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Fish Wastes as Source of Fertilizers
and Manures
Inain Jaies, Imtiyaz Qayoom, Farheen Saba, and Sameena Khan
Abstract Solid wastes such as fish carcasses, viscera, skin, and heads, as well as
liquid wastes, are produced in huge amounts during fish processing. Leaving these
wastes unattended is a concern for the environment as well as the human populace
residing in its proximity. Apprehension for environmental degradation, especially of
aquatic ecosystems is associated with high organic content in fish wastes which, if
discharged, will increase the productivity of waterbodies leading to pollution. On
the other hand, if these wastes are leftover or dumped improperly, they result in a
nauseating smell, thus making it arduous for humans to live nearby. There is however
an effective alternate method by which fish wastes can be utilized, resulting in its
scientific disposal and putting less stress on the environment. Fish waste can be a
good source of manure and fertilizers. Crops chiefly require nitrogen, phosphorous,
and potassium for growth as essential nutrient elements which can be mainly drawn
from fish wastes. Moreover, they can be a good source of calcium for soils that are
deficient in calcium levels. Fish-based fertilizers typically include substantial levels
of N, P, and Ca and essential minerals. Phosphate rock, which is a restricted resource,
provides more than 85 percent of the phosphorus used in agriculture. As a result,
using fish waste as a phosphorus-rich organic waste is a better option. Fish fertilizer is
an organic liquid fertilizer that works quickly and is manufactured from by-products
of the fishing business. It contains a lot of nitrogen, phosphorus, and potassium,
as well as trace minerals like calcium, magnesium, sulfur, chlorine, and sodium.
Fish emulsion, when used correctly, can increase crop yields, especially in cool
climes. This is because, in the cooler months, manure breaks down slowly, whereas
fish emulsion fertilizes at a constant rate. The commercial fertilizers, particularly
I. Jaies
Division of AAHM, Faculty of Fisheries, SKUAST-K Rangil Ganderbal, Jammu and
Kashmir 190006, India
I.
Qayoom (B) S. Khan
Division of AEM, Faculty of Fisheries, SKUAST-K Rangil Ganderbal, Jammu and
Kashmir 190006, India
e-mail: drsheikhimtiyaz@gmail.com
F. Saba
Department of Zoology, School of Sciences, MANUU Gachibowli, Hyderabad,
Telangana 500032, India
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024
S. Maqsood et al. (eds.), Fish Waste to Valuable Products, Sustainable Materials and
Technology, https://doi.org/10.1007/978-981-99-8593-7_15
329
Fish Wastes as Source of Fertilizers and Manures
330
fish based, are being utilized in crops of agriculture and horticulture and a number
of fertilizers can be produced by fish waste. Fish waste composting is a fantastic
approach to reduce waste volume, and compost supplemented with fish waste could
be a useful organic fertilizer. This book chapter will provide insight into the utilization
of fish wastes that are a boon to agriculture and soothe the environment as well.
Keywords
Fish waste
·
Fertilizers
·
Manures
·
Environmental pollution
1
Introduction
The term “fish waste” refers to a variety of fish species or by-catch items that
have no or very little commercial value, are damaged and underdeveloped species,
have economic worth but are not collected in sufficient numbers to justify sale.
According to Environmental Protection Agency (EPA), “fish waste can include bits
of flesh, shells, skin, guts, bones, or liquid stick water, among other things.” In
other words, fish waste includes several fish species or by-catch items having no or
very low commercial value, commercial species being undersized or damaged, and
commercial species not collected in sufficient quantities to merit sale (Caruso 2016).
