2. Modern Irrigation Methods:

(v) Sprinkler Irrigation Method:

In present times, when water crisis is developing very fast everywhere, we should adopt improved techniques of irrigation to encourage suitable water management. Sprinkler irription method is an easy and simple method of irrigation in present times.

The whole land becomes available for cultivation of crops, whereas in traditional irrigation methods, 15 to 20 per cent land remains vacant in depres­sions and boundaries. Modern equipment’s can also be used in it due to absence of depressions and boundaries. Rate of infiltration is higher in sandy soils where frequency of watering is more. Hence, sprinkler irrigation method is more suited to sandy soils.

In sprinkler irrigation method, water is taken from source to the fields through pipes, whereas in surface irrigation methods only 30-45 per cent water reaches the crops. Such loss of water is avoided in sprinkler irrigation method. The problem of water logging or ‘kallar’ may be caused in case of excess water from surface irrigation, whereas no such problem is caused in sprinkler irrigation method. The balance of groundwater is also maintained.

For development of sprinkler irrigation method, the following circumstances are essential:

1. It is done in areas having scarcity of water.

2. Uneven ground level where irrigation is not possible by other irrigation methods.

3. Places having maximum temperature where crops might get destroyed, sprinkler irrigation method maintains humid environment for the crops.

4 .Where soil textures may be of different nature, for example, sandy soil at some places and stony soil at others places.

5. It requires lesser number of labourers hence, it can be developed even where there are less workers.

6. Irrigation may be required in large areas.

7. There should be average technical knowledge.

In areas where change in temperature of earth, environment and humidity is required for growth of crops, sprinkler irrigation method is possible to a certain extent. Due to continuous spray of water, there IS improvement in physical conditions of earth and composition of soil. In kallar or reh soils, land can be improved by sprinkler irrigation, whereas surface irrigation needs much more water for it.

Thus, it is a suitable irrigation method for sustainable development of water resources in present times. It is installed in fields by three methods:

1. Permanent:

In this method, the main line and branch pipelines are permanently installed in the field. After that it is not possible to shift its place. In this system, labour involved in shifting of lines from time to time is saved but it is quite expensive. The pipeline remains safe being underground, whereas in case it is outside, the breakages are more by frequent changing. Such an arrangement is suitable for canal irrigated areas having ‘barabandi’ where water becomes available for a very limited time.

2. Semi-permanent:

In this method, the main pipeline is perma­nently fixed under the ground level but branch pipelines are kept outside temporarily so that by changing their places, the whole of the land might be irrigated.

3. Temporary:

In this case, the whole arrangement is temporary and their places can be transferred as per requirement. In this method, more irrigation is possible with lesser investment. It of course needs more labour.

Drip Irrigation:

A newly developed irrigation system known as drip irrigation or trickle irrigation, originally developed in Israel, is becoming popular in areas of water scarcity. In this irrigation system, a small amount of water is applied at frequent intervals in the form of water droplets through perforations in plastic pipes or through nozzles attached to tubes spread over the soil to irrigate a limited area around the plant.

A precise amount of water equal to the daily consumptive use or the depleted soil water needs to be applied. The soil water can be maintained at the field capacity during the crop growing period. Deep percolation losses can be completely prevented and the evaporation loss is also reduced.

The application of water and piping systems needs to be designed according to the type of crops, topography and weather conditions typical to the geographical area.

The basic equipment for drip irrigation consists of a water supply head, a main pipe, lateral pipes and drippers. The water flow in the pipe system is controlled with control valves and fertilizers can be applied at the water source. As water passes through the very small outlets of drippers, it is filtered before h is distributed in the pipe system.