efficient irrigation system

8/7/2019 Efficient Irrigation System

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Efficient

IrrigationSystems

Efficient

IrrigationSystems

IUCN Pakistan


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Pakistans agriculture is classified as irrigated agriculturewith about 18 million hectares (Mha) of irrigated area

contributing 90% of total agricultural produce. The area

with potential for agricultural production, if water is made

available is 26 Mha. Despite enormous losses in the

irrigation system and reduced supplies due to prolonged

drought and reduced river flow, the farmers are still usinghighly inefficient and obsolete methods of irrigation.

Irrigation practices followed in the Balochistan Province are

primitive and highly inefficient. Orchards and Fruit Farms in

particular are irrigated by flooding entire fields, which

reduces water use efficiency to less than 40 percent from

water source to crop use. There is immense need to savewater due to severe water crisis being faced by the country.

Modern irrigation technologies for field crops and orchards

can help increase water use efficiencies to 90%. Though

capital intensive, the future of irrigated agriculture in the

province depends on adopting these technologies for cropproduction as water is becoming an ever-increasing

hard-to-get resource and the gap between demand and

supply widens.

The following sections give brief description of different

efficient systems/technologies popular in other parts of theworld and which could be propagated in Pakistan in

general and Balochistan in particular.

Trickle system is basically a frequent, slow application of

water either directly onto the land surface or into the root

zone of the crop through mechanical devices called

emitters or applicators located at selected points along with

the water delivery lines. It is based on the fundamental

concept of irrigating only the root zone of the crop ratherthan the entire land surface and maintaining the water

content of the root zone at near optimum levels.

The uniformity of application is not affected by wind

because the water is applied at or below the ground

Background

Trickle System

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surface. A well-designed and maintained drip irrigation

system is capable of achieving an application efficiency of

90 percent. Generally it is suitable for row crops or forgrowing new orchards.

Types of Trickle Irrigation

There are two types of trickle irrigation systems that can be

installed. These are:

i) OOOnnn---sssuuurrr

fffaaaccceee dddrrriiipppIt is the slow, nearly continuous application of water

as discrete drops. It is most suitable for newplantation or very young trees in the orchards.

ii) SSSuuubbb---sssuuurrr

fffaaaccceee dddrrriiipppIt involves the use of point and line source emitter to

apply water below the soil surface. It is most suitable for

shallow rooted crops like vegetables, strawberries etc.Discharge rate is generally the same as in drip irrigation.

Advantages The depth of water penetrating in the root zone can be

improved appreciably.

Trickle Irrigation for trees

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Water saving is achieved by low application rate,

reducing the total evaporative surface, reducing run

off, and controlling deep percolation

Greater weed control and improved quality of crops

through direct fertilizer application and meeting exact

crop water requirements

Dry soil between crop rows makes cultural operations

and labor movements easier

Fertilizer can be injected in the irrigation water

Use of saline water is possible because irrigations are

frequent and salts are diluted

Requires low energy requirements while achieving

fairly high application uniformity

Bacteria, Fungi, pest and diseases that depend on

moist environment are reduced

Applicable to all types and topography

Minimum labor requirements to maintain and operatethe system.

Disadvantages Clogging of system components by physical, chemical

and biological factors

Trickle Irrigation on flower beds

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Crop root development is normally limited to the

wetted portion of the root zone, which reduces the

plants stability to withstand winds

Not economical for high plant density crops

Excess salts may accumulate at the soil surface and

towards the fringes of the wetted soil

System CostsTrickle systems are generally considered capital intensive.

However they have a long life in some cases exceeding

20 years with high quality component materials. The per

land unit cost of the systems is highly variable and

depends on the land area to be brought under tricklesystem, the type of crop, and the spacing between plants.

Typically, in Pakistan, the cost varies from Rs. 60,000 to

80,000 per hectare for systems installed with imported

components. For systems laid with local components the

cost may reduce to 40,000 to 60,000 per hectare.

