Magnesium ions and nitrate ions are needed by plants. A plant will not grow well if it cannot get enough of these ions, and it will show symptoms of mineral deficiency.
|Mineral ion||Needed for||Effects of deficiency|
|Magnesium||Making chlorophyll||Leaves turn yellow|
|Nitrate||Making amino acids||Stunted growth|
Fertilisers are used to replace minerals used by plants.
Nitrogen fertilisers - such as ammonium nitrate and ammonium phosphate - provide plants with water-soluble sources of nitrogen that they can absorb through their roots. They allow farmers to increase the yield and quality of their crops.
However, overuse can cause problems. Eutrophication happens when excess nitrate (or phosphate) enters rivers or lakes from fields. This can lead to the death of fish and other aquatic animals.