As irrigation accounts for 92% of water consumption, therefore proper attention is required to conserve this water. To meet this requirement we have following two methods: 

1. Sprinkler system. 
2. Drip irrigation. 
3. On field Practices 
 

Ground water recharge may in increased by soil conservation measures and artificial recharge procedures. The amount of water infiltrated into the soil varies with the condition of soil surface and the moisture content of the soil at the time of rainfall. The total amount of water infiltered depends on the infiltration opportunity time, which depends mainly on the slope of the land and the field structures like contour bunds, terraces and other structures, which tend to hold the runoff water over long periods on the land surface. 

Adaptability of Sprinkler system:  

• Sprinkler irrigation can be used for almost all crops (except rice and jute) and on most soils. It is however, not usually suitable in very fine textured soils (heavy clay soils) where the infilteration rates are less than about 4mm per hour.

• The flexibility of the sprinkler equipment and its efficient control of water application make this method adaptable to most topographic conditions without extensive land preparation. 

• The amount of water can be controlled to meet crop needs, and light application can be made efficiently on seedling and young plants. 

• Soluble fertilizers, herbicides and fungicides can be applied in irrigation water economically with little extra equipment. 

• Sprinkler irrigation is becoming increasingly popular in India in regions of water scarcity where available water is insufficient to irrigate the command area by surface irrigation. 

• Sprinkler are also being increasingly used for irrigating high valued plantation crops like tea, coffee, cardamom and orchards.   

COST CONCEPT FOR SPRINKLER SYSTEM (2001)

Sprinkler System
Cost for constructing well and installing motor.               = Rs. 1.00 lac.
Cost for electricity connection.                                    = Rs. 0.10 lac.

Sprinkler System Set
(a) Cost of Aluminium set.                                           = Rs. 0.50 lac.
(b) Cost of PVC set.                                                   = Rs. 0.30 lac.

Each Set Contains
(a) 40 Main/Lateral lines (30 pipes for supply, 10 spraying).
(b) 10 nozzle sets.
(c) 1 T-Section.
(d) 2 Bands.
(e) 1 End joint.

Area covered = 15 feet on both sides of the lateral lines.
Total time to cover an area of one acre = 12 hours excluding shifting time.
With each set one can cover maximum area = 10 acres.

Source: Irrigation Theory and Practices by A.M. Michael  
 

Drip Irrigation 

Drip or trickle irrigation is one of the latest methods of irrigation which is becoming increasingly popular in areas with water scarcity and salt problems. It is a method of watering plants frequently and with a volume of water approaching the consumptive use of plants, thereby minimizing such conventional losses as deep percolation, runoff and soil water evaporation. In this method irrigation is accomplished by using small diameter plastic lateral lines with devices called "emitters" or "drippers" at selected spacing to deliver water to the soil surface near the base of the plants. The system applies water slowly to keep the soil moisture within the desired range for plant growth. 

In comparison to surface irrigation methods, drip irrigation can achieve 90 percent or more application efficiency. 
 
Adaptability of drip irrigation system   

• Crops like grapes, sugarcane, papayas, banana, guava and most other types of fruit trees and vegetables have been found to respond well to drip irrigation. 

• There is considerable saving in water by adopting this method since the water could be applied almost precisely to the root zone and there is no need to wet the entire area between tree crops. 

• Amount of water supplied can be varied depending on the stage of growth of the plant. 

• The method reduces salt concentration in the root zone when irrigated with poor quality ground water. 

• Like the sprinkler method, drip irrigation permits the application of fertilizers through the system. 

• Moreover, the drip method of irrigation operates on much lower line pressure, thus providing a saving in energy requirement.   

COST CONCEPT FOR DRIP SYSTEM (2001)

Drip System
Cost for constructing well and tank.                        = Rs. 1.00 lac.
Cost of electricity connection.                               = Rs. 0.10 lac.
Cost of Drip Set containing Main/Lateral.                 = Rs. 0.60 lac.
lines, emitters, joints, etc.

Time taken to cover a given area depends upon the cropping intensity and soil characteristics. Generally drip system is used in orchards.

Source: Irrigation Theory and Practices by A.M. Michael.
 

• Agronomic practices like off-season tillage (prior to pre-monsoon showers) conserve soil moisture. Moisture penetration to a depth of 90 cm is achieved if the land is ploughed to a depth of 30 cm. Other practices like early sowing of seeds, moderate use of fertilisers, weeding, pest and disease control and timely harvesting increase the yield inspite of limited moisture in the soil. 

• Mulching the soil with organic residue conserves soil moistures. 

• Terrace cultivation of hilly slopes prevents water run off. 

• Contour ploughing and planting of grasses and trees check run-off water and increase the soil's capacity to retain moisture. 

• Green manuring (incorporation of fresh green leaves into the soil) and crop-rotation (cultivating different crops in rotation depending upon the soil and climate, e.g. cereals followed by legumes) conserve soil moisture.