Fertilisers and Agriculture
Plants need nitrogen, phosphorus and potassium.
About this topic
Plants need nutrients, mainly nitrogen (N), phosphorus (P) and potassium (K), which are the three numbers on fertiliser labels, the NPK ratio. Nitrogen builds proteins and chlorophyll, phosphorus helps roots and energy transfer, and potassium aids water balance and disease resistance. Fertilisers replace nutrients removed by harvested crops.
Common compounds include ammonium nitrate (about 35 percent N), urea (46 percent), ammonium sulfate, superphosphate made by treating phosphate rock with sulfuric acid, and potassium chloride. Ammonia, made by the Haber process, is the starting point for most nitrogen fertilisers. Soil pH matters because it affects nutrient availability, so farmers add lime to raise pH. Manure and compost release nutrients more slowly and improve soil structure.
Fertilisers have increased food production enough to support billions of people. But excess nitrate and phosphate run off into rivers and lakes, causing eutrophication: algae grow rapidly, die and decompose, using up oxygen and killing fish. Nitrates in drinking water can harm babies. Better practice includes precise application, slow-release fertilisers, crop rotation with nitrogen-fixing legumes such as beans, and buffer strips.
A misconception is that plants feed on fertilisers as food; they make their own food by photosynthesis and use fertilisers as mineral nutrients. Another is that organic and synthetic fertilisers supply different chemicals; plants absorb the same ions.
Key ideas
- Haber process fixes nitrogen
- NPK labels
- Runoff causes algal blooms
Quick check
Use cases: where Fertilisers and Agriculture helps
- Homework: review the key idea behind Fertilisers and Agriculture before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Fertilisers and Agriculture without notes.
- Visual learning: play with the interactive lab to see how Fertilisers and Agriculture changes when you adjust its inputs.
- Teaching a friend: explain Fertilisers and Agriculture in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Fertilisers and Agriculture?
Plants need nitrogen, phosphorus and potassium.
What will I learn in Fertilisers and Agriculture?
Haber process fixes nitrogen. NPK labels. Runoff causes algal blooms.
Is Fertilisers and Agriculture part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Fertilisers and Agriculture lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Fertilisers and Agriculture?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.