Basics of Irrigation | Methods of Irrigation

Irrigation is the process of applying water to the crops to fulfil their water requirements. Supplying sufficient water at the required time is the sole advantage of studying irrigation.

The points to be noted during irrigation are:

• What method of irrigation is to be used based on the soil type and soil moisture conditions?

• How much water is required for the proper growth of crops?

• When should the process of irrigation start for a particular crop?

The rate, frequency, amount and time of irrigation are different for different crops and are also different for various pes and seasons. We will see more about the pros and cons of irrigation.

Advantages of Irrigation

• It increases food production due to the increase in crop yield

• Adequate irrigation during dry seasons can prevent failure of crops against droughts

• Higher-income is obtained by farmers as irrigation allows all type of crops to be grown in many seasons.

Disadvantages of Irrigation

• Excess irrigation of fields may cause water-logging and cam degrade the soil fertility.

• The fertilizers and pesticides applied to the crops may seep into the groundwater when the crops are irrigated regularly.

Now let's see briefly about different types of irrigation methods.

Methods of Irrigation

Basically, there are 3 types of irrigation methods. They are surface, subsurface irrigation and sprinkler irrigation.

Surface Irrigation

Surface Irrigation includes the group of water application methods in which water is applied and distributed over the soil surface either by gravity or pumping. More than 75% of irrigation in India is done through various types of surface irrigation techniques. It is best suited for soils having low to moderate infiltration capacities.

They can be classified into 3 types - Flooding, Furrow Method and Contour Farming.

Flooding

Flooding is the type of surface irrigation, which means the direct application of water to the field.

There are two types of flooding, called

1. Uncontrolled/Wild Flooding: Quantity and the direction of flow is not under the control

2. Controlled/Free flooding: Controlled distribution of water from the outlet. Again in controlled flooding, there are various types of irrigation methods possible.

Controlled flooding is again of various types, which is well represented in the above flow chart. The important controlled flooding irrigation types are discussed below.

• Border/Strip Irrigation: Strips of earth bunds/levees are constructed. Water then supplied from the ditch to the field. Lengths of strips may vary around 100-400 m. Space between the strips may vary around 10-20 m. The slope of the strips should be less than 2%.

• Check Irrigation: This type of irrigation is adopted when there are levelled agricultural lands. The lands are enclosed by the bunds. In the land, water gets stagnated for a long duration.

• Basin Flood Irrigation: This is a special type of check irrigation. Basins are formed instead of level plots. Irrigation of Orchard trees is one of the examples of basin flood irrigation.

Furrow Irrigation

Small channels of water are called furrows. In this type of irrigation, the plant is not in contact with water directly. ⅕th to ½ nd of the land gets wetted, so less possibility of evaporation. It is used for crops like Maize.

Subsurface Irrigation

In this method of irrigation, water flows in the underground and nourishes the plant roots through capillary action. It is further classified into 2 types - Natural and Artificial Sub-irrigation.

Sprinkler Irrigation

Water supply through the sprinkler system in this irrigation. Uniform distribution of water takes place. This is a slightly costly system of irrigation.

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