For the survival and proper development of crop plants water is very important compound.
Fields have to be irrigated time to time according to the requirements of different crops. By evaporation, constant loss of water takes place from the plant body.
This results in decrease of water in the plants; so periodically water supply is needed to the plants. The artificial water supply to the crops or to the cultivated fields is called irrigation (Fig. 13.7).
There are so many sources of irrigation, such as lift irrigation, water wheel, swinging basket, sprinkler and tube well. A large amount of water is reserved under the ground, supplied by percolation water after rains. This water is drawn out by tube wells and water wheels.
Methods of Irrigation:
There are following methods of irrigation:
1. Flood irrigation:
The method is used if the land is flat and leveled. Water is allowed through canals or pump sets up to the field, but it is successful if water is available in plenty (Fig. 13.8).
2. Basin irrigation:
Pumpkin and sweet gourd are irrigated by this method. A ring or flat basin is made around the plant and a number of plants are connected with a ditch passing between the rows of plants. The soil around the plant is wet with water, not the entire soil or land.
3. Furrow Irrigation:
Potato, cotton, radish and sugarcane are the crops which are irrigated by furrow methods. In this method water is applied to the furrow between the two ridges and the top of the ridges is not directly supplied with the water (Fig. 13.9).
4. Sprinkler Irrigation:
This method is used where flood or furrow method is not possible. Water is sprayed on the standing crops in the form of artificial rain (Fig. 13.10).
5. Lift Irrigation:
Water is lifted from the underground wells by oil engines or electricity then water is supplied to the fields.
6. Drip Irrigation:
This is the latest irrigation system in which small amount of water is allowed to trickle slowly into the soil through mechanical devices.