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(searched for: doi:10.21061/ijra.v12i1.1353)
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Journal of the World Aquaculture Society; https://doi.org/10.1111/jwas.12856

Abstract:
The accumulation of excess solids within the hydroponic troughs of raft aquaponic systems is considered one of the most common problems in commercial production. These solids can negatively affect water quality during decomposition. They can also impact plant health by physically coating the plant roots, reducing nutrient uptake and inducing plant diseases such as Pythium. Manual removal is labor intensive and costly. Based on their detritivorous feeding behavior, the freshwater prawn, Macrobrachium rosenbergii, may have potential as a biological control of solids. However, in a preliminary trial it was found that prawn will damage unprotected plant roots. To address this, two trials were conducted to evaluate the impact of prawn on solids accumulation within the plant beds and the effectiveness of different mechanical approaches to protect the plant roots. Both trials used six replicate recirculating raft aquaponic systems. Three systems had no prawn and three had prawn (~8 g) stocked at five prawn per trough. The plant grown was Buttercrunch Bibb lettuce (Lactuca sativa) at a density of 24 plants/m2. Plant growth in Trial 1 was statistically analyzed using a 2 × 3 factorial with the main effects of presence of prawn (none or 5/trough) and root protection device (none, plastic screen, or cloth netting). Water quality and solids data were compared in systems with prawn and without prawn using a two sample t test. Trial 1 lasted 32 days. Trial 2 used a plastic mesh “false bottom” to exclude prawn from access to the plants over the entire beds. Trial 2 used six systems all with the false bottoms in place. The comparison of three systems with prawn and three systems without prawn and was conducted over two plant production cycles of 4 weeks each. All data was analyzed using a two sample t test. In Trial 1, the presence of prawn produced a highly significant (p ≤ 0.01) reduction of settled solid wastes within the troughs, but plant growth was significantly reduced (p ≤ 0.01) in beds stocked with prawn regardless of root protection device. In Trial 2, the presence of prawn again produced a highly significant (p ≤ 0.01) reduction of settled solid waste within the troughs. There was no significant difference (p > 0.05) in average plant weight with this root protection device in systems with or without prawn. This research demonstrates that freshwater prawn can reduce solid waste buildup in aquaponic plant beds, but that effective root protection is essential to maintain efficient plant production.
, Anthonie M. Schuur, Dallas Weaver, Kenneth Semmens
Reviews in Fisheries Science & Aquaculture pp 1-95; https://doi.org/10.1080/23308249.2021.1886240

