INTEGRATING BIOFLOC SYSTEMS WITH ORGANIC PLANT PRODUCTION AND RENEWABLE ENERGY AT KSU'S HIGH TUNNEL COMPLEX

Andrew J. Ray*, Leo Fleckenstein, John O. Bailey Barksdale, Adam Cecil, Nathan Kring
Division of Aquaculture, Kentucky State University, Land Grant Program
Frankfort, KY 40601 USA
andrew.ray@kysu.edu

Biofloc aquaculture systems contain a dense microbial community that is partly contained on small, naturally-forming particles known as biofloc.  The microbial community is responsible for cycling and assimilating the otherwise toxic nitrogen-based compounds ammonia and nitrite.  Research suggests that animals such as shrimp and tilapia can consume biofloc particles and gain nutritional benefits such as added protein and lipid which in turn can lower feed costs.  Because of the internal filtration in biofloc systems, very little water is used which increases biosecurity and allows the systems to be sited nearly anywhere.  

The Kentucky State University (KSU) Land Grant Program has developed a High Tunnel Complex on the University campus that includes biofloc fish tanks.  High tunnels are simple greenhouses, typically constructed using steel hoops and wood-framed end walls with transparent plastic sheeting strewn over them to help contain solar energy.  The KSU Complex contains four high tunnels that are 30.5 x 10.7m, a center walkway divides each tunnel down the length of the structure on the inside.  The south side of each tunnel has plant growing beds, while the north side has four 13 m3 fish tanks built of wooden frames with rubber liners.  Each tunnel has metal gutters along both long, outer side walls which collect rain water that is delivered to four, 9.5 m3 water storage tanks.  This water is used to irrigate crops and replace evaporation in the fish tanks.  A 9.7 kW photovoltaic solar array generates approximately enough energy to offset the electrical use of the complex; this energy is sold back to the utility company via net electrical metering.  

Current research projects include organic horticulture trials comparing high tunnel production to open field production, aquaculture trials, and aquaculture effluent fertilization experiments.  Aquaculture projects have examined the production of tilapia in biofloc systems during the warm months using low-energy artificial lighting to supplement sunlight and augment algal productivity.  Next, cool-water fish will be grown to evaluate whether pond stocker-size fish can be produced for a spring harvest.  The temperature dynamics of the high tunnels, especially the way that the relatively large volume of the fish tanks affect diurnal temperature swings is being studied.  Reclaimed filtrate from the settling chambers and fractionators on the fish tanks is being assessed for its nutritional quality as an aquatic feed ingredient.  This material is also being evaluated as a soil amendment for terrestrial crop production.

Research being conducted at the KSU High Tunnel Complex focuses on the sustainable integration of plant and fish production, thereby augmenting the efficiency and productivity of food production systems.