Biobeds originated in Sweden in response to the need for simple and effective methods to minimize environmental contamination from pesticide use, especially when filling spraying equipment, a typical point source of contamination.
What is a biobed?
The original Swedish biobed consists of three components in a 60 cm deep pit in the ground: a clay layer at the bottom (10 cm); a biomixture of straw, peat, and soil (50:25:25 vol %) filling the remaining 50 cm depth; and a grass layer covering the surface. The biobed is also equipped with a ramp to allow the sprayer to be driven and parked over the biobed. An efficient biobed promotes high pesticide binding capacity to retain the pesticides and high microbial activity to degrade them.
Biobeds have been in use in Sweden since 1993 when the first prototypes were built and studied. Several models have been built by farmers, who often reuse old building materials from the farm. The period when the highest pesticide levels are observed in biobeds is during the spraying season, i.e. when they are most intensively used. Once spilled, the pesticides are retained in the upper part of the biobed and most of them are degraded within one year.
The three pictures (right) show the building of a biobed at a farm
in Sweden, from the ground to the ramp on top of the grass layer.
Photo: Maria del Pilar Castillo