Fertilisers and Their Consequences

Lab Brief #5

🎯 Your mission

Set it up. Test it. Be amazed.

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

Ammonia from the Haber process makes nitrogen fertilisers that feed roughly half the world's population. But run-off carries nitrates into rivers, where algae bloom, die and are decomposed by bacteria that strip oxygen from the water — eutrophication.

Key words

eutrophication
Oxygen depletion in water caused by nutrient run-off feeding algal blooms.
NPK fertiliser
A fertiliser supplying nitrogen, phosphorus and potassium.

Make a hypothesis first

Before you start: write down what you think will happen, and why.

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

three jars with lids
pond water
plant fertiliser
labels
camera

Get ready

⚠️ Safety first

Keep jars sealed and labelled; never smell them directly or drink the contents.
Wash hands after handling pond water, which can carry harmful bacteria.

Step 1 of 4 · Read

Think about what you just learned: say what "eutrophication" and "NPK fertiliser" mean in your own words before you start.

Step 2 of 4 · Do

Set up three jars of pond water with none, a little and a lot of dissolved fertiliser. Leave them in light for two weeks, photographing weekly, and record clarity and any smell without opening them near your face.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

Eutrophication reduces oxygen in water because decomposing bacteria:

How sure are you?😐 maybe

Question 2 of 2

The N in an NPK fertiliser stands for:

How sure are you?😐 maybe

Mind = blown

🔬 The more you look, the more nature shows you.

Nice work!

You got 0 of 2 right.

All lessons

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✨ More to explore

🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.

👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

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Fertilisers and Their Consequences

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