The Aquaculture Program has been developing tilapia production systems for the US Virgin Islands since 1979. The initial efforts focused on cage culture of tilapia in watershed ponds that had multiple uses for livestock watering and crop irrigation.
The facility covers 0.8 hectares (1.95 acres) on the island of St. Croix, U.S. Virgin Islands. Tilapia research and production is vertically integrated with brood fish, egg hatching, fry and fingerling rearing, grow out, purge and processing, all occurring at the facility.
The UVI Commercial Aquaponic System is designed to produce fish and vegetables in a recirculating aquaculture system. The integration of these systems intensifies production in a small land area, conserves water, reduces waste discharged into the environment, and recovers nutrients from fish production into valuable vegetable crops. A standard protocol has been developed for the production of tilapia which yields 5 MT per annum. The production of many vegetable crops has also been studied but, because of specific growth patterns and differences of marketable product, no single protocol can be promoted. Each crop yields different value per unit area and this must be considered when selecting varieties to produce to provide the highest returns to the farmer. Taking the factors of density, growth period, yield and value into account gives a value per area per time ($/m2/week) which can be used to compare economic returns and make informed management choices. The crops studied by Bailey and Ferrarezi (2016) were spaced at a density of 30 plants per meter square and harvested after a production period of 3 weeks. One main consideration for the short production period was the establishment of pests, aphids and/or white fly, on crops grown longer than 3 weeks. By harvesting mature leaves at 3 week intervals pest populations were kept in check. Data on yield was collected at each harvest. Full heads were harvested for pah choi, leaves were harvested from kale, collards and Swill chard. Basil was planted at 16 plants per meter square and grown for 4 weeks. They were harvested by a "cut and come again" technique which trims upper leaves and stems leaving 15 cm of plant to regrow. Value of each crop per kilogram was obtained from a USDA ERS for the Miami terminal over the year May 2015 – April 2016. These values were then converted into value per week which allows comparison to crops with different production periods. Basil has the highest expected value of $3.96-4.96/m2/week followed by Pak choi with $3.92-4.32/m2/week. These crops had the highest biomass yield and that factor impacted the end value. Swiss Chard had low value with a range of value of $1.02-1.19/m2/week. Kale and collards yielded even less with $0.34-0.37 and 0.21-0.23/m2/week respectively. A similar economic analysis was made for fruiting crops roselle, cantaloupe, cucumber, okra and zucchini. Planting density and growth period were different for each crop. Yield data was recorded for each harvest over the production period and calculated on an area basis. Crop market value was determined from USDA Miami Terminal over the year May 2015 – April 2016. Roselle is a specialty crop whose price is not available from the USDA report. The local roadside market price of $8.82/kg was used. Roselle had the highest expected value of $1.89/m2/week. Cucumber had the next highest range of expected value, $1.24-1.32/m2/week followed by zucchini ($0.62-0.89), okra ($0.53-0.62) and cantaloupe ($0.14-0.16). Cantaloupe is planted at the lowest density, 0.67/m2 and has a long production period of 13 weeks.
How to cite this study: Bailey D.S. and R.S. Ferrarezi. Valuation of vegetable crops produced in the UVI commercial aquaponic system. UVI-AES 2016 Annual Report. In press.
Life cycle assessment identifies feed as an impediment to sustainable aquaculture (ISO 14040 and ISO 14044). Plant-based feeds reduce environmental impact. Producing feed to supplement the diet and substitute for purchased feed will have important ecological and economic advantages. Mustafa et al. (2016) determined the optimal sludge volumes for duckweed (Lemna minor) production. Our goal was to establish the guidelines for duckweed production in the U.S. Virgin Islands, providing basic information to increase the Aquaponics production in the territory and creating a possible source of incoming for local farmers interested in growing duckweed for Aquaponics growers. The solution nutrient content changed over 28 days indicating dramatic changes in NO3 content (from 0 to 17 mg/L). The yield more than double over 19 days (from 250 to 600 g). However, treatment with high sludge volumes showed the lowest yield, probably because the excessive algae growth and nutrient competition.
How to cite this study: Mustafa, A., D.S. Bailey, and R.S. Ferrarezi. 2016. Aquaponic waste as nutrient source for duckweed production used for fish feed. UVI 2016 Research Day, April 15. Kingshill, U.S. Virgin Islands.
