TURIN, ITALYPeat, or semi-decayed vegetation matter, has been used by commercial growers and amateur gardeners since the middle of the 20th century. Peat is added to potting soil to help retain moisture and provide additional nutrients. As the demand for peat grew, acres of peat bogs were being drained and destroyed. Now, concerns about the environmental impact of extracting peat from wetlands are mounting. And as peat supplies are reduced, the cost naturally increases. Diminishing supplies and environmental and economical concerns are encouraging researchers to find viable alternatives to this popular growing medium.
A recent research study led by Federica Larcher and Valentina Scariot of the University of Turin's Department of Agronomy evaluated five materials as partial peat substitutes. The results, published in HortScience, show these alternatives have potential.
The study focused on growing camellia, a woody plant that prefers acidic soils and is often grown in containers for decorative purposes. Three varieties of camellia ('Charles Cobb's', 'Nuccio's Pearl', and 'Dr. Burnside' ) were tested using a combination of peat and the following peat alternatives: green compost such as grass clippings and leaves, pumice, coconut husks broken down into fibers, composted coconut "peat", and pine bark. Each variety was also grown using the standard commercial Sphagnum peat as a control.
Plant growth and the ornamental quality of each plant was evaluated during each phase of cultivation, potting, before repotting, before and after branching and at the end of the experiment. "The alternative growing media testedperformed as well or better than the standard substrate," the study reports. However, green compost was the exception. Plants grown in green compost had the lowest evaluations in all categories. Green compost also increased pH levels with negative effects on plants.
The impact of the different growing media seemed to
|Contact: Michael W. Neff|
American Society for Horticultural Science