The Fertilizers Archives

1. Which one among the following fertilizers is a source of nitrogen ?

Which one among the following fertilizers is a source of nitrogen ?

Superphosphate

Potassium sulfate

Bone meal

Urea

This question was previously asked in

UPSC NDA-2 – 2024

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Urea, with the chemical formula (NH₂)₂CO, is a widely used nitrogenous fertilizer. It contains a high percentage of nitrogen by weight. When applied to soil, urea is hydrolyzed by enzymes to produce ammonia (NH₃), which is then converted to ammonium ions (NH₄⁺) and nitrate ions (NO₃⁻) that plants can absorb as sources of nitrogen. Superphosphate is a phosphorus fertilizer, potassium sulfate is a potassium fertilizer, and bone meal is primarily a source of phosphorus and calcium.

Plants require macronutrients like nitrogen (N), phosphorus (P), and potassium (K) for growth. Fertilizers provide these nutrients. Nitrogen fertilizers specifically supply nitrogen compounds to the soil.

Urea is an organic compound and is often considered the most important nitrogen fertilizer globally due to its high nitrogen content and ease of synthesis. Other common nitrogen fertilizers include ammonium nitrate (NH₄NO₃) and ammonium sulfate ((NH₄)₂SO₄).

2. Which one of the following is not used as fertilizer?

Which one of the following is not used as fertilizer?

Ammonium nitrate

Ammonium sulphide

Ammonium phosphate

Ammonium sulphate

This question was previously asked in

UPSC NDA-2 – 2018

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Fertilizers are substances used to provide essential nutrients to plants, primarily nitrogen (N), phosphorus (P), and potassium (K).
A) Ammonium nitrate (NH₄NO₃) is a common nitrogen fertilizer.
B) Ammonium sulphide ((NH₄)₂S) contains nitrogen and sulfur, but it is highly unstable and decomposes easily to ammonia and hydrogen sulfide gas. Due to its instability and potential toxicity (hydrogen sulfide), it is not used as a common agricultural fertilizer.
C) Ammonium phosphate (e.g., (NH₄)₂HPO₄ or NH₄H₂PO₄) are common fertilizers (like DAP and MAP) providing both nitrogen and phosphorus.
D) Ammonium sulphate ((NH₄)₂SO₄) is a common fertilizer providing nitrogen and sulfur.
Therefore, Ammonium sulphide is not used as a fertilizer.

Common fertilizers contain essential plant nutrients, primarily nitrogen, phosphorus, and potassium, often in the form of stable salts. Ammonium compounds are often used as sources of nitrogen, but their suitability as fertilizers depends on their stability and chemical properties in soil.

While ammonium sulphide contains nitrogen and sulfur, its instability makes it unsuitable for agricultural application. It is more relevant in laboratory chemistry or specific industrial processes rather than widespread use as a soil nutrient source.

3. Which one of the following statements about fertilizers is not

Which one of the following statements about fertilizers is not correct?

Urea is a phosphorus-containing fertilizer.

Application of fertilizer to the soil increases fertility of the soil.

Urea can be prepared by action of ammonia and carbon dioxide under high pressure and at high temperature.

Urea contains more nitrogen than other fertilizers.

This question was previously asked in

UPSC NDA-1 – 2022

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The correct answer is A) Urea is a phosphorus-containing fertilizer. This statement is incorrect because urea ((NH₂)₂CO) is a nitrogen-containing fertilizer.

– Fertilizers are substances that provide nutrients to plants, primarily nitrogen (N), phosphorus (P), and potassium (K), which are macronutrients.
– Urea has the chemical formula (NH₂)₂CO. It is a rich source of nitrogen, with approximately 46% nitrogen by weight.
– Phosphorus-containing fertilizers typically contain compounds like phosphates (e.g., calcium phosphate in superphosphate).
– Statement B is correct: Fertilizers add essential nutrients to the soil, thus increasing its fertility and supporting plant growth.
– Statement C is correct: Urea is synthesized industrially from ammonia (NH₃) and carbon dioxide (CO₂) under high pressure and temperature (Bosch–Meiser process).
– Statement D is generally correct in the context of solid nitrogen fertilizers; urea has one of the highest nitrogen contents among commonly used solid fertilizers.

Fertilizers can be organic (derived from plant/animal matter) or inorganic (synthetically produced or mined). Urea is an organic compound but is typically synthesized industrially and used as an inorganic fertilizer in agriculture. Different plants require different ratios of N, P, and K, and various fertilizers are available to meet these needs.