BRICK DUST AS A SUBSTRATE FOR EXTENSIVE GREEN ROOFS

Abstract

Extensive green roofs (EGR) contain less than 15 cm of substrate, which must be stable, with low density, high aeration and sufficient water and nutrient retention for adequate plant development. In search of alternative components to formulate this type of substrates, the objective of this work was to evaluate substrates with brick dust and its effect on the growth of species of the genus Sedum L. The trial consisted of four treatments/substrates composed of pumice stone (P), microleca (M), perlite (Pe), Sphagnum peat (T), enriched zeolite (Z) and brick dust (PL) in volumes indicated by the subscripts: 1) P20:M25:Pe40:Z15; 2) PL85:Z15; 3) P20:M25:Pe30:Z15:T10; and 4) PL75:Z15:T10. Three tables were made and divided into four experimental units of 1.2 m2 . The Sedum species evaluated were S. acre, S. alba, S. mexicanum and S. ruflexum. Physical and chemical analyzes were carried out on all
substrates. The surface area (cm2 ) covered by the vegetative part and survival was measured for each plant. All substrates had a pH value greater than 6.3 and a high initial electrical conductivity value, but low at the end of the trial. The aeration porosity in all substrates was greater than the water retention capacity. The surface covered by S. acre was greater in the substrate PL75: Z15T10 and by S. alba in the substrates P20: M25: Pe40: Z15 and PL75: Z15T10. Sedum mexicanum covered less surface in the substrate PL85:Z15, and no differences were observed with S. reflexum (P: 0.6114). Brick dust is a viable alternative for use in EGR.