Assessing trace element accumulation and depletion in agricultural soils in Lithuania.

The aim of this study was to critically assess the accumulation and depletion in total contents of trace elements from non-point pollution areas, specifically agricultural fields. Enrichment or depletion of trace elements was assessed using Al, Fe and V (control topsoil and B horizon) as reference elements. We found that various reference elements and selecting reference horizons could give contradictory results and lead to different assessments of the effects of various agricultural practices in Lithuanian soils. Cultivation on naturally acid soils in east and west Lithuania led to enrichment in some trace elements, predominantly Ag, Mn and Sr in sandy loams or loams of west Lithuania and B, Cu and Sr in sandy loams of east Lithuania. Differential fertilization led to Sr accumulation in calcareous silt loams of central Lithuania. Many experiments revealed Sr accumulation, which means that Sr concentrations have profoundly changed during decades of soil fertilization and liming in Lithuanian soils. Subsoil reference indicated a greater number of affected elements in almost all the cases. It is probable that other regional factors (such as atmospheric pollution and precipitation chemistry) influence differences in enrichment factors (EFs) between topsoils and subsoils. Research findings accord with earlier published results on changes of mobile element forms after liming and adds knowledge on the total amounts of affected elements. We suggest that assessment protocols using a few reference elements and soil layers allow filtering of datasets and indicate reliable changes in enrichment factors (EFs). However, changes occurred in other specific elements in specific circumstances, and these reference elements merit special attention. Reference selection procedures also merit further investigation and discussion. [ABSTRACT FROM AUTHOR]