Use of waste materials as nursery growing media for Pinus halepensis production

Peat moss is gradually being replaced by other materials as a growing medium in forest nurseries due to economic and ecological constraints. In this study, six different mixtures were tested, mixing peat moss (P) and pine bark (B) with digested sewage sludge (S) activated sewage sludge (A) and paper mill sludge (M), as growing media for Pinus halepensis seedlings; three different waste doses were applied. Seed germination percentage, seedling growth and foliar nutrient content after 1 year in a greenhouse and percentage survival after transplanting were recorded. The influence of base substrate (P or B) on germination percentage changed in different ways according the type of waste. The order of the different applied mixtures by suitability (germination rate and seedling growth) from best to worst was as follows: activated sludge with peat, activated sludge with pine bark, sewage sludge with peat, sewage sludge with pine bark, paper mill sludge with pine bark and finally paper mill sludge with peat.