Effect of fertilizer strategies on the grey water...

25/06/201524-26 June, 2015

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Researcher: A.D. Chukalla, PhD candidate

Supervisor: Dr. M. S. Krol, Associate Professor

Promoter: Prof. Dr. Ir. A.Y. Hoekstra, Professor

Effect of fertilizer strategies on the

grey water footprint in rain-fed and

irrigated agriculture

SWAT 2015

PULA/SARDINIA/ITALY

Content

Introduction

Objective

Data

Methods

Results

Conclusions

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Introduction

The water footprint is a comprehensive indicator of freshwater resources appropriation, showing water consumption volumes by source and polluted volumes by type of pollution. It composes the green, blue and grey components. (Hoekstra, 2011).

Water footprint(WF) reduction is increasingly required in the face of increasing water scarcity and in the move to close supply-demand gap for fresh water.



Introduction

Green/Blue WF

Grey WF

for nonpoint

source



4

Understanding water resources use by source (rainwater,

irrigation water from surface and groundwater, water from

capillary rise) is vital for water resources management.

Falkenmark and Rockström (2006) and Hoekstra et al.

(2011).

Introduction

Agriculture contributes, 92% of the global fresh water footprint (Mekonnen, M.M. and Hoekstra, A.Y. (2011))

Irrigation withdraws 70% of fresh water resources (Fischer et al., 2007).

Plants use only 10 to 30% of

the fresh water supply for biomass

formation(Howell et al., 2001; Wallace, 2000).



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(AQUASTAT – FAO)

Introduction

Water footprint of irrigated crop production can

be reduced by – (1) increasing yield, and (2) minimizing

losses (Hoekstra, 2013).

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Scale:

Basin,

Farm,

Field

WF =f(managements)

Objective

to explore the scope for reducing the water footprints of growing crops by a systematic model based assessment of management practises at field and basin scale.

(1) to explored the potential for reducing the green-blue water footprints of growing crops (p1).

(2) to explore the effect of fertilizer strategies on the grey water footprint of growing crops (p2).

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DataHumid

Arid

Climate

http://climexp.knmi.nl/selectdailyseries.cgi

Crop parameters

(Potato, tomato and maize

FAO database and

local conditions

Soilhttp://eusoils.jrc.ec.europa.eu/ESDB

and field data measurement

Groundwater



Green and

Blue WF of

growing

crops

1. Four irrigation techniques: Furrow, Sprinkler, Drip

and Subsurface drip (SSD);

2. Three irrigation strategies: full irrigation, deficit

irrigation & supplementary irrigation; + rain-fed;

3. Three mulching practices: no mulching, organic &

synthetic mulching.

EffectsManagement options

AquaCrop

&

WF

accounting

Modelling

Method (p1)

Cases: Four environments, three types of years, three soils and three crops

Environment

(Location)

Soil Type of

years

Crops Groundwat

er

Arid

(Eilat , Israel)

Loam

Sandy loam

Silty-clay-loam

Dry

Normal

Wet

Maize, potato

and tomato

Deep

Semi-arid

(Badajoz,

Spain)

Loam

Sandy loam

Silty-clay-loam

Dry

Normal

Wet

Maize, potato

and tomato

Deep

Sub-humid

(Bologna, Italy)

Loam

Sandy loam

Silty-clay-loam

Dry

Normal

Wet

Maize, potato

and tomato

average 1.5

m

Humid

(Eden, United

Kingdom)

Loam

Sandy loam

Silty-clay-loam

Dry

Normal

Wet

Maize, potato

and tomato

Deep

Cases: Four environments, three types of years, three soils and three crops



Method

RI

R RO

S

S )ET(DrR

t

S gg

d

d

S

S ET)(DrR

t

S CR-bCR-b Cd

d

RI

I RO

S

S ET)(DrI

t

S I-bI-b

d

d

Green and blue soil water separation

n

i

ig

g

Y

ETWF

1

)(

n

1i Y

i)CRb(ET

CRbWF

n

1i Y

i)Ib(ET

IbWF

(Results (p1): green – blue soil water separation

22-Mar 21-Apr 21-May 20-Jun 20-Jul0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

500.00

5

10

15

20

25

30

35

40

45

50

22-Mar 21-Apr 21-May 20-Jun 20-Jul

Crop growing period

Wate

r co

nte

nt

in t

he m

axim

um

eff

ecti

ve

roo

t zo

ne (

mm

)

Rain

, C

ap

illa

ry r

ise(C

R),

Irr

igati

on

(Irr

) (m

m)

Date, Crop growing period

CR mm S total Irri mm Rain mm Sg Sb

Figure : The green (Sg) and the blue (Sb) soil water stocks/storages at Bologna,

Semi-humid environment, for average year/2001/

PWP (mm)

