Norfolk Island soil clay content DSM attributes

Surface soil clay % and maximum clay % to 2m soil depth are two of nine soil attributes analysed as one component of a digital soil mapping exercise undertaken as part of the Norfolk Island Water Resource Assessment (NIWRA). It was selected due to its importance to groundwater recharge, surface water storage and managed aquifer recharge. Clay percent is a parameter influencing surface water infiltration, subsoil permeability and water holding capacity and has also been applied in the gully dam suitability rules in relation to construction and engineering properties for gully dams. These raster data represent modelled datasets of clay percent and are derived from field measured site data, limited laboratory analysis and environmental covariates. Data values are expressed as a percent. The measured site data attribute soil texture is used to represent clay content as defined by the National Committee on Soil and Terrain 2009 (NCST). Companion datasets presenting reliability of these data is also provided and can be found described in the lineage section of this metadata record. Processing was carried out in the ranger package inside R and attributes were modelled using a Random Forest approach. Further clay percent information can be found in the NIWRA technical report (Petheram et al., 2020). The DSM process is described in Appendix E of the NIWRA technical report.