Southern Russian researchers have demonstrated a powerful synergy: growing parsley using waste from sturgeon fish. Their 2021 study, published in E3S Web of Conferences, reveals that this aquaponics method outperforms traditional soil farming, delivering higher yields and extra profit while creating a sustainable closed-loop system.
Fish Waste Fertilizes Aquaponics Parsley Growth
Aquaponics effectively merges two established techniques: fish farming (aquaculture) and soil-free plant cultivation (hydroponics). This integrated approach solves two significant problems simultaneously. Firstly, fish naturally release waste products like ammonia, nitrogen compounds, phosphorus, potassium, and carbon dioxide.
In traditional closed aquaculture systems, these substances accumulate to toxic levels, requiring expensive water treatment or replacement. Secondly, hydroponic plant growth relies on adding these same nutrients—often as synthetic fertilizers—to water solutions.
Aquaponics creates a (selfsustaining) natural cycle: beneficial bacteria convert fish waste into nitrates, which plants like parsley absorb as vital nutrients. Consequently, the plants clean the water, which is then recirculated back to the fish tanks.
This closed-loop system reduces waste, saves water, and eliminates the need for chemical fertilizers. Furthermore, with rising consumer demand for environmentally friendly, chemical-free food, aquaponics presents a promising solution, particularly in resource-rich regions like southern Russia where this study was conducted.
Sturgeon-Parsley Aquaponics Trial Setup
The research team, led by Denis Yurin from the Krasnodar Research Centre, designed a clear comparative experiment at the Albashi LLC farm, starting May 20, 2020. They focused on the popular “Italian Giant” parsley variety, dividing the study into two groups with quadruple replication for reliability.
The control group used traditional soil farming. Specifically, seeds were planted 1 cm deep in fertile local chemozem soil (pH 6.3 ± 0.2), spaced 30 cm apart, at a density of 0.5 grams per square meter.
These plants received standard care: evening watering and mineral fertilizers—10g/m² ammonium nitrate and 5g/m² superphosphate—applied after seedlings emerged.
Conversely, the experimental group used a novel aquaponic system. Seeds were planted in perforated pots filled with neutral coconut fiber, arranged in angled tiers within a floating cylindrical structure.
This structure sat directly on a pool housing live sturgeon fish. Importantly, these parsley plants relied entirely on nutrients processed from the sturgeons’ waste, with absolutely no added fertilizers.
The team meticulously tracked germination rates, growth speed, plant height, root mass, total yield over three harvests, dry matter content, and safety markers like nitrate levels.
Aquaponics Boosts Parsley Superior Yields
The results provided compelling evidence for the aquaponic method’s advantages. Firstly, germination occurred significantly faster in the aquaponic system. Seedlings emerged in just 7 days, compared to 14 days for the soil group—a full week earlier.
Additionally, the germination rate was slightly higher in aquaponics (66.0%) versus soil (62.0%).
More importantly, yield—the amount of harvestable parsley—was consistently higher. At the first cut, aquaponic parsley produced 0.503 kg per square meter, surpassing the soil group’s 0.436 kg by 15.4%.
Over the entire 60-day cycle encompassing three harvests, the aquaponic system yielded 1.77 kg/m², a 7.3% increase over the soil group’s 1.65 kg/m². While plant height (~42 cm) and root mass (~8.3g) showed no significant differences, a notable finding involved dry matter content.
Soil-grown parsley contained 16.5% dry matter, whereas aquaponic parsley measured 12.6%—a statistically significant reduction (p<0.001). However, despite this difference, blind taste tests detected no variation in flavor or aroma between the two groups.
Crucially, safety testing confirmed both methods produced safe food: nitrate levels were equivalent and low, and all toxin measurements fell well below Maximum Allowable Concentration limits.
Aquaponics Profits Surpass Soil Farming
Beyond agronomic benefits, the aquaponic system demonstrated clear economic advantages. The researchers calculated production costs at 60 rubles per kilogram for both methods. However, due to the 7.3% higher yield, the aquaponic system generated an additional 0.12 kg of parsley per square meter.
Sold at the market price of 120 rubles/kg, this translated directly to an extra profit of 4.8 rubles per square meter. This profit boost stems partly from the innovative, cost-effective system design.
The setup featured a dedicated sturgeon pool (Model PM No. 198402) with a removable roof for light control, connected to the plant module—a cylinder holding tiers of perforated pots filled with coconut fiber, angled for optimal root exposure to the nutrient-rich water.
This design minimized installation and maintenance costs while maximizing space efficiency. Furthermore, the system eliminated fertilizer expenses entirely by utilizing fish waste. The closed-loop water recycling also meant drastic water savings compared to conventional irrigation.
Sustainable Farming Future With Aquaponics
This research offers powerful implications for the future of sustainable agriculture. The 7.3% yield increase and added profit per square meter make aquaponics an attractive option for herb farmers, especially those already involved in fish production like sturgeon farming, which is significant in Russia.
The method conserves vital resources: it uses up to 95% less water than soil farming through continuous recirculation and avoids synthetic fertilizers and pesticides entirely, preventing chemical runoff and producing truly “clean” food. This aligns perfectly with growing consumer demand for environmentally responsible produce.
Economically, the extra income from parsley sales can offset operational costs of fish farming, such as electricity for pumps, labor, and feed. Locally grown aquaponic produce also reduces “food miles,” allowing for fresher “field-to-plate” sales to schools, hospitals, or baby food manufacturers, enhancing both nutrition and community food security.
