Salinity and Sodicity Management

1
Salinity and Sodicity Management Water or soil
with salinity and/or sodicity levels
sufficiently elevated to have the potential to
have adverse effect on long-term sustainability
of either the soil or plant resource
2

• Using CBM/CBNG Product Water for Irrigation
  either as a sole source or as a component of
  blended water
• Salinity and Sodicity Issues, Irrigation,
  Infiltration and Movement of Water in Soil
• -low to modest salinity will enhance water
  movement
• salinity promotes/enhances aggregation,
  structural stability
• water which is free of electrolytes (salts)
  can/will cause dispersion of soil aggregates

3

• sodium in water can cause soil structural
  deterioration
• the causes are swelling, slaking, dispersion
• salinity can counteract sodium
• salinity can/will have an adverse effect on plant
  performance
• salinity is more dynamic (subject to change, less
  stable) than sodicity in soil
• salinity problems are corrected by drainage and
  leaching
• sodium problems are corrected by amendments,
  changing soil chemistry, drainage, and leaching

4
The issue of use or management of either
saline/sodic water or CBM/CBNG product water for
irrigation, either solely or blended, comes down
to three questions 1 - What are the specific
levels of salinity and sodicity that work? 2-
How to manage irrigation water to insure that the
necessary levels or criteria are not
violated? 3- If there is an adverse consequence,
how and what needs or can be done to resolve
problems created?
5

See also Van Voast, 2003
See poster by Roffe, 2003. .
6
CBM product water in the Powder River Basin -
knowns

• Trend of increasing sodium adsorption ratio
  (SAR), electrical conductivity (EC) and total
  dissolved solids (TDS) progressing north and west
  through the basin (Rice et al., 2000).
• CBM product water chemistry at outfall
• EC range of 0.4-4.3 dS/m SAR range of 5-68.7,
  median 8.8, median 1.3 dS/m
• TDS range of 270-2,730 mg/l, median 838 mg/l
• Note water chemistries do not remain the same on
  pumping from seam or on discharge from well EC
  and SAR can change significantly

7
North Dakota South
Dakota
Miles City
Forsyth
Powder
Yellowstone River
Tongue
EC 2.5-3.0 dS/m
EC gt 3.0 dS/m
Montana Wyoming
EC 1.5-2.0 dS/m
Belle Fourche River
Circle size is Proportional to TDS Number is
SAR
EC lt 1.2 dS/m
Figure compliments of John Wheaton, Montana
Bureau of Mines and Geology
North Platte River
Casper
8

• Most wells in southern portion are within the
  irrigation standards discharge from these wells
  would most likely influence the Powder River.
• Most wells in the northern section are above the
  limits for salinity and sodicity (Rice et al.,
  2002) this is particularly true for the Tongue
  River drainage.
• Soils are generally moderate to high in clays and
  can be saline-sodic predominant clay type in
  upper parts of watershed is generally smectite
  clays in lower part of the watersheds are mixed
  mineralogies.

9
CBM Product Water Chemistry

• CBM product water is bicarbonate rich and
  confined (under pressure) in coal seams.
• When product water is exposed to the atmosphere,
  discharged into surface water or applied to soil,
  sodium bicarbonate undergoes the following
  reaction
• NaHCO3 H CO3-2 Na
• (See poster by R. Drake, 2003 also Van Voast,
  2003)

10
CBM Product Water Chemistry

• Free carbonate (CO3-2) in solution is now
  available to bind with calcium in the surface
  water or soil to form calcium carbonate, i.e.,
  limestone or calcite.
• Ca2 2HCO3- CaCO3- H20 CO2

Van Voast, 2003 Patz and Reddy, 2003 see Poster
by R. Drake
11
Change in water chemistry for three water
qualities over a 9 day time period (subject to
evapoconcentration).
Initial vs. Final pH Initial vs. Final EC (dS/m) Initial vs. Final SAR Change EC Change SAR Change pH
Powder River 7.4 / 8.1 3.07 / 3.75 3.7 / 4.4 22.15 18.92 9.5
CBM 7.7 / 8.4 3.36 / 4.01 12.5 / 18.0 19.35 44.00 9.1
Saline-sodic CBM 7.5 / 9.1 5.42 / 6.71 20.7 / 33.8 23.80 63.29 21.3
Average Change Average Change Average Change Average Change 21.77 42.07 13.3
12
Changes in product water chemistry - from
discharge to downstream location
Mean values Mean values Mean values Mean values
pH -- EC dS/m SAR practical SAR true
Sue Draw DC 1 7.13 4.30 24.76 33.5
Site 3 8.54 4.20 29.74 44.1
Site 4 (below res.) 9.15 4.27 32.46 53.4
Change (discharge to Site 4) 28.3 increase lt1 decrease 31.1 increase 59.4 increase
Source Patz, Marji J. Coalbed Methane Product
Water Chemistry on Burger Draw, Wyoming, M.S.,
Department of Renewable Resources. University of
Wyoming. May, 2002.
13
Crop Tolerance to Saline Water
Tolerant EC gt 8 Semi-Tolerant EC 4-8 Sensitive EC lt 4
Crops Barley Sugarbeet Sunflower Wheat Oats Corn Safflower Potato Field Bean Peas Lentils
Forages Tall wheatgrass Bearless wildrye Altai wildrye Slender wheatgrass Western Wheatgrass Russian wildrye Barley Sweetclover Alfalfa Tall Fescue Wheat (hay) Orchardgrass Cicer milkvetch White clover Red clover Ladino clover Alsike clover Meadow foxtail
14
Saline and sodic conditions promote new plant
communities

