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1. 1.What is irrigation?Brieflyexplainthe differenttypesofirrigation are generallyfollowedin
Bangladesh.
Ans: Irrigation:The artificial applicationof watertoplantforits propergrowthand developmentis
calledirrigation.Itsis suppliedtosupplementthe wateravailable fromrainfall,residualsoil moisture
and groundwatercontribution.
Methodsof irrigation: There are a numberof irrigationmethodsaccordingtothe
soil,physiography,sourcesandamountof water,typesof crop ,labourcostcapital etc.The important
methodsof irrigationare showninthe Flow chart-
A. Surface irrigation: This methodsof irrigation iswidelyusedin Bangladesh.Surface irrigation
includesfloodirrigationcheck basin irrigation,border stripe irrigation,furrow irrigation and basin
irrigation.
1.Flood Irrigation
In this methods,water is allowedfrom the irrigation channel into the entire fieldandit slowlyspread
all the land. This methodsis practiced where water is in abundance and inexpensive.Itis followedin
smooth and evenland
Advantage of floodirrigation:
 Less time consuming
 Cost of irrigationis minimum
 There is no extra cost exceptlandleveling
 Labour requirementisminimum

2.  Waste of land is minimum
Limitationof flood irrigation:
 It isvery inefficientmethods
 Only 20-25% of the suppliedwater is usedby plant and rest amount islost by different
process
 It is not suitable in unleveledland
 There of no control of water
 There may be water loggingin lowerendof field
 Possibilityofsoil erosionis high
 Suitable crops: Rice,jute,Mustard,Pulses,Linseedetc
 2.Check Basin Irrigation: In this methodsthe fieldis dividedintoa number of plotsand
leveled.Itis alsoknown as bedmethods.water from the main channel issuppliedto the field
channelsone after another.Each fieldchannel supplieswaterto adjacentplots.
Advantages of CheckBasin Irrigation:
 Water can be supplieduniformly
 Soil erosionislower
 Water lossisminimum
 Water can be appliedefficiently
Limitationof Check Basin Irrigation:
 It ismore costlythanfloodirrigation
 More labourisrequiredforfieldlayoutandirrigation
 More landis wasteddue tochannel preparation
 Movementof farmanimalsandimplementsisdifficult
 Intercultivationisdifficultdue toobstructionbybunds
Suitable crops:Wheet,T.Aman,Mustard
3.Border strip irrigation

3.  Borderstripirrigationmethodsinvolvesirrigatingafieldbydividingitintolongstripseparated
by lowparallel borders(bounds).the size of the striprangesfrom30-300 m inlengthand3-15 m
inbreadth.Thismethodsforsuitable formediumtoheavytexturedsoulsbutnotforsandysoils.
 Advantage of Border strip irrigation
 Bordercan be usedforgrowingcrops
 Efficientof waterapplicationishigh
 Constructionof bordersiseasyand doesnotinvolve muchcost
 Labour requirementforirrigationislow thancheckbasinirrigation
Limitationof Border strip irrigation:
 Initial costforlandpreparationandlandgradingis high
 Excesswatermay accumulate atthe tail endof the strip
 It can be usedinlighttexturedsoils
 Suitable crops:Wheat,Oat,jowar,Mungbeen,uplandrice etc
 4.Furrow Irrigation: In furrowirrigationwaterisappliedinsmall streambetweenthe rowsof
crop grownon ridgesor furrowsides.Thismethodsof irrigationisgenerallyusedtoirrigated
row cropsand vegetables.
 Advantage of furrow irrigation:
 Great savingof wateroverother floodingmethods
 Irrigationwatercan be usedefficiently
 Flowof watercan be controlled
 Furrowacts as drainage channel
 Low cost forcrops whichare cultivatedinridge
Limitationof furrow irrigation:
 It isnot suitable forthe cropswhichdo notrequire ridge andfurrow
 More cost for furrowmaking
 It isunsuitable forlightirrigation

4.  Excessive waterflow inthe furrow canbreakthe ridge
 Weedsmaygrow I furrows
 Suitable Crops: potato,groundnut,sugarcane,coton,cabbage etc
5.Basin irrigation:
 Basinmethodsisalmostsimilartocheckbasinmethodwhere onlythe basinsaroundthe plant
are irrigated.Basinsare generallyroundinshape andoccasionallysquare orrectangular.Basins
are connectedbyan irrigationchannel.Thismethodissuitableforfruitcrops.
 Advantage of Basinirrigation
 A considerableamountof waterissaved
 Water applicationefficiencyisveryhigh
 Entire area doesnotrequire levelingexceptbasinarea
 Doesnot hamperthe fruitcrops
 No landiswasted
 Limitationof Basinirrigation
 Thismethodsisonlysuitable fortreesandshrubs
 Primarycost ishigh
 Channels andbasinsrestrictthe movementof animalsandfarmmachineries
 Suitable crops :Mango,apple,oraqngeberry,olive etc.
2.Define IrrigationandDrainage.Whatare the importance of irrigationanddrainage inrelationtocrop
productioninBangladesh.
 Ans:Drainage: Advantage waterisessentialforcropplantbut the excesswaterisharmful for
crops. Soas the irrigationisneededtomeetthe waterrequirement,the excesswatershould
alsodrainout immediately,the artificialremoval of excesswaterfromcropfield iscalled
drainage.
Importance of irrigationto crop production:

