title: The geochemical transformation of soils by agriculture and its dependence on soil erosion: An application of the geochemical mass balance approach.
abstract: Agricultural activities alter elemental budgets of soils and thus their long-term geochemical development and suitability for food production. This study examined the utility of a geochemical mass balance approach that has been frequently used for understanding geochemical aspect of soil formation, but has not previously been applied to agricultural settings. Protected forest served as a reference to quantify the cumulative fluxes of Ca, P, K, and Pb at a nearby tilled crop land. This comparison was made at two sites with contrasting erosional environments: relatively flat Coastal Plain in Delaware vs. hilly Piedmont in Pennsylvania. Mass balance calculations suggested that liming not only replenished the Ca lost prior to agricultural practice but also added substantial surplus at both sites. At the relatively slowly eroding Coastal Plain site, the agricultural soil exhibited enrichment of P and less depletion of K, while both elements were depleted in the forest soil. At the rapidly eroding Piedmont site, erosion inhibited P enrichment. In similar, agricultural Pb contamination appeared to have resulted in Pb enrichment in the relatively slowly eroding Coastal Plain agricultural soil, while not in the rapidly eroding Piedmont soils. We conclude that agricultural practices transform soils into a new geochemical state where current levels of Ca, P, and Pb exceed those provided by the local soil minerals, but such impacts are significantly offset by soil erosion.
authors.affiliation: University of Minnesota, Dept. of Soil, Water, and Climate, 430 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, United States. Electronic address: kyoo@umn.edu.
authors.forename: Kyungsoo
authors.initials: K
authors.lastname: Yoo
authors.affiliation: University of Minnesota, Dept. of Soil, Water, and Climate, 430 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, United States.
authors.forename: Beth
authors.initials: B
authors.lastname: Fisher
authors.affiliation: University of Delaware, Department of Plant and Soil Sciences, 531 S College Ave. 152 Townsend Hall, Newark, DE 19716-2170, United States.
authors.forename: Junling
authors.initials: J
authors.lastname: Ji
authors.affiliation: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311, United States.
authors.forename: Anthony
authors.initials: A
authors.lastname: Aufdenkampe
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, SE-90187 Umeå, Sweden.
authors.forename: Jonatan
authors.initials: J
authors.lastname: Klaminder
keywords: Anthropocene; Calcium; Chemical weathering; Fertilizer; Geochemical mass balance; Liming; Phosphorous; Soil erosion