Selenium mobility in soils under greenhouse vegetable production system: a comparative study on adsorption and desorption behavior and management implications

The intensification of agricultural practices, particularly greenhouse vegetable production (GVP), has raised concerns regarding soil selenium (Se) dynamics and environmental safety. However, the underlying impact of GVP on Se migration in different types of soils is still unclear. Therefore, this study took two soils types (Terric Anthrosols, Fluvic Cambisols) under the GVP system as the research object and studied adsorption and desorption behavior of Se in these Chinese soils.

Soils used in this experiment were collected from the plough layer (0–20 cm) of two different sampling sites of western China: Terric Anthrosols with six and twelve years of GVP, Fluvic Cambisols with six years of GVP, along with an open field soil next to the greenhouse. The batch equilibrium technique and reaction mechanistic model were employed to quantify the interactions between Se and the tested soils. Selenium residues were quantified using inductively coupled plasma mass spectrometry (ICP-MS).

The adsorption of Se in both the soil types increased with rising equilibrium concentration. The Se adsorption process was explained using the Langmuir and Freundlich isotherms, as well as mechanistic models. Soils under GVP exhibited lower Se adsorption capacities and higher desorption ratios, which can be attributed to the decreased heterogeneity of soil surfaces interacting with Se and the accumulation of P from fertilizers. In GVP soils, the adsorption of Se was observed to be 16.0–38.7% lower compared to corresponding open field soils. The kinetic analysis showed that GVP soils had less heterogeneous surfaces for Se interaction and shorter duration of adsorption reaction.

The findings emphasize the necessity for tailored Se fertilization strategies in GVP soils to ensure fertilization efficiency and to mitigate the environmental risk of Se migration. This study offers critical insights into the role of GVP system in altering soil properties, and calls for careful management to prevent excessive Se application in GVP soils.