NDA Chemistry · Industrial and Applied Chemistry

Fertilizers

The chemicals that supply the three plant nutrients — nitrogen (N), phosphorus (P) and potassium (K) — to soil, which nutrient each fertilizer carries, and how the common ones are manufactured.

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Why this matters

Five PYQs, all recall. The bank's favourite move is 'which is NOT a fertilizer' or 'which nutrient does urea supply?' — both answered by knowing the nutrient each fertilizer carries. Two reliable traps: urea is a NITROGEN fertilizer (not phosphorus), and ammonium sulphide is not a fertilizer at all.

Concept 1 of 2

Which nutrient each fertilizer supplies

Intuition

Every fertilizer supplies one or more of N, P and K. The bank asks which nutrient a named fertilizer carries, or which listed compound is NOT a fertilizer. Learn the nutrient column.

Definition

The nutrient each common fertilizer supplies:

Nitrogen (N) fertilizers: urea (CO(NH₂)₂), ammonium nitrate, ammonium sulphate, ammonium phosphate (also P), calcium ammonium nitrate.
Phosphorus (P) fertilizers: superphosphate of lime, ammonium phosphate (also N).
Potassium (K) fertilizers: potassium chloride (muriate of potash), potassium sulphate.
Ammonium sulphide ((NH₄)₂S) is NOT a fertilizer — it is a laboratory reagent.
Urea is the richest common nitrogen fertilizer (≈ 46% N), and supplies NO phosphorus.

Fertilizer	Nutrient supplied	Note
Urea	Nitrogen (N)	≈ 46% N — highest-N solid fertilizer Urea is a NITROGEN fertilizer, not a phosphorus one.
Ammonium nitrate	Nitrogen (N)	Common N fertilizer
Ammonium sulphate	Nitrogen (N)	Common N fertilizer
Superphosphate of lime	Phosphorus (P)	Made from rock phosphate + H₂SO₄
Muriate of potash (KCl)	Potassium (K)	Main K source
Ammonium sulphide ((NH₄)₂S)	None — not a fertilizer	A lab reagent Ammonium SULPHIDE is the odd one out — it is NOT used as a fertilizer (sulphate, nitrate and phosphate of ammonium all are).

Practice this conceptself-check · 4 quick reps

Try it yourself

A student says 'urea supplies phosphorus to the soil'. Is this correct? Which nutrient does urea actually supply?

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Which nutrient does urea supply?
2.
Which of ammonium nitrate, ammonium sulphide, ammonium phosphate, ammonium sulphate is NOT a fertilizer?
3.
Which nutrient does muriate of potash (KCl) supply?
4.
Is urea a phosphorus fertilizer?

From the bank · past-year question

Example 1Industrial and Applied ChemistryMODERATE

Which one of the following is

\textbf{\text{not}}

used as fertilizer?

[Q105 · Sep · 2018]

Urea = nitrogen, never phosphorus

'Urea is a phosphorus-containing fertilizer' is FALSE. Urea (CO(NH₂)₂) supplies nitrogen only. Phosphorus comes from superphosphate, not urea.

Ammonium sulphide is not a fertilizer

Ammonium nitrate, sulphate and phosphate are all fertilizers; ammonium SULPHIDE is not — it is an analytical reagent. The bank lists three real ammonium fertilizers plus the sulphide as the trap.

Drill 2 more on which nutrient each fertilizer supplies

Concept 2 of 2

How superphosphate and nitrolim are made

Intuition

A couple of fertilizers come with a 'how is it made?' question. Superphosphate is rock phosphate treated with sulphuric acid; nitrolim is calcium carbide heated with nitrogen. Learn the reaction in one line each.

Definition

The manufacturing facts the bank tests:

Superphosphate of lime is made by treating calcium phosphate (rock phosphate) with sulphuric acid — this converts insoluble phosphate into a soluble (plant-available) form.
Nitrolim (calcium cyanamide) is made by heating calcium carbide (CaC₂) with nitrogen: CaC₂ + N₂ → CaCN₂ + C. In soil it slowly decomposes to release ammonia.
Nitrolim supplies nitrogen only — it is inorganic and is NOT an NPK fertilizer.

Fertilizer	Made from	Key fact
Superphosphate of lime	Calcium phosphate + sulphuric acid	Makes phosphate soluble Superphosphate = rock phosphate (calcium phosphate) treated with H₂SO₄.
Nitrolim (calcium cyanamide)	Calcium carbide (CaC₂) + nitrogen	Decomposes to ammonia in soil Nitrolim supplies nitrogen only, is inorganic, and is NOT an NPK fertilizer.

Practice this concept4 quick reps

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Superphosphate of lime is made by reacting calcium phosphate with what?
2.
Nitrolim is prepared by heating calcium carbide with what?
3.
What does nitrolim decompose into in the soil?
4.
Is nitrolim an NPK fertilizer?

From the bank · past-year question

Example 2Industrial and Applied ChemistryMODERATE

Which statements are correct with regard to Nitrolim? I. Prepared by heating calcium carbide with nitrogen. II. Decomposes into ammonia in soil. III. It is an NPK fertilizer. IV. It is an organic fertilizer.

[Q84 · Apr · 2026]

Nitrolim is N-only and inorganic

Nitrolim (calcium cyanamide) supplies nitrogen ONLY — it is NOT an NPK fertilizer and NOT organic. The two correct statements about it are: made from calcium carbide + nitrogen, and decomposes to ammonia in soil.

Drill 1 more on how superphosphate and nitrolim are made

Summary — formulas & gotchas at a glance

A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.

Reference tables (2)

Which nutrient each fertilizer supplies6 rows

Fertilizer	Nutrient supplied	Note
Urea	Nitrogen (N)	≈ 46% N — highest-N solid fertilizer Urea is a NITROGEN fertilizer, not a phosphorus one.
Ammonium nitrate	Nitrogen (N)	Common N fertilizer
Ammonium sulphate	Nitrogen (N)	Common N fertilizer
Superphosphate of lime	Phosphorus (P)	Made from rock phosphate + H₂SO₄
Muriate of potash (KCl)	Potassium (K)	Main K source
Ammonium sulphide ((NH₄)₂S)	None — not a fertilizer	A lab reagent Ammonium SULPHIDE is the odd one out — it is NOT used as a fertilizer (sulphate, nitrate and phosphate of ammonium all are).

How superphosphate and nitrolim are made2 rows

Fertilizer	Made from	Key fact
Superphosphate of lime	Calcium phosphate + sulphuric acid	Makes phosphate soluble Superphosphate = rock phosphate (calcium phosphate) treated with H₂SO₄.
Nitrolim (calcium cyanamide)	Calcium carbide (CaC₂) + nitrogen	Decomposes to ammonia in soil Nitrolim supplies nitrogen only, is inorganic, and is NOT an NPK fertilizer.

Watch out for (3)

Urea = nitrogen, never phosphorus
→ Which nutrient each fertilizer supplies
Ammonium sulphide is not a fertilizer
→ Which nutrient each fertilizer supplies
Nitrolim is N-only and inorganic
→ How superphosphate and nitrolim are made

Mastery check — 3 interleaved questions

Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.

Example 1Industrial and Applied ChemistryEASY

Which one of the following statements about fertilizers is

\textbf{\text{not}}

correct?

[Q89 · Apr · 2022]

Example 2Industrial and Applied ChemistryEASY

Superphosphate of lime - a phosphate fertilizer - is obtained by the reaction of

[Q82 · Apr · 2026]

Example 3Industrial and Applied ChemistryEASY

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

[Q117 · Sep · 2024]

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