Sostituzione della torba con compost da reflui oleari nel vivaismo ornamentale

Peat is the most widely used substrate for potted plant production in nurseries and accounts for a significant portion of the materials used. Because of concerns about destruction of peat bogs, other organic materials have been investigated for their potential as substitutes for peat in growing media used for container or soilless crops. Compost made with olive mill waste (OMW) represents an interesting ingredient for the production of growth media in nursery cultivation. ISAFoM-CNR recently studied different low cost on farm composting technologies able to convert raw olive mill effluents into a organic matter useful for agronomic applications. This paper deals with the evaluation of two OMW compost used as substitute for peat in the preparation of growth media for potted plants. Both composts contained humid husk as major ingredient along with hygroscopic organic additives such as waste wool and straw. Composts differed for the composting procedure adopted: Co, dynamic thermal composting in turning pile; BB, static composting conducted in gas-permeable bags characterized by a mass to surface ratio able to ensure adequate passive aeration and thermal inertia. Growth and commercial performance of potted plants have been evaluated on three species: Abelia, Viburnum, Feijoa. In the preparation of the experimental growth media, peat has been partially (50%) or totally replaced by the two composts under trial. Plot treatments also included presence or absence of mineral fertilization. Both composts showed high nitrogen and potassium contents which supplied plant nutrition, especially in not fertilized plots. Most of the fertilized plots containing Co and BB showed performances comparable to control, evaluated either on epigeous dry matter weight or according to fixed commercial standards set by the company which hosted the trials. However, BB sometimes performed better that Co showing higher aptitude to replace peat.