Environmental Engineering Reference
In-Depth Information
These conditions are the main causes for the
formation of ROS and contribute to the photo-
inhibition of photosynthesis. The brown alga
Fucus evanescens produced ROS due to freezing,
high light, and desiccation stress (Collén and
Davison 1999 , 2001 ) which was detected with
fl uorescent dyes (Collén and Davison 1997 ).
Mastocarpus stellatus , a red alga, showed higher
antioxidant activity other than red seaweed
Chondrus crispus , because of its daily exposure
to high air temperature in the lower intertidal
zone. The activities of enzymatic and nonenzy-
matic antioxidants increase with tidal height and
also with temperature. In the high tidal levels,
the marine algae are continuously exposed to
both visible and ultraviolet radiation, resulting in
higher ROS production.
because of their alginate content, which helps
in conditioning the soil facilitating aeration,
moisture retention, and absorption of nutrient
elements. Seaweed liquid fertilizer (SLF) applica-
tion (spraying) sometimes reduces the incidence
of insect attack, and sugar beet and potato leaves
treated with seaweed extract had signifi cantly
fewer levels infested with aphids (20 %) than the
untreated leaves (83 %). The application of SLF
to improve the growth of terrestrial plants is
fast becoming an accepted practice. In general,
the reported benefi cial effects of seaweeds are
improvement of overall plant vigor, yield, quality,
and quantity of different plant parameters which
is able to withstand any adverse environmental
conditions (Balakrishnan et al 2007 ). Unlike,
chemical fertilizers, extracts derived from seaweeds
are biodegradable, nontoxic, nonpolluting, and
nonhazardous to humans, animals, and birds
(Anandhan and Sorna kumari 2011 ).
7
Utilization of Seaweed
as Fertilizer
7.1
Methods of Application
The use of seaweeds as manure in farming practice
is very ancient and was prevalent among the
Romans and also practiced in Britain, France,
Spain, Japan, and China (Thirumaran et al. 2009 ).
Seaweed manure is a slow but long-activating
fertilizer, and its application is well suited to light
sandy soils, which are generally defi cient in
potash. Physical condition of these light soils
also improves (crumb structure) on account of
the gelatinous nature of seaweeds. This is attrib-
uted to the high content of polysaccharides
and its consequent capacity for holding of water.
Seaweed extracts are used extensively in agricul-
ture as plant growth supplements and seaweed
meal takes months to become fully effective in
the soil as a plant nutrient. Seaweed concentrates
are known to cause many benefi cial effects on
plants as they contain growth-promoting hor-
mones (IAA and IBA, cytokinins) trace elements
(Fe, Cu, Zn, Co, Mo, Mn, and Ni), vitamins, and
amino acids (Challen and Hemingway 1965 ).
Hence, large quantities of seaweeds can be used
as manure in all parts of the country, either
directly in the form of compost. Seaweed fertil-
izer application improves the fertility of soils in
cultivated fi elds particularly the brown seaweeds
The seaweed fertilizers can be prepared by the
methods of manure (or) compost, crude manure,
and liquid preparation. Generally, seaweed
extracts are applied in small dosages. It is clear
that the active ingredients in seaweed extracts are
effective in low concentrations with Hoagland
solution protocol followed by Epstein ( 1972 ).
7.1.1 Manure (or) Compost
Seaweeds have been used as a food and manure
for plantation crops by coastal people in many
countries (Kaliaperumal et al. 1987 ). Recent
research suggests that application of seaweed
extract as seed treatment and/or foliar spray helps
signifi cant growth of plants. The extract contains
micronutrients, auxins and cytokinins, and other
growth-promoting substances (Spinelli et al.
2010 ). Seaweed and its derived products are used
as fertilizer in the coastal areas throughout the
globe. In India, it is used for coconut plantations
especially in Tamil Nadu and Kerala (Kalimuthu
et al. 1987 ). The high amount of water-soluble
potash and other mineral and trace elements
present in seaweeds is readily absorbed by plants
 
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