Intermittent circulation of simplified deep flow technique hydroponic system increases yield efficiency and allows application of systems without electricity in Haiti

Abstract

Abstract Background Many Haitians face severe food insecurity driven in part by a lack of adequate land for agriculture. Hydroponic systems can produce food without the requirement of arable land but are often prohibitively expensive and require electricity and water inputs that are impractical in most of Haiti. Results A deep flow technique (DFT) system named the Levo International, Inc. Victory Garden was tested with lettuce under constant and intermittent circulation. The average per-system yield of BSS from both treatments was 3631.75, 5013.75 and 2836.25 g in three experimental replicates. In replicates one and two, there were no significant differences in yield per circulation regiment. For the third replicate, we found a greater yield in constantly circulating systems. Each constantly and intermittently circulated system used 2.3814 kWh of energy for an estimated cost of $0.45 and 0.1386 kWh of energy for an estimated cost of $0.03, respectively. There was a significantly greater yield of BSS per energy input (g/kWh) in intermittently circulating systems compared to constantly circulating systems. There were no significant differences in water usage according to circulation. Electrical conductivity (E.C.) and pH were not significantly different between circulation treatment groups, except for pH in our third replicate which was significantly higher in constantly circulating systems. E.C. decreased and pH increased between the first week and last reading. The Victory Garden was tested with bell peppers under constant circulation and systems yielded an average of 3592.94 g of fruit. An adapted version of the Victory Garden was tested in Pignon, Haiti with bell peppers under manual twice-daily circulation and yielded an average of 2574.13 g and 3308.35 g in two experimental replicates. Conclusions Simplified DFT systems can produce both lettuce and peppers on par with field production. In this system type, we did not see a benefit to constantly circulating the nutrient solution.