Between 1961 and 2017, global food fish consumption climbed at an average
yearly rate of 3.1 percent, nearly double the rate of annual world population growth
(1.6 percent) (FAO 2020). It is believed that roughly two-thirds of fish are discarded
as garbage, posing significant environmental and economic implications (Coppola
et al. 2021). As a result, a significant increase in the quantity of production of fish
waste production around the world has been observed. The release of fish wastes
at such an enormous level has impressed upon the concerned stakeholders, poli-
cymakers, processing unit heads, and environmentalists to dispose and recycle the
wastes on scientific guidelines or otherwise, which may lead to serious environmental
concerns. Every year, a large amount of biomass is thrown, most commonly burnt,
which increases the energy consumption for its management and has its own environ-
mental impact. Fish waste has mostly been used as fish meal as it contains the same
quantity of proteins as present in fish meat (Mo et al. 2018). Moreover, fish waste
contains a sizable amount of biodegradable organic matter, that might be repurposed
to make waste-activated sludge more appealing as a co-substrate to boost the gener-
ation of methane during anaerobic co-digestion (Wu and Song 2021). Because of its
nutritional makeup, fish wastes can also enhance compost or provide plant nutrients.
Fish wastes can modify this sentence (Løes et al. 2018). Fish processing industries
generate solid wastes such as skin, viscera, fish heads, fish bones, and flesh leftovers.
Among liquid wastes, blood, water, and brine are released from drained storage tanks,
washing and cleaning of flesh, and blood and soluble compounds from the gut. In
addition to these wastes, detergents and other cleaning agents are also released as
liquid wastes from processing units. Some gaseous wastes such as carbon dioxide
and hydrogen sulfide are also liberated on account of various chemical reactions
carried out during processing, storing, or freezing processes.
Fish Wastes as Source of Fertilizers and Manures
331
Aquaculture wastes can be divided into two categories:
Solid wastes: Unused feed and feces from farmed fish are the primary sources
of solid waste (Akinwole et al. 2016). Sometimes fishes that fail to succeed
in the culturing process and retard or die underway also form huge wastes in
large culturing units. Suspended and settled solids are two more types of solid
wastes monitored in culturing units. Suspended solids are tiny particles that remain
floating in water unless coagulated or settled down by sedimentation. The removal
of these solids from culture systems is the most challenging (Cripps and Bergheim
2000). On the other hand, settled solids also form a source of waste, although these
settle down quickly but can easily be removed from the culture column on account
of their bigger particle size (Ebeling and Timmons 2012).
Dissolved wastes: These wastes are by-products of fish metabolism or degraded
leftover fish feed. Dissolved wastes contain nitrogen (N) and phosphorous (P) as
components of concern (Boyd and Massaut 1999). The retention of nitrogen
ranges from 25 to 30% (Boyd 2003) to 10–49% (Piedrahita 2003) while phos-
phorous retention ranges between 17 and 40% in different fish species (Boyd
2003).
2
Proximate Composition of Fish Waste
The term “proximate composition” is commonly used in the food industry to refer
to the components of crude protein, moisture, ether extract, crude ash, crude fiber,
and nitrogen-free extracts, which are given as percentages in the feed. The proximate
composition of fish waste is given in Table 1 (Palkar et al. 2018).
Fertilizers made from fish usually have high levels of N, P, and Ca. The macronu-
trients N, P, K, and Ca concentration varies between species and also relies on the
type of waste used. Fish scales are abundant in nitrogen and as rich source of calcium
(Ca) and phosphorous (P) as well. Fish bones consist of 60–70% minerals, primarily
calcium and phosphorus in the form of hydroxyapatite (Ghaly et al. 2013). In general,
the typical N–P–K values for inland fish are 120:11:13, and for marine fish, they are
130:16:11 (Bogard et al. 2015).
Table 1 Proximate
.
.
S.No
Component
Percentage
1
Moisture
77.09
±
0.14
%
2
Crude protein
15.20
±
0.15
%
3
Fat
4.03
±
0.07
%
4
Ash
3.30
±
0.11
%
5
Nitrogen free extracts
0.38
±
0.06
%
composition of fish waste
Fish Wastes as Source of Fertilizers and Manures
332
3
Synthetic Fertilizers and Their Hazardous Effects
“Synthetic fertilizers are chemically manufactured products containing one or more
of the primary elements that are essential for plant growth, viz., nitrogen, phosphorus,
and potassium,” (Anonymous, 2015, University of California Agriculture and Natural
Resources). They usually have various ratios of nitrogen, phosphorus, potassium,
calcium, magnesium, and other components. Unlike organic fertilizers, synthetic
fertilizers provide the necessary nutrients to the soil right away. There are various
benefits of using synthetic fertilizers compared to natural manures given in Table 2.
Synthetic fertilizers are essential for revitalizing the soil by delivering the nutri-
ents that plants require for successful growth. Nitrogen, potassium, and phosphate
are the most prevalent nutrient sources in mineral fertilizers. They work by giving
the appropriate mix of nutrients to the soil, which increases output and ensures
nutritious food. The soil would be depleted if fertilizers were not used, making it
harder for plants to thrive. Modern synthetic fertilizers are primarily made up of
nitrogen, phosphorous, and potassium compounds, with some additional nutrients
mixed in combination which varies between plant varieties in accordance with their
nutritional requirements. Nitrogen is an essential plant nutrient that aids in the plant’s
development and metabolic functions which impresses the incorporation of synthetic
chemicals such as ammonium nitrate, ammonium phosphate, and potassium sulfate
for making synthetic fertilizers. Synthetic fertilizers however have negative long-
term consequences. Continuous synthetic fertilizer use can degrade soil quality. It
disrupts the natural soil ecosystem, altering its pH and nutrient balance, causing
soil acidification, imbalanced nutrient levels, and reduced microbial activity, ulti-
mately diminishing soil fertility. In the long run, synthetic fertilizers harm the natural
makeup of soil. Iron, carotene, zinc, copper, vitamin C, and protein are all inade-
quate in plants that grow in highly fertilized soil. Studies have also shown that
beneficial soil bacteria that convert organic remains from dead plants and animals
into nutrient-rich organic materials are killed by synthetic fertilizers. Nitrogen and
phosphorous-based fertilizers drain into groundwater leading to an increase in water
contamination and toxicity. Some phosphates contain modest levels of radionuclides
(Tirado and Allsopp 2012) and some studies suggest increased radioactivity around
phosphate mining regions. The salt concentration in chemical fertilizers is one of the
Table 2 Benefits of synthetic fertilizers
1
Synthetic fertilizers provide the soil with precise amounts of nutrients in a constant
manner
2
Synthetic fertilizers are simple to use and have practically immediate results
3
Unlike organic fertilizers, which must break down before being absorbed, they operate
immediately on the soil
4
They are less expensive than organic fertilizers in general
5
They can be handled easily
Sabry (2015)
Fish Wastes as Source of Fertilizers and Manures
333
profound triggers that damage plants as well as soil, thus likely to impair agricultural
productivity. They raise nitrate content in soils. Plants grown in such soils turn to
poisonous nitrites in the intestines when eaten. According to Usry (2013), nitrate is
transformed into a very poisonous chemical (nitrite) in the digestive system of living
organisms. These toxic nitrites combine with hemoglobin in the bloodstream to
induce methemoglobin, which affects the vascular and respiratory systems, resulting
in asphyxia and, in extreme circumstances, death. Synthetic fertilizers are prone to
leaching into groundwater and surface water. Rainfall or excessive irrigation can
wash these chemicals into rivers and lakes, causing water pollution and contributing
to eutrophication, a phenomenon where excess nutrients disrupt aquatic ecosystems
by promoting algae overgrowth. In addition to this, the production and application of
synthetic fertilizers release ammonia and nitrous oxide into the atmosphere, leading
to air pollution and contributing to greenhouse gas emissions, further aggravating
climate change. Thus, counting all these problems related to the practice of synthetic
fertilizers, it becomes imperative to supplement or replace these chemicals with
environmentally safe nutrient-supplying products.
4
Application of Fish Waste as Fertilizer and Manure
The leftover fish can be utilized as a raw material in manufacturing organic fertilizers.
