This document provides an overview of irrigation and various methods of irrigation. It discusses the necessity, benefits and effects of irrigation. It then describes various surface irrigation methods including uncontrolled flooding, border strip method, check method, basin method and furrow method. It also discusses subsurface, sprinkler and trickle/drip irrigation methods. For each method, it provides details on how the method works and its advantages and disadvantages.
2. •Course no. - AGRON-504
•Course title - Principles and practices of water
management
•Topic name - Methods of irrigation
3. Introduction
Irrigation is the artificial application of water to the
land or soil.
It is used to assist in the growing of agricultural
crops, maintenance of landscapes, and revegetation of
disturbed soils in dry areas and during periods of
inadequate rainfall.
5. BenefitsOf Irrigation
Increase in crop yield
Protection from famine
Cultivation of superior crops
Elimination of mixed cropping
Economic development
Hydro power generation
Domestic and industrial water supply
8. SurfaceIrrigation
• In all the surface methods of irrigation, water is either
ponded on the soil or allowed to flow continuously over
the soil surface for the durationof irrigation.
• It doesnot result in high levelsof performance.
• Thisismainly becauseof uncertain infiltrationrates
which are affected by year-to-year changesin the
cropping pattern, cultivation practices, climatic factors,
and manyother factors.
9. UncontrolledFlooding
• When water isapplied to the cropland without any
preparation of land and without anyleveestoguide or
restrict the flow of water on the field, the method is
called ‘uncontrolled’, wild or ‘free’flooding.
• Uncontrolled flooding generally results in excess irrigation
at the inlet region of the field and insufficient irrigation at
the outletend.
• Efficiency isreduced becauseof either deep percolation
or flowing away of water from the field.
• Theadvantageof this method isthe low initialcost of
land preparation.
10. BorderStripMethod
• Border strip irrigation (or simply ‘border irrigation’)is a
controlled surfaceflooding method of applying irrigation
water. In this method, the farm isdivided into anumber
of strips. Thesestrips are separatedby low levees(or
borders).
• Theborder strip method issuited to soilsof moderately
low tomoderately high intake rates and low erodibility.
• Thismethod, however, requires preparation of land
involving high initial cost.
12. CheckMethod
• Thecheckmethod of irrigation isbasedon rapid
application of irrigation water to alevel or nearly level
areacompletely enclosed bydikes.
• In this method, the entire field isdivided into a
number of almost levelled plots (compartmentsor
‘Kiaries’) surrounded bylevees.
• Thismethod issuitable for awide rangeof soilsranging
from very permeable to heavysoils.
• Lossof water through deep percolation (near the supply
ditch) and surfacerunoff canbe minimised and adequate
irrigation of the entire farm canbeachieved. Thus,
application efficiency ishigher for thismethod.
• Thereissomelossof cultivable areawhich isoccupied by
the levees.
15. FurrowMethod
• Analternative to flooding the entire land surface isto
construct small channelsalong the primary directionof the
movement of water and letting the water flow
through these channelswhich are termed‘furrows’,
‘creases’or ‘corrugation’.
• Furrows necessitate the wetting ofonly about half to
one-fifth of the field surface.Thisreducesthe
evaporation lossconsiderably.
• Furrows provide better on-farm water management
capabilities for most of the surface irrigationconditions, and
variable and severe topographical conditions.
• Possibility of increasederosion
• Furrow irrigation requires more labour than anyother
surface irrigation method.
17. SubsurfaceIrrigation
•Subsurface irrigation (or simply sub irrigation) is the
practice of applying water to soils directly under the
surface. Moisture reaches the plant roots through
capillary action. The conditions which favor sub
irrigation are asfollows:
•Impervious subsoil at adepth of 2 meters ormore,
•Avery permeable subsoil
•Apermeable loam or sandyloam surfacesoil,
•Uniform topographic conditions, and
•Moderate groundslopes
18. SprinklerIrrigation
Sprinkling isthe method of applying water to the soil
surface in the form of aspraywhich issomewhat similar
to rain.
Rotating sprinkler-head systemsare commonly usedfor
sprinkler irrigation.
Eachrotating sprinkler headapplieswater to agiven area,
sizeof which isgoverned by the nozzlesizeand the water
pressure.Alternatively, perforated pipe can be usedto
deliver water through very small holes which are drilled
at closeintervals alongasegmentof the circumference of a
pipe
19. Sprinklers havebeen used on all types of soils on lands of
different topography and slopes, and for many crops. The
following conditions are favorable for sprinkler irrigation:
• Very previous soils which do not permit good
distribution of water by surfacemethods,
• Landswhich havesteep slopesand easilyerodible soils,
• Irrigation channelswhich are too small todistribute
water efficiently by surface irrigation,and
• Landswith shallow soils andundulating lands which
prevent proper leveling required for surfacemethods of
irrigation
20.
21. Advantages
• Lowwater loss(efficiency up to80%)
• Savingin fertilizer
• Suitable for anytopography
• Nosoil erosion
• Better seedgermination, free aeration of rootzone
• Uniform application of water
22. Disadvantages
• Highinitial cost, cannot adopt by ordinaryfarmers
• Poorapplication efficiency in windy weatherand
high temperature
• Highevaporation losses
• Water should be free of debris
• Physicaldamageto cropsby application of high
intensity spray
23. Trickle(Drip)Irrigation
• Trickle irrigation systemcomprises main line, sub mains,
laterals, valves(to control the flow), drippersor emitters ,
pressuregauges,water meters, filters , pumps, fertilizer
tanks,vacuumbreakers, and pressure regulators.
• Thedrippers are designedto supplywater at the desired rate
(1 to 10 liters per hour) directly to the soil. Lowpressure
headsat the emitters are considered adequate asthe soil
capillary forces causesthe emitted water to spreadlaterally
andvertically.
24.
25. Advantages:
• Lowwater lossand hencesaveswater
• Enhancesplant growth and plant yield
• Saveslabor andenergy
• Control weedgrowth
• No soil erosion
• Improves fertilizer applicationefficiency
26. Disadvantages:
• Highskill in design,installation, and subsequent
operation
• Cloggingof small conduits andopeningsinemitters due
to sand,clayparticles, debris, chemical precipitates and
organicgrowth
• Not suitable for closelyplanted cropssuchaswheat and
other cerealgrains