System Component MaterialsThe main components of the system are: main and lateral

pipes (PVC), fertilizer tank/injector (Aluminium or GI),

pump, tricklers/drippers (PVC), and system control

assembly (GI) and is locally available.

This system is a modified version of trickle irrigation

system. In this method water is applied to the land surface

as a small stream by tubular shaped bubblers that areattached to a buried or on the surface lateral line. The

system is suitable for growing orchards (particularly for

trees over two years of age).

Water is delivered at or near the root zone of plants in small

basins around the trunks of the trees to cover the root zone.Efficiency is achieved through minimizing evaporation and

deep percolation losses and eliminating runoff.

Generally discharge rate variations from bubblers due to

system head losses and unevenness in land topography

Bubbler Irrigation

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can be easily reduced with the help of a screwdriver. Deep

percolation, where water moves below the root zone, can

occur if a bubblers system is operated for too long aduration. On the other hand operating the system with

short duration can cause deficit irrigation.

Distribution can be adjusted for uniformity throughout a

field or for precise water delivery to individual plants based

on calculation of the moisture holding capacity of the rootzone and the daily irrigation requirements of the crop.

Bubbler systems consisting of bubblers, pipes, valves,

trenches, and basins, etc. require routine maintenance,

which is not very technical.

Advantages of Bubbler Systems Bubblers are visible and problems are noticeable

Bubblers require minimal filtration

Bubbler flow rate and wetted area are easy to adjust

Bubblers are durable and require little maintenance

Depth of water penetration in the root zone is

improved appreciably

The system allows better weed control

The soil between trees remains dry to allow easy

cultural and harvesting operations

Bubbler System cup formed by water spray

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Fertilizer can be mixed with irrigation water for directlyreaching root zone to improve crop yields and quality

Use of saline water becomes possible due to dilution

effect through frequent application of water

Energy requirements to operate the system are low at15-25 psi

Growth of bacteria, fungi, pests that thrive in moist

environment is reduced due to drier conditions around

the plant

Uniformity of application is relatively high and the

system can be laid for all topographic conditions

The system requires minimal labor requirements to

operate and maintain.

System CostsBubbler irrigation is basically just a slight modification over

trickle systems and as such the costs of these systems and

materials are similar to drip systems.

Sprinkler is a unique irrigation system. It is designed to

ensure maximum water saving, affordability and ease of

installation. Sprinkler irrigation systems are usually more

Bubbler System inverted shower

Sprinkler System

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efficient than flood irrigation systems and provide efficientcoverage for small to large areas. The system can save

water by about 35 to 40 percent when compared with flood

irrigation method.

In sprinkle irrigation system, rainfall like conditions are

created by spraying water into the air through a sprinklernozzle and allowed to fall on the land surface in a uniform

pattern. Water to the nozzles heads is delivered through a

system of pipes usually by pumping. It is then sprayed into

the air to wet the entire soil surface through spray heads so

that it breaks up into small water drops, which fall to the

ground. There are various types of sprinkler systemsavailable to suit various kinds of physical, climatic, soil, and

crop conditions. These include sprayers, centre pivot,

mobile, rain-gun systems, etc. The systems is also

adaptable to nearly all irrigable soils since sprinklers are

available in a wide range of discharge capacity and

allocation rates.

On an average, agricultural sprinkler systems are about 60

percent efficient. They are more susceptible to wind than

flood systems are, and can have much lower efficiencies in

windy conditions. The systems are suitable for almost all

field crops like wheat, gram, pulses as well as vegetables,cotton, soybean, tea, coffee, tobacco, sugarcane, and other

fodder crops and can be installed in residential and

industrial units, hotels, resorts, public & government

enterprises, playgrounds, and race courses. In recent years

the systems are being increasingly used for fire fighting, as

Sprinkler at work

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they can be programmed to automatically operate inside

building whenever a fire alarm goes off.

