What is the use of biochar in farming? 1) Biochar can be used as a part of the growing medium in vertical farming. 2) When biochar is a part of the growing medium, it promotes the growth of nitrogen-fixing microorganisms. 3) 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 ?

The correct answer is D. All three statements are true, and the question tests whether you understand biochar as a soil amendment rather than a fertiliser.

Biochar is produced by pyrolysis, which means heating biomass such as crop residue or wood in low-oxygen conditions. The result is a porous, carbon-rich material with a large surface area.

• Statement 1 is correct. Biochar is used as a component of soilless growing media, including in vertical farming systems, where it helps hold nutrients and moisture in a limited volume.
• Statement 2 is correct. Its pores act as a habitat for beneficial microbes, and studies show that biochar can increase populations of nitrogen-fixing bacteria.
• Statement 3 is correct. The porous structure increases water-holding capacity, so the medium stays moist for longer between irrigations.

The core concept is soil amendment through improved physical and biological properties. For Mains, link this to soil health, carbon sequestration and the use of crop residue under the circular economy, which also ties into the push on stubble management.

Trap: Many aspirants assume biochar works as a fertiliser because it is added to soil. It supplies few nutrients itself; its value lies in improving the growing medium.