09. Water productivity in irrigation - Palanisamy et al.docx

7/24/2019 09. Water productivity in irrigation - Palanisamy et al.docx

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Water Productivity at Farm Level in Bhavani Basin, Tamilnadu -

Estimation, challenges and approaches

K.Palanisami and T.Ramesh

Water Productivity

Growing demand for water for industry and municipalities, combined with environmental

problems results in less water for agriculture in the future. One of the approaches to meet

the future water shortages will be increasing water productivity which means raising crop

yields per unit of water consumed. Over the past three decades, this has been achieved

largely through higher crop yields per hectare. In its broadest sense, it means getting

more value or benefit from each drop of water used for crops, fish, forests and livestock

while maintaining or improving ecosystems and the services they provide. Within

agriculture, this means obtaining more production or value from every drop.

Water productivity or yield per unit of water, like yield per unit of land, is partialproductivity of just one factor. urther, the definition of water productivity is scale!

dependent. or a farmer, it means getting more crop per drop of irrigation water. "ut, for

society as a whole, concerned with a basin or country#s water resource, this means getting

more value per unit of water resource used. Increasing water productivity is then the

function of several components at different levels vi$., plant, field, irrigation system and

river!basin. %n increase in production per unit of water diverted at one scale does not

necessarily lead to an increase in productivity of water diverted at a larger scale. &he

classical irrigation efficiency decreases as the scale of the system increases '(eckler et

al., )**+. "asin water productivity takes into consideration beneficial depletion for


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al., )**+. "asin water productivity takes into consideration beneficial depletion for

"ut, with the declining crop yield growth, attention has turned to the potential offered by

improved management of water resources. &he amount of reuse 'or recycling of water is

often underestimated. When reuse is taken into account, the options for further increases

in water productivity are much smaller than were e0pected at first.

urther, classical irrigation efficiency is defined as the crop water re/uirement 'actual

evapotranspiration minus effective precipitation divided by the water withdrawn or

diverted from a specific surface!water or groundwater source. 34osses# in this approach

include transpiration and evaporation 'evapotranspiration, but also seepage, percolationand runoff, processes in which the water is not consumed. &hese latter so!called 3losses#

may be captured or recycled for use elsewhere in the basin. &hus, classical measures of

efficiency tend to underestimate the true efficiency and ignore the important role of

surface irrigation systems in recharging groundwater and providing downstream sources

of water for agriculture and other ecosystem services.

5rop water productivity is defined in either physical or monetary terms as the ratio of theproduct 'usually measured in kg over the amount of water depleted 'usually limited to

crop evapotranspiration, measured in m+. Occasionally 6 for e0ample, in the conte0t of

supplemental irrigation 6 there is a felt need to e0press the productivity of the applied

irrigation water. In that case, the denominator refers to irrigation water only, not to

rainfall. Obviously, vales of irrigation!water productivity cannot be compared with waterproductivity with depleted water in the denominator.

&his study taking into account the multiple uses of water, /uantifies the productivity of

water in irrigated agriculture, along with livestock and fishery components.


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Water re/uirement is therefore, a demand and the supply would consist of contributions

from any of the sources of water, the major source being the irrigation water 'I:,

effective rainfall ': and soil profile contribution '( including that from shallow water

tables. ;umerically therefore water re/uirement is given as

W: 8 I:9 :9 (

Irrigation water is calculated at farm level using pump discharge rate, hours of irrigation

in single time and number of irrigation to a particular crop.

I: 8 ump discharge rate < hours of irrigation 'one time < ;o. of irrigation

ffective rainfall is generally taken as => ? probability level. It is minimum assured

rainfall that will be available in + years out of @ years. It is calculated by using a

minimum period of )> years past rainfall. &he rainfall data will be arranged in

descending order and the rainfall /uantity that falls at =>? probability level considered aseffective rainfall of particular month or year.

#rop output %economic yield&

Grain yield of particular crop 'kg is considered for working water productivity in

physical term. If we want e0press in economic term, the income from grain yield and the

additional income from byproducts also taken in to account.

#rop !ater productivity


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Livestoc" output

&otal milk yield '4ts per animal per lactation period can be calculated.

Livestoc" !ater productivity %LWR&

4ivestock water productivity 8 Dilk yield 'ltsB total water used 'm+

8 Gross return ':s.B total water used 'm+

Fishery !ater re$uirement %FWR&

Euantity of water maintained in the fish pond as dead storage is calculated using the si$e

of the fish pond and height of water column. &he /uantity of water added to the fish pond

at particular interval to maintain the dead storage can be accounted as evaporation loss

from the fish pond. Water used for fish feeds is considerable as negligible amount.

W: 'D+ 8 Cead storage 9 vaporation loss

Fishery output

&otal fish yield in a unit time and unit area is calculated. &he sediments obtained from

fish pond may be accounted as nutrient value basis in economical terms.

