Previous Year Question
What is the use of biochar in farming?
Biochar can be used as a part of the growing medium in vertical farming.
When biochar is a part of the growing medium, it promotes the growth of nitrogen-fixing microorganisms.
When biochar is a part of the growing medium, it enables the growing medium to retain water for longer time.
Which of the statements given above is/are correct?
1 and 2
Only 2
1 and 3
1, 2 and 3
Correct Answer: D
Detailed Solution
Biochar is a stable, carbon-rich and charcoal-like substance.
It is produced by heating wood, crop residues and other biomass under a limited supply of oxygen.
This thermochemical process is called pyrolysis.
Biochar is lightweight and porous and can therefore be used as a component of soil or another growing medium in vertical farming. Hence, Statement 1 is correct.
Its use may improve aeration, structure and root development in the growing medium.
The porous surface of biochar provides microhabitats for beneficial microorganisms to live and grow.
Under suitable conditions, it may promote the activity and growth of nitrogen-fixing microorganisms. Therefore, Statement 2 is correct.
Its effects depend upon the biochar feedstock, production temperature, soil properties and crop type.
The micropores of biochar can absorb and retain water.
Therefore, adding it to a growing medium may increase water-holding capacity and keep water available for a longer period. Hence, Statement 3 is correct.
Biochar may increase the cation-exchange capacity of soil and reduce the leaching of certain nutrients.
It may also help improve the pH of acidic soils and increase the efficiency of fertilizer use.
Its stable carbon can remain in soil for long periods and may therefore contribute to carbon sequestration.
Biochar is not a complete fertilizer under every circumstance, and its inappropriate or excessive use may cause harm instead of benefit.
Safe use requires examination of the biochar feedstock, potential contaminants and the required application rate.