Effect of Agricultural Practices on Trace‐Element Distribution in Soil

Abstract The impact of agricultural practices on the spatial distribution of trace elements (TEs) in the surface horizon of Albeluvisols was studied by comparing three types of situation with an increasing anthropogenic gradient: a forest soil, considered as a reference, and cultivated soils with and without spreading of sewage sludge. Total cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) were determined in soil surface horizons. The quantity of particles finer than 2 µm, organic carbon (OC), iron (Fe), manganese (Mn), and calcium (Ca) contents were also measured and used as tracers of soil components that may have contained TEs. Governing factors of the spatial variability of TEs were searched for through comparison of the descriptive statistics (mean and coefficient of variation) and the determination of the best multivariate model predicting TE contents. Nickel and Cr distributions seem to be mainly linked to variability of the parent material composition, whereas that of Co is related to redox pedological processes. In addition, agricultural practices play a role in TE distribution, through the input of TEs, mostly Cd, Cu, and Zn, via sewage sludge spreading and liming amendments, and lateral (homogenization) and vertical (mixing of horizons) redistribution through tilling the soil.