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Solar Panel

Data Logger

Probes

Cable

Depth cm

10

110

70

20

40

Sensors

Cable Data logger

Solar Panel

Fig.1Citrus Tree

Probe

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EnviroSCAN Probe Installation

The EnviroSCAN probe is installed using specialized tools to minimize disturbance of the soil profile and insure a tight contact between the access tube and the soil.

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SENSORELECTRODES

CABLEACCESSTUBE

EnviroSCAN Probe Design

TOP CAP

ZONEOFCOVERAGE

Fig. 1

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Dielectric ConstantThe dielectric constant of water depends upon the polarization of its molecules in an electric field.The dielectric for :– water = 80– soil matrix < 10– air = 1

The dielectric contant of the SWA mixture is dominated by water-volume fraction

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Capacitance probe can be inserted in PVC access tube or placed directly in the soil.Field results indicated that portable probes were unable to give acceptable soil water content especially for coarse textured and fine sandy loam soils.Air gaps, changes in bulk densities and poor field installation of the access tubes are serious problems with portable probes.

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Fig.2

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Fig.2

Max After Rain

Before Rain

Total Rain = 17 mm (100%)Effective Rain = 12 mm (70%)Interception = 05 mm (30%)

Irrig Eff. =75%

Irrig Eff. =82%

Irrig Eff. =77%

1 hr Irrigation7 mm

2 hr Irrigation14 mm

No Effect beyond 20 cm

4/7/2003 17Depth below the soil surface (cm)

0 20 40 60 80 100 120

Volu

met

ric S

oil W

ater

Con

tent

(%)

4

6

8

10

12

14

02 PM Feb. 108 PM Feb. 101 PM Feb. 211 PM Feb. 2

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WABAMO

Model DescriptionCitrus Evapotranspiration &

Water Leaching

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Evapo-transpiration

Transpiration

Evaporation

Rain

Runoff

Leaching

Root Zone Water Storage

Irrigation

Below RootZone

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Water Mass balance Equation

ET = I + Qv + ∆W

ET = EvapotranspirationI = Rain & IrrigationQ v = Drainage Below Rootzone )W = Soil Water Storage variation between two time steps

ET = I + Qv + W

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20

30

40

50

60

Wat

er C

onte

nt (m

m )

3040506070

0 30 60 90 120 150 180 210 240 270 300 330 3605060708090

100110

Below Root Zone

Root Zone

Total Profile

Calender Day (1997)

Water contentSetting level 1 Setting level 2

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Daily Evapotranspiration for a Young Citrus Grove (1997)

Calender Day 0 30 60 90 120 150 180 210 240 270 300 330 360

Dai

ly E

vapo

tran

spira

tion

(mm

)

1

2

3

4

5

6

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Calculated Cumulative Evapotranspiration for a Young Citrus Grove (1997)

Calender Day 0 30 60 90 120 150 180 210 240 270 300 330 360

Dai

ly E

vapo

tran

spira

tion

(mm

)

200

400

600

800

1000

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Calculated Water Leaching Below a Young Citrus Grove (1997)

Day of the Year0 50 100 150 200 250 300 350

Dai

ly L

each

ing

(mm

)

0

10

20

30

40

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Days of the Month (April 1996)27.0 27.5 28.0 28.5 29.0

Hou

rly

ET

(mm

)

0.0

0.1

0.2

0.3

0.4

0.5

0.61.8 m2 wetting area

16.3 m2 wetting area7.3 m2 wetting area

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27.0 27.2 27.4 27.6 27.8 28.0 28.2 28.4 28.6 28.8 29.0

Cum

ulat

ive

Dai

ly E

T (m

m)

0

1

2

3

4

5

61.8 m2 wetting area

16.3 m2 Wetting area

7.3 m2 Wetting area

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Cumulative Leaching Below a Citrus Grove (1997)

Calender Day0 30 60 90 120 150 180 210 240 270 300 330 360

Cum

ulat

ive

Leac

hing

(mm

)

150

300

450

600

750

900