Methods of applying water in irrigation fields
We can be applied to the land for irrigation by various methods. The choice of the method of application of water depends upon the available water supply, the type of soil, the topography of the land, the type of crop to be irrigated, etc. the classification are: –
- Surface irrigation
- Subsurface irrigation and
- Sprinkler irrigation
Surface irrigation methods
In this method, water is applied to the surface of the lad. There are various types of surface irrigation methods that are described in below.
Subsurface irrigation methods:-
In this method, water is applied beneath the land surface. The subsurface irrigation can be classified as:
Natural subsurface irrigation: Leakage water from sources of water such as streams, lakes, ponds, canals, etc. goes underground and during the passage to the subsoil, it may irrigate crop by capillarity.
Artificial subsurface irrigation: In this method, water is applied beneath the land surface through a network of buried perforated or open jointed pipes. As water is passed under pressure in these pipes, it comes out through open joints. The depth of pipes should not be less than 40 cm so that these do not cause any interference to the cultivation. Evaporation losses are reduced. The method is expensive because of the high cost of pipes and the installation. The water used should be of good quality so the perforation does not get clogged.
Drip or trickle irrigation:
Drip or trickle is a special type of subsurface method in which water is applied beneath the land surface near the roots of the plants in the form of small drops. The components of drip irrigation systems are the control head, pipe network, and emitters. The control head consists of an overhead tank, water measuring device, a pressure control device, a filter, and a pumping unit.
The pipe network consists of a mainline and a no of laterals. A no. of small diameter pipes, called trickle lines, are provided which take water from the lateral pipes and carry it to the root of crops.
Emitters should be provided on every trickle line with proper spacing. This method has high application efficiency, less evaporation loss, and a high cost of pipes and the installation.
- In this method, water is applied to the land in the form of a spray. It consists of a pumping unit, a network of pipes, and sprinklers. The pump lifts water from a water source and supplies it to the lateral pipelines through the main pipeline and a sub-main pipe.
- The water from the lateral passes through the risers and the sprinkler, which sprays over the land. The sprinkler may be of the fixed nozzle, perforated pipe, and rotating type.
- This method avoids the necessity of leveling of undulating land, eliminates deep percolation loss, and ensures even spread of water. In this method, fertilizers can be uniformly applied because they are mixed uniformly with irrigation water itself.
- This method is favorably adopted when the land topography is irregular, the land gradient is Tepper and the land soil is excessively permeable. The method is expensive because of the high cost of pipes and the installation. It is better to use good quality water.
Suitability of sprinker irrigation.
Sprinkler irrigation, also named overhead irrigation, is the method of watering the plants, over the field in the form of a spray or a jet which breaks into drops or droplets that are created by expelling water under pressure from a nozzle. Sprinkler irrigation simulates the natural rainfall of controlled frequency, duration, and intensity.
It enables to make economical use of water through a controlled and more or less uniform application over the entire land surface. Besides irrigation, sprinklers can also be an effective method of applying water with soluble nutrients and pesticides to the crops. To prevent pounding and surface runoff, sprinklers are designed to apply water at a rate that does not exceed the infiltration capacity of the soil.
Sprinkler irrigation is particularly suitable in the following conditions.
i) Coarse soil with poor water holding capacity where it will be difficult to maintain water distribution by surface irrigation method.
ii) Sloppy or undulating topography where land leveling is impractical or uneconomical.
iii) Poor water availability where quantity of water is not sufficient to irrigate by surface method.
iv) Feasibility to grow high value crops-fruits, vegetables, spices etc.
Techniques of surface irrigation and their suitability
The various surface irrigation method can be classified as follows :
a) Free Flooding :-
By free flooding is meant admitting the water at one corner of the field and letting it spread over the entire field. This method may be adopted where water is plentiful and cheap and the crop does not suffer from excess water eg rice.
There will be over-irrigation and large percolation losses at the corner at which the water enters while insufficient irrigation will be achieved at the farthest end. This method involves less labor because no land preparation is done in the form of levees, field ditches, grading (slope), etc.
b) Border strip, method: –
In this method, the field are divided into strips which are level across but sloping along their lengths. The width of each strip mainly depends on stream size (the discharge to be applied to the strip) and land slope.
The length and slope of the border strip are dependent on soil type, as the velocities should not be so small as to cause erosion and should not be so small as to result in a very uneven depth of infiltration from head to tail of the strip.
c) Check flooding: –
In this method, the field is divided into a number of compartments, and the water is admitted into each in turn from the farmer’s watercourse running alongside. Each compartment is essentially level. This results in a more even spread of water and avoids wastage. However, some loss of cultivated area occurs. It requires constant attendance and works during irrigation.
d) Basin flooding :-
This method is a special type of check flooding and is adopted specially for orchard trees. One tree is generally placed in the basin and the surface is flooded by ditch water.
e) Furrow irrigation: –
It consists of applying water to the furrow (a series of the long narrow channels) in between the rows of the plants to be irrigated. The water reaches the root of the plants by percolation. In this method, water is not applied to the entire surface area of land and hence evaporation losses are less. It is an excellent method for row crops like potatoes cauliflowers etc. Interesting For you: Diversion head works in irrigation- Layout and functions of component
f) Contour farming :-
In contour farming, the land to be irrigated is divided into strips aligned along the contours of the land. These strips are known as terraces. At the outer side of each strip, a low levee or dike or bund is constructed while follows the boundary configuration along the contour.
5. Advantage and disadvantages of differents methods
|1. No control over||1. No control over water.|
|2. Initial cost is less.||2. Wastage of water.|
|3. Not highly skilled man power is required||3. Chances of water loging.|
|4. Not highly developed technology is required||4. Corps may suffer from excess water|
|5. It is very easier to supervise.||5. Level tract of land is required.|
|6. Chances of erosion of soil.|
|1. No wastage of water||1. Initial cost is more.|
|2. Control over water.||2. Highly skilled man power is required|
|3. Chances of erosion of soil.||3. Highly developed technology is required|
|4. Chances of destriuction is less||4. It is very difficult to supervise.|
|1. Control over watr.||1. High cost.|
|2. Saving of water.||2. Effect of the pressure|
|3. Saving of labor||3. Effect of the wind.|
|4. Protection of soil and crops from the extreme weather conditions||4. Leaf scortch of due to salt.|
|5. Adaptation to marginal soils.||5. Clogging of nozzle.|
|6. Effiecient use of land.||6. Energy or pressure required|
|7. Frost and climate control.||7. Frequent supervision required|
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