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:

[UPSC Civil Services Exam – 2013 Prelims]

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: (c)        

Explanation:

• Burning coal can produce nitrogen oxides as flue gases, which can contribute to atmospheric pollution. However, unless these oxides enter the nitrogen cycle, they do not add nitrogen to the soil. After coal is burned, what remains is Fly Ash, which lacks nitrogen content. Therefore, statement 2 is incorrect.
• 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. Hence statements 1 and 3 are correct.