Beginner Topic 652 of 1102 Inorganic Chemistry
Fertilizers
NPK fertilizers supply nitrogen, phosphorus and potassium for plant growth.
In-depth explanation of Fertilizers
Plants need large amounts of nitrogen, phosphorus and potassium, the three macronutrients, and fertilizers supply them in various forms. Nitrogen comes as ammonia, ammonium nitrate or urea, phosphorus as calcium phosphates, and potassium as potassium chloride or sulfate. Fertilizer labels give an NPK ratio of the percentages by mass of nitrogen, P2O5 and K2O. Nitrogen fertilizer depends on the Haber-Bosch process, which uses an estimated 1 to 2 percent of world energy. Excess fertilizer runoff causes eutrophication, in which algal blooms deplete the oxygen that aquatic life needs.
Going deeper: Fertilizers
Key ideas: Primary nutrients are N, P, K, shown as NPK grade. Urea contains 46 percent N, ammonium nitrate 35, ammonium sulfate 21, superphosphate Ca(H2PO4)2 provides P, and potash KCl provides K. Urea is made from NH3 + CO2 giving NH2CONH2 + H2O. Calculate nutrient percent by mass as mass of element divided by molar mass times 100. P is reported as P2O5 and K as K2O equivalent.
Common mistakes and connections: Students compare fertilizers by compound mass instead of nutrient content. Excess N causes runoff, eutrophication, and algal blooms that deplete oxygen. Ammonium fertilizers acidify soil over time. Nitrate leaches more readily than ammonium, because soil particles hold positive ions. Links to Haber process, phosphoric acid and solubility.
Visualization of Fertilizers
A 10-10-10 fertilizer: 10 percent each of N, P2O5 and K2O by mass, with the remainder as filler and other components. The interactive lesson shows this as a live animation or chart.
Worked example and use case
A bag labelled 10-10-10 contains 10 percent each of nitrogen, phosphorus and potassium compounds by mass.
Frequently asked questions about Fertilizers
What is Fertilizers?
NPK fertilizers supply nitrogen, phosphorus and potassium for plant growth.
Is Fertilizers a beginner, intermediate or advanced topic?
Fertilizers is a beginner topic in Inorganic Chemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Fertilizers?
Study these earlier topics in Inorganic Chemistry first: Nitric Acid, Phosphorus Allotropes, Phosphoric Acid.
What comes after Fertilizers?
The next topics in Inorganic Chemistry are Oxygen Family and Ozone.
Can I practise Fertilizers with quizzes?
Yes. The interactive lesson includes a self-check question on Fertilizers, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Fertilizers fits in Inorganic Chemistry
Fertilizers is topic 37 of 113 in Inorganic Chemistry.