Effects of Municipal Waste Leachate on Seed Germination in Soil-Compost Mixtures

The goal of revegetation projects on degraded or polluted lands is to create a near-natural, stable, and quick-response ecosystem that does not require particular management after establishment and that is compatible with the surrounding landscape. Municipal waste compost (MWC) is commonly used in revegetation projects as a source of organic matter. The aim of this study was to investigate the germination percentage and average time of germination of 23 species (12 cultivated grasses and legumes and 11 native herbs) as affected by the leachates from soil, three different mixtures of soil-compost, and pure compost. The treatments influenced the average time of germination (ATG); legumes were the most affected species, followed by grasses and wild herbs. The percentage of germination of Festuca arundinacea was not affected by the presence of compost leachate, while Lolium multiflorum was the most sensitive species. A higher content of compost in the mixture caused a delay in germination of all the grasses. Most of the legumes were able to germinate in the leachate of the soil-compost mixtures, but their germination was delayed; Trifolium pratense had the highest sensitivity in terms of average time of germination. The native herbs Lepidium sativum, Matricaria chamomilla, and Sanguisorba officinalis germinated without any adverse effect when treated with leachate from high levels of MWC; the germination of Amaranthus cruentus was influenced by all levels of MWC in substrates, suggesting a high specific sensitivity for toxic components of leachate from MWC-soil mixtures.