Phosphorus Deficiency. Image credit

Phosphorus Deficiency. Image credit

ZIMSEC O Level Notes Combined Science: Mineral Nutrition Experiment

Aim: Investigating the effects of mineral elements on plant growth.


Young wheat or pea seedlings, test tubes, mineral solutions/culture solutions, cotton wool, foil or black paper, stands for test tubes.


  1. Set up each plant as above, the opaque/dark covering prevents growth. Pour the culture solution in a test tube filled with washed sand.
  2. Use five test tubes one contains the first culture solution contains all the minerals (phosphorus, nitrogen and potassium) necessary for healthy plant growth. The other test tubes have two minerals except one of each. For example the second test tube could have potassium and phosphorus but no nitrogen and so on. The last test tube should have only distilled water.
  3. Observe the seedlings over a period of several weeks.
  4. Examine the seedlings on a daily basis and take note of the following:
  5. the root length of the plants, the length of the plant shoots, the colour of the leaves and the number of leaves.
  6. Make sure that the seedlings have enough solution by constantly adding distilled water whenever necessary, do not use tap water as it contains the minerals naturally.


Results of the experiment. Image credit

Results of the experiment. Image credit

  • During the first weeks the seedlings in all the culture experiments will appear healthy.
  • This is because they have all the minerals necessary for growth stored inside their seeds.
  • After these have been used up the effects of each mineral deficiency begins to show up.
  • The second test tube has no Nitrogen and the seedlings will appear stunted and have yellowish leaves.
  • In¬†test tube without Phosphorus (the one labelled -P above) the plants will have stunted roots and the seedlings will have purple leaves.
  • In the test tube without Potassium (the one labelled -Mg above) the seedlings will have yellow leaves/brown leaves margins.
  • There will be very little growth in the plant with distilled water.


  • Plants require mineral elements in order to have healthy growth.
  • These minerals include Potassium, Nitrogen and Phosphorus.

To access more topics go to the Combined Science Notes page.