Effects of Saline-Sodic Water on Soil
Chemical and Physical Properties
Kim Hershberger
My Study
Assess the effects of modestly saline-sodic water on
soil chemical and physical properties of selected
soil materials.
Overall Goal-Determine the suitability of irrigating
with modestly saline-sodic waters, while still
maintaining the sustainability of the soil.
Two laboratory experiments which subjected soils of
varying clay content to diverse wetting/drying
regimes using two water qualities.
Irrigable Acreages within the Buffalo
Rapids Irrigation District
Soil
Series
Taxonomy
Texture
Acres
Cherry
Fine-silty, mixed, frigid Typic Ustochrepts
sicl
6052.4
Marias
Fine, smectitic, frigid Chronic Haphsturts
sic
3527.1
sicl
3045.3
fsl/l
2640.8
Spinekop Fine-loamy, mixed, superactive, frigid
Aridic Haplustepts
Trembles Coarse-loamy, mixed, calcareous, frigid
Typic Ustifluvents
Havre
Busby
Fine-loamy, mixed calcareous frigid Ustic
Torifluvents
Coarse-loamy, mixed Borollic Camborthids
sil/sicl 2157.8
fsl
2002.1
TEXTURAL CLASSES
1- Clay % 0-11% - Loamy Sand, Sandy Loam, Loam
2- Clay % 12-22% - Sandy Loam, Loam, Silt Loam
3- Clay % 23-33% - Loam, Clay Loam, Silty Clay Loam
4- Clay % 34+ - Silty Clay Loam, Silty Clay, Clay
Baseline Chemistry Data
18
16
14
Baseline EC, dS/m
12
Baseline SAR
10
Baseline ESP, %
8
6
4
2
0
4
6
7
8
9 15 17 18 19 21 21 22 23 26 28 29 30 33 33 34 37 44 45 52 56
Ranked Clay %
Water Quality Targets
POWDER RIVER
EC = 1.56 dS/m
SAR = 4.54
pH = 8.03
CBM (PRODUCT WATER)
EC = 3.12 dS/m
SAR = 13.09
pH = 8.22
Wetting Regimes

1X Wet/Dry with P.R.
 1X Wet/Dry with CBM
 5X Wet/Dry with P.R.
 5X Wet/Dry with CBM
 5X Wet/Dry with P.R. followed by leaching
with 1 pore volume distilled water
 5X Wet/Dry with CBM followed by leaching
with 1 pore volume of distilled water
Study of Soil Chemical
Responses

Treatment effect on soil
chemistry was evaluated by
monitoring the resultant
saturated paste extract EC
and SAR and comparing
results with baseline
conditions.
 Comparisons made by
analyzing data based on
their textural class.
Methods

Soil materials were saturated according to the
water quality x wetting regime treatment
combinations.

1X treatments-following wetting soils were oven
dried.

