Method of irrigation

The common methods are indicated schematically as follows:

A. Surface irrigation

1. Uncontrolled or wild flooding:

• Done where water is abundant and excessive.

2. Controlled flooding:

• Water is spread over the land with proper methods to control the depth of application.

I. Check basin:

• Field divided into small plots making ridges/ bunds.
• 3×4 or 5×6 m².
• Water distributed from main ditch to subsidiary ditch.

II. Ring method:

• In Orchard.
• Circular basins.
• High water efficiency.

III. Zig-Zag method:

• Whole area divided into square or rectangular plots.
• Suitable for level plots.

Iv. Border Strip method:

• Strips of 10-20 m width and 60-300 m length,
• Done for crop which don’t tolerate flooding.

3. Furrow irrigation:

• It is narrow trench made by plough for conveying and controlling surface water in between row crops.
• Only ½ – 1/5^th surface is wetted, thus evaporation loss is very much reduced.

B. Sub-surface irrigation

• Water applied directly to the root zone by maintaining artificial water table.
• Pipe under soil is installed (10-60 cm below surface).
• Water reaches the plant root through capillary action.
• Preferable if there is little impermeable sub-surface soil at a depth of 2-3 m and uniform slope of land.
• Not suitable where the topography is irregular.

C. Drip Irrigation:

• Water is applied in the form of drop close to the root zone of the plant.
• Water is applied with minimum pressure from the main line.
• Suitable for all crops except paddy.
• Suitable in fields where water is scarce and in saline soil.
• Water loss is minimized from deep percolation, evaporation and runoff.

D. Sprinkler irrigation system:

• Sprinkler irrigation is a method of applying irrigation water which is similar to natural rainfall.
• Water is distributed through a system of pipes usually by pumping.
• It is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground.