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For trout, stocking rates of 30 to 50 kg/m 3 are normal at the end of a rearing cycle, while for marine species, such as sea bass and sea bream, the achievable load is lower, between 15 and 20 kg/m 3. The total volume required for a raceway is calculated by dividing the total amount of fish in kg by the desired stocking rate in kg per m 3. [17]
A maize crop yielding 6–9 tonnes of grain per hectare (2.5 acres) requires 31–50 kilograms (68–110 lb) of phosphate fertilizer to be applied; soybean crops require about half, 20–25 kg per hectare. [21] Yara International is the world's largest producer of nitrogen-based fertilizers. [22]
Organic nutrients increase the abundance of soil organisms by providing organic matter and micronutrients for organismal relationships such as fungal mycorrhiza, [47] (which aid plants in absorbing nutrients), and can drastically reduce external inputs of pesticides, energy and fertilizer, at the cost of decreased yield.
To produce one kilograms of farmed salmon, products from several kilograms of wild fish are fed to them – this can be described as the "fish-in-fish-out" (FIFO) ratio. In 1995, salmon had a FIFO ratio of 7.5 (meaning 7.5 kilograms of wild fish feed were required to produce one kilogram of salmon); by 2006 the ratio had fallen to 4.9. [ 102 ]
Urea is the most used fertilizer in the world, due to its high content of nitrogen, low cost and high reactivity towards water. [32] When exposed to ocean waters, urea is metabolized by phytoplankton via urease enzymes to produce ammonia. [33] + +
The plant had a production capacity of 570,000 tons per annum (TPA) and an initial construction cost of US$303 million. [12] The plant was supplied by Haldor Topsoe and was commissioned in 1982 after an additional investment of US$15 million. [12] As of 2024, FFC-I has a capacity to produce 403,000 TPA of ammonia and 695,000 TPA of urea. [13]
Researchers also quantified the water quality parameters and nutrient budgets in (5 kg fish m −3) green water seabream ponds. [ 15 ] [ 17 ] The phytoplankton generally maintained reasonable water quality and converted on average over half the waste nitrogen into algal biomass .
Mariculture, sometimes called marine farming or marine aquaculture, [1] is a branch of aquaculture involving the cultivation of marine organisms for food and other animal products, in seawater. Subsets of it include ( offshore mariculture ), fish farms built on littoral waters ( inshore mariculture ), or in artificial tanks , ponds or raceways ...