28-12-2012, 03:15 PM
BENEFICIAL AND EFFECTIVE MICROORGANISMS for a SUSTAINABLE AGRICULTURE AND ENVIRONMENT
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INTRODUCTION
The uniqueness of microorganisms
and their often unpredictable nature and
biosynthetic capabilities, given a specific
set of environmental and cultural conditions,
has made them likely candidates
for solving particularly difficult problems
in the life sciences and other fields as
well. The various ways in which microorganisms
have been used over the past
50 years to advance medical technology,
human and animal health, food processing,
food safety and quality, genetic engineering,
environmental protection, agricultural
biotechnology, and more effective
treatment of agricultural and municipal
wastes provide a most impressive record
of achievement. Many of these technological
advances would not have been
possible using straightforward chemical
and physical engineering methods, or if
they were, they would not have been
practically or economically feasible.
Nevertheless, while microbial technologies
have been applied to various agricultural
and environmental problems
with considerable success in recent years,
they have not been widely accepted by
the scientific community because it is often
difficult to consistently reproduce
their beneficial effects. Microorganisms
are effective only when they are presented
with suitable and optimum conditions
for metabolizing their substrates including
available water, oxygen (depending
on whether the micro-organisms are obligate
aerobes or facultative anaerobes), pH
and temperature of their environment.
Meanwhile, the various types of microbial
cultures and inoculants available in
the market today have increased rapidly
because of these new technologies. Significant
achievements are being made in
systems where technical guidance is coordinated
with the marketing of microbial
products. Since microorganisms are
useful in eliminating problems associated
with the use of chemical fertilizers and
pesticides, they are now widely applied
in nature farming and organic agriculture
(Higa, 1991; Parr et al.,1994).
Preservation of Natural Resources and
the Environment
The excessive erosion of topsoil from
farmland caused by intensive tillage and
row-crop production has caused extensive
soil degradation and also contributed to
the pollution of both surface waters and
groundwater. Organic wastes from animal
production, agricultural and marine processing
industries, and municipal wastes
(e.g., sewage and garbage), have become
major sources of environmental pollution
in both developed and developing countries.
Furthermore, the production of
methane from paddy fields and ruminant
animals and of carbon dioxide from the
burning of fossil fuels, land clearing and
organic matter decomposition have been
linked to global warming as "greenhouse
gases" (Parr and Hornick, 1992b).
Chemical-based, conventional systems
of agricultural production have created
many sources of pollution that, either
directly or indirectly, can contribute to
degradation of the environment and destruction
of our natural resource base. This
situation would change significantly if
these pollutants could be utilized in agricultural
production as sources of energy.
Beneficial Microorganisms
for Soil Quality and a More Sustainable
Agriculture. As will be discussed
later, crop growth and development
are closely related to the nature of
the soil microflora, especially those in
close proximity to plant roots, i.e., the
rhizosphere. Thus, it will be difficult to
overcome the limitations of conventional
agricultural technologies without controlling
soil microorganisms. This particular
tenet is further reinforced because the
evolution of most forms of life on earth
and their environments are sustained by
microorganisms. Most biological activities
are influenced by the state of these
invisible, minuscule units of life. Therefore,
to significantly increase food production,
it is essential to develop crop
cultivars with improved genetic capabilities
(i.e., greater yield potential, disease
resistance, and nutritional quality) and
with a higher level of environmental.