LO 3.8 - Growing media other than soil. Flashcards
Question
What are some types of growing media other than soil?
Growing media other than soil
Growing Media
* Peat
* Bark
* Coir
* Composted green waste
* Perlite
* Vermiculite
* Rockwool
* John Innes Composts
* Hydroponics
Growing media other than soil
Question
What are some properties of Peat?
Growing media other than soil
Peat
* Almost sterile, free from pests, disease and weeds.
* Contains almost no nutrients.
* Is light, clean and not unpleasant to handle.
Growing media other than soil
Question
How does Peat handle water?
Growing media other than soil
Peat
* Peat has a high water-holding capacity. it can lead to problems with overwatering and lack of air.
* Should not be allowed to dry out, they become hydrophobic and are difficult to re-wet.
Growing media other than soil
Question
How to use Peat in pots?
Growing media other than soil
Peat
* It is important not to compact the peat when filing pots – they are ‘loose-filled’ to maintain the air spaces.
Growing media other than soil
Question
Describe the use of Bark as a growing media?
Growing media other than soil
Bark
* Typically conifer bark. Normally the waste of fencing and timber.
* Chipped and matured in heaps.
* Often contains a certain amount of white wood.
* Needs to be well composted/screened.
Growing media other than soil
Question
What is Coir?
Growing media other than soil
Coir
* Coir is a product produced from the outer husks of coconuts. In use since Victorian times.
AFP ranges from 24 – 30% useful where waterlogging must be avoided.
Growing media other than soil
Question
What is a major disadvantage of using Coir?
Growing media other than soil
Coir Disadvantage
* The major disadvantage of coir is its inability to hold nutrients.
This can be overcome by adding clay minerals.
Growing media other than soil
Question
What are different types and grades of Coir?
Growing media other than soil
Coir types
* Available in different grades.
* Pith/dust is very fine, suitable for germinating seeds but can be poorly aerated. Good water holding.
* Coarser fibres or chips drain better and give better aeration.
* Also available in blocks or sheets.
Growing media other than soil
Question
List some properties of Composted green waste.
Growing media other than soil
Composted green waste
* Good source of potassium and micronutrients
* Good water holding
* Sustainable
* Variable source materials – quality control important
* May contain pathogens, herbicides
Growing media other than soil
Question
What is Perlite?
Growing media other than soil
Perlite
* Volcanic rock material, crushed and heat-treated, causing it to expand into highly porous white granules.
* Sieved into various grades for horticultural use. It improves aeration, moisture retention and drainage. Chemically inert.
* Normally added to mixes at 5-20% by volume.
Growing media other than soil
Question
What is Vermiculite?
Growing media other than soil
Vermiculite
* A naturally occurring mineral. When heated it exfoliates, forming concertina-like compressible particles.
* Has a large surface area relative to its volume and thus a high cation exchange capacity and buffering capacity.
* Used at 5-15% by volume in compost mixes to improve CEC and buffering capacity.
* Also improves aeration and water-holding.
* Often used as a seed covering..
Growing media other than soil
Question
What is Rockwool?
Growing media other than soil
Rockwool
* Rocks (basalt, dolomite) melted at high temperature to form molten matrix, air stream cools the material and forms long fibrous strands.
* Good aeration, light, clean.
* Used in the form of cubes or sheets, or shredded and mixed with other materials.
Growing media other than soil
Question
What are John Innes composts?
Growing media other than soil
John Innes composts
* John Innes composts were developed in the 1930s, and provided for the first time a formula for a ‘standardised’ compost.
* Two drawbacks: (i) difficulty in getting reliable supplies of sterilised loam and (ii) being soil based, they are heavy to transport.
* Loam, peat, sand, fertiliser in different proportions for eg pricking out seedlings, rooted cuttings, veg plants, shrubs.
Growing media other than soil
Question
What is Hydroponics?
Growing media other than soil
Hydroponics
* Growing plants in nutrient solutions rather than soil or composts.
* Inert material such as gravel, vermiculite, perlite, rockwool used for mechanical support.
* Potentially a more efficient and sustainable method of food production than conventional agriculture/horticulture.
Growing media other than soil
Question
How does Hydroponics work?
Growing media other than soil
Hydroponics
* Passive systems rely on capillary action
* Ebb and flow: tray is regularly flooded with nutrient solution and then drained
* Nutrient film technique: constant flow of nutrient solution circulating around roots
Growing media other than soil
Question
What are advantages of Hydroponics?
Growing media other than soil
Hydroponics Advantages
* Water conservation: less water is used as water is re-circulated or stored for later use.
* Growth rates increase, allegedly by up to 25%
* Potential for year-round production
* More top growth, less root growth
* No soil-borne pests/diseases
* No weed problems
* Less chemical use
* No tillage operations
Growing media other than soil
Question
What are disadvantages of Hydroponics?
Growing media other than soil
Hydroponics Disadvantages
* More complex & more expensive to set up.
* Nutrients need to be carefully balanced.
* Humid environment can favour fungal disease.
* Pump failure can cause whole crop to fail.
* Water-borne diseases can spread easily (Pythium, Phytophthora, Fusarium)
Growing media other than soil
