title: Managing land application of coal seam water: A field study of land amendment irrigation using saline-sodic and alkaline water on a Red Vertisol.
abstract: Coal seam (CS) gas operations coproduce water with gas from confined CS aquifers. This CS water represents a potential agricultural resource if the water is able to be chemically amended to comply with management guidelines. Stoichiometric quantities of sulphur and gypsum amendments can be used to neutralise the alkalinity and reduce the sodicity of CS water respectively. These amendments can either be mixed in-line at a water treatment plant or applied directly to land prior to the application of CS water (a practice termed land amendment irrigation - LAI). This study compared the efficacy of LAI with in-line chemical amendment of CS water and irrigation with non-saline, non-sodic and non-alkaline (good quality) water under field conditions in southern Queensland. Soil chemical properties, soluble Ca, Mg, K, Na, electrical conductivity (EC), pH, chloride and alkalinity, as well as saturated hydraulic conductivity were measured to determine the impact of the irrigation treatments on soil chemical and physical conditions. Irrigation of lucerne pasture using solid-set sprinklers applied a total of 6.7 ML/ha of each treatment irrigation water to the experimental plots over a 10-month period. Alkalinity was neutralised using LAI, with no increase in soil alkalinity observed. Soil sodicity did not exceed threshold electrolyte concentration values under either CS water irrigation treatment. Soil chemical and physical properties were comparable for both LAI and in-line chemical amendment of CS water. Soil saturated hydraulic conductivity was maintained under all irrigation treatments. Results showed that the constrained capacity of the irrigation system was unable to meet crop evapotranspiration demand. This resulted in accumulation of salt within the root-zone under the CS water treatments compared to the good quality water treatment. LAI successfully chemically amended Bowen Basin CS water facilitating its beneficial use for agricultural irrigation.
authors.affiliation: National Centre for Engineering in Agriculture, University of Southern Queensland, West Street, Toowoomba, Queensland, 4350, Australia. Electronic address: John.Bennett@USQ.edu.au.
authors.forename: J McL
authors.initials: JM
authors.lastname: Bennett
authors.affiliation: National Centre for Engineering in Agriculture, University of Southern Queensland, West Street, Toowoomba, Queensland, 4350, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Marchuk
authors.affiliation: National Centre for Engineering in Agriculture, University of Southern Queensland, West Street, Toowoomba, Queensland, 4350, Australia.
authors.forename: S R
authors.initials: SR
authors.lastname: Raine
authors.affiliation: Santos, Queensland Business Unit Environment, Brisbane, Queensland, 4000, Australia.
authors.forename: S A
authors.initials: SA
authors.lastname: Dalzell
authors.affiliation: David Macfarlane Consulting, 2/120 Ryan St, West End, Queensland, 4101, Australia.
authors.forename: D C
authors.initials: DC
authors.lastname: Macfarlane
mesh_terms: D003031:Coal; D060587:Groundwater; D006801:Humans; D007220:Industrial Waste; D011793:Queensland; D012964:Sodium / Q000737:chemistry; D012965:Sodium Chloride / Q000032:analysis; D012987:Soil / Q000737:chemistry*
chemical_list: D003031:Coal; D007220:Industrial Waste; D012987:Soil; D012965:Sodium Chloride; D012964:Sodium
keywords: Coal bed methane; Coal seam gas; Gypsum; Salinity; Sodicity; Threshold electrolyte concentration