Nayana

ROLE OF MICROBIAL
COMMUNITIES IN SOIL
HEALTH AND AGRICULTURE
Submitted by : Nayana R
Register No : 23371028
INTRODUCTION
The role of microbial communities in soil health and
agriculture is multifaceted. Microorganisms contribute to
nutrient cycling, disease suppression, and soil structure. They
enhance plant growth by facilitating nutrient availability and
promoting root development. Additionally, microbial diversity
influences soil resilience and overall ecosystem stability,
making it a crucial aspect for sustainable agriculture practices.
Soil provides the medium for root development, and with the
exception of carbon, hydrogen, oxygen and some nitrogen,
plants depend on soil for all other nutrients and water. Soils
develop by the disintegration of rocks, and minerals therein,
through biotic actions of the microbes and the fauna
sustained by them. Earlier, only the physical and chemical
properties of soil were considered important. However, the
role of soil biodiversity in maintaining fertility, and the
interdependence of soil biological activities with physical and
chemical characteristics is well recognized now (Abbott and
Murphy 2003; Fitter 2005; Suzuki et al. 2005; Madsen 2005;
Manlay et al. 2007). Physical properties and the amount of soil
organic matter (SOM) determine the microbial diversity that
varies with depth, and soil health.
SOM adds to soil fertility, water retention and has a great influence on
the growth of the above ground vegetation. Biological indicators such as
microbial biomass, soil respiration, enzyme activities and microbial
diversity indicate soil health. Significance of soil biodiversity for
sustainability of the farming systems has been discussed at length
(Brassard et al. 2007). Microbial diversity is an excellent indicator of soil
health (Nielsen and Winding 2002). They report that variation in
microbial population or activities precede changes that can be noticed in
some cases as early signs of soil degradation or amelioration. Water and
nutrient supply from soil, particularly N and P, determine the plant
growth both in natural and agro-ecosystems. The above ground
vegetation is the ultimate source of C for the microbes in the rhizosphere
that, in turn, support the macro-fauna. Thus, the above ground
vegetation influences the below ground microbial community structure
and soil properties (Orwin and Wardale 2005).
One primary function of microbial communities is nutrient
cycling. Bacteria and fungi decompose organic matter,
breaking down complex compounds into simpler forms that
plants can absorb. This process releases essential nutrients,
such as nitrogen, phosphorus, and potassium, back into the
soil, promoting plant growth. Additionally, certain microbes
form symbiotic relationships with plant roots, enhancing
nutrient uptake and facilitating the conversion of atmospheric
nitrogen into a usable form.
Microorganisms also contribute to soil structure. Fungal
hyphae, for example, form networks that stabilize soil
aggregates, improving water infiltration, aeration, and root
penetration. This enhances the overall physical properties of
the soil, crucial for plant development and resistance to
erosion. Moreover, microbial communities play a pivotal role
in disease suppression. Certain bacteria and fungi act as
biocontrol agents, suppressing harmful pathogens and
protecting crops from diseases. This natural defense
mechanism can reduce the need for chemical pesticides,
promoting sustainable and environmentally friendly
agricultural practices.
In agriculture, the concept of the
"soil microbiome" is gaining
attention. This refers to the diverse
and dynamic community of
microorganisms present in the soil.
Farmers are increasingly recognizing
the importance of fostering a healthy
soil microbiome to optimize crop
productivity. Practices such as cover
cropping, crop rotation, and reduced
tillage can positively impact microbial
diversity and activity.
• Mycorrhizal Associations:
• Arbuscular Mycorrhizae (AM):
Fungi form symbiotic
relationships with the roots of
most plants, aiding in nutrient
absorption, especially
phosphorus.
• Ectomycorrhizae (ECM):
Common in trees, these fungi
create a sheath around root tips,
enhancing nutrient exchange.
Organic matter is mainly present in the top 20–30 cm of most soil profiles
and is essentially an array of organic macromolecules consisting principally
of combinations of carbon, oxygen, hydrogen, nitrogen, phosphorus and
sulphur. Soil organic matter is commonly measured as the quantity of
organic carbon. The global pool of organic carbon in soil to a depth of 1 m
has been estimated at 1,200–1,550 Pg (2 m: 2,370–2,450 Pg), and as such
is significantly greater than either the biological-biota (560 Pg) or
atmospheric (760 Pg) carbon pools (Baldock 2007). Almost all organic
matter in soil is directly and indirectly derived from plants via
photosynthesis. Thus atmospheric carbon dioxide is transformed by
reduction into simple and complex organic carbon compounds, which in
combination with key nutrients enable the plant to function and grow.
Carbon dioxide is released directly from plants by respiration, but most of
the fixed carbon is retained and ultimately transferred to the soil ecosystem
via a combination of spatially distinct pathways over a variety of timescales.
The most important pathways are the direct addition of senes-cent material
as above-ground and below-ground detritus, return of ingested plant matter
in animal faeces, and exudation of soluble organic compounds from roots.
However, modern agricultural practices, including the use of
synthetic fertilizers and pesticides, can disrupt microbial
communities. Excessive use of chemical inputs may lead to
imbalances, negatively affecting soil health. Sustainable
agriculture aims to mitigate these impacts by promoting
practices that support microbial diversity and ecological
balance. In conclusion, the role of microbial communities in
soil health and agriculture is multifaceted. From nutrient
cycling to disease suppression and soil structure
improvement, these microscopic organisms are integral to
maintaining a resilient and productive agricultural system.
Embracing sustainable practices that nurture the soil
microbiome is essential for ensuring long-term food security
and environmental health.

Nayana

Uploaded by

Copyright:

Available Formats

Nayana

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Nayana

Uploaded by

Copyright:

Available Formats

ROLE OF MICROBIAL

You might also like