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A farmer can add nitrogen to soil using a natural (organic) fertiliser such as manure, or an artificial (inorganic) fertiliser such as ammonium nitrate.
| Feature | Natural fertiliser | Artificial fertiliser |
|---|---|---|
| Form of nitrogen | in organic molecules | soluble inorganic ions |
| Release of nitrate | slow | rapid |
| Cost of a given mass of nitrogen | lower | higher |
Using the table, explain why a natural fertiliser releases nitrate to the soil more slowly than an artificial fertiliser.
Suggest two advantages, other than cost, of using a natural fertiliser rather than an artificial fertiliser.