Advantages of sprinkle System System losses (runoff, seepage) substantially reduced

Over irrigation is completely eliminated and uniformity

of application is high

Irrigation water requirements reduced as compared to

other methods

No land levelling required in the field and land use for

productive purposes can be maximized

Fertilizer can be injected in the irrigation water to

reach the root zone directly

The system allows better weed control

Limitations of sprinkle System Poor uniformity and application efficiency in high wind

regimes and/or dry and hot conditions

Capital cost is high with greater operational costs due

to higher energy requirements

Not suitable for paddy crops

Crops prone to diseases due to moist environment

Rain Gun sprinkler

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Water with impurities and sediments may damage the

system

Cost of Sprinkler Irrigation SystemsAs for trickle irrigation, the cost of these systems is highly

variable and depends on the selected system type. A simple

rain-gun would cost around Rs. 30,000 and can be used to

irrigate over 25 acres under a rotational system. Centre

pivots are meant for very large farms and may cost Rs. 5million for a moderate sized system to irrigate 20 ha of

cropped area in one go. Pop-up systems used for irrigating

lawns are relatively cheaper and cost about Rs. 50,000 per

ha. As the systems operate under high heads, the pumping

costs are high.

In Pakistan basin irrigation is the most widely used practice

for irrigating field crops. The application efficiency of such

systems is generally very low due to deep percolationlosses, field undulations, un-compatible intake discharges,

and run-off losses. Improving and developing crops

specific field layouts can reduce the losses. Bed and furrow

irrigation system for field crops can help save water to a

great extent.

Bed and Furrow Irrigation

Bed and Furrow Method for Vegetable

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In the bed and furrow method, water is applied only in

furrows. Experiments have proved that cotton grown on

bed and furrow system had the maximum water useefficiency and yield against other methods of irrigation.

Water saved in bed and furrow irrigation can be used to

increase the cropping intensity and also for leaching the

salts in salt affected soils. An operational problem with

bed and furrow is that with the passage of time, the

furrows become cemented due to silt deposition. Waterthen moves laterally and vertical seepage of the water

reduces considerably. However with minor maintenance the

problem can be overcome.

Since water is applied in furrows, the effect of water borne

and water transmitted diseases on the crop health areminimal. The weeds, which are transported through canal

water, are trapped in the furrows from which these can be

removed or controlled easily. Moreover, the same field may

be used for inter-cropping e.g. sugarcane in furrows and

wheat on beds etc.

The cost of the bed and furrow system is low and may

consist of some tractor hours.

Bed and Furrow Method plants on beds

11 Desig

n:AzharSaeed,IUCNPak

istanCountryOffice


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IUCN-The World Conservation Union

Founded in 1948, The World Conservation Union brings

together States, government agencies and a diverse range of

non-governmental organizations in a unique world partnership:

over 1000 members in all, spread across some 140 countries.

As a Union, IUCN seeks to influence, encourage and assistsocieties throughout the world to conserve the integrity and

diversity of nature and to ensure that any use of natural

resources is equitable and ecologically sustainable.

The World Conservation Union builds on the strengths

of its members, networks and partners to enhance their

capacity and to support global alliances to safeguardnatural resources at local, regional and global levels.

IUCN Pakistan has six programme offices in cities from the

north to the south, multiple field offices and a large portfolio

of projects. It is one of the 7 Country Offices of IUCN's Asia

Programme, covering 17 countries with a workforce of

nearly 500.

Where we are:

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fffiiiccceee 1 Bath Island RoadMarker Cottage, Zarghoon Road Karachi 75530

Opposite Railway Station Pakistan

Quetta,Pakistan Tel:++92-21- 5861540

Tel:++92- 81- 840450-2 Fax:++92-21- 5861448

Fax:++ 92- 81- 820706 E-mail:[email protected]

E-mail: [email protected]

efficient irrigation system

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