Evaluation of olive pomace and green waste composts as peat substitutes for organic tomato seedling production

Compost based substrates for producing organic tomato seedlings (Lycopersicum esculentum L. cv. Rio Grande) were evaluated in a peat substitution experiment. Two composts made from olive pomace waste (OWC) and green waste (GWC) were produced and characterized, in comparison with a sphagnum peat moss, for the main physicochemical parameters and for their germination index. Both composts were used as growing media components at four rates (20%, 45%, 70%, 90% on a volume basis) and their performances were compared to peat based control growing media. During plant growth, nitrogen was added as blood meal. Plants were collected 36 days after sowing, plant performance parameters (stem length, leaves, stem and total fresh and dry biomass, leaves number and chlorophyll content values), and NPK shoot contents were measured. Treatments GWC 20%, 45% and OWC 20% showed the best performances, while 70% for green waste compost and 45% for olive pomace compost could be considered as upper limits for producing satisfactory organic tomato seedlings. © 2011 by The JG Press, Inc. All rights reserved.