Objective

Multicomponent Solute Transport
in Two Multifactorial Experiments

To evaluate the effectiveness of HYDRUSHYDRUS-1D topredict:• Water content and fluxes• Concentration of individual cations(Na+, Ca2+, Mg2+)

Department of Soil Science,Science, Estaç
Estação Agronó
Agronómica Nacional, Oeiras, Portugal• Overall salinity (Electrical conductivity – EC)• Sodium Adsorption Ratio (SAR)

N. L. Castanheira• Exchangeable Sodium Percentage (ESP)

T. B. Ramos, M. C. Gonç
Gonçalves, A. Prazeres & J. C. Martins

Department of Rural Engineering, University of Évora,vora, Évora,vora, Portugal

The experiment

Triple Emitter Source System• Two locations
Alvalade
Mitra• Two different soils
Alvalade – Fluvisol – Medium texture
Mitra – Anthrosol – Coarse texture• Time period
June 2004 to February 2007
3 irrigation cycles and 3 rainfall leaching cycles• CultureMaize• Trickle irrigation system
A triple emitter source irrigation system was used for water, salt
salt(Na+), and fertilizer (N) application.
application
Based on Israelian designs

1Triple Emitter Source System

Triple Emitter Source System

Fresh water

Salt Gradient

SalineSolution

Nitrogen
Solution

Saline water

Fertilizer water

FreshWaterSource
Group IGroup IIGroup III

Group IV

Nitrogen Gradient

Monitoring irrigation and leaching cycles(20, 40, and 60 cm)• Soil water content (TDR)• Electrical conductivity from soil solution

Ceramic Cups

• Soluble cations from soil solution

Soil sampling before and after each irrigation
cycle (0-20, 20-40, and 40-60)

INPUT DATA•Electrical conductivity of soil saturation extract• Soluble cations of soil saturation extract• Exchangeable cations
SAR =• Cation exchange capacity (CEC)• Sodium Adsorption Ratio (SAR)• Exchangeable Sodium Percentage (ESP)( Na + )(Ca2++ Mg 2 + )2+ESP =Nax100(CEC )2

Soil Surface• Soil initial conditions• Soil hydraulic properties• Solute transport parameters• Gapon selectivity coefficients• Ionic concentrations of irrigation waters• Root distribution• Rainfall (daily) / Irrigation water• Soil Evaporation (E) = ETc- T• Crop Transpiration (T) = ETc × Soil Cover Factor(Leaf Area Index measured every week)
8.06.0ETc = ET0 × Kc
Kc for maize (FAO)

3.0
2.0
1.0
0.0
04-03-2004 20-09-2004 08-04-2005 25-10-2005 13-05-2006 29-11-2006 17-06-2007
Evaporation

Transpiration

Soil Hydraulic Properties•

Measured in the laboratory- Suction tables- Pressure plate- Evaporation method- Hot Air method• Soluble cations of soil saturation extract• Exchangeable cations

4.0

Daily ET0 (Penman-Monteith)• Dry bulk density
Na+, Ca2+, Mg2+, K+

5.0

days

Soil Initial Conditions• Soil water content, TDR

Alvalade

7.0(mm)• 2 Soils• Soil layers
Alvalade (0(0-30, 3030-75, 7070-100 cm)
Mitra (0(0-30, 3030-50, 5050-90 cm)• Time period
June 2004 – February 2007
• Boundary Conditions
Surface: Water fluxes
Bottom: Free Drainage•Described with the MualemMualem-van Genuchten
equation using RETC code

Na+, Ca2+, Mg2+, K+• Cation exchange capacity (CEC)

3

Soil Hydraulic Properties

Solute Transport Parameters

Alvalade- Chloride breakthrough curves- CXTFIT 2.1

Mitra

Gapon Selectivity Coefficients

Ionic Composition of irrigation waters
AlvaladeNaMz

cT = ∑ cii =1+Na +(Ca2+ 1/ 2)

Mitra1201201001008080meq/L

K Ca / Na =Ca 2 +meq/L• Determined from initial soil conditions(Exchangeable and Soluble cations)

6060

4040

202000Ca2+

Mg2+

Na+

K+Ca2+

Mg2+

Na+K+

Fresh Water

Fresh Water

Saline Water (2004-2005)

Saline Water (2004-2006)

Saline Water (2006)

4

Root Distribution• Monitored using a Minirhizotron
technique associated with a video
camera system

RESULTS• Roots distributed over 60 cm depth

Water content

Electrical Conductivity (EC)GI A - HYDRUS
GI A - Measured
GIV C - HYDRUS
GIV C - Measured

5Na+ concentration

GI A - HYDRUS
GI A - Measured
GIV C - HYDRUS
GIV C - Measured

Mg2+ concentration

GI A - HYDRUS
GI A - Measured
GIV C - HYDRUS
GIV C - Measured

Ca2+ concentration

GI A - HYDRUS
GI A - Measured
GIV C - HYDRUS
GIV C - Measured

Sodium Adsorption Ratio (SAR)

GI A - HYDRUS
GI A - Measured
GIV C - HYDRUS
GIV C - Measured

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Exchangeable Sodium Percentage (ESP)
Alvalade
16-09-2004
01024-09-2004
152000ESP (% )20406020n = 282n = 379

b = 1.00
b = 0.86

CEn = 247n = 363b = 1.17
b = 1.16

Na+n = 242n = 356b = 1.05
b = 0.91

Ca2+

n = 227n = 345b = 1.21
b = 1.40

Mg2+

n = 233
n = 343b = 1.38
b = 1.61

SAR

n = 219n = 327b = 0.73
b = 0.61

ESP

n = 36n = 36b = 1.50
n = 1.444060

GIA - Hydrus
GIA - Observed
GIVC - Hydrus
GIVC - Measured

0.2

θ

5 10 15 20 25 30 35 400Depth (cm)Depth (cm)0.0Mitra

ESP (% )5

Statistical Analysis
0.4

Determination
Coefficients
0.6

0.8

1.0 R

2

Alvalade
MitraConclusions• HYDRUSHYDRUS-1D has successfully simulated water regime, and theeffects of different irrigation waters on the geochemistry of thethestudied Fluvisol and Anthrosol.
Anthrosol.

CONCLUSIONS• The best correspondence was obtained for water content, EC, andsoluble sodium.
• Soluble magnesium and calcium, and SAR were predicted lesswell.
• HYDRUSHYDRUS-1D proved to be a powerful tool for evaluating irrigation
management, and for predicting the effects of irrigation water
quality on the soil and groundwater quality.
quality.
• Models, such as HYDRUSHYDRUS-1D, should be used to establish soundirrigation policies and to mitigate environmental risks.

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