Methods of irrigation

A. Surface irrigation

• In this system, water is applied directly to the soil surface This act as the reservoir for the moisture

• This method is applicable in arid, semiarid region where topography is leveled
• It is less expensive but more water loss due to evaporation

The different methods of surface irrigation are as follows:

1. Flood irrigation:

• Here, irrigation is done by flooding the entire field in a continuous sheet
• Water is applied to the field through a canal
• It is easier and cheaper but it requires a large amount of water

2. Border-Strip system (Check-basin system):

• In this system, land is divided into long narrow strips
• The strips are 3-10 metres wide and length depends upon the slope(50-300 m)

3. Farrow system (Corrugation):

• In this system, water is applied between two ridges
• This method is suitable for the root crops such as potato and for papaya, banana, pineapple, etc
• Small furrow is prepared in between two rows and water is supplied in fruit crops
• The furrow should vary from 7.5 to 15 cm but it requires high labour cost

3. Basin system:

• In this method, circular or square basins are prepared just below the dip area of an individual fruit plants

• Irrigation channels are provided between the rows of trees to feed the basin with water
• This is most popular method practiced in orchard and ornamental tree crops

4. Ring basin irrigation system:

• In this system, 10-20 cm deep and 75 cm wide rings are prepared for each fruit plant
• Distance of ring from the plant depends upon plant size
• Similar to basin, a canal is prepared between two rows and water is supplied
• Ring and basin methods are commonly used for orchard crops

B. Sub- surface irrigation (underground irrigation)

• Here, the water is applied by underground system
• This has two methods:

a. By digging deep ditches:

• Deep ditches are made on the field and water moves laterally and vertically through capillaries and saturates the root zones

b. By applying porous or perforated pipes:

• Here, perforated pipes are laid underground below the root zones and water under pressure is distributed through these pipes
• The water reaches the root zone by capillary movement

3. Spray or sprinkle irrigation

• In this system, water pressure is applied to the surface of any crop or soil in the form of a thin spray from above through sprinkler heads or nozzles

• Sprinklers are fixed or rotating types
• In this method, pesticides can also be sprayed with water
• Sprinklers are adopted to wide range of soil type and uneven topography and slopes but it needs high cost
• This method is popular in cash and orchard crops, especially useful in rolling land that cannot be leveled or on steep slopes with erodiable and shallow soils

4. Drip or trickle irrigation

• It is the latest method of irrigation
• Drip irrigation is the frequent, slow application of water drop by drop to the root zones of crop through small outlets (emitters) located along small plastic delivery lines
• The application rate is so slow often less than 3-7.5 litres/hr/emitter
• This method is used to irrigate orchard crops and vegetables
• This method is developed by an Arabian country Israel where the water is very scarce