Objectives

Impact of soil micromorphological features oncharacter of water flow and solutetransport
R. Kodeš
Kodešová
ová, M. Koč
Kočárek, J. Kozá
Kozák
Department of Soil Science and Geology, University of Life Sciences,Sciences,KamýckáKamýcká 129, 16521 Prague 6, Czech Republic
V. Kodeš
Kodeš
Department of Water Quality,
Quality, Czech Hydrometeorological Institute, NaŠabatce 17, 14306 Prague 6, Czech Republic
J. Šimůimůnek
Department of Environmental Sciences,Sciences, University of California Riverside,
Riverside,Riverside,,CA92521, USA
Riverside
N. Vignozzi,,M.
PagliaiVignozzi
CRACRA-ABP, Piazza M Azeglio 30, II-50121 Florence, Italy¾ Micromorphological study of different horizons of varyingsoil types¾ Evaluation of soil hydraulic properties assuming the soil

porous structure¾ Field study of herbicide behavior in soils¾ Numerical modeling of herbicide transport in soil
¾ Laboratory evaluation of herbicide behavior in soils

Studied Soil Types

Studied Soil Types,Soil Micromorphology
andSoil Hydraulic Properties

Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)
orthogneiss)

ApAp1
Ap2
Bt1

BthBthAp

BCk
BCk
Ck

Bw

Bt2
BCC

Ck

1

Micromorphological Images
Characterizing Ap horizons

Pore-size Analysis

Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol

Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)
orthogneiss)(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)
orthogneiss)0 – 29 cm (Ap1)

0 – 23 cm (Ap)Ap)

0 – 29 cm (Ap)Ap)

¾ Thin soil sections prepared from large soil aggregates¾ Images resolution of 300 dpi, Nikon CoolPix 4500.

Depth

Porosity

Depth

Porosity

Depth

Porosity

0-29 cm

33.7 %

0-23 cm

6.2 %0-29 cm

32.4 % †2929-40cm

3.1 %

23-37cm
37cm

5.9 %

2929-62 cm

11.8 %

4040-75 cm

12.2 %

3737-44 cm

13.9 %

6262-84 cm

12.3 %

7575-102 cm

10.1 %

4444-125 cm

3.4 %102102-120 cm

13.9 %

120120-145 cm

7.3 %¾ ImageImage-processing filters, ArcGIS raster processing tools¾ Pore diameters > 40 μm¾ Pressure head range between -2 and -70 cm (†macropores)

Soil Water Retention Curves andHydraulic Conductivities

Herbicide Transport
in the Soil Profiles

Constant head test
MultiMulti-step outflow experiment¾ Water balance¾ Numerical inversion¾¾

2

Chlorotoluron Transport in Soils
Field Experiment¾¾

Observed Chlorotoluron Distributions

4 m2 – 2 liters of solution 0.5 g/liter
Soil sampling 5th, 13th and 35th day

Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)orthogneiss)

Concentration [μg/g]
0246Concentration [μg/g]

Concentration [μg/g]

801024608246810000-5-5-10
T=5 days
T=13 days-15-10-15
T=5 days-20

T=13 days-25

T=35 days

Depth [cm]Depth [cm]Depth [cm]-5T=5 days
T=13 days-15

T=35 days

T=35 days-30-20-10-20¾ The chlorotoluron mobility increases from Haplic Luvisol to Haplic
Haplic Cambisol
and to Greyic Phaeozem.
¾ The pesticide mobility reflects the soil porous system and atmosphericatmosphericboundary conditions.

Haplic Luvisol

Numerical Simulations – HYDRUS-1D(parent material loess)zz

SingleSingle-porosity
model

Observed data

One flow domain
Richards equation (RE) and convectiveconvective-dispersion equation (CDE)

Concentration [μg/g]

Concentration [μg/g]
024681000¾ DualDual-porosity modelz-5

T=5 days
T=13 days-10¾ DualDual-permeability modelzz

Matrix domain - Set of equations: RE and CDE
Macropore domains - Set of equations: RE and CDE

68010Concentration [μg/g]
46810-5

T=5 days
T=13 days
T=35 days

-20

20-15

T=35 days-20

4-5-10-1520Depth [cm]Mobile domain - Set of equations: RE and CDE
Immobile domain - Mass balance equations

Depth [cm]z

DualDual-porosity
model

Depth [cm]

¾ SingleSingle-porosity model-10

T=5 days
T=13 days-15
T=35 days-20¾ Fraction of immobile domain - micromorphological images¾ Numerical inversion of multimulti-step outflow data
¾ Distribution in the highly connected domain of larger pores, fromfrom which it
penetrated into the soil aggregates.