Fishery !ater productivity

' &otal fish yield 'kgB total water used 'm+

Total (arm level !ater productivity8&otal income from whole system ':s.B total water used 'm

+

+ Preliminary Results


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&able 1. roductivity per unit /uantity of water under canal system

articulars4ower "havani roject

-ead region &ail region

1. 5rop addy addy

). (oil type :ed non!

calcareous

:ed non!

calcareous

+. (eason (ep!Cec (ep!Cec

@. arieties I: )* I: )*>. 5ost of cultivation ':sBha 1+H@1 1+11H

H. Grain yield 'kgBha @H+* @)H>

=. (traw yield 'tBha H.* >.+

. Gross return ':sBha 1F*** 1=@*H

F. ;et return ':sBha >+>F @)F*

1*.ffective rainfall 'm+ )HF* ++F*

11.Irrigation water applied 'm+ 1+=)* 1)1**

1).&otal water consumed'm+ 1H@1* 1>@F*1+.roductivityB m

+

1.roduct 'kgB m+ *.)) *.)=>

).Gross return ':sB m+ 1.1H 1.1)

+. ;et return ':sB m+ *.++ *.)

1@. Water re/uirement 'litBkg +>@@ +H+)

Tan" system

In tank irrigation systems, system tanks recorded ma0imum yield and productivity per

unit of water than non! system tanks '&able ). ;on! system tanks which depend upon


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1).Well water applied 'm+

1+.&otal water consumed'm+

[email protected] m+

11)*1@>*

1@1*1+*>*

1.roduct 'kgB m+

).Gross return ':sB m+

+. ;et return ':sB m+

*.))

*.F

*.1

*.)+

*.F)

*.1@1>. Water re/uirement 'litBkg @>=H @+=+

Well )rrigation

Well irrigation has recorded the ma0imum output per unit /uantity of water due to

effective utili$ation of water. -owever, compared to other systems total /uantity of

water consumed by crop is low due to limited but controlled water supply by the farmers.

5ompared to rice, sugarcane crop has recorded ma0imum productivity and profit per unit

of water. It could be concluded that rice yielded comparatively low returns per unit

/uantity of water both in terms of product and profit. 5ompared to rice, sugarcane crop

followed by groundnut recorded ma0imum productivity and profit per unit of water'&able +.

&able +. roductivity per unit /uantity of water under well irrigation

Particulars Paddy *ugar cane #otton +round nut

(oil type :ed soil :ed soil :ed soil :ed soil(eason %ug!Cec 2un!Day %ug!2an 2ul!Oct

arieties I: )* 5O5H=1 D57> &D15ost of cultivation ':sBha 11)H* @*)@* >H* =)**


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&able @ . Euantity of water used, roductivity and rofit per unit /uantity of water in

different systems for addy

articulars Water used

'lBkg

roductivity

'kgB m

Gross return

':sB m

;et return

':sB m

I 5anal systemK

+>@@ *.)) 1.1H *.++-ead

&ail +H+) *.)=> 1.1) *.)

II &ank systemK

@>=H *.)) *.F *.11 (ystem tank) ;on system tank @+=+ *.)+ *.F) *.1@

III Well systemK )FF> *.++ 1.+1 *.@+

)nput se at (arm level

&he input use details are important to compare the productivity of water, as the influence

of inputs such as fertili$er, labour and seed should be avoided while calculating the

productivity of water. %verage /uantities of inputs used by farmers in different systems

are given in &able >. It is observed that the variability in input use is very less in all the

locations and hence it is assumed that influence of these inputs on crop production is

considered uniform across each system.

&able >. %verage Input use in different irrigation systems

Particulars %"gha& P %"gha& K %"gha&*eeds

%"gha&

La/our

%daysha&

#anal system'addy


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turn produced ma0imum water productivity per unit of water '&able H.. %mong the

irrigation methods, drip irrigation has recorded the ma0imum water productivity

compared to surface irrigation.

Water productivity is e0pressed both in terms of product or profit per unit of

evapotranspiration, or irrigation water or total water used 'IW9. Da0imum water

productivity was observed under flower crop such as rose followed by grapes and banana.

In general, fruit crops produced higher water productivity that grain crops '&able =.

In wetland ecosystem, the water productivity can be improved by introducing fishery.

With the same /uantity of water used in rice cultivation, it is possible to increase the

water productivity by several times if it is used for fish production '&able .

