Sequential phosphorus and iron extractions and phosphate sorption index across soil horizons in acidic and non-acidic tundra, Toolik, Alaska (2022-2023)

The goal of this study was to measure the various pools of inorganic and organic phosphorus, the minerals associated with those pools of phosphorus, and the various pools of iron through the soil profile across differing soil moisture conditions. Soils were collected over the summer of 2022 and 2023 along two tundra hillslopes (one acidic and one non-acidic) near Toolik Lake. Each study hillslope had three sites with soil moisture conditions delineated as Dry, Mesic, and Wet, with three replicate 5 x 5 meter (m) plots at each site. Soil samples were collected from each replicate plot of the non-acidic tundra in the summer of 2022 and of the acidic tundra in the summer of 2023. Soils were extracted using a 2-inch stainless steel corer and were frozen upon return from the field. The sampled soils were separated by horizon and then were subsampled for a sequential phosphorus extraction, sequential iron extraction, and phosphate sorption index.