While the lower dry matter content in aquaponic parsley warrants attention—possibly requiring drying for longer shelf life—the proven safety, taste parity, and higher yields solidify its potential.
Consequently, this model is highly scalable for urban vertical farms, regions facing water scarcity, or traditional fish farms seeking profitable diversification, marking a significant step towards more resilient and efficient food systems.
Key Terms and Concepts
What is Yield: The measurable amount of crop (like parsley leaves) harvested from a specific area, usually expressed as weight per unit area (e.g., kilograms per square meter). It directly indicates the productivity and efficiency of a farming method. Example: Aquaponic parsley yielded 1.77 kg/m², 7.3% more than soil’s 1.65 kg/m².
What is Germination: The biological process where a seed starts to develop, sprouting and beginning to grow into a seedling after absorbing water and under suitable conditions. It marks the start of the plant life cycle. Example: Parsley seeds sprouted in just 7 days in the aquaponic system.
What is Germination Rate: The percentage (%) of seeds that successfully sprout and begin growth out of the total number planted. A higher rate indicates better seed viability and optimal growing conditions. Example: 66% of aquaponic parsley seeds germinated compared to 62% in soil.
What is Dry Matter: The solid components of a plant (proteins, fiber, minerals, sugars) remaining after all the water has been removed. It reflects the plant’s nutritional density and substance. Example: Soil-grown parsley had 16.5% dry matter, aquaponic had 12.6%.
What is Nitrate (NO₃⁻): A form of nitrogen that is a key plant nutrient, essential for growth. It is the end product of breaking down fish waste in aquaponics. High levels in food can be harmful to humans. Example: Plants absorbed nitrates converted from sturgeon waste.
What is Ammonium (NH₄⁺): A nitrogen compound directly excreted by fish as waste. It is toxic to fish at high concentrations but is converted by bacteria into less harmful nitrites and then nitrates for plants. Example: Bacteria processed fish ammonium into plant food.
What is pH: A scale from 0 (acidic) to 14 (basic), measuring how acidic or alkaline water or soil is, with 7 being neutral. It critically affects nutrient availability and the health of fish and plants. Example: The study soil pH was measured at 6.3 ± 0.2.
What is Maximum Allowable Concentration (MAC): The highest legally permitted level of a potentially harmful substance (like heavy metals or nitrates) in food or water, set to ensure consumer safety. Example: Toxins in the parsley were “significantly lower than MAC values.”
What is Profit Margin: The financial gain calculated as selling price minus the cost of production. A higher margin means the farming method is more economically efficient. Example: Higher parsley yield gave an extra profit of 4.8 rubles/m² in aquaponics.
What is Closed-loop System: A sustainable system where waste outputs (like fish effluent) are recycled as inputs (like plant fertilizer), minimizing external resources and pollution. Example: Aquaponics reuses fish wastewater to nourish plants.
What is Biogens: Essential nutrient elements, primarily nitrogen (N), phosphorus (P), and potassium (K), released from decaying organic matter or animal waste. They are fundamental for plant growth. Example: Fish biogens became nutrients for parsley.
What is Lemnoponics: A specific type of aquaponics where plants are grown on floating rafts in ponds covered with duckweed (Lemna minor). Duckweed helps absorb excess nutrients. Example: Basil was grown successfully in lemnoponic systems at Albashi.
What is Chemozem: Highly fertile, dark black soil rich in organic matter (humus), found in regions like southern Russia. It’s prized for traditional agriculture. Example: The control group parsley was grown in chemozem soil.
What is Overhead Cost: Ongoing business expenses not directly tied to a specific product unit, like rent, electricity, or administrative salaries. They must be covered by profits. Example: Electricity for sturgeon tank pumps was an overhead in aquaponics.
What is Synergy: When the combined effect of two or more elements (like fish farming and plant growing) is greater than the sum of their individual effects. Example: Aquaponics creates synergy—fish waste feeds plants, plants clean water.
What is Nutrient Solution: Water enriched with dissolved minerals essential for plant growth, used in hydroponics and aquaponics. In aquaponics, fish waste naturally creates this solution. Example: Parsley roots absorbed nutrients from the fish-waste solution.
What is Root Mass: The total weight of a plant’s root system. Healthy root development is crucial for water and nutrient uptake and plant stability. Example: Root mass was similar (8.4g soil vs 8.1g aquaponic) for parsley.
What is Economic Effect: The financial impact or result of using a particular method, often measured as increased profit, reduced costs, or higher efficiency. Example: The 7.3% higher parsley yield created a positive economic effect.
What is Environmentally Friendly: Products or practices that cause minimal harm to the natural environment. Aquaponics reduces chemical use and water waste. Example: Aquaponic parsley used no synthetic fertilizers or pesticides.
What is Recirculation: The process of continuously reusing water within a system, like aquaponics, after it has been treated (by plants). It drastically reduces water consumption. Example: Water cleaned by parsley roots was recirculated back to the sturgeon tank.
What is Tasting Test: Evaluating food products (like parsley) by sensory analysis—taste, aroma, texture—to assess quality and consumer preference. Example: No taste difference was found between soil and aquaponic parsley.
What is Growing Season: The period from seed germination or planting until the crop is ready for harvest. A shorter season allows more crops per year. Example: Parsley’s growing season was 60 days in both systems.
Reference:
Yurin, D. et al. (2021). Results of growing parsley using aquaponics method. E3S Web of Conferences 285, 02017. https://doi.org/10.1051/e3sconf/202128502017