&able . 5omparison of water productivity of rice and fish at farm level

articulars Water productivity'kg B m+

':s. B m+

:ice *.@H ).=>

ish +.* ==.1+

Factors in(luencing the productivity o( crops

Production (unction analysis

5rop yields are not only depending upon the irrigation water applied but also on the levelof other factors such as labour, fertili$ers, capital'money available with the farmers to

spend on other inputs, and soil types. roduction function analysis was carried out to


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&able F. :esults of the regression analysis of factors influencing paddy yield in different

systems

Inputs 5anal (.&anks ;.&anks Wells

Output elasticity

4abour *.)+M *.@M *.+1 *.1@Water *.@>M *.)@M *.@)M *.+=M

ertili$er *.11M *.)= *.+ *.1>

5ost *.+H *.1H *.+) *.+>M

(oil *.>H *.* *.)1 *.++

5onstant ++.>@ )=.1> ).F1 +@.)1:

) *.+@ *.+= *.+> *.>1; )@ @> H+ )F

;oteK (.&anks8system tanksL ;.&anks8non!system tanks.L ;8;umber of observations

M (ignificant at > per cent level

&able 1*. Darginal productivity of inputs in paddy cultivation in different systems,

'kgBunit of inputInputs 5anal (.&anks ;.&anks Wells

4abour >.@H F.* ! !Water 1+.)F H.*@ 1*.*@ 1*.+

ertili$er @.F ! +.) !5ost ! ! ! *.)1

(oil ! ! ! !

;oteK marginal productivities were worked out for those variables whose coefficients

were significant in the regression.

@. The challenges


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1*

>. Future approaches

%t plant level identification of traits and genes for drought and salt tolerance be furtherintensified using conventional and molecular breeding techni/ues. &his will result in

increase in production without concomitant increase in & through changes in harvest

inde0.

%t field level, introduction of supplemental irrigation and drip and sprinkler will enhance

the crop productivity. Institutional and Governmental policies will also promote the

spread of these technologies which could result in higher productivity. :educing

unproductive water outflows through the following ways will also be helpful vi$.,

minimising idle periods during land preparation, soil management to increase resistance

to water flow and water management to reduce hydrostatic pressure.

%t basin level, integrated water and land management will be much helpful in enhancing

land and water productivity.

Re(erences

2acob,W.A, :."arker and C.Dolden. )**+. NImproving Water roductivity in

%gricultureK ditors Overview in Water roductivity in %gricultureK 4imits and

Opportunities for Improvement. 'ds Aijne.2.W., :."arker and C.Dolden. 5%"I

ublishing. 7A.

alanisami, A. %.:ajagopal and %. Dohamed %li. 1FF=. roductivity per unit of water

under various land uses mi0es in &amilnadu. Water &echnology 5entre, &amilnadu

%gricultural 7niversity 5oimbatore


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&able H . Water productivity of different agriculture enterprises at field level

Farm type Enterprises nit Water %m

1

& 2ield %"g& )ncome %Rs.&

WP%)P&

%"g m1&

WP%)P&

%Rs. m1&

#rops alone

"anana!surfaceirrigated

1.> acres 1)1.H 1*>** 1)H*** 1.)F 1>.>1

"anana!drip irrigated *.> acre )>)@.> >*** H**** 1.F )+.=H

4eaf vegetable *.)> acre 1** >** @*** *.@H +.=*

Total (arm 3.34 53467.5 - 568777 - 59.48

#rops : ;airy

:ose! surface irrigated 1 acre H))*.*+*H***

;os.=H>** ! 1).+*

:ose! drip irrigated 1 acre ))H@.@+@****

;os.>*** ! +=.>*

Dai$e *.> acre ===.H ** @** 1.*) H.1=

Cairy 1 ;o. )@.)++**

litBlactation)H@** 1+).FH lits 1*H+.H>

Total (arm 3.4 acres 63** )>*** ).=1 )=.1+

"anana !drip 1 acre H++H 1@@** 1=)** ).)= )=.)=

ishery 1 acre H@@. )HH=* HHH=>* ==.1+ ==.1+

Total (arm 1 acres 54673.8 - Water Productivity (or total !ater used %)rrigation !ater : Precipitation&


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Ta/le = . Water Productivity %Rs. per m1o( !ater& in respect to Evapo-transpiration %WPET&, irrigation %WP)& and total

!ater productivity %WP)P& (or di((erent crops at (armers? situation

*.o #ropnit

%acres&

Total

ET %m1

&

Total

)W %m1

&

Total !ater

%)W:P& %m1

&

)ncome

%Rs.&WP %ET& WP %)& WP%)P&

1. "anana !(urface 1.> FFH* =)FF.H 1)1.H 1)H*** 1).H> 1=.)H 1>.>1

"anana !Crip *.> ++)* 1FH).> )>)@.> H**** 1.*= +*.>= )+.=H

). :ose !(urface 1.* +*>.F >*FH. H))*.* =H>** )*.1* 1>.*1 1).+*

:ose !Crip 1.* +*>.F 11@*.@ ))H@.@ >*** )).++ =@.>+ +=.>

+. Dai$e! (urface *.> >** @FF.H ===.H @** F.H* F.H* H.1=

@.4eaf vegetable !

(urface*.)> 1*H. F@1 1** @*** +H.+ @.)> +.=*

>. Grape!Crip 1.* 1@)1.@ +>=.H F)1.H )>*** 1=.>F HF.F )=.1+

09. Water productivity in irrigation - Palanisamy et al.docx

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