Problem of Applying Sodium Selenate to Increase Selenium Concentration in Grassland Plants in Southern Belgium

Abstract

In a survey of grasslands, mean selenium (Se) concentration in Holcus lanatus was 83 μg kg⁻¹ (less than 100 μg kg⁻¹, the minimal concentration protecting mammals from deficiency disorders). Despite rather high levels of soil extractable Se, plant Se availability was supposed to be low because of high soil humus concentration. A pot experiment with common grassland species showed contrasting responses to selenate addition (9 g Se ha⁻¹ yr⁻¹). Lolium perenne leaves reached 470 μg kg⁻¹, and Trifolium pratense reached 292 μg kg⁻¹. The controls were less than 100 μg kg⁻¹. Leaves of others species showed greater values both in control and treated series and no significant difference. In a second pot experiment, Melilotus albus, a supposed secondary accumulator, and Lolium perenne as a control were submitted to moderate increased selenate additions (up to 45 g Se ha⁻¹ yr⁻¹). The results confirmed that Melilotus albus was a better accumulator with a leaf concentration that could reach the toxicity level of 2 mg kg⁻¹.

Keywords:

• Belgium
• fertilizer
• grassland
• plants
• selenium
• soil

Acknowledgments

The authors are indebted to Dr. Célia Joaquim-Justo and Dr. Jean-Luc Hornick for critically reviewing this manuscript and thank the botanical gardens of Alkmaar, Gembloux Agricultural University, Lasi University, Leiden, Limoges, Münster, Nantes, Oldenburg University, Paris, Varsovia University, and Wroclaw University for furnishing seeds.