Modeling Crop Growth under varying

Water Table Scenarios

Ajay K Singh

Thesis Objectives

• To investigate the crop water and

nutrient uptake under different soil water

conditions due to free drainage and

constant water table conditions.

• To do a comparative study of different

crop growth models.

• To couple DRAINMOD model to a crop

growth model.

Sap flow

Sap Flow System

• Direct transpiration measurement

• Non-invasive and flexible

• Constant heat-energy balance

• Real-time monitoring and recording

• Measures absolute mass-flow

•Stem gages: 9 to 32 mm

• The energy balance is:

• Pin = Qr + Qv + Qf (W) (1)

• Pin = V2 /R (W) from Ohm’s law

Energy Balance Equations

Stem-gage principles

Stem-gage

control box

Solar panel

Lysimeter: X-sectional view

Perlite

Sandy loam soil

10 cm

50 cm

16 cm

Unsaturated zone

Saturated zone

Mario

tte

bo

ttle

Water Tube

Air tu

be

Ajay Singh

Plastic bin Pipe (ID: 5cm)

Observation Well

Blocks

Lysimeters

Photosynthesis meter

Licor 6400

Leaf area meter – Licor 3000A

SPAD-meter

Source: Minolta

Nitrogen Treatments

A. Greenhouse (Macdonald Campus) 2007-2008

There are four nitrogen treatments:

1. A – 100 Kg/ha

2. B – 140 Kg/ha

3. C – 180 Kg/ha

4. D – 270 Kg/ha

Water Table is maintained at 50 cm from the soil surface.

Nitrogen Treatments

B. Gagnon (Bedford) 2007

There are three nitrogen treatments:1. A – 90 Kg/ha

2. C – 180 Kg/ha

3. D – 270 Kg/ha

There is a free tile drainage. The tiles are placed one meter deep and 10 m wide.

Nitrogen Treatments

C. St. Emmanuel ( Corteau-du-lac) 2008-2009

There are three nitrogen treatments:1. A – 90 Kg/ha

2. C – 180 Kg/ha

3. D – 270 Kg/ha

Water table Management

1. Free tile drainage

2. Water table at 0.6 m with sub-irrigation

Plant Parameters

• The Parameters that are currently monitored /measured:

• WT

• ET

• Corn Water use

• Leaf area

• Photosynthesis

• Stem diameter

• No. of leaves

• Plant height

• Nitrogen content in the leaf

• Dry biomass

Greenhouse- Diameters of Corn by Treatment

0

5

10

15

20

25

13-mai 18-mai 23-mai 28-mai 2-juin 7-juin 12-juin 17-juin

Av

era

ge

dia

me

ter

of

co

rn s

tem

(m

m)

Treatment A'

Treatment B'

Treatment C'

Treatment D'

Stem Diameters vs N2 treatments

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

26-May 28-May 30-May 1-Jun 3-Jun 5-Jun 7-Jun 9-Jun 11-Jun 13-Jun

To

tal L

eaf

Are

a (

cm

^2)

A'

B'

C'

D'

Leaf Area vs N2 treatments

Greenhouse- Plant height by treatment

0,00

50,00

100,00

150,00

200,00

250,00

13-mai 18-mai 23-mai 28-mai 2-juin 7-juin 12-juin 17-juin 22-juin

Heig

ht

of

pla

nt

fom

base t

o t

ip o

f lo

ng

est

leaf

(cm

)

Treatment A'

Treatment B'

Treatment C'

Treatment D'

Plant Height vs N2 treatments

References

• ftp://ftp.dynamax.com