3Greyic Phaeozem

Haplic Cambisol(parent material loess)(parent material orthogneiss)
orthogneiss)

Concentration [μg/g]

Concentration [μg/g]
02

4

6

DualDual-permeability
model

8002

4

60-5-5-5-10-10-102

4

60

82

468

100

0

T=13 days-25

T=35 days

T=13 days-25

T=35 days

-30

-30

T=5 days-20-25

T=13 days

T=5 days-15

T=35 days-30¾ Fraction of large pore domain affected by clay coatings – pressure heads
between -2 and -70 cm - micromorphological images¾ Numerical inversion of multimulti-step outflow data
¾ Larger capillary pore pathways and sufficient infiltration fluxes
fluxes that occasionally
filled up these pores

6Concentration [μg/g]

8010

T=13 days

4610

T=13 days-10
T=5 days-15

T=13 days
T=35 days

T=35 days-20

8-5

T=5 days
-15

20-10

T=35 days-20

4-5-10Depth [cm]-20-15Depth [cm]T=5 days

Depth [cm]Depth [cm]Depth [cm]T=5 days-20-1520-5-15

DualDual-permeability
model

Concentration [μg/g]

Concentration [μg/g]

Concentration [μg/g]
080SingleSingle-porosity
modelObserved data

Depth [cm]SingleSingle-porosity
model

Observed data

-20

¾ Fraction of macropore domain – total porosity, pressure heads > -2cm
¾ Movement down to the depth of 12 cm in the macropore domain¾ Large gravitational pores were less active during the monitored period

Conclusions¾ The pesticide mobility reflects the soil porous

system and atmospheric boundary conditions.

¾Haplic Luvisolzz¾Greyic Phaeozemzzz¾

highly connected domain of larger pores, aggregates
the lowest daily precipitation rates

Herbicide Transport
in the Soil Column

larger capillary pore pathways
presence of clay coatings
sufficient infiltration fluxes

Haplic Cambisol
zzzmacropores
the highest infiltration rate
inactive large gravitational pores

4Chlorotoluron Transport in Soils
Laboratory Experiment

Observed Pressure Heads
Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)
orthogneiss)Time [min]50Time [min]Time [min]100150050

100015050000-50-100-150-200
Upper Tensiometer
Lower Tensiometer-250-50-100-150-200-250

Upper Tensiometer
Lower Tensiometer

Pressure Heads [cm]50

Pressure Heads [cm]Pressure Heads [cm]

050

50

100150-50-100-150-200-250-300-300-300-350-350-350

Upper Tensiometer
Lower Tensiometer¾ Fast reaction of both tensimeters in Haplic Luvisol¾ Air affect

Chlorotoluron solution applied on the top followed by ponded infiltration
infiltration
Outflow chlorotoluron concentrationsChlorotoluron content within the soil sample¾¾¾

Observed Water Fluxes andChlorotoluron Concentrations
Cumulative
infiltration /outflow
-3500

4

Haplic Luvisol

0

Greyic Phaeozem

-20

100

200
Time [min]300400

Haplic Cambisol(parent material loess)loess)(parent material orthogneiss)
orthogneiss)

0.5

1

1.5

Haplic Cambisol

3-4

2

1-6-8

Greyic Phaeozem-10

Haplic Luvisol
Haplic Cambisol00

Greyic Phaeozem-10Concentration [μg cm ]1000

Haplic Luvisol(parent material loess)loess)

Concentartion (μg g )5Greyic Phaeozem - Infiltration
Haplic Luvisol - Outflow
Haplic Cambisol - Outflow

1500

Final distribution

Depth (cm)Haplic Luvisol - Infiltration
Haplic Cambisol - Infiltration
Greyic Phaeozem - Outflow

3Cumulative infiltration / Outflow [cm ]2000

Outflow
concentration

Micromorphological Images
Characterizing Ap horizons-120200

400

600
3Cumulative Outflow [cm ]800-14¾ The infiltration/outflow increases from Haplic Cambisol to Haplic
Haplic Luvisol and toGreyic Phaeozem.
¾ Similar concentration outflow from Greyic Phaeozem and Haplic Luvisol
Luvisol¾ Low aggregate stability in Haplic Luvisol¾ Thin soil sections prepared from the undisturbed soil samples

5Pore Size and Shape Analysis
Characterizing Ap horizons

Conclusions¾ The pesticide mobility reflects the soil porous

Haplic Luvisol

Greyic Phaeozem

Haplic Cambisol(parent material loess)loess)(parent material loess)loess)(parent material orthogneiss)
orthogneiss)system, aggregate stability.

¾0.012

0.012

Elongated0.008

Irregular
Regular0.004

Elongated0.008

Irregular
Regular0.004

z<100100200200300

300400400500500- >1000
1000

Size Classes [μm]0.000

IrregularRegular

0.004

¾

100200200300300400400500500- >1000
1000

Size Classes [μ m]Greyic Phaeozemz<100<100highly connected domain of larger pores
low aggregate stability

Elongated
0.008

0.000

0.000

Haplic Luvisolz0.02130.012

0.0166

0.016

Porosity [-]0.016

Porosity [-]Porosity [-]Ap Horizon, 0-32 cm

Ap Horizon, 0-21 cm

Ap Horizon, 0-35 cm
0.016

100200200300300400400500500- >1000
1000z

Size Classes [μ m]¾larger capillary pore pathwayspresence of clay coatings

Haplic Cambisolzz

macropores
active large gravitational pores

Thank you for your attention

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