nitrogen-limited production

8/8/2019 Nitrogen-limited production

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PRINCIPLES OF CROP GROWTH

SIMULATION MODELLING

Nitrogen-limited production


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The Rice System and boundary at field level

Radiation, CO2 O2

Nitrogen

Temperature,

Soil N uptake


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I. N demand by crop


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0

0.01

0.02

0.03

0.04

0.05

0.06

0 0.5 1 1.5 2

Fr ( 1 dr matter)

Development stage ( )

seedbed

NMAXL

NMINL

Basic assumption:

crop strives towards maximal N content


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Stem N content }

50% leaf N content


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0.0

0.5

1.0

1.5

2.0

0 50 100 150 200 250

i a icle at har est (%)

i cr atfl weri (k ha1

)

Pa icle c te t = f( i cr atfl weri )


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1. Daily potential N demand by leaves (NDleaf):

NDleaf= N%max(Wleaf+HWleaf) - Nleaf(kg N ha-1 d-1)

2. Daily potential N demand by crop (NDcrop):

NDcrop = NDleaf+ NDstem + NDpanicle (kg N ha-1 d-1)

Translocation

3. Daily maximum N uptake by crop isphysiologically limited: max is 8 kg N ha-1 d-1

=> Potential N uptake = minimum(NDcrop,8)


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I. N availability in the soil


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Indigenous soil N supply

Mineralization (SOM turnover)

N in rain

Biological N fixation

In ORYZA2000: no dynamic soil N modelling

Soil N supply estimated from :

1. (total N uptake in 0-N trials )/duration2. fine-tuning by model calibration

At IRRI: Soil N supply 0.5-0.8 kg N ha-1 d-1


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Fertilizer N supply

Fertilizer application x recovery fraction

Recovery fraction is calculated from

experiments

Aggarwal et al., 1997

Pengand Cassman, 1998

1

3

4

6

7

9

1

1 1

Development stage

PI Flowering Maturity


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Total soil N availability

1. Indigenous soil N supply

+

2. Fertilizer application x recovery fraction

Unrecovered fertilizer N is either lost orcarried over to next seasons crop


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III. Nitrogen-driven crop growth


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Actual N uptake

= minimum (demand, supply)

Crop N demand

Soil N supply

(indigenous + fertilizer)

Actual crop N uptake


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Soil

Stem

Leaf

Panicle

Nuptake

N translocation

N loss

N redistribution


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Effect of N in crop on growth

1. Leaf photosynthesisVan Keulen and

Seligman, 1987

In ORYZA2000:Adapted based on

ShaobingPengdata


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2. Leaf expansion rate

3. Accelerated leaf death rate

Leaf expansion reduction factor=

f(actual N% leaf, maximum N% leaf)

Accelerated leaf leaf death factor=

f(actual N crop, maximum N crop)


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Photosynthesis

Assimilatepool

Biomass

Roots

Developmentstage

Maintenancerespiration

Growthrespiration

Partitioning

Development

rate

Light

y

LAI N

Leaves N

Stems N

Panicles N

Soil Navailable

Stem Nuptake

Net fertilizer N

supply

Indigenoussoil N

Leaves N

uptake

Crop model

Nitrogen-limited

Production


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Input

1. Weather data: daily temperature, radiation

=> Weather data file

2. Management, additional:fertilizer Napplication, fertilizer N recovery, soil N supply

=> Experiment data file

3. Crop characteristics, additional:Max and min N

contents of organs, Max N uptake, etc

=> Crop data file


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Experimental data file

*--------------------------------------------------------------------*

* 6. Nitrogen parameters *

*--------------------------------------------------------------------*

SOILSP = 0.8 ! Indigenous soil N supply (kg N/ha/d) (0.8)

* Table of fertilizer rate (kg N/ha) (second column) versus days after sowing

* in the seed-bed (!) (first column)

FERTIL =

0., 0.,

11., 0.,

12., 60.,

13., 0.,

29., 0.,30., 60.,

31., 0.,

66., 0.,

67., 60.,

68., 0.,

94., 0.,

95., 45.,

96., 0.,

366., 0.

* Table of recovery fraction of Nitrogen in the soil (-) second column

* versus development stage (DVS) (first column) STANDARD VALUE

RECNIT =

0.0, 0.30,

0.2, 0.35,

0.4, 0.50,

0.8, 0.75,

1.0, 0.75,

2.5, 0.75


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Output

Time course of leaf area index, biomass

of various crop organs Time course of crop N contents and

crop N uptake

Yield, yield components


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IR 2, Los Baos

Dry season 1992

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 10 20 30 40 50 60 70 80 90 100 110 1 20

TIME

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70 80 90 100 110 1 20

TIME

Leaf Area

Index

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0 10 20 3 0 40 50 6 0 70 80 9 0 1 00 110 1 20

T I M E

Total

Panicle

Leaves

Biomass

225 kg N ha-1

0 kg N ha-1


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0.00

0.01

0.02

0.03

0.04

0.05

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 0

DVS

0.00

0.01

0.02

0.03

0.04

0.05

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 .9 1 . 0 1 . 1 1 . 2 1 . 3 1 . 4 1 . 5 1 . 6 1 . 7 1 . 8 1 . 9 2 . 0

DVS

225 kg N ha-1

0 kg N ha-1

Fraction leaf N ( kg kg1)

Development stage

Nmax

Nmin

Nmax

Nmin

N content

in leaves


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N uptake (kg/ ha)N supply (kg/ ha)

Y eld (kg/ ha)

N supply (kg/ ha)

400 300

11

40 0

yObserved

o S mulated

IR 2; 1993 DS

17 treatments

0-400 kg N ha-1

D fferent splits

nitrogen-limited production

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