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Karthick, N. (2014). Biopotentials of Organic Fertilizers

Produced from Three Different Seaweeds on Soil Biota.

Ph.D. Thesis, Manonmaniam Sundaranar University,

Tirunelveli, India.

1. INTRODUCTION

1.1. General Introduction

India is primarily an agricultural country with around 70% of the population situated

in rustic areas and directly occupied in agriculture. The emerging population is placing load

on food production and to meet this increasing demand, farmers are using chemical fertilizers

to enhance their crop production. During the last two decades, marine chemical ecology has

matured from a science where natural products chemists discovered secondary metabolites

and assumed ecological functions or where biologists observed ecological interactions and

assumed the underlying chemical mechanisms into a stronger field where chemical and

biological aspects are simultaneously investigated using ecologically realistic conditions

(Hay, 1996). Hansra (1993) reported that chemical fertilizer mixed with pesticides gets

accumulated in plant which lead to health crisis in humans due to biomagnifications. The

undesirable effect in inorganic fertilizers on soil and environment is foremost science to

examine alternative biofertilizers (Metting et al., 1990).

The seaweeds are an important component of the marine living resources of the

world. They are presented largely in shallow coastal waters of sea, backwaters and estuaries.

Seaweeds are non-flowering plants which lack root, true shoot, stem, flowers and leaf system.

Seaweeds usually grow vertically away from the substratum which carry them closure to

light. They are rich on hard substrates and usually extend to a depth of 30-40 m. They enclose

different vitamins, minerals, trace elements, protein, iodine, bromine and bioactive

substances. Many polysaccharides are recovered from seaweeds.

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Commercially available varieties of marine macroalgae can be classified as green

algae (Chlorophyta), brown algae (Phaeophyta) and red algae (Rhodophyta). The seaweeds

are classified depending on their nutrient and chemical composition. Most of the compounds

in marine algae exhibit anti- bacterial activities. Many metabolites isolated from marine algae

have been shown to possess bioactive effort. These seaweeds are bestowed with diverse

source of bioactive natural products that reveals biomedical and anti-microbial properties

(Padmini et al., 1988; Arunkumar et al., 2005; Kulik, 1995).

Seaweeds provide structurally diverse and biologically active secondary metabolites.

The tasks of these secondary metabolites are defense mechanism against fouling organism,

herbivores and pathogens. Arunkumar et al., (2005) have worked on the bioactive potential of

seaweeds against plant pathogenic bacterium, Xanthomonas oryzae causing blight disease in

rice.

Seaweeds have been habitually used in human and animal nutrition. Seaweeds are

rich source of bioactive compounds such as vitamins, carotenoids, protein, dietary fibre,

minerals and essential fatty acids. Important polysaccharides such as agar, alginates and

carragenans obtained from seaweeds are used in pharmaceutical as well as in the food

industries. Marine organisms are a rich resource of structurally novel and biologically active

metabolites. So far many chemically unique compounds of marine origin with different

biological activities have been isolated and a number of them are under investigation and/or

being developed as new pharmaceuticals (Faulkner, 2000).

Extract of seaweed is often found on the list of ingredients on cosmetic packages

particularly in hand, face and body creams or lotions. This frequently refers to the use of

alginate in the product and their use in cosmetics.

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From the time immemorial, the macroscopic marine algae have been closely

associated with human life and are being exhaustively used in numerous ways as a source of

food, feed, fertilizer, medicine and chiefly for economically important phycocolloids

(Levering et al., 1969; Chapman, 1970). Marine algae contains more than 60 trace elements

in a concentration much higher than in terrestrial plants. They also contain protein, bromine,

iodine, vitamins and substances of stimulatory and antibiotic nature. In the marine algae, the

phytochemicals are extensively used in various industries such as confectionary, food, textile,

dairy, pharmaceutical and paper mostly as gelling, stabilizing and thickening agents.

Seaweeds are potentially excellent sources of highly bioactive secondary metabolites that

could lead to the development of new functional ingredients (Pelegrin et al., 2008).

1.1.1. Green Algae

Systematic Position

Kingdom : Plantae

Phylum : Chlorophyta

Class : Bryopsidophyceae

Order : Bryopsidales

Family : Caulerpaceae

Genus : Caulerpa

Species : scalpelliformis

Green seaweeds are found on both sandy and rocky beaches. The green colour of the

seaweeds is due to the green pigment chlorophyll required for the photosynthesis of light.