Basil is a fast-growing crop on Aquaponics systems. Previous research has indicated that basil is a high cash-value for Aquaponics, and the evaluation of specie adaptation in tropical conditions is mandatory to recommend new varieties for the CAS. Bailey et al. (2016) conducted two trials to assess different basil varieties for production in Aquaponics. In the first trial (Summer 2015), they evaluated five basil varieties (‘Genovese’, ‘Spicy Globe’, ‘Lemon’, ‘Purple Ruffles’ and ‘Red Rubin’), on a completely randomized design (CRD) with four replications. In the second trial (Fall 2015), we evaluated seven varieties (‘Genovese’, ‘Spicy Globe’, ‘Lemon’, ‘Purple Ruffles’, ‘Red Rubin’, ‘Cinnamon’ and ‘Thai’), on a CRD with three replications. In the first trial, ‘Spicy Globe’ (12.11 kg/m2) and ‘Genovese’ (11.36 kg/m2) presented the highest total yield and ‘Purple Ruffles’ the lowest (3.49 kg/m2) (p<0.0001). Plant fresh weight followed the same trend, and dry weight was higher on ‘Genovese’ (220.5 g/plant) (p<0.0001). Leaf anthocyanin was higher on the red varieties ‘Red Rubin’ (34.36 ACI) and ‘Purple Ruffles’ (28.35 ACI) (p<0.0001). Chlorophyll content was higher on ‘Genovese’ (48.594 CCI) (p<0.0001). In the second trial, ‘Genovese’ (6.52 kg/m2), ‘Cinnamon’ (5.94 kg/m2) and ‘Spicy Globe’ (5.78 kg/m2) showed the highest total yield and ‘Purple Ruffles’ the lowest (1.48 kg/m2) (p<0.0001). Plant fresh weight followed the same tendency, and dry weight was higher on ‘Cinnamon’ (81 g/plant) (p<0.0001). Leaf anthocyanin differed in all varieties over time, with larger values on ‘Purple Ruffles’ (80.5 ACI) and ‘Red Rubin’ (36.5 ACI) (p<0.0001). Chlorophyll content was a response of variety and plant development, with readings ranging from 12 (‘Lemon’) to 18 CCI (‘Cinnamon’) (p<0.0001). On both trials, plant width and height increased over time as expected (p<0.0001). Based on our results, we recommend ‘Spicy Globe’ and ‘Genovese’ during Summer and Fall, were Cinnamon’ is also an alternative. The total yield reflected the measured plant morphology. Varieties with smaller plant size can be spaced closely to increase total yields.
How to cite this study: Bailey, D.S., S. Balkaran, J. Bernier, and R.S. Ferrarezi. Assessment of basil varieties for production in the UVI Commercial Aquaponic System. ASHS 2016 Annual Conference, August 8-11. Atlanta, Georgia.
Controlled water stress imposed during the reproductive stage of fruit crops are well-known for increasing flowering and fruit quality. However, deficit irrigation is challenging to apply on recirculating Aquaponics systems due to the use of deep water hydroponic troughs for vegetable production. Ferrarezi et al. (2016) evaluated the effect of partial root and canopy cut (combination of partial cuts; 0%, 25%, 50% and 75%) performed before two different harvest schedules (10 days after cutting or at fruit maturation) on cantaloupe fruit sugar content. Sugar content increased only on the treatments with no root cut, 75% and 25% of canopy cut and fruits harvested at the maturation (9.1 and 8.4°Brix), with a negative effect on the treatment with 75% of root cut, no canopy cut and fruits harvested at the maturation (3.7°Brix) (p=0.0060). The treatment with no root or canopy cut and fruits harvested at the maturation promoted the highest yield (30,227 kg/ha), indicating a negative effect of the partial cutting on fruit total yield (p=0.0072). No treatment response was found on fruit length and width, fruit hardness, fruit pulp thickness, leaf chlorophyll and anthocyanin content, root and shoot dry weight and shoot fresh weight (p>0.05). Even though the results indicated an increase in fruit sugar content, more research is necessary to develop an alternative cultural practice for increasing cantaloupe fruit sweetness in Aquaponics without compromising total yield.
How to cite this study: Ferrarezi, R.S., D.S. Bailey, S. Balkaran, and J. Bernier. 2016. Partial root and canopy cutting to increase cantaloupe fruit sweetness in the UVI Commercial Aquaponic System. ASHS 2016 Annual Conference, August 8-11. Atlanta, Georgia.
Farmers in the Virgin Islands have several options to consider when choosing to add aquaculture production to their farm enterprise. Two tilapia production systems have been developed by the UVI-AES Aquaculture Program; they are aquaponics and biofloc production systems. Each of these systems has unique resource requirements, production inputs/outputs and potential to meet market requirements. A farmer must consider these opportunities and constraints in the selection of the system. An aquaponic system combines the production of fish and vegetables in an integrated system that combines water and pumping resources while reclaiming fish waste as nutrients for plant growth. The system requires a high capital investment and ongoing operating costs, primarily feed and energy inputs. Fish and plants are grown at high densities to cover those costs and produce a regular income stream. The biofloc system is primarily a fish production system with the potential for agronomic production of vegetables. The system is moderately stocked with tilapia and relies on in situ use of fish waste by flocs of microscopic organisms: phototrophs, heterotrophs and autotrophs to maintain water quality. Initial capital investment is low and operating costs of feed and energy are moderate. Enterprise budgets, cash flow statements and balance sheet analysis are used by Bailey and Nandwani (2014a) to evaluate the investment and choose the appropriate production system that meets the farmer's goals.
