Avoiding the Point of No Return : Maintaining Infiltration to Remediate Saline-Sodic Vertosols in High Rainfall Environments
Saline-sodic soils are difficult to manage because they are often too saline and alkaline for plant survival. These soils are also prone to dispersing, developing poor physical structure, and eroding if salinity is reduced without addressing the sodicity. Cost-effective methods are needed to leach salts without also causing the soil to disperse due to the decreasing ionic strength of the soil solution. We tested the ability of gypsum, both alone and combined with elemental sulfur and organic matter to remediate the upper 15 cm of a strongly saline-sodic alkaline Vertosol when leached with deionised water in repacked columns. Prior to leaching, all amendment combinations reduced soil alkalinity by 80 % and dispersion by 47 % by displacing exchangeable sodium (Na). After leaching with 600 mm of deionised water, electrical conductivity of the soil solution (EC ss ) reduced from an average of 38 to 4.8 dS m -1 at 8 cm depth. Importantly, structure was maintained in all amended soils, despite this reduction in EC ss . In contrast, for the control treatment, there was a concomitant loss of soil structural stability as EC ss decreased. This decrease in stability also occurred in the subsoils of all treatments (which were not amended) because the applied calcium (Ca) precipitated before it could be leached to remediate the deeper layers. This study demonstrated that it was critical to first apply amendments as deep in the soil profile as possible to prevent the development of a non-saline sodic soil. Leaching the soil with low ionic strength water removed excess soluble salts from the plant root zone. We estimated that > 300 mm of water (rainfall or irrigation) was required to leach through the root zone to ensure a suitable soil profile for establishing of salt tolerant pioneer species such as Rhodes grass ( Chloris gayana Kunth)
Year of publication: |
[2022]
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Authors: | Das, Bianca T. ; Menzies, Neal W. ; Dalzell, Scott A. ; McKenna, Brigid A. ; Kopittke, Peter M. |
Publisher: |
[S.l.] : SSRN |
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