No soil necessary?
It sounds odd, but remember that plants need just three things to survive: nutrients, water, and sunlight. The only thing soil offers is nutrients. In order for hydroponics to work, nutrients are delivered in solutions with water, and sunlight can be substituted with special lamps.
So if soil is unnecessary, why isn’t hydroponic gardening more popular? Though it has its advantages, there are some complications.
- Plants can be grown anywhere.
- Sterile (most pests and diseases are carried in soil).
- The water is reusable (saves 20 times more water than soil based gardening).
- No need to set up and test soil.
- Smaller root systems (since the roots dip directly into the nutrients, they do not need to grow long).
- Plant energy diverts into leaf and stem growth, producing a higher yield.
- Less time needed for growth.
- Seasonal plants can be grown year round.
- Computers can automate parts of the gardening.
- Space efficient.
- Easier to harvest.
- High cost.
- Planting systems are high maintenance.
- Constant supervision (computers can aid).
- Vulnerable to power outages (generators can help).
- Bacteria can grow in the water.
- If the water is tainted/one plant gets diseased, all plants are affected.
- Plants can die rapidly.
- Much more complicated than soil based gardening (some may be nutrient heavy, give off compounds that can be harmful to other plants, grow larger leaves to take in more light, etc.).
Methods of growth
Nutrient Film Technique
Plants are put into holes with nutrient enriched water passing through the roots. Pumps are used to pump the water at the bottom back to the top where the water runs back down across the chutes. This can be done with pipes, as seen above, or plastic trays. The plants can be held in place with styrofoam.
An aquarium style air pump is used to pump oxygen into the nutrient solution, reaching the roots. The plants themselves are suspended above the water, allowing some space for the roots to grow down into the solution. A styrofoam board or tray is used to hold the plants. There would be a lip hanging over the edge of the solution container. In the tray, a layer of material such as gravel, clay pebbles, or vermiculite would hold the plants steadily in place.
Flood and Drain/Ebb and Flow Method
Plants are suspended over the water so the roots can grow into the nutrient water solution. A pump fills the tray with water until the roots are flooded. The pump shuts off until the water drains, allowing the roots to be submerged for a certain period of time. Once it finishes draining, the pump will flood the roots again, repeating the process over and over again.
This is the hydroponic version of drip irrigation. A pump pushes water through a tube with small holes in it, dripping water into each plant’s container. If there’s any extra water, it will drip into the tray, return to the reservoir tank, and be reused.
Nylon wicks are extended from the trays by the roots of the plants to the bottom of the reservoir. Water rises from the reservoir through the wicks and into the trays. The water enriches the roots and excess water will drip into the plant tray. An air stone can be used for further oxygen enrichment, but is not necessary.
Hydroponics focuses on water, while aeroponics, though a type of hydroponics, uses air. Plants are stuck into boards, with the boards left open so the roots can hang freely. Instead of being suspended into a liquid solution, it is suspended in a nutrient enriched mist. This can allow plants to more easily be packed together. Another advantage of aeroponics is that it uses much less water. Even the water that isn’t used by the roots will be reused.