Q. Which of the following adds/add nitrogen to the soil?

1. Excretion of urea by animals
2. Burning of coal by man
3. Death of vegetation

Select the correct answer using the codes given below:

• 1 only
• 2 and 3 only
• 1 and 3 only
• 1, 2 and 3

Answer: (c) 1 and 3 only

Notes

• When coal is burnt, nitrogen helps to form oxides which may be released as flue gases and thereby pollute the atmosphere.
  • It does not add nitrogen to the soil unless the oxides so created enter into the nitrogen cycle.
  • Then, what remains after burning coal is Fly Ash.
  • Fly Ash is devoid of nitrogen content.
• Nitrogenous Waste products of Living organisms such as urea and uric acid and dead remains of organisms are converted back to inorganic ammonia by the bacteria.