Aeroponics – SS3 Horticulture and Crop Production Lesson Note (First Term)

Aeroponics is a method of growing plants without soil, in which the roots hang in the air inside a closed box or tower and are sprayed with a fine mist of nutrient solution.

Behavioural objectives

1. Define aeroponics.
2. Name the main parts of an aeroponic system.
3. Explain how an aeroponic system works.
4. Distinguish between high-pressure and low-pressure aeroponics.
5. State the advantages of aeroponics.
6. State the risks of aeroponics.

What is aeroponics?

Aeroponics is a soilless growing method in which plant roots hang in air and receive water and nutrients as a mist.

• No soil: the plant is held in a hole in the lid of a box or in a tower.
• No pool of water: the roots do not soak in water as they do in hydroponics.
• Misted food: a nutrient solution (water with dissolved plant nutrients) is sprayed onto the hanging roots.
• Leaves in the light: the stems and leaves grow above the box.

How is aeroponics different from hydroponics?

Hydroponics grows plants with their roots in a nutrient solution. Aeroponics grows plants with their roots in air and sprays them with mist.

What are the main parts of an aeroponic system?

An aeroponic system has five main parts: a chamber, a reservoir, a pump, misters and a timer.

• Growing chamber: a closed, dark box or tower in which the roots hang.
• Reservoir: a tank that holds the nutrient solution.
• Pump: pushes the nutrient solution through pipes to the nozzles.
• Misters: nozzles that break the liquid into tiny droplets.
• Timer: switches the pump on and off at set times.

How does aeroponics work?

In aeroponics, a timer switches on a pump that sends nutrient solution through misters, which spray the roots hanging in the dark chamber.

1. The plant is placed in a hole in the lid, with its leaves above and its roots inside the chamber.
2. The timer switches the pump on every few minutes.
3. The pump forces nutrient solution from the reservoir to the misters.
4. The misters turn the liquid into tiny droplets, like the spray from a spray bottle.
5. The roots are covered in mist and take in water and nutrients.
6. The pump switches off and the roots hang in moist air with plenty of oxygen.
7. Extra solution drips back into the reservoir to be used again.

What are the types of aeroponics?

There are two main types of aeroponics: high-pressure aeroponics (HPA) and low-pressure aeroponics (LPA).

High-pressure aeroponics (HPA)

• Pump: a powerful pump that forces the solution through very fine nozzles.
• Droplets: very small, almost like fog, so roots absorb them easily.
• Use: mainly commercial and professional farms.
• Cost: needs specialised and more expensive equipment.

Low-pressure aeroponics (LPA)

• Pump: an ordinary, cheaper pump.
• Droplets: larger, more like rain than fog.
• Use: hobby growers and small farms.
• Cost: simpler and cheaper to set up.

How do HPA and LPA compare?

What are the advantages of aeroponics?

The advantages of aeroponics are fast growth, low water use, no need for land, healthier plants and easy harvesting.

• Fast growth: roots get plenty of oxygen and regular nutrients, so plants often grow faster than in soil.
• Saves water: the mist is used efficiently and extra solution is recycled, so very little water is wasted.
• No land needed: systems can be set up in a shipping container, a garage or a tall building, which suits cities.
• Fewer soil problems: the clean, closed chamber lowers the risk of soil-borne diseases and root rot.
• Easy harvesting: root and tuber crops such as potatoes can be picked clean without digging.

What are the risks of aeroponics?

The risks of aeroponics are quick root drying, blocked nozzles, constant monitoring and the cost of equipment.

• Power failure: roots hang in air, so they dry out and die quickly if the pump stops. This is a serious problem where electricity supply is unreliable.
• Blocked nozzles: small mineral particles can clog the misters, so the roots receive no mist and the crop can be lost.
• Constant monitoring: the farmer must check the nutrient level of the solution regularly.
• Technical skill: the farmer must know how to clean, repair and set up the equipment.
• Set-up cost: pumps, timers, misters and chambers cost money, especially for HPA.

Evaluation

1. Define aeroponics.
2. Describe how the pump, timer and misters work together to feed the plant.
3. State two differences between high-pressure and low-pressure aeroponics.
4. Why do the roots in an aeroponic system die quickly if the power fails?

Assignment

State any three advantages and two risks of aeroponics. Explain each point in one or two sentences.