Types And Methods Of Irrigation
Irrigation is one of the most important components in agriculture. There are different types and methods of irrigation used worldwide. In this article types, methods, and importance of irrigation are briefly discussed.
What Is Irrigation?
The process of supplying water artificially to the crops in an adequate amount for cultivation is known as Irrigation. Crops require water for their production at frequent intervals but in a controlled manner. An excessive amount of water is also harmful to crops and may damage the growing crops.
So irrigation is necessary for a controlled flow of water. However, irrigation is not much needed during the monsoon season if there is adequate rainfall. But on the other side, many crops are damaged during the rains as it does not have a controlled flow.
Necessity And Importance Of Irrigation
Like sunlight & air, water is the basic requirement of crops. The requirement of water for crops is fulfilled by the only source which is rainfall. But as stated in the above paragraph, rainfall does not all in a controlled manner and so it is necessary to have an irrigation system.
Water supply in an optimum quantity and proper intervals is necessary to obtain the maximum yield of the crop. This is possible when you have a proper and systematic irrigation system.
The necessity of irrigation is summarised as follows:-
i) When the rainfall is non-uniform and an inadequate amount.
ii) To increase the yield of crops.
iii) As insurance against drought.
iv) For growing a number of crops during the year.
Types Of Irrigation
There are various methods of irrigation, which are used to provide the required amount of water to crops. Depending upon the types of crops, the type of irrigation is used. Let us see different types of irrigation methods in detail below.
- Surface irrigation,
- Sub-surface irrigation,
- Sprinkler irrigation.
Surface irrigation is a method of irrigation in which the water is provided to the crops through the surface of the land. This irrigation method is mostly used where there is a bit sloppy area so the water can flow down evenly to the crops covering the whole area of land.
Surface irrigation is further classified into three types. They are as follows:-
- Flooding method
- Furrow method, and
- Contour method.
In flooding irrigation, the water is released in the field where the crops are grown and the field is filled up with water. In older times, flooded irrigation was carried out manually with a bucket. But nowadays, water is released through pumps and wells and the field is flooded.
The flooded method of irrigation is useful where the crops like rice are to be grown, which remains to be submerged in water for a longer time. The flooding method is again divided into two parts.
i) Controlled flooding and
ii) Uncontrolled flooding.
i) Controlled flooding
In this type of irrigation, the water is released in a proper and controlled way. Controlled flooding can be done using different ways such as check basin, zigzag method, border strips, etc. But all the methods of controlled flooding irrigation require prior preparation of land. The field is divided into small parts and the channels are excavated into it. After that water is released and the small divided portions are filled up with water.
ii) Uncontrolled Flooding
Uncontrolled flooding is also known as wild flooding. In this irrigation method, no preparation of land is done before releasing the water. Water is just released with no control over the flow and the field is filled up with water. In the rainy season when the water is overflowed in the rivers or streams, it is allowed to flow from the rivers and streams by just directing to the field.
In this method of irrigation, a series of long & narrow channels are dug in the direction of the slope. These channels are known as furrows. The water is released in the furrows, which also avoids the unnecessary spreading of water in the whole field.
The water-filled in the furrows slowly infiltrates into the ground and reaches the roots of the plants. Due to the furrows, the wetted area in the field reduces by approximately 30 to 50 percent, hence resulting in reduced loss of water. This type of irrigation is used for crops such as cotton, tobacco, potatoes, sugarcane, etc.
Contour farming method of irrigation is used in the hilly region where the land is sloppy. This method also controls soil erosion. In the contour farming method of irrigation, the land is divided into a series of stripes, which are known as terraces or benches.
The strips are formed in a stepped manner. The vertical distance between the two steps varies from 30 cm to 60 cm. The boundary of the step is constructed with a bund which helps to retain the irrigation water.
Sub-surface irrigation is a method in which the water is directly supplied to the roots of the crops. This method can be further classified as follows:-
- Natural sub-surface irrigation,
- Artificial sub-surface irrigation,
- Drip or trickle irrigation.
Natural Sub-surface Irrigation
In this method of irrigation, the water is reached to the roots of plants from the water table. The roots of plants acquire water from the groundwater table. For this, the water level of the water table needs to be maintained. This could be maintained by making channels near the crops which are spaced at a distance of 15 to 100 m apart.
The channels help in maintaining the water table, to ensure an adequate quantity of water available for the crops. These channels are also known as seepage channels. Sometimes the flow of water is stopped to avoid waterlogging.
Artificial Sub-surface Irrigation
In this irrigation method, water is supplied to the roots of the plants artificially through a network of perforated pipes buried under the soil near the roots of plants. In this system of pipes, water is made to pass under pressure. The pipes are buried 0.3-0.5 m deep under the soil. The main advantage of artificial sub-surface irrigation is that it eliminates the evaporation of water.
Drip irrigation is one of the latest methods known for the irrigation of crops. It is also known as trickle irrigation. The trickle irrigation method was first found in Israel. In this type of irrigation, a device known as an emitter emits the droplets of water directly near the roots of the crop.
A nozzle is fitted into the emitter which supplies the water droplets at a rate of around 2 liters to 10 liters per hour. Due to the capillary action of the soil, the water spreads vertically as well as laterally.
Sprinkler irrigation is a modern-day technique of irrigation in which a system of pumps releases a spray of water. The spray of water resembles a slow rainfall in the form of drizzle. Sprinkler irrigation is also known as overhead irrigation or spray irrigation.
Sprinkler irrigation consists of a network of components like pipes, valves, sprinklers, and pumps. This system is adopted where the surface irrigation methods are not that efficient. Sprinkler irrigation is more useful under the situations like:
- The topography is irregular.
- Erosive soil.
- Where the depth of soil is generally shallow.