The colours vary between species from bright green to yellow or dark shade. Many of them

can tolerate low salinity and will colonize areas where rivers meet the sea. They spread and

Plate 1 : Caulerpa scalpelliformis

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grow by two main methods - fragmentation and by releasing reproductive spores. The latter is

more problematic in the Caulerpa species and can present some challenges to successfully

keep them for long term in the marine aquarium. Green macro algae occur high on the

intertidal shore, in tidal pools and channels as well as in rocky reef environments, sometimes

to considerable depths. Some green algae can nurture in areas of softer sediments either

growing on shell fragments and small stones or extending from solid substrate across softer

sediments with stolons or runners (eg. Species of Caulerpa, Plate 1). The spongy textured

green codium comes in a number of forms, growing either as thalli that are divided into dark

green finger like branches or as crusts which can be convoluted, glassy and smooth or form

domed circular patches.

1.1.2. Brown Algae

Systematic Classification

Kingdom : Chromista

Phylum : Ochrophyta

Class : Phaeophyceae

Order : Fucales

Family : Sargassaceae

Genus : Sargassum Plate 2: Sargassum wightii

Species : wightii

The Phaeophyceae or brown algae are a large group of mostly marine multicellular

algae. The rock seaweeds and leathery kelps are often the most conspicuous algae in their

habitats. Regardless of size or form two visible features placed the Phaeophyceae apart from

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other algae. First member of the group possess a characteristic colour that range from an olive

green to various shades of brown. The particular shade depends upon the amount of

fucoxanthin present in the algae. Second, all brown algae are multicellular. The brown algae

include the largest and fastest growing of seaweeds. Fronds of Macrocyctis may grow as

much as 50 centimetres per day and the stipes can grow 6 centimetres in a single day, a

holdfast serves to anchor the algae in place on the substrate where it grows. A stipe is a stalk

or stem like structure present in algae which may grow as a short structure near the base of

the algae as in Laminaria, or it may develop into a large, complex structure running

throughout the algal body as in Sargassum (Plate 2). Many algae have a flattened portion that

may resemble a leaf and this is termed a blade, lamina or frond. Gas filled floats called

Pneumotocysts provide buoyancy in many kelps and members of the Fucales. These bladder-

like structures occur in the lamina so that it is held nearer the water surface and thus receives

more light for photosynthesis.

1.1.2. Red Algae

Kingdom : Plantae

Phylum : Rhodophyta

Class : Florideophyceae

Subclass : Corallinophycidae

Order : Corallinales

Family : Corallinaceae

Genus : Cheilosporum Plate 3: Cheilosporum spectabile

Species : spectabile

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The majority of seaweeds are red algae which remain flexible and revolve into many

colours such as violet, red, brown, green or even yellow. The red algae or Rhodophyta are

one of the oldest group of eukaryotic algae and are also one of the largest with about 5,000 -

6,000 species of mostly multicellular, marine algae including many notable seaweeds. Most

Rhodophytes are marine although there are freshwater species. There are very few single

celled red algae.

The red colour of the seaweeds is due to the larger amount of red phycobilin pigments

(Plate 3) overriding the green pigment chlorophyll. The pigments that colour it have a

purpose enabling the seaweeds to photosynthesize light from a specific part of the light

spectrum. Within the group of phycobilins two pigments are of importance namely

Phycoerythrin and Phycocyanin which absorbs blue, green and yellow light. These parts of

the spectrum are the type of light that penetrates the deepest in sea water. The red pigments

absorb the light but chlorophyll is still required to process it. This method allows red seaweed

to survive in low light condition where green seaweeds could not.

Seaweeds are considered as a source of bioactive compounds as they are able to

produce a great variety of secondary metabolites. They are characterized by a broad spectrum

of biologically active compounds with anti-oxidant, anti-fungal, anti-viral and antimicrobial

activities which have been detected in sea weeds belonging to brown, red and green varieties.

The seaweeds in the sea are constantly exposed to potentially dangerous co-existing microbes

and they have apparently evolved with chemical defence strategies by synthesizing array of

secondary metabolites in order to defend against the microbial thread (Kubanek et al., 2003).

