State what is meant by the term Hydroponics
The growing of plants in water with no soil or other media.
Explain the role of aeration
The substrate will provide air or the solution is aerated
Explain the role of nutrient supply and nutrient levels
Exact levels of appropriate nutrients can be applied in a solution. They can be monitored and re-circulated
Explain the role of pH control
Adjustments to the nutirent solution can be made by adding chemiclas so that a constant pH can be maintained.
In large scale hydroponics there will a constant monitoring of the solution for nutritent levels, toxins and the pH
Explain the role of water supply and quality
- plants are never water stressed
- water loss is greatly reduced: evaporation is minimised and draingage is controlled
- origin of water is important in terms of chemical content and pathogens and purified water may be necessary
Explain the role of pest and disease control
- as most are carried out indoors lends itself to biological controls
- plants are isolated from natural balancing systems e.g. soil
- focus is on avoiding any contamination in the first place
Explain the role of automation
- a mjor feature of hydroponics is the reduction in labour through automation
- once set up all watering and feeding is automatic though other operations will still be manual e.g. crop support, pruning and harvesting
- housplants in hydroponic systems require littel maintenance
State the situation in which water culture can be used
Green Walls:
- hydroponic or trickle/drip irrigation system
- To make use of available space in urban situations and to improve the appearance of walls.
- A watering system capable of delivering a nutrients solution would be fitted at the same time
Vegetable Production:
- Glasshouse crop production (NFT, Substrate Culture)
e. g. tomatoes, salad leaves
Interior Landscaping:
- Houseplants. Self watering systems
Describe NFT
Nutrient Film Technique
- crops are supported by clips in a closed system
- the plants are initially raised in an erect permeable material like rockwool
- set on a gradual, even slope made up of flexible plastic tubes with a shallow film of water (1inch deep)
- solution moves by gravity slowly down past and between the roots allowing them to take up the required nutrients from the controlled solution
- the solution then returns to a collection tank for testing and subsequent re-use on the same crop
- the use of both water volume and amount of nutrients is very efficient with minimum wastage and loss to evaporation
Describe Substrate Culture
Rockwool
- Rockwool is a granite like rock that has been crushed, melted and spun into fibres that can be made into slabs
- It holds water well and has good aeration
- plants can be raised in small cubes of it and set out in an NFT system or bolsters of rockwool can be wrapped in polythene and plants grown in it to maturity
- Nutrients in solution are applied as a drip feed and arranged to cross the root systems and drain out
Identify the environmental issues of growing plants in water culture
- energy required
- a lot of resources are used to set up: plastics, electrical equipment etc
- safe disposal of the nutrient solution: should be in a closed system and not allowed to drain into the soil under the crop causing groundwater contamination
- rockwool can be re-used for more than one crop
