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There is increasing demand for more detailed soil maps to support fine-scale land use planning, soil carbon management, and precision agriculture in Saskatchewan. Predictive soil mapping that incorporates a combination of environmental covariates provides a cost-effective tool for generating finer resolution soil maps. This study focused on mapping soil properties for multiple soil horizons in Saskatchewan using historical legacy soil data in combination with remote sensing band indices, bare soil composite imagery, climate data, and terrain attributes. Mapped soil properties included soil organic carbon content (SOC), total nitrogen, cation exchange capacity (CEC), electrical conductivity (EC), inorganic carbon (IOC), sand and clay content, and total profile soil organic carbon stocks. For each of these soil properties, a recursive feature elimination was undertaken to reduce the number of features in the overall model. This process involved iteratively removing features such that random forest out-of-bag error was minimized. Final random forest models were built for each property and evaluated using an independent test dataset. Overall, predictive models were successful for SOC (R2 = 0.71), total nitrogen (R2 = 0.65), CEC (R2 = 0.46), sand content (R2 = 0.44) and clay content (R2 = 0.55). The methods used in this study enable mapping of a greater geographic region of Saskatchewan compared to those previously established that relied solely on bare soil composite imagery. [ABSTRACT FROM AUTHOR]

Digital soil mapping of wetland soils has met with limited success in part because terrain attributes based on hillslope hydrology are inappropriate for predicting the pedological consequences of wetland hydrology. Our objective is to synthesize recent developments in the hydrology and hydrochemistry of wetlands in the northern Prairie Pothole Region (PPR) and apply this enhanced understanding to the predictive mapping of wetland soils. The landscape-scale distribution of freshwater vs. brackish/saline soils is controlled by salt transport by episodic surface fill-and-spill events and (more rarely) by groundwater–surface interactions. Both sets of hydrological processes lead to ponds in lower-elevation spillways having more saline conditions. At nine freshwater ponds studied at three study areas (Swift Current, St. Denis, and Melfort, Saskatchewan) the elevation threshold between wetland-recharge (i.e., gleyed soils with deep (2- to 5-m) zones of carbonate depletion) and wetland-discharge (i.e., carbonated soils with no B horizon formation) soils corresponds to the maximum water level recorded at the nine ponds over approximately 40 years of water level measurements. The band of discharge soils surrounding the wetland extends for approximately 1 m elevation above of this water level elevation. The spatial distribution of wetland-recharge and wetland-discharge soils in freshwater ponds provides an enduring record of pond hydrological conditions and can be readily adapted to predictive soil mapping in this region. [ABSTRACT FROM AUTHOR]