5.  To ensure the propergrowthand development of plantbysupplyingadequate water.
 To make the plant nutrientsoluble sothattheycan be easilyuptakenbyplant
 To accelerate the decompositionof organicsubstances
 To control soil temperature
 To softentillage pansandclods
 To control some destructivespestsanddiseases
 To avoidshort durationdrought
Water for foodproduction:
For vegetative growthanddevelopment,plantsrequire,withinreachof theirroots,waterof
adequate quality,inappropriatequantityandatthe righttime.Most of the water a plantabsorbs
performsthe functionof raisingdissolvednutrientsfromthe soil tothe aerial organs,fromwhere it
isreleasedtothe atmosphere bytranspiration:agricultural wateruse isintrinsicallyconsumptive.
Cropshave specificwaterrequirements,andthese varydependingonlocal climaticconditions.
Whereasan indicative figure forproducingone kilogramof wheatisabout1000 litresof waterthat
isreturnedto the atmosphere,paddyrice mayrequire twice this amount.
Importance of drainage to crop production:
 Drainage improvesthe soil structure and increasesproductivity
 It facilitatesproper growth of crop plants
 It facilitatesearly ploughingand planting
 It facilitatesproper root growth
 It increase soil erosion
 It increase soil temperature
 It preventthe soil from water logging

6. 5 importance of drainage:
1. Drainage ensurespropersoil aerationismaintainedinthe field.Excesswater(afterarainfall for
example),cancause standingwater(orsaturatedsoil) whichwillchoke ourcrops.
2. Drainage reducessoil andnutrientlossviarunoff where waterflowsonthe soil surface,causing
erosion.
5. Drainage can be such sothat waterand soil sedimentsare channelledandcollectedinsediment
ponds/basins/ditches,wherecollectedwatercanbe savedforfuture use duringperiodsof dryweather
or the collectedsoil sedimentsreturnedbacktothe farm.
3.What is AWD? BrieflyexplainAWDas a water saving technologyin Bangladeshrice production.
Ans: Rice is the staple food of 164 million Bangladeshis, accounting for 77% of the total
cropped area and two-thirds of the value-added of crop production, with an agrarian
structure dominated by marginal and small farm holdings. During the past decades,
rice production in Bangladesh experienced an impressive intensification. In the north
and north-western divisions of Rajshahi and Rangpur, the increase in rice production
is largely attributed to an unprecedented expansion of dry season cultivation,
triggered by the liberalization policy for small-scale irrigation equipment.
The change to dry season rice, constituting about 60% of national rice production,
was largely due to groundwater irrigation by shallow tube wells (STW) and deep tube
wells (DTW). This practice led to the massive extraction of groundwater, an
overexploitation of groundwater, locally manifested by declining groundwater tables
in Rajshahi. Correspondingly to the expansion of irrigation, demand for energy
increased, as electricity or fuel are needed to lift groundwater to the surface. This
also touches on the chronically deficient energy situation of Bangladesh.
To address problems of water scarcity, researchers had been looking for ways to
decrease water consumption of the rice crop. Alternate Wetting and Drying (AWD) is
a technology developed by the International Rice Research Institute (IRRI). The
technology is based on the knowledge that rice tolerates up to 30% reduced water
supply during the main growing period compared to conventional irrigation. To
determine the timing of irrigation, the water level in the soil is monitored by a
perforated plastic tube, which is inserted into the rice field. AWD requires irrigation
when the water level drops to 15 cm below the soil surface.
Under technical assistance from IRRI (Dr. Hamid Miah), a number of NGOs like RDRS
implemented AWD technology in farmers’ field during boro rice season. This technology was
piloted in 109 farmers’ field in 2009-2010, where farmers cultivated boro rice with reduced
number of irrigations (11 irrigations instead of 17) and received almost the same yield as in the
case without AWD system. This reduced irrigation saved 35% irrigation cost. However, it was
observedthat weed infestation was occurred in AWD plots, which resulted in increased hired
labourer cost for weeding.Although the number of irrigation was reduced significantly (30%)
and the corresponding irrigation cost was reduced by 35%, the benefits went tothe pump owners
due to a fixed rate arrangement system between pump owner and farmers settled at the beginning