Compost made from fish waste will give the added benefit of containing nutrients
such as calcium, magnesium, and potassium. It helps to keep compost in good shape,
sanitary, and without contaminants like phytotoxic chemicals and heavy metals
(Kinnunen et al. 2005). The benefit of using fish waste as compost is that it can
solve issues with fish waste discarding by transforming it into completed products
with a good market value and the least stress on the environment. In horticultural
crops, the compost created from seaweed and fish waste works well as soil amend-
ment as shown by the yields of lettuce and tomatoes (Illera-vives et al. 2015). When
compared to crops getting mineral fertilizers or no fertilizers, the use of compost at
a rate of 66 tha-1 considerably enhanced the production of tomatoes and was related
to larger diameter of fruit and higher fruit weight. When compared to the control
and mineral fertilizer treatments, the compost residual effect was noteworthy and led
to greater commercial yields of lettuce. According to Enviro-Fish Africa., 2006 fish
waste from tilapia beneficiation after composting with crushed grass, was tested as
a source of humic acids to stimulate the growth of the lettuce plant (Busato et al.
2018). In lettuce, the humic acid extract (20 mg L−1) greatly enhanced the amount
of dry and wet root matter.
Fish Wastes as Source of Fertilizers and Manures
334
5
Procedure for Making Fish Waste as Fertilizers
and Manures
Fish waste compositing is a relatively new and ecologically beneficial method of
disposing of fish waste to get rid of unwanted fish mass. This also allows us to get rid
of their awful odor and convert waste into a valuable marketable product. Fish waste
is collected and layered with carbon, nitrogen, air, and moisture for composting. Fish
wastes such as viscera comprising of the digestive system, kidney, air bladder, liver,
ovary, and testis, and leftover organs like scales, fins, and gills are put into a trench
for decomposition. The digestive system, fins, scales, gills, liver, kidney, air bladder,
ovary, testis, and other waste organs are placed as the first layer. For the carbon
supply, the second layer is sawdust or any other wood product. After dumping the
fish waste into the pit, care is to be taken for the first seven days since the pit emits a
foul odor, increasing the risk of disturbance from dogs, cats, and other predators. As
the microorganisms require moisture for the decomposition process, watering is one
of the significant factors during the process. Temperature is an important aspect of
the decomposition process, and shade is essential to prevent the pit from drying out.
Aeration of the well is also required for the breakdown process. Bacillus, Rhizobium,
and Azotobacter (Phosphate solubilizing bacteria, PSB), are some of the bacteria that
can be employed to speed up the breakdown process (Fig. 1). All layers are blended
after one month for well aeration, and this process is to be repeated every 15 days until
the fertilizer is ready. Every month, the pit is monitored. Excellent quality fertilizer
is made in 180 days (Balkhande 2020). After the fertilizer has been prepared, it
is filtered through the mesh, and a sample is sent to any KVK for NPK and other
micronutrient analyses (Balkhande and Chavhan 2020).
Fig. 1 Simple procedure for
production of fertilizer from
fish waste
Fish Wastes as Source of Fertilizers and Manures
335
6
Advantages of Using Fish Waste: Economic Benefits
and Prevention of Environmental Pollution
Every year 20 million tons of fish are discarded annually from global fisheries,
accounting for 25% of total marine fishery catch production (Kim and Mendis 2006).
Among the items that are discarded constitute fish processing wastes, by-products,
and non-target species. More than half of all fish tissues, including skin, fins, heads,
and viscera are predicted to be thrown away as “waste.” Furthermore, fish processing
sector discards are estimated to account for up to 75% of total product volume (Olsen
et
al. 2014). Because fish waste causes so many problems, it should be recycled as
much as possible. Fishery wastes have become a global concern in recent years,
influenced by a variety of operational, biological, and technical elements and socioe-
conomic factors as well (Arvanitoyannis and Kassaveti 2008). Disposing of this
detritus has long been a challenge for fish merchants who clean and process fish,
from enormous commercial food processors to small sport fishing operations. Fish
waste cannot be kept for longer than 24 h due to its high protein content. Furthermore,
fish processing sector discards are estimated to account for up to 75% of total product
volume (Olsen et al. 2014). Gonçalves et al. 2007 observed significant trammel net
discards in the Mediterranean Sea, with a total of 137 species (79.7% of the total)
thrown away and an overall discard rate varied from 15 to 49% for Greece to Portugal,
respectively.
