AquaCropA new model for crop predictionunder water deficit conditions

- Calibration for potato -

Gabriella IZZIgabriella.izzi@fao.org

Centro Internacional de la Papa (CIP)La Molina, Lima, Peru22 September, 2008

Objectives

• General framework

• Main issues related to AquaCropcalibration for potato

• AquaCrop performances

• Description of AquaCrop

• Discussion, feed-backs, & contacts

Background• Revision of the 1979 FAO I &

D Paper no.33,

“Yield Response to Water”

• Consultative process

• Separation herbaceous-crops and trees:AquaCrop &

Guidelines

Ya ETa

1 - = Ky 1 -

Ym ETc

Why another model?U

ncer

tain

tyU

ncer

tain

ty

ComplexityComplexity

structure

parameters

total

• AquaCrop is explicit and mostly intuitive, and maintains anoptimum balance between simplicity, accuracy and robustness

• AquaCrop differs from other models for its relatively small number of parameters

• AquaCrop is aimed at practical end-users: farmers and irrigation associations, extension services, governmental agencies, NGOs, planners, economists, as well as researchers and students.

AquaCrop main characteristics

• AquaCrop as unique crop response to water modelwith crop-specific parameters

AquaCrop Network & CGIAR

Evolution from Paper 33

CanopyCanopyTranspirationTranspiration

BIOMASSBIOMASS

CropCropEvapotEvapotranspirationranspirationYIELDYIELD

EHI

Paper 33

{AquaCrop

long-term sums

daily time-steps

Ky

WP

Water-driven model

Atmosphere

Soil

AquaCrop Conceptual Framework

Crop

Man

agem

ent

Rain

AquaCrop Conceptual Framework | Atmosphere

CLIMATE

RS , T, RH, u

ETo

T (oC) CO2

Data needed for calibration | Atmosphere

Rainfall ETo Tmin & Tmax

Phenology Canopy CoverLeaf expansion gs

Senescence

Rooting depth

AquaCrop Conceptual Framework | Crop

CGC

CCx

start of canopy senescence

time to harvest

cano

py c

over

timetime to full canopy

CDC

CCo

Canopy Cover (CC) follows the exponential growth during the first halfof the full development (Eq. 1) and an exponential decay during the second half of the full development (Eq. 2)

  tC GCoeCCCC ⋅= (1)

  tCGCoxx e)CCCC(CCCC ⋅−⋅−−= (2)

AquaCrop Conceptual Framework | Crop

Data needed for calibration | Crop

PhenologyIn-season CCDensity

Es Ta

Phenology Canopy CoverLeaf expansion gs

SenescenceBiomass

WP

Rooting depth

AquaCrop Conceptual Framework | Crop

T (oC) ETo

(g m-2 mm-1)∑

=CT

BiomassWP(g m-2)

)2000(COO

C

*

2ETT

BiomassWP

⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛=

∑

Σ ETc (mm x 1000)0.0 0.3 0.6 0.9

Bio

mas

s (k

g m

-2)

0

1

2

3

SorghumSunflowerChickpeaWheat

 ∑ CT Σ(ETc/ETo)0 40 80 120 160

Bio

mas

s (k

g m

-2)

0

1

2

3

SorghumSunflowerChickpeaWheat

∑ )ET/T( OC

AquaCrop Conceptual Framework | Crop

Data needed for calibration | Crop

In-season dry biomass

Es Ta

Phenology Canopy CoverLeaf expansion gs

SenescenceBiomass

WP

YieldHI

Rooting depth

AquaCrop Conceptual Framework | Crop

T (oC) ETo

Data needed for calibration | Crop

In-season yield

AquaCrop conceptual framework | Crop

Water stress coefficients

AquaCrop conceptual framework | Crop

Water stress coefficients

Data needed for calibration | Crop

Different water regimes

Soil water (&

salt) balanceInfiltration

Redistribution

Runoff

Rain

Ks

Es Ta

AquaCrop Conceptual Framework | Soil

deeppercolation

Texture 1

Texture 2

Texture …

Ksat

FC

PWP

Irrig.

