Development of Potting Soil Mixes from Local Wastes
Almond Tree/South Dade Nurseries in Dade County, Florida, required a financially and environmentally sound substitute for the potting soil mix currently in use: a mixture of peat, pine bark and sand. Peat is expensive and depletes a natural resource that could be saved if a good quality substitute can be found.
1.) Develop a potting soil mix from composted organic materials, including sewage sludge and organic waste products that have been source-separated from the rest of the refuse stream and are currently going to landfills and incinerators.
2.) Evaluate the potting soils for fertility, moisture retention and performance in a greenhouse setting.
The producers grew four varieties of nursery stock (green buttonwood, silver buttonwood, gumbo limbo and Christmas palm) in containers filled with the professional potting mix and also in containers filled with composted yard waste. The composted yard waste came from a nearby municipality, which screened it for non-yard waste materials prior to delivery. All of the plants in both sets of containers were fertilized identically with 16-4-8 fertilizer and also received the same amounts of water. A pre-emergence herbicide was applied equally to both sets.
After one year, the plants grown in the composted yard waste performed as well as those grown in the professional potting mix. Furthermore, the professional potting mix cost $21.28/cubic yard while the composted yard waste cost $15.00/cubic yard. The producers now use their own potting mix in their nursery.
Field days, seminars and mailings were used to disseminate information on the new potting mix.