The environmental impact of fish wastes on aquatic ecosystems is an essential
feature, as the organic wastes released into the water bodies could drastically alter
the benthic assemblage biodiversity and community structure. (Vezzulli et al. 2008).
Furthermore, fish wastes cause a huge economic loss, despite the fact that they may
be used as a source of nutrition for farm fishes. As a result, the management of fish
discards encompasses a variety of issues, the most important of which is the need
to reduce this source of pollution and to find the best solutions to the problem. As a
result, better fish waste management is required to address environmental concerns
while also making complete use of biomass for high-value commercial reasons. Fish
waste management is an appealing issue because it indicates a way to address the
environmental implications of fishery discards while also providing a tool to utilize
them as a source of feed for farmed fish, so supporting aquaculture expansion in a
sustainable manner in the future. The use of fisheries wastes and by-products has
the potential to reduce waste that would otherwise be thrown, resulting in nutrient
enrichment and eutrophication of aquatic bodies. As a source of high-value chem-
icals, fish wastes, and by-products can be used effectively as fish manure, which
would not only protect the environment but also give economic security.
Fish Wastes as Source of Fertilizers and Manures
336
7
Fish Wastes: A Successful Source of Manures—A Case
Study
Fish can be utilized to generate both liquid and solid fertilizers (Davis et al. 2004.).
Fertilizer made from fish source material can boost the output of some fruit plants by
up
to 60% (Glogoza 2007). Organic fertilizers are an excellent choice. Vanny et al.
(2019) employed. Solid Organic Fertilizer (SOF) is made from Tilapia (Oreochromis
mossambicus) fish waste by utilizing Bakasang traditional fermentation technology.
In TambakLorok Market, Kusuma and Yulianto (2019) investigated the use of fish
waste processing as a compost raw material. They claim that the TambakLorok
Market is a market where locals sell their own fish catches. However, due to the
enormous number of fish that are caught, not all of the fish captured can be used. In
the TambakLorok market and at the fish auction site as well, the fish waste is
normally only stacked in a few spots. It is vital to process fish waste in order to
lessen the environmental impact, one of which is the use of fish waste as a compost
raw material. Compost made from fish waste has the added benefit of containing
nutrients such as potassium, calcium, and magnesium. Furthermore, compost from
fish waste helps to ensure that the compost is hygienic and free of pollutants such as
heavy metals and phytotoxic chemicals (Kinnunen et al. 2005).
8
Constraints in Using Fish Waste as Fertilizers
and Manures
The major disadvantages in using fish waste as fertilizer or manure include:
Because the amount of nutrients in organic fertilizer is typically low, using it is
more of a process than an event, requiring a large volume of fertilizer to achieve
the necessary nutrient dose.
In addition, the composition varies.
The process of producing fish excrement is unpleasant and time-consuming.
Mineralization and the release of nutrients, particularly nitrogen, are both slow
processes.
9
Conclusion
A large amount of fish waste is generated by fish processing plants due to the rapid
expansion of aquaculture. If left untreated, this waste has the potential to radically
alter the community structure and biodiversity of an ecosystem. Because the fertilizer
is
organic and high in nitrogen, phosphorus, and potassium, it may be transformed into
fish dung and fertilizer with ease. This organic fish-based fertilizer can be used
.
.
.
.
Fish Wastes as Source of Fertilizers and Manures
337
to boost compost or offer plant nutrients. It will also safeguard the ecosystem from
the negative effects of synthetic fertilizers.
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