Ag Illustrated – December 2009 (Research News, Pg.9)
Fish farmers in Alabama who produce tilapia in greenhouse-enclosed tanks can turn the wastewater from those tanks into a new source of on-farm income, say two College of Ag scientists and Alabama Ag Experiment Station researchers.
Jesse Chappell, Extension fisheries specialist and associate professor of fisheries and allied aquacultures, and horticulture professor Jeff Sibley have developed a system in which nutrient-rich fish wastewater from a tilapia tank is piped to an adjacent horticultural greenhouse, where it’s used to irrigate and nourish all manner of plants. So in addition to fish, producers would have high value, organically grown ornamental shrubs, bedding plants, cut flowers, herbs and fresh produce to market.
Chappell says that when greenhouse tilapia are fed, they retainat most 50 percent of the nutrients in the feed and excrete the rest. With the fish-and-plant-production system, a producer can turn a wastewater disposal problem into profit.
One crucial factor in such a system, however, is the nutrient load of the wastewater. The volume of nutrients depends on a number of production variables–including the kind of fish in the tank, how many there are, how big they are, how much water the tank will hold and how much water is in the tank–and determining how those factors impact nutrient levels has been a central element of the study.
Sibley says once all data have been collected and analyzed, the information will be distributed to farmers through printed materials and through educational aquaculture Web sites such as ALEARN (www.alearn.info)/ The materials, which include nutrition details as well as how-to information to help farmers set up their own systems, should be available in early 2010.