Storage and export of nutrient and oxyhydroxide elements across glaciated soils and watersheds in western Massachusetts, USA

Abstract

Quantifying the geologic, pedogenic, and human processes governing elemental release and transport in glaciated terrains is complex but has several important ramifications for nutrient storage, formation of secondary minerals, and protection of surface and groundwater resources.Here, soils and river waters were studied in three subwatersheds of the Deerfield river from October 2018 to January 2020 to determine if nutrient (Ca, K, P) and oxyhydroxide elements (Al, Fe, Mn) were retained within the soil or exported from the watershed via river water at comparable rates in: Supra-glacial till Forested soils, Fluvial Agriculture soils, and Sub-glacial Till Hydric soils. This study found higher soil storage, soil water transport, and watershed export of nutrients in the Fluvial Agriculture subwatershed compared with the Supra-glacial Till subwatershed. The Supra-glacial Till subwatershed had the greatest overall river water nutrient export as it was the largest subwatershed but when considered with area-normalized basis, the Fluvial Agricultural soils exported 3x to 6x higher nutrients. When considering the oxyhydroxide elements, Al was not significantly different among geologic deposits and land covers. Iron concentrations in soils and soil water were not significantly different between hydric and forest soils, despite higher acidity, higher dissolved organic carbon, and lower electropotential in the former. Agricultural soils were enriched in Mn likely due to continuous agriculture since 1677 CE, which is unreported in agricultural fields of New England with potential impacts on soil C dynamics or microbial communities.