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1.2. Seaweed Liquid Fertilizer

Seaweed Liquid Fertilizer (SLF) holds trace elements, macro nutrients, organic

substances like amino acids and plant growth regulators such as cytokinin, auxin and

gibberellins. Verkleij (1992) stated that use of SLF improved the water retention capacity of

soil. Currently we use chemical fertilizers in great quantities to compensate the deficiency of

nutrients in soil. It is observed that the copious use of chemical fertilizers affects soil and

plants in due course.

Singh and Yadav (1992) have reported that the application of organic matter as a

source of some portion of required nutrients will have positive impact on soil physical and

chemical properties which ultimately will increase the productivity. The value of seaweed as

fertilizers is not only due to nitrogen, phosphorus and potash content but also because of the

presence of trace elements and metabolites similar to plant growth regulators (Booth, 1969).

The seaweeds are prepared in different forms such as SLF (Seaweed Liquid

Fertilizers), LSF (Liquid Seaweed Fertilizers), LF (Liquid Fertilizers) and are either wholly

or finally chopped powdered algal manure which have been used and all of them have been

reported to produce beneficial effects on cereals, pulses and flowering plants. Seaweed

manures have the advantage of being free from weeds and pathogenic fungi. Promising

increased crop yield, resistance to stress, nutrient uptake, improved seed germination of

reduced incidence of fungal and insect attack have been resulted by the application of SLF.

Seaweeds are known to contain substantial quantities of plant growth regulators (Mooney and

Van Staden, 1985), Cytokinin (Smith and Van Staden, 1984), IAA (Abe et al., 1972),

gibberllins and gibberellin like substances (Bentley, 1960; Radley, 1961; Sekar et al., 1995).

Hence, marine algae particularly seaweeds have a vital role to play in agriculture especially

in the third world country where irrational use of chemical fertilizer and pesticides is a cause

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Table 1: Comparative Analysis of Seaweed Liquid Fertilizer (SLF) Preparation by

Various Scientific Groups

Seaweeds SLF preparation References

Sargassum

wightii,

Gelidella aerosa,

Ulva lactuca

500 gm powder of each Seaweed was extracted in a

soxhlet apparatus for 8 hrs in petroleum ether for 50ºC.

250 mg of the crude paste was dissolved in 5 ml of

acetone and 245 ml of water and centrifuged. The

supernatant was considered as 100% SLF.

Immanuel and

Subramanian

(1999)

Sargassum

polycystum

1 Kg of freshly chopped seaweed was boiled with

1litre of distilled water for 1 hour and then filtered.

The filtrate was taken as 100% SLF.

Erulan et al.,

(2009)

Sargassum

wightii

500 gm of dry powder was soaked in 100 ml of ethyl

alcohol for 12h.The residue ofthe extract was boiled

with 300 ml of distilled water for 30 minutes and

filtered.The volume was made up to 500 ml with

distilled water and is known as 100% SLF.

Jothinayagi (2009)

Padina pavonia,

Dictyota

dichotoma

100g powder was soaked in 500 ml of distilled water

and boiled for 60 minutes and filtered. The resulting

cooled extract was taken as 100% SLF.

Bai et al., (2011),

Kumar and Sahoo

(2011)

Sargassum

johnstonii

500g of seaweed powder was soaked in 5 L of water

and heated for 45 min at 60ºC. The filter extract was

cooled and recovered about 3 L and taken as 100%

SLF. From this extract, 0.1-8% concentrations were

used.

Kumari et al.,

(2011)

Gracilaria

corticata,

Ulva faciata,

Sargassum

ilicfolium

50g of powder was soaked and boiled in 50 ml of

distilled water for 1 h and filtered through muslin cloth

and the filtrate volume was made up to 50 ml and these

extract was treated as 100% extract.

Pise and Sabale

(2010)

Kappaphycus

alvarezii

The fresh material were homogenized by a grinder at

ambient temperature, filtered and stored. These filtrate

was taken as 100% SLF. 2.5-15% diluted SLF was

used.

Rathore et al.,

(2009)

Chaetomorpha

linum,

Gracilaria

verucosa

10g of powder was soaked in 100 ml of distilled water

followed by autoclaving for 30 minutes. The

autoclaved materials were filtered after cooling

through a cheese cloth and used as 100% extract.

Sethi and

Adhikary (2008,

2009)

Sargassum

wightii

1kg of seaweed was cut into small pieces and boiled

with 1L distilled water and filtered. The filtrate was

taken as 100%.