5X treatments-intermediate drying cycles for 24
hours at 95 deg F; following fifth wetting soils
were oven dried.
For 5X+d, after fifth
drying to 95 deg. F, soils
were placed on wire
mesh racks where ~1
pore volume of D.I.
water was poured on the
surface of each sample.
Leachate water was
allowed to drain for 24
hrs. Following drainage
period, soils were oven
dried.
Resultant Mean Saturated Paste Extract EC and
SAR for Textural Classes (across all treatments)
Textural Class
1
2
3
4
n
Mean
EC (dS/m) +
Mean
SAR+
9
13
16
11
3.08 a
3.39 a
3.28 a
3.78 b
6.06 a
6.04 a
5.34 a
7.91 b
Resultant Mean Saturated Paste EC and SAR for
Treatment Combinations (across all textures)
Water Quality
Treatment
Base
1X P.R.
1X CBM
5X P.R.
5X P+d
5X CBM
5X C+d
49
49
49
49
49
49
49
Mean EC Mean SAR
(dS/m)
0.82 a
2.56 a
1.51 b
5.94 b
2.46 c
3.92 b
3.21 d
4.94 b
3.02 e
4.86 b
6.93 f
11.31 c
5.73 g
10.85 c
EC (dS/m) (saturated paste extract)
4
3.5
Baseline
1X Wet/Dry-P.R.
1X Wet/Dry-CBM
3
2.5
2
1.5
1
0.5
0
1
2
Textural Class
3
4
EC (dS/m) (saturated paste extract)
Baseline
10
5X Wet/Dry-P.R.
9
5X Wet/Dry-CBM
8
7
6
5
4
3
2
1
0
1
2
Textural Class
3
4
EC (dS/m) (saturated paste extract)
12
Baseline
10
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM + distilled
8
6
4
2
0
1
2
Textural Class
3
4
SAR (saturated paste extract)
20
Baseline
18
1X Wet/Dry-P.R.
16
1X Wet/Dry-CBM
14
12
10
8
6
4
2
0
1
2
Textural Class
3
4
25
SAR (saturated paste extract)
Baseline
20
5X Wet/Dry-P.R.
5X Wet/Dry-CBM
15
10
5
0
1
2
Textural Class
3
4
SAR (saturated paste extract)
30
Baseline
25
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM + distilled
20
15
10
5
0
1
2
Textural Class
3
4
35
30
ESP (%) = (1.18 x SAR) + 0.51
R2 = 0.94
ESP % (soil)
25
20
Baseline
ESP = 15
1X Wet/Dry-P.R.
15
1X Wet/Dry-CBM
5X Wet/Dry-CBM
SAR =12
10
5X Wet/Dry-CBM + Distilled
5X Wet/Dry-P.R.
5X Wet/Dry-P.R. + Distilled
5
0
0
5
10
15
SAR (soil solution)
20
25
30
30
Ayers and Westcot (1976)
25
SAR = 1.46 (EC) + 1.29
R2 = .54
SAR (soil)
20
Severe
Reduction in
Infiltration
Slight to
Moderate
Reduction in
Infiltration
No Reduction in
Infiltration
15
SAR = 12
10
Baseline
1X Wet/Dry-P.R.
1X Wet/Dry-CBM
5X Wet/Dry-CBM
5
5X Wet/Dry-CBM + Distilled
5X Wet/Dry-P.R.
EC = 3
5X Wet/Dry-P.R. + Distilled
0
0
2
4
6
EC (dS/m)
8
10
12
Soil Chemistry Conclusions
1.Repeated irrigation with saline-sodic water will
result in a general increase in the soil salinity and
sodicity.
2.Repeated irrigation or dispersal of CBM product
water to irrigable land is likely to result in elevated
soil salinity levels substantially higher than
published thresholds for some irrigated crops.
3. Soil solution salinity will equilibrate at an EC value
approximately 2-3 times the EC of the applied
water; soil solution SAR appears to equilibrate at a
level comparable to the SAR of the applied water as
long as leaching occurs.
4. Application of salt-free water following elevation of
soil solution salinity and SAR through repeated
wetting effectively reduced soil solution salinity
while having little or no effect on sodicity.
5. The lowering impact of rainfall on EC and SAR is
more predominant when salt concentrations are
high, and in coarser-textured soils.
6. The greatest increases in EC and SAR upon wetting
with either CBM or P.R. water were in coarsertextured soils.
7.In few instances of this study were soil solution
salinity x sodicity combinations measured which
exceed these thresholds following single wetting
events. In essentially all instances where salinesodic water was repeatably applied, the resulting soil
solution salinity and sodicity were significantly
elevated to levels in close proximity to the
previously published EC x SAR standards.
8. Results of this study appear to be consistent with
previously published reports of the relationship
between exchangeable sodium percentage (ESP)
and solution SAR, i.e., SAR = 0.8 x ESP
(approximately). Utilizing an ESP threshold of 15,
the majority of treated soil samples exceeding this
value resulted from alternate wetting regimes with
CBM product water followed by simulated rainfall.
Soil Physical Properties Study
Methods

Soil water retention was measured at 1/10 - 15 -bars of applied
pressure.
 Water content was measured after soils had undergone treatment
combinations (same as the soil chemistry study treatments.
 For 1X treatments, soils were saturated for 24 hrs before pressure was
applied.
 For 5X treatments, soils were placed on wire racks for wet/dry cycles
and transferred to pressure plates for the final wetting period.
Methods cont.

