Water Resources Research Act Program

Principal Investigators: Jason Danaher, Kathryn Lincoln

Abstract: The scarcity of water, lack of consistent rainfall and high rate of evaporation make it difficult to cultivate cash crops in semi-arid climates. Integrating aquaculture and vegetable crop production could prove to be invaluable in areas like the U.S. Virgin Islands, where water supplies are inconsistent and recycling of water and nutrients are justified. Aquaculture sludge has the potential to act as a nutrient rich water source and organic fertilizer; however, feasibility of directly applying aquaculture sludge to agronomic crops has either not been economical for production facilities or problematic to delivery systems. Irrigation systems require very low concentrations of suspended matter in the water source, but a significant portion of aquaculture sludge contains high concentrations of suspended organic matter (TSS), which can clog emitters. Technologies, such as geotextile material, were recently applied to the dairy, swine and aquaculture industry to research the materials ability to dewater sludge. Research demonstrated geotextile material, trademarked Geotube, significantly reduced solids concentration in animal sludge and created a filtrate that may be more applicable in irrigation systems. One objective of this project is to evaluate Geotube for the recovery of wastewater from aquaculture sludge for use on agronomic crops. A second objective of this project will be to evaluate Geotube for the recovery and reuse of solids and establish if the solids nutrient concentration is of good enough quality to amend micro and macro nutrient levels in production plots. A series of experiments will be conducted on the University of the Virgin Islands Integrated Model Farm, which produces freshwater fish (Oreochromis niloticus) and a variety of agronomic crops. A 0.2-ha plot of land will be used to test the feasibility of irrigating using Geotube filtrate and establish the quality and quantity of nutrients available in filtrate and retained solids. Sweet peppers (Capsicum annum) will be cultivated using drip irrigation lines when tensiometers indicate soil moisture stress. General plant health, plant height and marketable yield will be calculated and compared at harvest. Water use will be determined weekly from flow meter readings and total irrigation water required will be determined monthly. Data on rainfall and pan evaporation will be collected from a UVI weather station located adjacent to the model farm. Desired goals of the project would include production of a water source available for agronomic crops during seasonal water shortage or persistent droughts and an organic solids source that would help to amend soil macro and micro nutrients between production cycles.