Date of Award
Master of Science
Plant and Soil Science
Extensive urban development has led to the resurgence of green roofs. These vegetated roofs provide significant ecological and economic benefits including mitigation of the urban heat island effect, reduced storm-water runoff, lower energy costs, increased biodiversity, and improved aesthetics, as well as food production and security. Urban agriculture and food security are becoming increasingly important factors of the green roof renaissance. Due to weight load limitations of potential buildings, the ability to produce quality food in shallow media, less than 6.75 cm, could encourage green roof food production. The effectiveness of a commercially available green roof media and a vermicompost custom blended green roof media was evaluated in two experiments on the roof of the Agriculture building at Southern Illinois University Carbondale. In a randomized complete block design, twelve green roof modular trays (six 61 cm x 61 cm and six 46 cm x 56 cm) were filled to the depth of 5.72 cm with each media type. Each block consisted of four treatments with three replications in two locations on the roof. One location received full sun and the other only partial shade. Two commercially-grown annual herbs, sweet basil (Ocimum basilicum) and Thai basil (Albahaca tailandesa) and parsley (Petroselinum crispum var. neapolitanum; Petroselinum crispum `Krausa'; and Petroselinum crispum crispum) were evaluated during the two experiments. The first experiment ran from mid-May to mid-July, 2011, and the second experiment ran from mid-August to late September, 2011. Media content, mineral analysis, and biomass were recorded for each treatment. Hand irrigation was utilized as needed. In the first experiment, media, and an interaction of sunlight and media produced significant (P< 0.05) results for parameters of shoot height, shoot width and shoot weight. Sunlight, specifically partial shade, produced significant (P< 0.05) for shoot to root ratio. The commercially available green roof media produced more significant results for the parameters measured than the vermicompost-blend. In the second experiment, an interaction was detected for basil shoot width; otherwise all other variables evaluated for basil were insignificant. Media, specifically the commercial green roof media, was significant (p< 0.05) for parsley shoot height, with an interaction of sunlight and media; shoot weight and dry shoot weight, and with an interaction of sunlight and media for shoot width. No significant results were observed with the other parameters measured. The experiments indicated that the production of annual herbs on a green roof environment is possible. Further, the experiments found that the commercially available green roof media performed better than the custom vermicompost blend. Modular tray type had limited effect on results, but the advantage of pre-planting the trays before placement onto a green roof environment is an incentive for its use.
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