Mulching and amending with compost: results of a long term project on some ornamental species in different environments

The use of compost for soil amending and as a mulching material can increase success during the establishment and management phases of plants in urban green areas. Costs can also be reduced, especially in the management phase, but a number of conditions have to be met before benefits from the use of composts can be fully realized. Above all general quality factors have to be fulfilled especially those concerning high stability, the absence of unpleasant smell, a low or medium salt content, and absence of polluting substances or particles inhibiting germination and growth. Also, the specific quality demands on compost have to be related to nutrient content and particle size. There is no such thing as the “perfect” compost, but several, each designed for a site-specific purpose. Based on these premises and because there is a limited scientific information in Italy on compost use, a long term project on some ornamental species in different environments was initiated in 2003 and it’s still running. The project is carried out both in the nursery and in the urban stand on several tree and shrubs species, using compost both for amending and as mulching material. The following tree species were used: horsechestnut (Aesculus hippocastanum), littleleaf linden (Tilia cordata), English oak (Quercus robur), Norway maple (Acer platanoides), hornbeam (Carpinus betulus), hedge maple (Acer campestre), European elm (Ulmus minor syn. Ulmus carpinifolia). The shrubs used were cherry laurel (Prunus laurocerasus), St. John’s Worth (Hypericum x moserianum). Different types of compost were also used: raw compost, mixed compost (green waste+household wasting material), composted pine bark.