Sivasankari et al.,

(2006)

Sargassum

polycystum

500g of Seaweed powder was boiled in 1000 ml of tap

water for 30 minutes and the volume was made to 500

mL and used as 100%.

Ramamoorthy et

al., (2006)

Gracilaria

corticata,

Caulerpa

scalpelliformis

10 g of Seaweed powder was mixed with 200 ml of tap

water and autoclaved for 30 minutes, cooled,

centrifuged and supernatant was dried at 60ºC for 48h.

The dried seaweed extract was considered as 100%

SLF.

Thangam et al.,

(2003)

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of concern. An extract from seaweed was shown to improve stress tolerance in a number of

plant species. This was mediated by an increase in the concentration of bioactive molecules

including antioxidants in the treated plants (Rayorath et al., 2009; Zhang and Schmidt, 2000).

Extensive regional tribals would need to be conducted with the product to determine

the environmental limits on biological activity and monitor the survival and dispersal of the

inocula (Davison, 1988). Hence, use of modern agriculture in coincidence with traditional

farming practices is the sustainable solution for the future.

1.3. Chemical Liquid Fertilizers

Organic Agriculture is one of the greatest ranges in production methods that are

supportive to the environment. Cost of inorganic fertilizers is very high and sometimes it is

not available in the market for which the farmers fail to apply the inorganic fertilizers to the

crop field in the optimum time. On the other hand, the organic manure is easily available to

the farmers and is cost effective compared to that of inorganic fertilizers. Shelke et al., (1999)

has reported that only inorganic fertilizer application could affect the soil health which in turn

may affect flowering and fruiting, so the collective application of manures and fertilizers may

contribute the nutrients appropriately and also keep the suitable condition for flowering,

fruiting and their development. Application of chemical fertilizers and pesticides alter the

agriculture scenario in the world. Rash methods of cultivation and better use of quick release

of chemical fertilizers over irrigation rendered the soil weak for cultivation. Higher

application of chemical fertilizers results in higher impact on cost of production,

transportation and overheads. It results in erosion of local capital and poverty.

Yadav et al., (2002) has reported that soil organic matter was decreased by chemical

fertilizer application but was improved with all types of organic manure application. The

rapid industrialization that took place at the turn of the 20th

century, the pollution of air, water

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and soil has become a major global problem. Some of the compounds that contribute to

pollution naturally happen in the environment at low levels, but are currently found at

elevated levels due to the input from industrial and other anthropogenic sources. Other

contaminants known as Xenobiotics do not naturally happen in organisms or in the

environment. Most of these are structurally and chemically strange to the organisms and

pathways that transform or degrade molecules in the environment and are thus potentially

persistent pollutants.

1.4. Soil Biota

Soil is a vital part of the terrestrial ecosystem and is considered as a store house of

microbial activity. The long term application of inorganic fertilizers is to increase the

productivity of crop and they lead to the ill-effect of the ecology of the agricultural systems.

Nowadays there is much usage of more number of chemical fertilizers to increase the

productivity but it causes several damages to the ecology of the soil and their fertility.

Agricultural practices are being modified with organic farming for health benefits of human

beings (Kramer et al., 2006). The utilization of biofertilizers is to increase the plant growth

and development and it is eco-friendly to the environment. The use of seaweed as manure in

farming practice is very ancient and is prevalent among the Romans. Soil biota plays an

important role in ecological processes in the soil and in the provision of various ecosystem

services such as maintenance of soil structure, water regulation and supply of nutrients

(Brussaard et al., 1997; Swift et al., 2004; Mulder, 2006; Kibble white et al., 2008).

1.4.1. Earthworms

The earthworms play a highly significant role in the soil ecosystem by taking part in

the organic matter cycle and altering the soil structure. They make nitrogen obtainable for

plant growth by nourishing on organic matter in the soil. Earthworms play a vital role in a

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variety of soil and they contribute to the complex process of decomposition while affecting

aeration, water transport and soil structure (Edwards and Lofty, 1969). The earthworms have

the capability to enhance the soil fertility. The earthworms consume decaying matter in the

soil. They release casting which are good for plant growth. Earthworms have been studied as

a readily available, easily maintainable, an economic test species for assessing chemical

pollution in soil. The earthworms play a major role in enhancing soil fertility. In many soils,

earthworms play a main part in transferring large pieces of matter (eg. Dead leaves) into rich

humus and thus improving soil fertility (Sharma et al., 1983). Earthworm have special gland

which enclose their digestive tube. These tubes take in calcium from the soil and have the

effect of neutralizing any harmful result of absorbing too much carbon dioxide. The calcium

carbonate is then excreted. It is in this way the earthworm manages to exist happily in the soil

without having threat to life by coming to the surface to breathe.