FC (mm)

(Results (p1): Effect of the management options on ET, Y and WF

0

200

400

600

800

1000

1200

1400

0 200 400 600 800 1000

WF

(m

3/t

)

Evapotranspiration (mm)

Maize Potato Tomato

Figure: Effects on WF from the whole experiment

14

15

20

25

200 250 300 350 400 450

Yie

ld (

ton

/ha)


Sprinkler Furrow Drip SubsurfaceDrip

Full

Deficit

Supplementary

5

9

13

17

21

25

150 200 250 300 350 400

Yie

ld (

ton

/ha)


Without mulching Organic Synthetic

Rain-fed

supplementary

deficit

Full

Figure: ET-Y plot for

mulching practices at

rain-fed and drip

irrigated field.

Figure: ET-Y

relationship for irrigation

techniques with no

mulching practice.

Results (p1): Effect of the management options on ET, Y and WF

Case: potato, loam soil,

normal year, Semi-arid

environment (Badajoz –

Spain).

ET↓= saving

Y↑=f(T↑)=yield increase

Results (p1) Effect of the management options on ET, Y and WF

44 43

84 89

0

50

100

150

Rain-fed Supplementaryirrigation

Deficitirrigation

Fullirrigation

Green WF Blue WF (m3/t)(m3/t)

0

50

100

150

200

250

300

Rainfed Supplementaryirrigation

Deficitirrigation

Fullirrigation

ET-green (mm) ET-blue (mm)

Blue Water saving 144m3/ha

Yield reduction 1ton/ha

Blue water added 215m3/ha

Yield increase 7ton/ha

Figure: Effects of the irrigation strategies with drip on Yield, green and blue WF. Case: potato, loam soil, normal year, Semi-arid environment i.e. Badajoz – Spain.

11 ton /ha18 ton/ha

26 ton/ha 27 ton/ha

Rainfed Supplementaryirrigation

Deficitirrigation

Fullirrigation

Yield (ton/ha)

16

Results (p1): Reduction in the total WF

Reference (furrow irrigation with full irrigation and without mulching practice)

a

b c

The box and whisker

plot shows the WF-

reduction values for the

whole cases:

(a) whole management

practices;

(b) four irrigation

techniques, with FI

and NoML; and

(a) four irrigation

techniques, with DI

and NoML.

17

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Dri

p &

Sub

SD

rip

Dri

p &

Sub

SD

rip

To

tal

WF

re

du

cti

on

(%

)Arid Semi arid Subhumid Humid Avg of all cases

FI DI

Synthetic

mulching

Full Irrigation No mulching

Deficit Irrigation No mulching

Full Irrigation Organic mulching

Deficit Irrigation Organic mulching

Figure: The mean total WF reduction categorized by the environments for the

whole cases

Results (p1): Reduction in the total WF

18

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Furr

ow

Sp

rin

kle

r

Dri

p

Su

bS

Dri

p

Dri

p &

Sub

SD

rip

Dri

p &

Sub

SD

rip

To

tal

WF

re

du

cti

on

(%

)

Green WF reduction Blue WF reduction Total WF reduction

Full Irrigation No mulching

Deficit IrrigationNo mulching

Full IrrigationOrganic mulching

Deficit IrrigationOrganic mulching

FI DISynthetic mulching

Figure: The mean green, blue and total WF reduction; for the whole cases

Results (p1): Reduction in the green-blue WF

Conclusions

The average reduction in the consumptive WF is: 8-

10% if we change from the reference to drip or SSD;

13% when changing to OML; 17-18% when moving to

drip or SSD in combination with OML; and 28% for

drip or SSD in combination with SML.

Reduction in overall consumptive WF always goes

together with an increasing ratio of green to blue WF.

The WF of growing a crop for a particular environment

is smallest under DI, followed by FI, SI and rain-fed.

Conclusions

Growing crops with sprinkler irrigation has the largest

consumptive WF, followed by furrow, drip and SSD.

Furrow irrigation has a smaller consumptive WF

compared with sprinkler, even though the classical

measure of ‘irrigation efficiency’ for furrow is lower.

Grey water footprint component

Simulating the effect of fertilizer strategies on the grey

water footprint of growing crops (p2).



Grey WF of

growing

crops

1. Moisture supply strategies: irrigated (full

irrigation) and rain-fed;

2. Fertilizer strategies:

types: mineral and organic fertilizer

Quantity: without, existing,

EffectsManagement practices

Apex

&

Global WF

accounting

standard

Modelling

Method (p2)

Cases: Semi-arid environment, three types of years, three soils and potato crop

Method (p2)

Green

and blue

water

supply

Uptake by crop

Figure: soil water nutrient balance

Thank You

Effect of fertilizer strategies on the grey water...

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