Abstract:
Aquaponics is the integration of aquaculture and hydroponics where nutrients released by growing fish are utilized by plants grown in a soilless culture, often in a controlled environment. Potential advantages of aquaponics include improved sustainability, reduced resource consumption, and fewer environmental impacts compared to conventional aquaculture. Based on a 2014 survey, it was found that most respondents were practicing aquaponics as a hobby. Other groups of respondents were educators, non-profit organizations that operate aquaponic systems, commercial operators, and consultants that sell goods, material, and services. Although many proponents cite the opportunity to create a commercially viable food production system few (if any) ventures have demonstrated sustainable financial outcomes. In general, much of the peer-reviewed aquaponic publications and popular literature, and despite the efforts of some investigators, lacks a methodical scientific basis for describing the essential mechanics, relationships, and culture methods within aquaponic systems. Many systems evolved from small-scale experimental facilities devised by trial and error methods and were implemented with locally limited appropriate species, limited finances, and distorted market situations. Many of the published aquaponic experiments are based on small systems, short growth trials, and weak experimental design. The predominant system design approach is based on a relatively small number of experiments. This review introduces notation and algorithms that are intended to standardize the numerous critical values essential in aquaponics for purposes of determining design criteria and operational parameters including flows, the concentration of water quality constituents, metabolite production, and productivity of plant and animal segments in an aquaponic systems. The objective of this systematic approach is to employ scientific methods that provide research results that can be replicated, challenged, and improved. This methodology is expected to facilitate more rapid development of scientific information, productive systems, and rational economic applications. This approach is crucial for commercial applications where production cost, product value, and investment returns are of critical importance for practitioners that envision investment in new ventures. For hobbyists and educators, economic issues may not be as important as the self-sufficiency and natural synergism aspects, personal satisfaction, and the learning experience that result from existing state-of-the-art of aquaponic practices. These outcomes remain for all and a clearer understanding of smaller personal systems is likely to be enhanced.
Published: 29 April 2020
by MDPI
Abstract:
Aquaponic nutrient studies often use various types of water containing high levels of mineral nutrients for water supply, making it difficult to accurately determine deficient nutrients limiting crop yield and quality across the systems. To avoid interference with background nutrients, we used reverse osmosis water in this study. The objectives were to identify critical nutrients that affect the yield and quality of cherry tomato-, basil-, and lettuce by characterizing nutrient composition and concentration in aquaponic systems in comparison to hydroponic systems. Daily release rate (mg L−1) of macronutrients derived from fish feed (41% protein, 1.1% phosphorus, 1% fish weight) was in decreasing order of SO4–S (16) > PO4–P (2.4) > NO3–N (1.0) > K (0.8) > Cl (0.5) > NH4–N (0.4) > Ca (0.2) > NO2–N (0.13) > Na (0.11) > Mg (0.02), in which daily inputs of Mg and Ca in aquaponics were found to be only 1–2% and 4–6%, respectively, of those in hydroponics. Subsequently, the average concentrations of all nutrients were significantly lower in aquaponics than in hydroponics during a 3-month production except for Cl, NH4–N, NO2–N, and Na. The concentration of Mg remained below 5 mg L−1 in all aquaponic systems, while the concentration of Ca rapidly decreased in tomato-based aquaponics, especially during fruiting. SPAD value (chlorophyll content) was associated with concentrations of leaf N, Mg, and/or Ca. Specifically, lower SPAD value was correlated with lower leaf Mg and Ca for tomato and lower leaf Mg for basil but neither Mg nor Ca for lettuce. The aquaponic solution contained nearly six-times higher Na than the hydroponic solution, resulting in three-times higher Na concentration in the edible portion of the crops. Compared to a lettuce-based aquaponic system, tomato- and basil-based systems retained more desirable water quality parameters (i.e., stable pH, lower temperature), had lower electrical conductivity (EC) via greater biomass production and, therefore, more efficient nutrient removal, and had lower feed conversion rate and higher fish biomass increment. Regardless of crop species, vegetative shoot biomass was significantly reduced in aquaponics than in hydroponics. However, the marketable yield of tomatoes was similar between aquaponics and hydroponics, while those of basil and lettuce were reduced in aquaponics by 56% and 67%, respectively, in comparison to hydroponics. Our results highlighted potential solutions to design proper nutrient management practices essential for the development of successful aquaponic production systems. Considering that ingested fish feed does not provide sufficient levels of Mg and/or Ca for crop production, it is suggested to supplement Mg before crop transplanting and Ca before fruiting of fruity crops to improve crop growth and quality in aquaponic systems, especially when high-quality water is used for water supply.
Nallely Estrada-Perez, , , Iram Zavala-Leal, Carlos A. Romero-Bañuelos, Elia Cruz-Crespo, Cecilia Juárez-Rossete, Delia Domínguez-Ojeda, Antonio Campos-Mendoza
Published: 27 September 2018
Aquaculture Research, Volume 49, pp 3723-3734; https://doi.org/10.1111/are.13840

Abstract:
We propose stochastic models for predicting and analysing the production of tilapia (Oreochromis niloticus), lettuce (Lactuca sativa), and cucumber (Cucumis sativus) cultivated in an aquaponic system. Fish and plants were cultivated in a shade house using 30, 60, and 90 fish/m3 employing an NFT system. Results from Monte Carlo simulation showed that higher yields of tilapia and cucumber, as well as larger plant sizes, were obtained by stocking at the highest density (90 fish/m3). At this density, with 95% confidence, yields of tilapia varied from 39.60 to 59.26 kg/m3, the final length of lettuce leaves varied from 13.53 to 28.5 cm, the final length of cucumber plant varied from 119 to 235.3 cm, and biomass of cucumber varied from 0.98 to 0.99 kg/m2. Regression and sensitivity analyses showed that dissolved oxygen, density, temperature, and electrical conductivity significantly affected the production of tilapia; density, nitrites, pH, and temperature influenced lettuce production; ammonium, pH, and density affected the production of cucumber plants; and ammonium and density influenced yields of cucumber. The greatest certainty to achieve higher yields of large tilapia was found at low densities. For plants, there was more certainty of harvesting larger products when cultivated with tilapia stocked at the highest density. A preliminary economic analysis of tilapia production showed that net revenues ranged from USD$ 18.50 to 81.76 per system, and that the best results were obtained when using the highest stocking density. We conclude that the models are useful for predicting and analysing the production of an aquaponic system.
D. Castillo-Castellanos, , , A. Radilla-García, J. T. Nieto-Navarro, C. A. Romero-Bañuelos, J. González-Hernández
Published: 26 October 2015
Aquaculture International, Volume 24, pp 637-646; https://doi.org/10.1007/s10499-015-9954-z

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Jason J. Danaher, R. Charlie Shultz, James E. Rakocy, Donald S. Bailey
Journal of the World Aquaculture Society, Volume 44, pp 374-383; https://doi.org/10.1111/jwas.12040

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