Selected Earthworm

Eudrilus eugeniae (Kinberg, 1867)

It is also known as the African night crawler worm and is of epigeic variety.

Systematic Position

Phylum : Annelida

Subphylum : Clitellata

Class : Oligochaeta

Order : Haplotaxida

Family : Eudrildae

Genus : Eudrilus

Species : eugeniae

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Habitat

Eudrilus eugeniae is found to be distributed originally in equatorial West Africa but

presently found in most parts of the world.

Characteristics of Eudrilus eugeniae

Length 90 - 158 mm, diameter 5 - 8 mm, segment number 145 - 196, setae closely

paired, clitellum annular between XIV- XVIII and less enough developed ventrally. Male and

prostatic pores paired combined, large, immediately in front of furrow 17/18 between setal

lines absent. Absence of Penial setae. Female and spermathecal pores paired, combined

moderately sized transverse slits centered at or just median to tested holandric, paired ovaries

in segment XIII with the ovisacs. Prostomium epilobic and dorsal porsal pores are absent.

Reproductive Biology

Temperature range: minimum: 7°C, maximum: 32°C

Reproductive rate: about 7 young ones per worm per week under ideal conditions

Cocoon production / worm/ year: 73-347

Average number of young ones per cocoon: 1.4 - 2.7

Time of emergence from the cocoon: 15 - 30 days under ideal conditions.

Hatching success: about 67%

Time to sexual maturity: 30 - 95 days under ideal conditions.

1.4.2. Plants

Historical records confirm that the use of seaweeds in Agriculture is old practice and

widespread wherever there are abundant resources in the coastal regions of Norway, Ireland,

France, Britain. Thivy (1960) reported that the seaweeds exactingly brown algae develop the

fertility of soil in cultured fields as their algin content helps in conditioning the soil,

facilitating aeration, moisture retention and absorption of nutrient elements. Bhosle et al.,

(1975) prepared a seaweed liquid fertilizer and revised its effect on Phaselous vulgaris.

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Seaweed fertilizers are found to be superior to chemical fertilizers due to high level of

organic matter, micro and macro elements, vitamins and fatty acids and are also rich in

growth regulators. The Diagrammatic representation of Seaweed Liquid Fertilizer to crop

plants and their mechanisms are represented in Plate 4.

Plate 4 : Diagrammatic representation of Seaweed Liquid Fertilizer to crop plants and

their mechanisms

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Test Plant

Tomato (Solanum lycopersicum)

Kingdom : Plantae

Division : Magnoliophyta

Class : Magnoliopsida

Order : Solanales

Family : Solanaceae

Genus : Solanum

Species : lycopersicum

Tomato is a typical red fruit that originated in America and spreaded all over the

world. Many varieties are widely grown, often in green house in cooler climate. Tomato is

consumed in many ways such as raw, sauce, ingredients in food and in drinks. Botanically, it

is a fruit but it is considered as vegetable for culinary purpose. The fruit is highly rich in

lycopene which may have beneficial health consequences. The plant grows till the range of 1-

3 metre in height; often have weak stem which sprawls on ground. Among the other

nutrients, seaweed contains 1.2 % nitrogen which it transports to plant roots when used as a

fertilizer. Nitrogen is essential for the leafy growth of plants. Seaweed also holds potassium

which aid plants grow more vigorously. Seaweed fertilizers also boost the production of a

variety of crops including potatoes, peppers, cucumbers, okra, apples and oranges. These

developments are likely because seaweed contains phosphorous which makes the growth of

healthy fruit. Seaweed contains phosphorous which aid the plant to develop healthy with

strong root systems. Seaweed also recovers soil texture, greatly improving drainage and

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aeration.