7. of the season. It means the user has to pay the full payment as agreed despite reduced number of
irrigation provided.
4. What do you meanbyHydrologycycle?Brieflyexplainthe hydrologycycle of water.
Ans: Hydrologytreatsthe watersof the Earth,theiroccurrence,circulation,anddistribution,their
chemical andphysical properties,.However,hydrologyforirrigationincludesthose segmentsof the field
pertinenttoplanning,designing,andoperationof irrigationprojectsforthe control anduse of water.
The conceptsof the hydrologiccycle is useful tounderstandoccurrence anddistributionof
precipitation.”
• At beginningwaterevaporatesfromthe oceans.
• The resultingwatervaporistransportedbymovingairmasses.
• Under the properconditions,the watervaporiscondensedtoformclouds,whichinturnmay
resultinprecipitation
 A portionof waterfindsitswayoverand throughthe surface soil to streamchannels

8. • Otherwaterpenetratesfurtherintothe groundtobecome partof the groundwater
• Consequentlyunderthe influence of gravity,bothsurface streamflowandgroundwatermove
towardslowerelevationsandmayeventuallydischarge intothe ocean.
• The greaterpart isretainedinthe soil nearwhere itfallsandisultimatelyreturnedtoocean
• A significantpartisinterceptedbyvegetation
• There are fourphasesof hydrologiccycle
• Precipitation (rain,hail,sleetorsnow)
• Evaporation& transpiration
• Surface streamflowand
• Groundwater
Sources ofprecipitation: The Hydrologic cycle- (rain, hail,sleetor snow)
Sources ofirrigation water:
Surface – River,dam, lake, ponds
Underground- Wells,STW,DTW,Canats, -
5. Define Drainage.Whatare the objectiveof drainage?How drainage improvesthe soil productivityfor
bettercrop production?
Ans:Drainage: Advantage waterisessentialforcropplantbut the excesswaterisharmful forcrops.So
as the irrigationisneededtomeetthe waterrequirement,the excesswatershouldalsodrainout
immediately,the artificialremovalof excesswaterfromcropfieldiscalleddrainage.
Objective ofdrainage:
 Drainage improvesthe soil structure and increasesproductivity
 It facilitatesproper growth of crop plants
 It facilitatesearly ploughingand planting
 It facilitatesproper root growth
 It increase soil erosion
 It increase soil temperature

9.  It preventthe soil from water logging
Drainage improvesthe productivityof soilsin the followingway:
 Removesexcess water
 Improvessoil structure
 Increase the depthof root zone
 Improvesthe air circulation in the soil
 Improvesthe organic matter decayand nitrification
 Reduce erosion;higher infiltrationreduce soil erosion
 Removessoluble saltsfrom the root zone or soil profile
 Increase soil temperature
 DecreasesCO2 accumulation and increase oxygenlevel
 Increase the availabilityof nutrientsto plants.
6. Whatdo you meanby soil structure and soil texture?What are the texture classificationof soil?
 Ans: Soil structure
 Soil structure is the shape that the soil takes on based on itsphysical and chemical properties.
Each individual unitof soil in the overall structure is calleda ped. Soil structure is most easily
determinedbytaking a sample of soil that has not beendisturbedand lookingcloselyat its
shape.The shape of the soil will fall into one of the followingcategories:granular, crumb,
blocky, platy,prismatic, columnar, single-grained,ormassive.
 Soil texture:Soil texture isasoil propertyusedto describe the relative proportionof different
grainsizesof mineral particlesinasoil.Particlesare groupedaccordingtotheirsize intowhat
are calledsoil separates.These separatesare typicallynamedclay,silt,andsand.Soil texture
classificationisbasedonthe fractionsof soil separatespresentinasoil.The soil texture triangle
isa diagramoftenusedtofigure outsoil textures.
 Soil texture classification
 Soil texturesare classifiedbythe fractionsof eachsoil separate (sand,silt,andclay) presentina
soil.

10.  Classificationsare typicallynamedforthe primaryconstituentparticle sizeora combinationof
the most abundantparticlessizes,e.g."sandyclay"or"siltyclay."
 A fourthterm,loam,isusedto describe aroughlyequal concentrationof sand,silt,andclay,and
lendstothe namingof evenmore classifications,e.g."clayloam"or"siltloam."
 In the UnitedStates,twelve soil texture classificationsare definedbythe USDA:
 Determiningthe soil texturesisoftenaidedwith the use of a soil texture triangle.
 Clay, Silt,Sand ,Loam ,Siltyclay ,Sandy clay ,Clay loam ,Siltloam ,Sandy Loam ,Loamy
sand,Siltyclay loam ,Sandy clay loam