Theory:

Every living beings need water to survive.
Water is important for proper growth and development of every living organism.
Water is an essential element in agriculture.

mosel-4336787_1920.jpg
The supply of water to crops at regular intervals is called irrigation.
Water is an essential element in agriculture for the following reasons: 
  1. The plant roots absorb water. And, along with water, minerals and fertilisers are also absorbed.
  2. Plants contain nearly 90% water.
  3. Water is essential because germination of seeds does not take place under dry conditions.
  4. Water also helps the transportation of dissolved nutrients to each part of the plant.
  5. Fields have to be watered regularly to maintain the moisture of the soil for healthy crop growth.
The time and frequency of irrigation varies from crop to crop, soil to soil and season to season. In summer, the frequency of watering is higher when compared to other seasons.
 
Sources of irrigation:
The sources of water for irrigation are — wells, tubewells, ponds, lakes, rivers, dams and canals.
 
dam Image by Russ McElroy from Pixabay.jpg
 
Traditional Methods of Irrigation:
 
The water available in wells, lakes, and canals need to be lifted up to the field through different methods in different regions.
 
Cattle or human labour is used in these methods. So these methods are cheaper, but less efficient. Examples of  traditional ways of irrigation are:
(i) Moat (pulley-system)
(ii) Dhekli
(iii) Rahat (Lever system)
 
Modern Methods of Irrigation:
 
Modern methods of irrigation employs electricity and engineering in order to use the water efficiently. As it involves power and machinery, it incurs a cost.
These are two prominent methods of modern irrigation.
 
(i) Sprinkler irrigation system:
Sprinkler Image by Brenda Bonebrake from Pixabay.jpg
In this system, the water is sprinkled through small tubes and rotating nozzles attached to a major pipeline with water. When water is forced through the smaller tubes from the main pipeline, it activates the nozzles and make the water sprinkle to the adjoining area.
Sprinkler is very useful for lawns, coffee plantation and several other crops.
Sprinkler system is particularly useful in uneven surface areas.
 
(ii) Drip irrigation system:
 
Drip irrigation By Borisshin - Own work, CC BY-SA 4.0,.jpg
 
In this system, the water is made to fall drop by drop near the roots, hence, called drip system. This system best suits for watering fruit trees and gardens. In this system, water is not wasted. It is a boon for farmers in the dry regions with inadequate water resources.
Reference:
Image credit :
Drip irrigation  image - By Borisshin - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47378701
river Image - Image by Peter H from Pixabay , https://pixabay.com/photos/mosel-river-vineyards-wine-vines-4336787/
Sprinkler Image by PierrePPitlo from Pixabay,https://pixabay.com/photos/mountains-scenery-sprinklers-tree-4131823/
Dam image - from pixabay, https://pixabay.com/photos/dam-river-water-landscape-power-929406/