1.4.3. Microbes

Microbes play a vital role in assisting the uptake of nutrients in a crop. Rhizobia,

among several of these microbes are quite popular for leguminous crops. Microbial

inoculation involves the selection and multiplication of plant beneficial micro-organisms and

applying them to plants, seed or soil. The main use of micro-organisms is as biofertilizers for

improved plant nutrition and as biological control agents to struggle against pests, weeds and

diseases. Microbial inoculation of plants is of great importance in less intensive low-input

agricultural systems in developing countries (Davison, 1988). Mm

Pseudomonas and several other bacteria facilitate nutrient uptake and form a very

friendly network around the roots. Symbiotic organisms form a pleasant environment in the

soils more abundantly in the tropical climates. It empowers the local community to use its

own resources in terms of biodiversity resources and rights, saves on application of high cost

Figure 1 : Pie-Chart representing the field trials of Seaweed

Liquid Fertilizers in different crops in various Publications (%).

Pulses(47%)

Vegetables(25%)

Cereals(17%)

Oilseeds(4%)

Spices(4%)

Ornamental plants(3%)

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fertilizers, render the soil health and avoids interference with the environment. Biologically

active compounds may be liberated from blue-green algae growing on the surface of moist

soils. Such compounds may also release exudates from algae grown in liquid culture. The

blue-green algae (Cyanobacteria) are another source of biological nitrogen. They are

distributed in symbiosis with the water fern, Azolla. Cyanobacteria are structurally diverse

assemblages of aerobic Gram-negative eubacteria (Prokaryotes) characterized by their ability

to form oxygenic photosynthesis. Microorganisms contribute to aggregation of soil particles

by the binding action of filamentous organisms and the production of adhesive extracellular

polysaccharides (Martin, 1971; Lynch, 1981). Seaweeds are rich basis of polysaccharides

which may affect soil aggregation directly or indirectly after disintegration by soil microbes.

They lessen the molecular atmospheric nitrogen to ammonia which can be utilized for

amino acid and protein biosynthesis. Nitrogen compounds which can be digested by other

plants are ultimately released to the soil after death of the algal cells and subsequent

mineralization and nitrification. Algal nitrogen fixation release the fixed nitrogen and its

assimilation by higher plants may be rapid (Stewart, 1967). The algal extracts of

Westiellopsis prolifica analysed by Fogg and Pattnaik (1966) showed that ammonium and

amide-nitrogen accounted for most of the total extracellular combined nitrogen. Pre-treatment

of seeds of vegetable crops with extract of Westiellopsis prolifica promoted germination and

the subsequent growth of development.

1.4.4. Nematodes

Nematodes are one of the most abundant multicellular organisms on earth and are

found in all the territory and ecosystems of the biosphere. They occur in soil, decaying

organic matter of all forms of plant life and most animals including domesticated and wild

animals (Norton, 1978). Microscopic, roundworm invertebrates with a body cavity and

complete digestive tract, they are non segmented, appendageless and have bilateral symmetry

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(Poinar, 1983). Plant parasitic nematodes constitute one of the most devastating and widely

distributed pest group and are responsible for tremendous disease symptoms in different

crops resulting in heavy loss (Bhatti, 1994). The root knot nematodes (Meloidogyne sp.)

alone are reported to cause 5% loss on worldwide basis which is much higher in the tropical

and subtropical countries (Taylor and Sasser, 1978). Pesticides are regularly used for the

control of pests and diseases. A control strategy of nematode should be developed which may

be safe and cost effective (Abid et al., 2005).

1.5. Bioformulation

To be a desirable microbial insecticide, the agent should not moderate in potency by

appropriate processing. The preference of formulation may be vitally important in practical

application. For example, if heavy rainfall is expected, dust would be unsuitable and a spray

containing a good sticker would be required. There are two main types of formulations of

microbial insecticides:

(1) Liquid Formulation

(2) Dusty Formulation

(1) Liquid Formulation: Water is generally used as diluent. Suitability of water as a

diluent is relatively higher for relatively resistant forms such as polyhedral and spores.

The use of oil as a carrier for microbial insecticide came in part from the need to fit

such products into established procedures and to use existing equipment for their

application in the field. Solubility, cheapness and good sticking and spreading

properties are the desired characteristics of the oils used.

(2) Dusty Formulation: The earliest microbial insecticides were formulated in dry form

and were used as dusts or wettable powders. Such formulations are still prepared for

certain microbial insecticides.

