Irrigation is defined as the science of the artificial application of water to the land in accordance with the crop requirement throughout the crop period for full-fledged nourishment of the crops ( the artificial application of water to the land for the purpose of raising crops ).
Necessity of irrigation
- Inadequate rainfall: When rainfall at the place is inadequate to meet the water requirement of the crops, irrigation is necessary.
- Uneven distribution of rainfall: Irrigation is necessary when the rainfall in the region is adequate but it is not evenly distributed over time.
- Increasing the yields of crops: The yield of crops per hectare is substantially increased by irrigation as the supply of water is properly controlled. Although the rainfall may be adequate for the ordinary crops it may not cater to the needs of high yielding varieties that require more water. In such a case, the yield can be substantially increased by irrigation.
- Growing number of crops: The rainfall in a region may be sufficient to grow only one crop in a year but it may be inadequate when a number of crops 2 to 3 are grown in the same year.
- Growing perennial crops: As rainfall is not regular, irrigation is necessary for the perennial crops.
~ Growing superior crops
~ For controlled water supply
Function of irrigation
- Reliable and continuous supply of water.
- Continuous cropping with high yields.
- Sub- surface drainage and sub-soil aeration.
- Maintaining and water depth within the root zone.
Scope of irrigation
It deals with all dimensions extending from the watershed to the agriculture farms. Broadly the scope of irrigation can be divided into the following categories:
1) Engineering aspect
- Storage, diversion and lifting of water
- conveyance of water to agriculture lands
- Application of water to agriculture lands
- Development of water power
~ drainage and relieving waterlogging
2) Agricultural aspect
- Depth of water
- Distribution of water
- The capacity of soil and flow of water
- reclamation of lands
Irrigation methods / Irrigation types
Previously I had told you the meaning of irrigation but here i am going to explain to you about methods of irrigation. Irrigation may broadly be divided into followings:
A) Surface irrigation: In surface irrigation methods, the water is directly applied to the surface of the land. It further classified as follows;
- Flow irrigation: When water is available at a higher level and it is supplied to lower level by mere action of gravity then it is called flow irrigation. It further subdivided as follows;
- Perennial irrigation: constant and continuous water supply throughout the crop period
- Flood irrigation: This type of irrigation is called inundation irrigation. In this method of irrigation, the soil is kept submerged and thoroughly flooded with water so as to cause saturation of land.
- Lift irrigation: If water is lifted by some mechanical or manual means such as by pumps etc and then supplied for irrigation then it is called lift irrigation.
B) Sub-surface irrigation:
~ In this type of irrigation, water does not wet the soil surface.
~ It may be divided into two types;
- Natural sub-surface irrigation: When underground irrigation is achieved simply by natural processes without any additional extra efforts it is called natural subsurface irrigation.
- Artificial sub-surface irrigation: When a system of the open jointed drain is artificially laid below the soil so as to supply water to crops by capillary then it is called artificial subsurface irrigation.
Advantages of Irrigation
- Increase in food production
- Elimination of mixed cropping
- Generation of hydropower
- Domestic water supply
- Flood control
Disadvantages of Irrigation
- Water pollution by seepage
- Irrigation may result in colder and damper climate, resulting in marshy land
- Breeding of bacteria and mosquitoes causing an outbreak of a disease like malaria
- Waterlogging due to over-irrigation
- Procuring and supplying irrigation is complex and expansive in itself.
I hope you liked my article on “Irrigation meaning | Irrigation types | Irrigation methods”