Runoff

Data needed for calibration | Soil

FC, PWP, KsatSoil layers

Field Management

Water Management

• Fertility level (non-limiting; high; moderate; poor)

• Field-surface practices (mulching; soil bunds)

Rainfed

• User defined schedule (timing and depth)

• Model-generated schedule (fixed interval; fixed depth;% of RAW)

• Irrigation method (drip; sprinkler;surface » basin; border; furrow)

Irrigation

AquaCrop Conceptual Framework | Management

Data needed for calibration | Management

Irrigation depthIrrigation date

Data needed for calibration | Management

Fertility level

AquaCrop performances

Maize

TexasTexas

CaliforniaCaliforniaFloridaFlorida

SpainSpain QuzhouQuzhou

I treatment biomass

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120 140

DAP

cum

DM

(g/m

2)

DM

Biomass

I (Full IRR) treatment Ground Cover

0

20

40

60

80

100

0 20 40 60 80 100 120 140

DAP

GC

(%)

Calc GC

CC

Maize

Treatments:Full Irrigation (I)Rainfed (NI)Irrig. day 55 onward (I55)

NI treatment biomass

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120 140

DAP

cum

DM

(g/m

2)

DM

Biomass

California

NI (No IRR) treatment Ground Cover

0102030405060708090

100

0 20 40 60 80 100 120 140

DAP

GC

(%)

Calc GC

CC

I55 (IRR on Day55) treatment Ground Cover

0

20

40

60

80

100

0 20 40 60 80 100 120 140

DAP

GC

(%)

Calc GC

CC

I55 treatment biomass

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100 120 140

DAP

cum

DM

(g/m

2)

DM

Biomass

Biomass YieldMeasured Simulated Measured Simulated

24.3 22.7 11.4 10.816.8 16.8 5.2 6.221.2 22.4 10.3 10.6

Cotton

SpainSpainTexasTexas GreeceGreece

TurkeyTurkey

SyriaSyria

Cotton

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14

Observed (t ha-1)

Sim

ulat

ed (t

ha

-1)

Yield

Biomass

1:1

Treatments:Full IrrigationDeficit Irrigation

Spain

Cotton

Treatments:Full IrrigationDeficit Irrigation

Syria

Wheat

TexasTexas

KansasKansas

SardiniaSardinia

QuzhouQuzhou

LuanchengLuancheng

FengquiFengqui

Wheat

Treatments:98-99 – Full Irr.99-00 – Full Irr.

ChinaYield

Measured Simulated

6.72 6.506.22 7.09

China Quzhou Wheat 98-99

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250DAP

Bio

mas

s (t

/ha)

China Quzhou Wheat 98-99

-20

-10

0

10

20

30

40

0 50 100 150 200

DAP

Min

and

Max

Tem

pera

ture

(oC

)

China Quzhou Wheat 98-990

25

50

75

100

0 50 100 150 200 250DAP

Can

opy

Cov

er (%

)

0

25

50

75

100

0 50 100 150 200 250DAP

Can

opy

Cov

er (%

)

China Quzhou Wheat 99-000

5

10

15

20

25

30

35

40

0 50 100 150 200 250DAP

Bio

mas

s (t

/ha)

China Quzhou Wheat 99-00

China Quzhou Wheat 99-00

-20

-10

0

10

20

30

40

1 31 61 91 121 151 181 211

DAP

Min

and

Max

Tem

pera

ture

(oC

)

Quinoa

BoliviaBolivia

Quinoa

Treatments:Full IrrigationDeficit Irrigation

Bolivia

Conclusions

• AquaCrop calibration and validation need solid datasets, under a variety of agro-climatic, water and fertilization conditions

• AquaCrop needs to be calibrated for potato

• AquaCrop shows first encouraging results, under full, deficit and rainfed conditions

Thank You