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Caesart and Burr (1991) have suggested that in powder formulation, the active

material is chosen to be in the spore form to increase the shelf life and effectiveness of active

material. Gram-positive microorganism that produces heat and desiccation resistant spores

can be formulated into stable, dry-powder products to propose a biological solution to the

problem of biofertilizer agent formulation. Schisler et al., (2004) has reported that

amendments can be grouped as either carriers (fillers, extenders) or amendments that improve

the chemical, physical or nutritional properties of the formulated biomass.

Brar et al., (2006) and Tu and Randall (2005) have reported that the active material

is mixed with carrier materials such as water, clay, talc, oil or others to make the formulation

safer to handle, easier to apply and better suited for storage. In some formulations,

enrichment materials comprising of nutrient-rich medium such as molasses, trehalose,

maltose and sucrose are incorporated to further enhance the viability of core (active)

materials.

1.6. Other Uses of Seaweeds

1.6.1. Fertilizers and Soil Conditioners

There is a long history of coastal people using seaweeds especially the large brown

seaweeds to fertilize nearby land. Generally drift seaweed or beach-washed seaweed is

collected. In Cornwall (United Kingdom), the practice was to mix the seaweed with sand, let

it rot and then dig it in. For example in a more tropical climate like the Philippines, large

quantities of Sargassum have been collected, used wet locally but also sun dried and

transported to other areas. In Puerto Madryn (Argentina), large quantities of green seaweeds

are cast ashore every summer which interfered with the recreational uses of beaches.

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Figure 2: Schematic representation of the uses of Seaweeds

Part of this algal mass has been composted and then used in trials for growing tomato

plants in various types of soils. In all cases, the addition of compost increased water holding

capacity and plant growth which indicates that composting simultaneously solved the

environmental pollution problems besides producing a useful organic fertilizer.

1.6.2. Animal Feed

For a long time, animals such as sheep, cattle and horses that lived in coastal areas

have eaten seaweed especially in those European countries where large brown seaweeds were

washed on the shore. Today, the accessibility of seaweeds for animals has been increased

with the production of seaweed meal. Norway is one among the early producers of seaweed

meal using Ascophyllum nodosum. Seaweeds grow in the eulittoral zone so that it can be cut

and collected during low tides. France used Laminaria digitata, Iceland both Ascophyllum

and Laminaria species and the United Kingdom, Ascophyllum. Chapman and Chapman

Seaweeds

Fertilizer

Animal & Fish

feed

Cosmetics

Chemicals

Food for

humans

Waste Water

Treatment

Biofuel

Pharmacy

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(1980) discussed several feeding examinations and have tables showing the protein, fat, ash

and fibre of some fresh seaweeds and seaweed meal as well as the vitamin and mineral

content of the seaweed meal.

1.6.3. Biomass For Fuel

In 1974, the American Gas Association decided to look for a renewable source of

methane (natural gas) and subsidised a project to produce seaweed on farms in the ocean,

harvest it and convert it to methane by a method of anaerobic fermentation. The project was

divided into two parts: one the production and harvesting of the seaweed (biomass), the other

the conversion of the biomass to energy (methane that could be burned to produce energy).

The seaweed selected was the "giant kelp" that grows off the coast of California, Macrocystis

pyrifera because of its high growth rate and ease of harvesting by mechanical means. A test

farm was built in the ocean, 8 km off the coast of Southern California and 100 kelp plants,

12-22 m long and taken from natural beds were placed on the farm test structure. Bird and

Benson (1987) stated that more work is necessary to find better methods for the conversion of

biomass to methane on a large scale although the bench-scale work already done specifies

that net energy can come from bioconversion with good yields of methane. More engineering

research is needed for the design of suitable open-ocean structures that will allow the kelp to

survive storms and excessive wave movements and currents. Methane from marine biomass

is a long-term project and research and development have been scaled down possibly to be

revived when a crisis threatens in natural gas supplies (Morand et al., 1991).

