Factors Affecting Spatial and Temporal Variability of Metals in Drainage Water from Arable Fields

Abstract

Respecting fertilizer application, the metal content in drainage water is studied under conventional agricultural management from 2013 to 2014 in two adjacent fields located in the North German Plain. Findings are compared with data of nutrients, main ions, and dissolved organic carbon, as well as element contents in fertilizers and geogenic background values of soils. Comparatively low metal concentrations are found in drainage water. These results are in line with metal contents of applied mineral fertilizers, of cattle slurry, and random analysis of the two soils considered. Relating to effective ordinances, the applied fertilizers occasionally pose a risk for the groundwater or downstream water bodies. Concentrations of some metals (Al, Co, Cr, Pb, and V) are rather affected by soil erosion than by fertilizers. Besides fertilizers and soil erosion, mainly pedo‐hydrological conditions, which differ between the two fields, influence element profiles in tile drainage by the extent of anoxia and subsequent denitrification and sulfate reduction. Against the background of climate change, further investigations with respect to possible changes in soil water budget are necessary.

Variability of metals in drainage water from arable fields is investigated. Drainage improves topsoil conditions by amelioration. It also may aggravate diffuse pollution by shortening residence time of water in soil. In the study, besides fertilizers and soil erosion, mainly pedo‐hydrological conditions influence metal concentrations in tile drainage. Measures to minimize soil erosion should supplement careful use of fertilizers.