5X+d-Same procedure
as the 5X
– Final wetting on the
plate consisted of DI
application
Mean Gravimetric Water Content at Applied Pressure
Potentials for each Textural Class (across all
treatment combinations)
Texture -1/10 bar -1/3 bar
1
0.25 a
0.11 a
2
0.33 b
0.21 b
3
0.39 c
0.28 c
4
0.45 d
0.32 d
-1 bar
0.06 a
0.13 b
0.20 c
0.23 d
-5 bar
0.05 a
0.10 b
0.15 c
0.18 d
-15 bar
0.04 a
0.08 b
0.11 c
0.14 d
Mean Gravimetric Water Content at Applied
Pressure Potentials for each Treatment
Combination (across all textures)
WQ Treatment
-1/3
bar
0.23 a
-1 bar
-5 bar -15 bar
1X P.R.
-1/10
bar
0.37 a
0.16 a
0.12 a
0.09 a
1X CBM
5X P.R.
5X P+d
5X CBM
5X C+d
0.37 a
0.35 b
0.35 b
0.35 b
0.35 b
0.22 a
0.23 a
0.23 a
0.23 a
0.23 a
0.16 a
0.14 b
0.16 a
0.15 c
0.16 a
0.12 a
0.12 a
0.12 a
0.12 a
0.12 a
0.09 a
0.09 a
0.09 a
0.09 a
0.09 a
Difference in Pw from Baseline (1X P.R.)
g H2 0/g dry soil
0.2
0.15
0.1
1X Wet/Dry-CBM
1/10 (-bar)
5X Wet/Dry-PR
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM
5X Wet/Dry-CBM + distilled
0.05
0
-0.05
-0.1
-0.15
1
-0.2
2
3
Textural Class
4
Difference in Pw from Baseline (1X P.R.)
g H 20/g dry soil
0.2
0.15
0.1
1X Wet/Dry-CBM
1/3 (-bar)
5X Wet/Dry-P.R.
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM
5X Wet/Dry-CBM + distilled
0.05
0
-0.05
-0.1
-0.15
1
2
3
-0.2
Textural Class
4
Difference in Pw from Baseline (1X P.R.)
g H 20/ g dry soil
0.20
0.15
0.10
1X Wet/Dry-CBM
1 (-bar)
5X Wet/Dry-P.R.
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM
5X Wet/Dry-CBM + distilled
0.05
0.00
-0.05
-0.10
-0.15
1
-0.20
2
3
Textural Class
4
Difference in Pw from Baseline (1X P.R.)
g H 20/g dry soil
0.20
0.15
1X Wet/Dry-CBM
5 (-bar)
5X Wet/Dry-P.R.
5X Wet/Dry-P.R. + distilled
0.10
5X Wet/Dry-CBM
5X Wet/Dry-CBM + distilled
0.05
0.00
-0.05
-0.10
-0.15
1
-0.20
2
3
Textural Class
4
Difference in Pw from Baseline (1X P.R.)
g H20/g dry soil
0.20
1X Wet/Dry-CBM
15 (-bar)
5X Wet/Dry-P.R.
0.15
5X Wet/Dry-P.R. + distilled
5X Wet/Dry-CBM
0.10
5X Wet/Dry-CBM + distilled
0.05
0.00
-0.05
-0.10
-0.15
1
-0.20
2
3
Textural Class
4
Textural Class #1
0.4
Water Content (g H20/g drysoil)
0.35
1X Wet/Dry-P.R.
0.3
1X Wet/Dry-CBM
5X Wet/Dry-P.R.
0.25
5X Wet/Dry-P.R. + distilled
0.2
5X Wet/Dry-CBM
0.15
5X Wet/Dry-CBM + distilled
0.1
0.05
0
0
2
4
6
8
10
12
14
Matric Potential (h) (-bars)
Textural Class #2
1X Wet/Dry-P.R.
0.6
Water Content (g H 20/g dry soil)
1X Wet/Dry-CBM
0.5
5X Wet/Dry-P.R.
0.4
5X Wet/Dry-P.R. + distilled
0.3
5X Wet/Dry-CBM
0.2
5X Wet/Dry-CBM + distilled
0.1
0
0
2
4
6
8
10
Matric Potential (h) (- bars)
12
14
Textural Class #3
1X Wet/Dry-P.R.
Water Content (g H 20/g dry
soil)
0.6
1X Wet/Dry-CBM
5X Wet/Dry-P.R.
0.5
5X Wet/Dry-P.R. + distilled
0.4
5X Wet/Dry-CBM
5X Wet/Dry-CBM + distilled
0.3
0.2
0.1
0
0
5
10
15
Matric Potential (h) (-bars)
Water Content (g H 20/g dry soil)
Textural Class #4
0.7
1X Wet/Dry-P.R.
0.6
1X Wet/Dry-CBM
0.5
5X Wet/Dry-P.R.
5X Wet/Dry-P.R. + distilled
0.4
5X Wet/Dry-CBM
0.3
5X Wet/Dry-CBM + distilled
0.2
0.1
0
0
5
10
Matric Potential (h) (-bars)
15
Soil Physical Properties
Conclusions
1. Water content associated with matric potential
differed significantly due to predominant soil
texture at all matric potentials investigated in this
study.
2. Significant differences in water holding capacity of
coarser-textured soils occur due to water quality
treatment more often at greater matric potentials.
In finer-textured soils differences in water holding
capacity due to water quality treatment are more
likely to occur at lower potentials.
3. Significant changes in water holding capacity due
to water quality treatment are only on the order of
0.02-0.04 g H20/g dry soil. The change reflected
a decrease in water holding capacity in textural
classes 1 & 2 and an increase in water holding
capacity in textural class 3.
4. Reductions in water retention in coarser-textured
soils are attributable to the loss of large pore
spaces.
5. The addition of saline-sodic water had the
greatest effect on soil physical properties
when the soil is near saturation. Changes
in water holding capacity are likely to
have non-discernible impact on irrigation
suitability.
6. Successive wetting/drying cycles can
cause aggregate coalescence and the loss
of interaggregate porosity; this appeared
to occur more often in the coarser-textured
soils.
7. Although statistically significant differences were
detected among water quality treatments,
differences were not large enough to have a
significant ecological impact.
8. CBM product water applied at these levels did not
have a consistent significant impact on soil
physical properties, i.e., water-holding capacity.
Acknowledgements
ACKNOWLEDGEMENTS
Committee:
Dr. Jim Bauder (chair), Dr. Douglas
Dollhopf, Dr. Jon Wraith
Funding:
Prairie County Conservation District, Buffalo
Rapids Irrigation District, Department of Energy
Bernard
Schaff, Susan Winking, and Bauder Students