How to cite this study: Bailey, D.S. and D. Nandwani. 2014a. Selection of an Aquaculture Production System for Farmers in the US Virgin Islands. Book of Abstracts, p 24, Aquaculture America 2014. February 9-12, 2014. Seattle WA.
Two aquaculture production systems have been developed by the UVI Aquaculture and Horticulture research program: the UVI Aquaponic System and a biofloc system. The systems were designed to address the constraints and opportunities of local farmers and promote their integration with other traditional farming activities. The systems intensify production to minimize land requirements, conserve fresh water which is scarce and reclaim fish wastes as nutrients for either hydroponic or agronomic vegetable production. The program is well known for the development of design criteria and operation guidelines for these systems and has trained over 600 individuals from around the globe. The UVI Aquaponic System in particular has been adopted by many entrepreneurs in temperate zones facing the same limitations of available land and water and the desire to reclaim nutrients instead of discharging them into the environment. Adoption of these aquaculture systems by U.S. Virgin Islands farmers has been limited. Most attempts to implement the technology have been on the home/hobby scale. Only one investor developed a commercial-scale farm which ceased operation after a hurricane in 1995. To better inform local farmers about the production and costs of the UVI designed systems a decision tree was developed by Bailey and Nandwani (2014b). A decision tree helps farmers select a production system given their individual constraints: access to capital and availability of land and water. An assumption is made for equal production of tilapia and the costs associated with that production is evaluated for each system. Evaluation of FCR, survival, production (kg/m3 and kg/ha), energy inputs (kg/kWh) and labor guide the decision process. The addition of vegetable crops in hydroponic beds or adjacent fields adds additional costs and revenues to both systems. Given this decision making process, a farmer can make an informed decision and select the best production system for his enterprise.
How to cite this study: Bailey, D.S. and D. Nandwani. 2014b. Selection of an aquaculture production system for farmers in the US Virgin Islands. Proceedings of the Caribbean Food Crops Society. 50:185.
The UVI Aquaponics System is a food production technology which integrates tank fish culture components with hydroponic vegetable cultivation. The integration conserves land and water and recovers waste nutrients from fish into a valuable vegetable crop. The primary waste from fish metabolism is ammonia-nitrogen which is converted by biological nitrification processes into nitrate-nitrogen which is used by plants to grow stems and leaves. Previous research at UVI-AES has focused on the production of lettuce and other leafy vegetables. Research has been limited on production of fruiting plants which need phosphorus and calcium to promote fruit set and produce quality fruit. The purpose of the study of Balkaran et al. (2014) was to quantify zucchini (Cucurbita pepo var. cylindrica) production when foliar sprayed with different levels of calcium and phosphorus. To determine the effect of calcium on the zucchini production we look at both the marketable and nonmarketable production. In the calcium group, five set of plants were treated including a control group that was not treated. The calcium application rates of 0 (control), 1.25, 2.5, 3.75 and 5 mg/L were applied weekly to the plant leaf surfaces. The plant that was sprayed with a 3.75 mg/L concentration of calcium was most effective and had a great production of zucchinis, 33.9/m2 for the production period. The control group however produced a high amount of unmarketable zucchinis (28.5/m2). The marketable yield mass of 7.5 kg/m2 with the 3.75 mg/L concentration was most effective. The same method was used to determine the effect of different levels of phosphorus on the zucchini plants. Five sets of plants were used for this experiment including a control group. The phosphorus application rates of 0 (control), 0.5, 1, 1.5 and 2 mg/L were applied weekly. The plant that received the 1 mg/L concentration of phosphorus was most effective and had a great production of marketable zucchinis. It also yielded the highest mass (7.4 kg/m2). The plant that received 0.5 mg/L concentration of phosphorus was yielded the greatest number of unmarketable zucchinis. Foliar application of both calcium and phosphorus was effective in elevation production number and mass for zucchini grown in an aquaponic system. Future research will evaluate combined nutrients to further enhance production.
How to cite this study: Balkaran, S., D.S. Bailey, and D. Nandwani. Effect of foliar spray application of calcium and phosphorus on fruit production of zucchini (Cucurbita pepo). Proceedings of the Caribbean Food Crops Society. 50:186. 2014.
Early barrel and wading pool systems developed by Watten and Busch, circa 1980.
UVI Aquaponics Workshops are offered from January - May each year. The Workshop is offered to interested students, entrepreneurs and farmers. This education program makes extensive use of the facilities with hands-on training in the practical aspects of aquaponic and biofloc systems and tilapia production.
Contact the program leadership for more information.
News and Links from Workshop ParticipantsBerea College Jackson L. Oldham Aquaponics Facility