Turfgrass Growth and Evapotranspiration in Intensive Green Roof Systems

The aim of the study was to investigate the effects of several intensive green roof substrates and drainage systems on turfgrass growth and evapotranspiration. Two studies were performed in outdoor lysimeters having an internal diameter of 30 cm and a height of 45 cm. The lysimeters were filled with 2 different drainage systems. The first drainage system consisted either from 15 cm pumice and a geotextile on top [G] while the second drainage system consisted from 10cm pumice and 5 cm sorted sand [S]. In the first study [A] the substrates were SL60-P-40, SL60-P-20-PER20, SL60-PER40, SL30-P-40-PER30, SL30-PER70, while in the second study [B] the substrates were SL30-P-20-PER30-L-20, SL30-P-20-PER30-PV20, SL30-P-20-PER30-LV20, SL30-PER40-PV30, SL30-PER70, where SL=Sandy Loam soil, P= Peat, PER=Perlite, L= Hellenic pumice, PV=Italian Pumice, LV= Italian Lava. Each study was replicated in two different time periods (autumn and spring). The lysimeters were seeded with Festuca arundinacea and the growth of the turf was determined by clipping's dry weight. In study A turf growth was promoted mostly in substrate SL60-P-40 in both seasons. The least turf growth was observed in substrate SL30-P-40-PER30 during the autumn while there were no significant differences among the substrates in the spring. The effect of drainage system was not significant concerning the growth and the evapotranspiration in any of the two studies.