Which of the following chemicals is used for soil sterilization?

Correct option is C

Soil sterilization is a critical practice to eliminate soil-borne pathogens, weed seeds, nematodes, and harmful microorganisms before planting crops, especially in nurseries and protected cultivation.
Key Points:
· Formalin (Formaldehyde solution):
· A widely used chemical for soil sterilization.
· Generally applied as a diluted solution (around 2–5%) and then covered with a plastic sheet for 24–48 hours.
· Action:
· Kills a wide range of fungi, bacteria, nematodes, and weed seeds.
· After treatment, soil must be aerated well to allow harmful vapors to dissipate before sowing.
· Precautions:
· Treated soil should be exposed to air for 2–3 weeks before sowing to prevent seedling injury.
Other Options Explained:
· (a) Sulphur:
· Used as a fungicide (dusting or spraying), not for soil sterilization.
· (b) 2,4-D:
· A selective herbicide used for weed control, not for sterilizing soil.
· (d) Alcohol:
· Used for surface sterilization (e.g., sterilizing instruments), not soil.