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

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

-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

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?

See also Van Voast, 2003; See poster by Roffe,

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 dS/m SAR range of , 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 CBM product water in the Powder River Basin - knowns

Montana Wyoming North Dakota South Dakota Powder Casper Miles City Forsyth Belle Fourche River North Platte River Tongue Yellowstone River Circle size is Proportional to TDS Number is SAR Figure compliments of John Wheaton, Montana Bureau of Mines and Geology EC < 1.2 dS/m EC ~ dS/m EC ~ dS/m EC > 3.0 dS/m

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.

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: NaHCO 3 H + + CO Na + (See poster by R. Drake, 2003; also Van Voast, 2003)

CBM Product Water Chemistry Free carbonate (CO 3 -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. Ca HCO 3 - CaCO H CO 2 Van Voast, 2003; Patz and Reddy, 2003; see Poster by R. Drake

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 / / / CBM 7.7 / / / Saline- sodic CBM 7.5 / / / Average % Change:

Changes in product water chemistry - from discharge to downstream location: Mean values pH -- EC dS/m SAR practical SAR true Sue Draw DC Site Site 4 (below res.) % Change: (discharge to Site 4) 28.3% increase <1% 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.

Tolerant EC > 8 Semi-Tolerant EC = 4-8 Sensitive EC < 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 Crop Tolerance to Saline Water

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 cordgrassCattail Baltic rushesAmerican bullrush Salt cedarAlkali grass

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

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 EC=1.9dS/m and EC=3.5dS/m correspond to applied water EC. EC applied = 3.5 dS/m EC applied = 1.9 dS/m EC, dS/m

SAR of groundwater over a 32-week period of irrigation of Hordeum marinium (no drainage). Bold horizontal lines at SAR=3.5 and SAR=10.5 correspond to applied water SAR SAR applied=10.5 SAR applied =3.5

The Soil Issue – Some soil-related management options

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)

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.

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 > 15% and > 35% swelling clay. Sodic soil has exchangeable sodium percentage (ESP) greater than 15%. 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 Green line – as EC increases at fixed SAR, relative HC increases

Moderate to severe risk of dispersion Slight to moderate dispersion potential Little to no risk of dispersion

Water Quality Treatment Mean EC (dS/m) Mean SAR Treatment EC x SAR Base a2.56 a 1.6 x 4.5 1X P.R b5.94 b 3.1 x X CBM c3.92 b 1.6 x 4.5 5X P.R d4.94 b 1.6 x 4.5 5X P+d e4.86 b 3.1 x X CBM f11.31 c 3.1 x X C+d g10.85 c Resultant Mean Saturated Paste EC and SAR for Treatment Combinations (across all textures)

(See poster by Hershberger, 2003)

The Soil Issue – Some case studies of soil responses

- 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 (<12 mmol c L -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. Leaching and Reclamation of Soil Irrigated with Moderate SAR Waters. J.E. Mace and C. Amrhein. SSSAJ 65: , 2001

Fig 1 (pg 200) Value divided by 10 = EC in dS/m 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.

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.

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

The Soil Issue – Some case studies of soil responses

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 Al’s site/Birney, MT, 9/2003, deep, well-drained, fine sandy loam; no watertable present; Al’s Moorhead site, shallow, poorly drained silty clay loam, shale subsoil at 18’, shallow water table EC (dS/m paste extract) v. soil depth – Al’s Barley, 9/2003

Al’s site/Birney, MT, 9/2003, deep, well-drained, fine sandy loam; no watertable present; Al’s Moorhead site, shallow, poorly drained silty clay loam, shale subsoil at 18’, shallow water table SAR v. Soil Depth – Al’s Barley, 9/2003 Baseline-no CBM discharge water; irrigated with Powder River Continuous CBM discharge water; EC = 2.25 dS/m, SAR = ~63, Birney; Baseline-no CBM discharge water, Birney site; irrigated with Tongue River

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 = dS/m, SAR = 70.8, pH =

Baseline-no CBM discharge water Continuous CBM discharge water Intermittent CBM discharge water Beehive site/Birney, MT, 9/2003, deep, well-drained, fine sandy loam; no water table present Applied water: EC = dS/m, SAR = 70.8, pH =

Continuous CBM discharge water; EC = dS/m, SAR = 35.9, pH = 8.3 Continuous CBM impoundment overflow site; EC = dS/m, SAR = 35.9, pH = 8.3 Frequent CBM discharge water; EC = dS/m, SAR = 35.9, pH = 8.3 Baseline-no CBM discharge water EC (dS/m) v. soil depth – Schoolhouse site, 9/2003 Schoolhouse site/Moorhead, MT, 9/2003, shallow, poorly drained silty clay loam, shale subsoil at 18’, shallow water table

Continuous CBM impoundment overflow site; EC = dS/m, SAR = 35.9, pH = 8.3 Continuous CBM discharge impoundment; EC = dS/m, SAR = 35.9, pH = 8.3 Frequent CBM discharge water; EC = dS/m, SAR = 35.9, pH = 8.3 Baseline-no CBM discharge water SAR v. soil depth – Schoolhouse site, 9/2003

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.

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

Thank you Jim Bauder, MSU