1.6.4. Cosmetics

“Extract of seaweed" is frequently found on the list of constituents on cosmetic

packages mainly in face, hand and body creams or lotions. Milled seaweed filled in sachets is

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sold as an additive to bath water sometimes with addition of essential oils. Thalassotherapy

has come into trend in recent years especially in France. Mineral-rich seawater is used in a

range of therapies including hydrotherapy - massage and a variety of marine mud and algae

treatments. One of the treatments is to cover a person's body with a paste of fine particles of

seaweed sometimes cling wrapped and warm the body with infrared lamps. It is said to be

useful in various ways including for relief of rheumatic pain or the removal of cellulite. Paste

mixtures are also used in massage creams with promises to rapidly restore elasticity and

suppleness to the skin. The seaweed pastes are made by freeze grinding or crushing. The

seaweed is washed, cleaned and then frozen in slabs and are either pressed against a grinding

wheel or crushed sometimes with additional freezing with liquid nitrogen that makes the

frozen material more brittle and easier to grind or crush. The result is a fine green paste of

seaweed (De Roeck-Holtzhauer, 1991).

1.6.5. Waste Water Treatment

There are two main areas where seaweeds have the potential for use in wastewater

treatment. The first is the treatment of sewage and some agricultural wastes to reduce the

total nitrogen and phosphorus containing compounds before release of these treated waters

into rivers or oceans. The second is for the removal of toxic metals from industrial waste

water. The addition of heavy metals such as copper, nickel, lead, zinc and cadmium by

seaweeds became apparent on analysis of those seaweeds which were used as human foods.

The heavy metal content especially of the large brown seaweeds varied according to their

geographic source and sometimes to their proximity to industrial waste outlets. From these

studies, the idea of using seaweeds as biological indicators of heavy metal pollution either

from natural sources or from activities such as mining or disposal of industrial wastes

emerged into existence. This has been successfully implemented using brown seaweeds

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such as Sargassum, Laminaria and Ecklonia and the green seaweeds, Ulva and

Enteromorpha (Pan, Lin and Ma, 2000).

1.6.6. Seaweed as Medicine

Many human body substances require particular mineral elements as part of their

respective structure. Examples are iron for haemoglobin and iodine for thyroxine. For our

body to function we use proteins called enzymes. Most enzymes require one or more co-

enzymatic factors; these co-enzymatic factors are usually one or more metals. Chronic dietary

shortages or disease-related mineral depletions can produce both specific and general disease

conditions: Iodine shortage results in varying degrees of thyroid dysfunction; poor absorption

of dietary calcium can result in osteoporosis. Adequate residential body mineral supplies are

critical for optimal body system functioning. Insufficient potassium can lead to hypertension.

The algin in brown seaweeds has been shown to dissolve deposits in arteries.

Laminaria have also been shown in Japanese studies to reduce cholesterol levels and high

blood pressure. Fucoidan, a component found mostly in kelp is believed to be responsible for

the ability to discourage the formation of blood clots as effectively as heparin but without

negative side effects according to Swedish studies.

1.7. Significance of the Present Study

Nowadays, the agricultural practices are being adapted with organic farming for the

health benefits of human beings and the use of seaweeds as a fertilizer empowers the rural

farmers to use its own resources, saves the elevated rate of fertilizers, makes the soil healthier

one and avoids interference with the environment. With the initiation of green revolution

there has been a quantum jump in the use of synthetic herbicides and pesticides throughout

the world to sustain high yielding crop varieties. Constant use of this inorganic chemicals

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leads to thrashing of soil fertility and organisms present in the soil. Risk evaluation is

normally intended at the protection of human health and ecosystem and the interrelationship

of these two is easy to observe. The role of earthworms in this study is to obtain more

information on the environment quality and to make sure the environmental safety. Van Hook

(1974) reported that earthworms could serve as useful biological indicators of contamination

because of the fairly consistent relationship between the concentrations of certain

contaminants and earthworms. There is an essential need to test the chemicals causing

toxicity to soil biota because they play a vital role in the terrestrial ecosystem. The eco-

friendly Seaweed Liquid Fertilizer (SLF) is recommended to farmers for attaining the better

growth of plants and also in improvement of soil fertility and their ecosystems. The recent

challenges to food production due to the increasing occurrence of biotic and abiotic stresses is

likely due to climate change and will further reduce yields and/or will have an impact on

crops in the 21st

century (IPCC, 2007). Therefore, research into developing sustainable

methods to alleviate these stresses should be a priority. Recent studies have shown that

seaweed extracts protect plants against a number of biotic and abiotic stresses and suggests

potential for field application. Further, seaweed extracts are considered an organic farm

contribution as they are environmentally benevolent and safe for the health of animals and

humans.