The management of nitrogen is a critical factor in aquaculture. Feeds contain proteins which when uneaten or digested results in ammonia.
Ammonia is water exists as Total Ammonia Nitrogen (TAN) described by the following equation:
NH4+ ↔ NH3 + H+
Feeding rate is a crucial factor in generation of ammonia in an aquaculture pond, and this can be described by
PTAN = (Daily Feed in Grams) X (%age of Protein Content in Feed) X 0.092
PTAN is the total ammonia production in grams per day.
In well managed aqua farms, the TAN is consumed by healthy population of plankton, which is then fed by the fishes. This further aids in reduction of Feed Conversion Ratio (FCR). You see, phytoplankton are unicellular chlorophyll containing organisms which take up nitrogen for their photosynthesis. They are a rich source of amino acids and antioxidants, hence as energy source for the fish.
Aquaponics is the science of combining aquaculture and agriculture/horticulture in a single process. The classical indoor method is well known: Separate fish tank where the feed is administered. The nutrient rich aquaculture water is pumped in to a hydroponics unit where vegetables or crops are grown and harvested. The water after getting filtered through the hydroponics unit then recirculates back into the fish tank. This controls the use of fertilizers and optimizes productivity. Not to forget a better utilization of the nitrogen factor.
In aquaponics, the growth of plants from the aquaculture water fed system results in consumption of NH4+ which in turn converts NH3 to NH4+ for balance as explained in the first equation. Nitrifying bacteria present in the plant grow beds/biofilters convert ammonia to NO3- from which plants take up their nitrogen requirements in aquaponics (Figure 1).
This process is catalyzed first by Nitrosomonas bacteria by the following equation:
NH3 + 1½O2 ↔ NO2- + H2O + H+ + 84 kcal mol-1
Followed by the second step conversion by Nitrobacter bacteria:
NO2- + ½O2 ↔ NO3- + 17.8 kcal mol-1
Ammonia is water exists as Total Ammonia Nitrogen (TAN) described by the following equation:
NH4+ ↔ NH3 + H+
Feeding rate is a crucial factor in generation of ammonia in an aquaculture pond, and this can be described by
PTAN = (Daily Feed in Grams) X (%age of Protein Content in Feed) X 0.092
PTAN is the total ammonia production in grams per day.
In well managed aqua farms, the TAN is consumed by healthy population of plankton, which is then fed by the fishes. This further aids in reduction of Feed Conversion Ratio (FCR). You see, phytoplankton are unicellular chlorophyll containing organisms which take up nitrogen for their photosynthesis. They are a rich source of amino acids and antioxidants, hence as energy source for the fish.
Aquaponics is the science of combining aquaculture and agriculture/horticulture in a single process. The classical indoor method is well known: Separate fish tank where the feed is administered. The nutrient rich aquaculture water is pumped in to a hydroponics unit where vegetables or crops are grown and harvested. The water after getting filtered through the hydroponics unit then recirculates back into the fish tank. This controls the use of fertilizers and optimizes productivity. Not to forget a better utilization of the nitrogen factor.
In aquaponics, the growth of plants from the aquaculture water fed system results in consumption of NH4+ which in turn converts NH3 to NH4+ for balance as explained in the first equation. Nitrifying bacteria present in the plant grow beds/biofilters convert ammonia to NO3- from which plants take up their nitrogen requirements in aquaponics (Figure 1).
This process is catalyzed first by Nitrosomonas bacteria by the following equation:
NH3 + 1½O2 ↔ NO2- + H2O + H+ + 84 kcal mol-1
Followed by the second step conversion by Nitrobacter bacteria:
NO2- + ½O2 ↔ NO3- + 17.8 kcal mol-1
Hence the stocking density of plants is a crucial factor to balance the nutrient requirements for crop production.
We had constructed a proposed model for a rainwater reservoir pond designed for polyculture of Indian major carps (IMC); Rohu, Catla and Mrigal with freshwater giant prawns or scampi, Macrobrachium rosenbergii. Feed and probiotics get fed in the reservoir pond, while a solar powered motor pumps the nutrient rich pond water in to a vegetation patch via timed sprinklers (Video below). The veggie patch has a specially designed based inclined towards the pond which channels the percolating water towards the reservoir. The sprinklers are programmed to switch off after a certain time by which six inches of top soil is wet. As a back-up for dry seasons, 40 ft. table water pump is operated on solar for a monthly 30% water exchange.
We had constructed a proposed model for a rainwater reservoir pond designed for polyculture of Indian major carps (IMC); Rohu, Catla and Mrigal with freshwater giant prawns or scampi, Macrobrachium rosenbergii. Feed and probiotics get fed in the reservoir pond, while a solar powered motor pumps the nutrient rich pond water in to a vegetation patch via timed sprinklers (Video below). The veggie patch has a specially designed based inclined towards the pond which channels the percolating water towards the reservoir. The sprinklers are programmed to switch off after a certain time by which six inches of top soil is wet. As a back-up for dry seasons, 40 ft. table water pump is operated on solar for a monthly 30% water exchange.
Sustainability is a race to plug the excess flow of nutrients and limit the use of fertilizers. We must respect our environment to reap dividends.
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