Trace element concentrations in leachates and mustard plant tissue (Sinapis alba L.) after biochar application to temperate soils

Amsterdam

2014

498–508

Sonderdruck

203625

Highlights: Trace element (TE) behavior in biochar-amended soils depended on soil type. Biochar-treated soils showed increased leachate concentrations of Mo, As, Se and B. Biochar increased plant concentrations of Mo and B, but decreased Cu and Mn. TE behavior was mainly influenced through biochar-induced liming. TE behavior was also affected by changes in CEC, EC, OC and DOC.
Biochar application to agricultural soils has been increasingly promoted worldwide. However, this may be accompanied by unexpected side effects in terms of trace element (TE) behavior. We used a greenhouse pot experiment to study the influence of woodchip-derived biochar (wcBC) on leaching and plant concentration of various TEs (Al, Cd, Cu, Pb, Mn, As, B, Mo, Se). Three different agricultural soils from Austria (Planosol, Cambisol, Chernozem) were treated with wcBC at application rates of 1 and 3% (w/w) and subsequently planted with mustard (Sinapis alba L.). Soil samples were taken 0 and 7 months after the start of the pot experiment, and leachate water was collected twice (days 0 and 54). The extractability (with NH4NO3) of cationic TEs was decreased in the (acidic) Planosol and Cambisol after wcBC application, whereas in the (neutral) Chernozem it hardly changed. In contrast, anionic TEs were mobilized in all three soils, which resulted in higher anion concentrations in the leachates. The application of wcBC had no effect on Al and Pb in the mustard plants, but increased their B and Mo concentrations and decreased their Cd, Cu and Mn concentrations. A two-way analysis of variance showed significant interactions between wcBC application rate and soil type for most TEs, which indicates that different soil types may react differently upon wcBC application. Correlation and partial correlation analyses revealed that TE behavior was primarily related to soil pH, whereas the involvement of other factors such as electrical conductivity (EC), organic carbon (OC) content and dissolved organic carbon (DOC) was found to be more soil and TE-specific.
Abbreviations: BCbiochar; wcBCwoodchip-derived biochar; TEtrace element; SOMsoil organic matter; OCorganic carbon; ECelectrical conductivity; CECcation exchange capacity; SSAspecific surface area; LOQlimit of quantification
Keywords: Biochar; Trace elements; Heavy metals; Soil remediation; Leaching; Plant uptake