that issues like seepage and erosion don’t occur.

This system is a permanent structure, hence only maintenance is required for getting its benefits for a long time, and it also improves groundwater storage.

raja
Updated on 10-Oct-2022 12:46:49

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