Soil is one of the most important constituent of Agriculture. Plants
derive almost all nutrients from soil and so its purpose serves beyond
the fact that it’s the substrate on which the plant grows. The soil
types vary from region to region and so do the type of plants that grow
on them. All types of soil are made up of two basic components which are
biotic and abiotic. It’s the continuous nutrient cycle that takes
place at the biotic-abiotic interface that plays a crucial role in plant
growth and sustainable agriculture. There are tremendous amounts of
biochemical reactions occurring in what seems like a lifeless soil.
Increased use of fertilizer has increased the cost of production and
decreased the soil quality. In order to better understand basic needs of
the plants, it is important to go to the root cause, literally.
Soil ecosystem is a complex interaction of biochemical process between
the soil biota. These biological processes have both direct and indirect
impact on plant growth. Soil microorganisms that are present in the
rhizosphere of the roots of plants are constantly interacting with the
plants for transportation, mobilization and solubilization of
nutrients. These soil bacteria that aid plant growth are referred to as
Plant Growth Promoting Rhizobacteria (PGPR). PGPR can further be
classified into symbiotic bacteria also referred to as iPGPR
(intercellular/internal PGPR) that live inside the plant root cells and
free living rhizobacteria also referred to as ePGPR
(extracellular/external PGPR) that live outside the plant root cell.
The most studied and effective iPGPR is the Rhizobia which is
symbiotically associated with the leguminous plants and helps in the
formation of root nodules and Nitrogen fixation. Rhizobium species such as Allorhizobium, Mesorhizobium, Azorrhizobium and Sinorhizobium been found to have significant impact on plant growth. On the other hand free living bacteria such as Azatobacter, Azospirillum, Bacillus and Klebsiella species have also proven to enhance plant growth by Nitrogen fixation
The soil health is without doubt vital for good
yield of plant. The right balance of biotic and abiotic constituents in
the soil can lead a way to sustainable and optimal agriculture. The
following conclusions can be drawn from the studies reflected in this
article.
- Presence of good amount of organic and inorganic matter is essential to support nutrient cycle.
- Soil biota help plant growth by supporting nutrient uptake, providing disease resistance and holding up soil structure
- The presence of a healthy population of soil biota reduces the need for external inputs for soil growth
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