Teacher Resource 5: Hydroponic Vs Soil

Teacher Resource 5

Hydroponic vs soil

Commercial growers are increasingly using hydroponics as it encourages quick growth and shelves of hydroponic plants can be grown one above the other enabling more plants to be grown in a particular space.

The concept of hydroponics is likely to be relatively new to learners, who will often take for granted that plants grow in soil.

This practical activity will highlight how plants can grow without soil and will compare the growth of a plant grown in soil to the growth of a plant grown hydroponically.

Depending on budgets and available lab technician time, departments may buy a hydroponics system or make one. The following websites show examples of how they can be made:

A discussion with lab technicians within the department will be required to choose the best method for your department.

Teachers/technicians will want to grow plants that germinate relatively quickly such as lettuce or spinach and the easiest way to ensure they germinate so that every group has seedlings to measure the growth of is to sow a good quantity of seeds in compost 10 -12 days prior to the lesson. Learners can then take the seedlings, clean the soil from them and plant them in their containers of soil or hydroponic medium.

Learners work in groups of four to plant a seedling in a pot containing compost and a hydroponics pot containing water and liquid fertiliser (it is important to use the instructions on the side of the fertiliser bottle to mix the correct amount of fertiliser and water. Lab technicians may want to do this prior to the lesson and put into large bottles for the learners to use).

Discuss with learners the method, how they will keep the test fair e.g. how often to water the plants, keeping them at similar temperatures and light intensities etc. as well as how often to take measurements and how they will measure growth, such as height of plant, number of leaves, mass of plant at the end of the test.

Groups could decide on their own parameters or decide as a class what will be measured and teachers could make a spreadsheet for groups to add their data, increasing repetition and therefore reliability.

The length of time to take measurements may vary depending on the type of plants and conditions, but learners should get a good set of results over a 4-6 week period, so planning ahead and setting up the experiment at the beginning of a half term would be worth doing.

To stretch learners’ teachers may want to ask learners to compare fertilisers with different nutrients in, or compare different brands of general purpose fertiliser to see if that has an effect on plant growth.