• Typically, application of saline and sodic water
  promotes the development of salt-tolerant,
  halophytic communities
• Commonly occurring species which should be
  considered as indicators of changing salinity
  conditions include
• Prairie cordgrass Cattail
• Baltic rushes American bullrush
• Salt cedar Alkali grass

15

• Species
• Perennial Barley
• (Hordeum marinium)
• Big Saltbrush
• (Atriplex lentiformis)
• Saltbush
• (Atriplex wytana)

16
EC of shallow groundwater over a 32-week period
of irrigation of Hordeum marinium (Maritime
barley) (no drainage, average of all water table
positions). Bold horizontal lines at EC1.9dS/m
and EC3.5dS/m correspond to applied water EC.
EC, dS/m
EC applied 3.5 dS/m
EC applied 1.9 dS/m
17
SAR of groundwater over a 32-week period of
irrigation of Hordeum marinium (no drainage).
Bold horizontal lines at SAR3.5 and SAR10.5
correspond to applied water SAR
SAR applied10.5
SAR applied 3.5
18
The Soil Issue Some soil-related management
options
19
Almost without exception in semi-arid regions the
soil solution in irrigated fields will be more
saline than the salinity of the irrigation water
because of evapotranspiration that leaves the
salts from the irrigation water in the soil and
the dissolution of some soil minerals (Rhoades et
al., 1973). Irrigation may increase the salinity
and sodicity of the soil profile to a point at
which plant growth is reduced (Maas and Hoffman,
1977).. And the soil structure may be damaged
(Ben-Hur et al., 1998)
20
To avoid accumulation of salt in the soil, salt
leaching from the root zone needs to be conducted
(Ben-Hur et al., 2001). The leaching fraction is
the water that is intentionally applied in excess
of plant water needs to hold the salt
concentration of the soil below a specific value.
It is the fraction of the applied water that
appears as drainage water (Rhoades et al.,
1973). The water percolating below the root zone
moves downward to the groundwater and may cause
the water table to rise.
21
Effect of EC and SAR of applied water on relative
hydraulic conductivity (Source Shainberg and
Letey, 1984).
Red line as SAR increases, relative HC
decreases at fixed EC

• Sodic water is any water with a SAR greater than
  12. Sodic water is not necessarily saline.
• Potential impact of sodium is often assessed with
  ESP gt 15 and gt 35 swelling clay.
• Sodic soil has exchangeable sodium percentage
  (ESP) greater than 15.

