This document discusses surfactants and their applications in agriculture. It begins by defining surfactants and their structure, then describes the main types - anionic, cationic, amphoteric, and nonionic. It discusses factors to consider when choosing surfactants for crop production. The document outlines the major applications of surfactants in herbicides, fungicides and insecticides. It details the effects of surfactants on plants and soils, as well as their use in agrochemical formulations. Finally, it explores the potential applications of biosurfactants in agriculture as more sustainable alternatives to synthetic surfactants.
3. 1. Introduction
A surfactant is a surface-active agent,
also known as a wetting agent, when
used in a small quantity, distinctly affects
the surface characteristics of a system.
A surfactant consists of a hydrophilic
polar head group, often ionic, and a
hydrophobic tail, usually a long-chain
hydrocarbon.
Soaps and chemical detergents are typical
examples of surfactants
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4. 2.1. Aninonic
surfactants
• Surfactants of this type contain anionic
functional groups at their heads.
• The sodium searate in soap can dissociate,
and the sodium forms free positive ions
when it contacts water
• Since anionic surfactants are negatively
charged, they increase the retention of
cations.
Sodium searate
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5. 2.2. Cationic surfactants
The charge of this type of surfactant is pH-
dependent because the cationic functional group is
dependent on the dissociation of amines.
Cationic surfactants favour the retention of
anionic nutrients such as nitrate-nitrogen and
phosphorus.
A typical example of this type of surfactant related
to agriculture is cetylpyridinium chloride (CPC
with the molecular formula of C21H38NCl).
Cetylpyridinium chloride (CPC)
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6. 2.3. Amphoteric surfactants
This type of surfactant has the characteristics of
both an acid and a base, and is capable of reacting
as either an anionic or cationic surfactant .
They are also known as zwitterion surfactants and
were formerly called dipolar ions.
They have both cationic and anionic centres
attached to the same molecule and carry both a
positive and a negative charge.
Cocamidopropyl betaine
(CAPB)
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7. 2.4. Nonionic surfactants
This type of surfactant
contain no electrical
charge.
These surfactants are widely
used in agriculture because
they are compatible with all
types of pesticides.
They usually have a long
alcohol chain with a
hydrophilic alcohol head and
hydrocarbon tail.
Monolaurin
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8. Surfactants choose for crop production
The
surfactants
choose
needs to be
effective to
minimize
soil water
repellency.
Some
surfactants
may have a
double
effect, both
reducing
water
surface
tension and
increasing
water
retention.
The
surfactants
choose
must be
also cost-
effective.
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9. Agricultural surfactantsby application
The market for
agricultural
surfactants, by
application,
has been
segmented into
herbicides,
fungicides,
insecticides.
Agricultural
surfactants
are almost
always
present in
herbicide
treatment
solutions.
Their aim is to
improve spray
droplet
retention and
penetration of
active
ingredients into
plant foliage.
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10. Effect of surfactants on plants
i. Surfactant used for
clean-up of contaminated
soil.
ii. Surfactants are known
to possess powerful
bactericidal properties and
are capable to modify the
physical and chemical
properties of the soils.
iii. They solubilize
nonpolar plant substances
such as the lipoid part of
the cell wall
i. Agricultural surfactants
help fertilizers, pesticides,
and soil conditioners
spread through the soil
matrix, sorb to soil, or
adhere to plant leaves
ii. They lower the
interfacial tension between
air-water and soil-water
surfaces.
iii. Surfactants can help
some surfaces wet more
easily
i. Surfactants either
increase or decrease
aggregate stability in soils,
depending on soil
composition.
ii. Applying surfactants in
water-repellent soil
increase irrigation
efficiency.
iii. Block polymers are a
class of nonionic
surfactants specially
formulated to enhance the
surfactant’s sorption to soil
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11. Surfactants used in agrochemical formulations
Agrochemical
formulations require
surfactant, which is
essential for enhancing
biological performance of
the agrochemical,
increasing the foliar
uptake of herbicides,
growth promoters.
Around
230,000 tonnes
of surfactants is
used annually
in
agrochemical
products.
Surfactant softens
the crystalline
waxes in cuticle and
thus increases the
mobility of the
agrochemicals
across the cuticle
membrane.
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12. Applications of biosurfactants in agriculture
Biosurfactants
are low
molecular weight
surface-active
compounds
widely produced
by bacteria, yeast
and fungi.
They can be
reused through
regeneration too
as compared to
synthetic
surfactants,
hence
commercially
exploited.
Biosurfactants are
derived from
renewable resources
and are low or
nontoxic,
biodegradable,
demonstrate
excellent surface
activity, possess high
specificity, show
effectiveness under
extreme conditions.
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13. These biosurfactants
can be widely used in
areas related to
agriculture for
enhancement of
biodegradation of
pollutants to improve
the quality of
agriculture soil.
These
biosurfactants
can replace the
harsh surfactant
presently used
in pesticide
industries.
These natural
surfactants are
found to be
utilized as carbon
source by soil
inhabiting
microbes
Biosurfactants
can be effectively
used for removal
of hydrocarbons
as well as heavy
metals.
Several
biosurfactants
have
antimicrobial
activity against
plant
pathogens.
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15. Conclusion
Biosurfactant costs, their
efficacies in the field and
purity of compounds have
to be improved to allow
their use at a higher
degree in crop protection.
In this respect,
combination of
biosurfactants should be
considered to increase
efficacy in field
conditions.
Finally, given their
interesting properties it
is now time to really
consider eco-friendly
biosurfactants as
biocontrol solutions in
integrated pest
management.
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16. References
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Doerr, S. H., & Thomas, A. D. (2000). The role of soil moisture in controlling water
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