Green line as EC increases at fixed SAR,
relative HC increases
22
Moderate to severe risk of dispersion
Slight to moderate dispersion potential
Little to no risk of dispersion
23
Resultant Mean Saturated Paste EC and SAR for
Treatment Combinations (across all textures)
Water Quality Treatment Water Quality Treatment Mean EC (dS/m) Mean SAR
Treatment EC x SAR Base 49 0.82 a 2.56 a
1.6 x 4.5 1X P.R. 49 1.51 b 5.94 b
3.1 x 13.0 1X CBM 49 2.46 c 3.92 b
1.6 x 4.5 5X P.R. 49 3.21 d 4.94 b
1.6 x 4.5 5X Pd 49 3.02 e 4.86 b
3.1 x 13.0 5X CBM 49 6.93 f 11.31 c
3.1 x 13.0 5X Cd 49 5.73 g 10.85 c
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(See poster by Hershberger, 2003)
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The Soil Issue Some case studies of soil
responses
26
Leaching and Reclamation of Soil Irrigated with
Moderate SAR Waters. J.E. Mace and C. Amrhein.
SSSAJ 65199-204, 2001
- SAR 1, 3, 5, 8 - EC 0, 0.25, .5, 1.0, 5.0,
10.0 dS/m - Soils amended with gypsum and
sulfuric acid and subsequently leached with
simulated rainfall - Outcomes - At low EC (lt12
mmolcL-1, EC 1.2 dS/m) internal swelling
occurred, reducing the number of large,
free-draining pores, reducing water holding
capacity and conducting porosity of soil at low
tension, i.e., soil does not drain as readily
after wetting.
27
Fig 1 (pg 200)
EC 3.0 dS/m
Interpretation as SAR of applied increases from
1 to 8, the entire HC curve drops as EC of
applied water increases from 0 to 10 dS/m, the
HC at any SAR increases. In some situations,
even at low SAR, HC can decrease with reductions
in EC.
Value divided by 10 EC in dS/m
28
Mace and Amrhein, 2001 Loss of hydraulic
conductivity occurred at all SAR was reversible
with gypsum additions. At SAR 5 and 8,
irreversible plugging of soil pores by dispersed
clay. Conclusion Hydraulic conductivity of soil
decreased as a function of increasing SAR and
decreasing EC. Even modestly saline-sodic water
used for irrigation can have an adverse effect on
soil structure, especially during rainfall.
29
Fig 4 (pg 202) Interpretation Effectiveness of
gypsum application is highest on soils previously
treated with water of SAR 1-3 Significant
difference of responsiveness of soils previously
irrigated with low SAR v. high SAR
water Hydraulic conductivity increase most
evident immediately after gypsum application and
significantly decreases with second and
subsequent leaching event Implication gypsum
applications need to be repeated as long as water
of elevated SAR is applied
30
The Soil Issue Some case studies of soil
responses
31
EC (dS/m paste extract) v. soil depth Als
Barley, 9/2003
Continuous CBM discharge water EC 2.25 dS/m,
SAR 63, Birney
Baseline-no CBM discharge water irrigated with
Powder River
Baseline-no CBM discharge water, Birney site
irrigated with Tongue River
Als site/Birney, MT, 9/2003, deep, well-drained,
fine sandy loam no watertable present Als
Moorhead site, shallow, poorly drained silty clay
loam, shale subsoil at 18, shallow water table
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SAR v. Soil Depth Als Barley, 9/2003
Continuous CBM discharge water EC 2.25 dS/m,
SAR 63, Birney
Baseline-no CBM discharge water irrigated with
Powder River
Als site/Birney, MT, 9/2003, deep, well-drained,
fine sandy loam no watertable present Als
Moorhead site, shallow, poorly drained silty clay
loam, shale subsoil at 18, shallow water table
Baseline-no CBM discharge water, Birney site
irrigated with Tongue River
33
EC, dS/m v. soil depth - Beehive Site, 9/2003
Intermittent CBM discharge water
Continuous CBM discharge water
Baseline-no CBM discharge water
Beehive site/Birney, MT, 9/2003, deep,
well-drained, fine sandy loam no water table
present
Applied water EC 1.7-1.8 dS/m, SAR 70.8, pH
8.5-8.6
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Intermittent CBM discharge water
Baseline-no CBM discharge water
Continuous CBM discharge water
Beehive site/Birney, MT, 9/2003, deep,
well-drained, fine sandy loam no water table
present
Applied water EC 1.7-1.8 dS/m, SAR 70.8, pH
8.5-8.6
35
EC (dS/m) v. soil depth Schoolhouse site, 9/2003
Continuous CBM impoundment overflow site EC
1.6-1.8 dS/m, SAR 35.9, pH 8.3
Frequent CBM discharge water EC 1.6-1.8 dS/m,
SAR 35.9, pH 8.3
Continuous CBM discharge water EC 1.6-1.8
dS/m, SAR 35.9, pH 8.3
Baseline-no CBM discharge water
Schoolhouse site/Moorhead, MT, 9/2003, shallow,
poorly drained silty clay loam, shale subsoil at
18, shallow water table
36
SAR v. soil depth Schoolhouse site, 9/2003
Continuous CBM impoundment overflow site EC
1.6-1.8 dS/m, SAR 35.9, pH 8.3
Continuous CBM discharge impoundment EC
1.6-1.8 dS/m, SAR 35.9, pH 8.3
Baseline-no CBM discharge water
Frequent CBM discharge water EC 1.6-1.8 dS/m,
SAR 35.9, pH 8.3
Schoolhouse site/Moorhead, MT, 9/2003, shallow,
poorly drained silty clay loam, shale subsoil at
18, shallow water table
37
Sustainability of crop production in
Saline/Sodic Conditions

• Certain conditions need to be met
• the soil being irrigated must be well-drained
• salt tolerant crops should be the primary crops
  grown
• rotations should be planned to provide for a
  sequence of progressively more salt tolerant
  crops
• salts should be leached out of the soil in the
  spring or winter
• as the salinity of either the irrigation water or
  soil solution increases (with prolonged crop
  water use and through the irrigation season), the
  volume of irrigation water applied should be
  progressively increased.

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Management of Sodic Soils

• Basic rule
• the first thing you need is good drainage - an
  outlet to which to send the sodium when it is
  displaced.
• a source of calcium (already in the soil or as an
  amendment), and exchange process,
• a source of water to flush the sodium from the
  system

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Thank you Jim Bauder, MSU