2102 - Organic Matter Flashcards
Organic Matter definition
Anything that has been alive but is now dead.
Includes Plant, Animal and Micro-Organism remain and waste products.
Ph of different materials
Peat - Acid Coir - Neutral Green Manure - Acid Wood Ash - Alkaline Ammonium Sulphate - Acid
Soil Improver is…
Organic Matter that is incorporated into the soil to improve it.
- Provides food for soil benefiting organisms and micro-organisms
- Releases and Recylcles nutrients, improving soil fertility
- Improves Soil Structure with the addition of humus (helps with bonding of soil aggregates)
- Humus improves soil Cation Exchange Capability, or nutrient buffering.
- Improves water retention
- Helps warm the soil earlier in Spring (dark colour)
Mulch is….
Organic or Inorganic material spread on the surface of soil (to a depth of 5-7cm)
- Conserves soil moisture by reducing loss through evaporation
- Suppress weed growth and germination
- Evens out soil temperature fluctuations, cooler in summer and warmer in winter
- Protects soil from capping, physical barrier
- Organic Mulch will eventually rot and be incorporated into the soil, improving soil structure and fertility
Types of Bulky Organic Matter - Farm Yard Manure
- consists of straw and animal waste
- must be well rotted before use
- variable nutrient content, but wide ranging
- Availability is location dependant
- Potentially unpleasant to handle
- may contain weed seeds
Types of Bulky Organic Matter - Spent Mushroom Compost
By-Product of Mushroom production
- clean, cheap, easy to handle
- decomposes quickly
- High PH 7+ (alkaline)
- Availability is location dependent
Types of Bulky Organic Matter - Garden Compost
Composted domestic and garden waste
- Quality and nutrient content is variable
- only as good as the materials used
- only usually available in small quantities
- may contain weed seeds
Types of Bulky Organic Matter - Municipal Green Waste
By-product of civil recycling
- very variable quality
- may contain weed seeds and other undesirable materials
- cheap
- location dependant
- High pH 7+
- Only suitable as a mulch
Types of Bulky Organic Matter - chipped bark
By-product of timber production
- Clean easy to handle
- aesthetically pleasing
- low water holding capacity
- slow to break down
- Can remove Nitrogen from the soil as it breaks down
- Only suitable as a mulch
Types of Bulky Organic Matter - Leaf Mould
Leaves from deciduous trees and shrubs
- Open fibrous structure
- Aesthetically pleasing
- Variable pH but usually Acidic
- Low Nutrient levels
- Soil Structure and Mulching
Types of Bulky Organic Matter - Green Manure
Quick growing, non woody plants, grown in-situ to incorporate into the soil
- effective on a large scale
- Protects soil, prevents soil erosion and capping
- can tie up the plot for extended periods
- can harbour pests and disease
- suitable for improving soil structure and fertility
Types of Inorganic Mulch - Polythene Sheeting
- blocks light, good for suppressing weed germination and growth
- reduces water evaporation
- black material will warm soil earlier in season
- Can be planted through
- Can harbour Pests, such as slugs
- Not aesthetically pleasing
- Poor environmental impact (plastic waste)
Types of Inorganic Mulch - Woven Fibres
- similar to Polythene but last longer
- allows air supply to soil
Types of Inorganic Mulch - Gravel
- long lasting
- aesthetically pleasing
- potentially help plant crown rot by keeping them free of moisture
- easily displaced
- not effective against perennial weeds
Types of Inorganic Mulch - Glass chips
- Expensive
- Minimal suitability to garden style
- long lasting
Types of Bulky Organic Matter - Composted Straw
By-product of wheat and barley production
- Cheap and readily available
- may contain pesticides
- break down quickly
- suitable as a mulch
What can affect compost quality?
- The ingredients used
- The composting process
Good Materials for Composting
- Grass clippings (not too much or compost will not decompose correctly)
- Hedge trimmings
- Leaves
- Soft to fibrous stems
- uncooked vegetables
- moderate amounts of newspaper
- non propagative parts of weeds
Poor Materials for Composting
- Cooked Vegetables
- Meat products
(both may attract vermin) - Faeces (dog, cat)
- Diseased plant material
- material treated with pesticides
- excessive high levels of carbon (wood, straw, cardboard)
- propagative parts of weeds
Carbon to Nitrogen ratio
Optimum ratio is 25:1
Well Rotted Farmyard Manure, Green Manure, Grass Clippings Leaves - All Low in Carbon 15:1 to 20:1
Paper is high - 170:1
Wood excessively high 700:1
Carbon to Nitrogen ratio Effect
Too little Nitrogen, eg bark chips, can lead to a slowing of the decomposition process. Not enough for N for the micro-organisms for growth.
Too low Nitrogen in a mulch, can lead to micro-organisms robbing Nitrogen from the soil to aid decomposition of the mulch. Eg Woodchip Mulches.
Nitrogen fertilisers, Sulpahte of Ammonia or Urea can be applied to offset this loss.
25:1 is the optimum ratio.
Too high nitrogen can aid in rapid decomposition but can lead to excessive heat and potential fires in compost heaps.
Too much grass clippings may not decompose, leaving a slimy mess.
Cold Composting
- slow process, 3 years
- requires little management
- can be used on a small scale, ie garden compost bins
Hot Composting
- rapid process (hotter = faster)
- requires active management
- equal mix of green / brown material added in layers
- well aerated (oxygen supply)
- appropriate moisture content
- use of fertilisers as compost accelerators
(urea or sulphate of ammonia) - addition of lime if compost becomes too acidic
Composting Method
- sheltered site, open to the ground for worm/organism access
- minimum dimensions of 1m3
- balance of ventilation and insulation
- easy access for gardener (wheelbarrow?)
- Fill a well ventilated compost bin with 25:1 green (nitrogen rich) / brown (carbon rich) material, in layers (10/15cm)
- shred or breakdown larger material for faster decomposition
- Consider addition of compost accelerator and pH neutraliser
- Turn heap regularly (2/4 weeks) to ensure good Oxygen supply
- Keep compost moist but not saturated
High Temperatures will help kill weed seeds, pests and disease.
Composting Systems - Trench
- Trench dug and filled with undecomposed organic matter
- Covered with soil
- Used for growing vegetables with high nutrient and water requirements
- runner beans and squash
Composting Systems - Sheet
- Similar to mulching technique
- Covering plot with layer of biodegradable material, often cardboard
- Covered with organic matter
- Both materials are slowly broken down and incorporated into the soil
- acts as a mulch, surpassing weeds and conserving water
- may not be aesthetically pleasing
- might attract pests
Composting Systems - Wormery
- Small self contained unit that uses Tiger Worms to compost soft organic waste.
- contains soft bedding above a liquid pan
- Worms are added to the bedding along with small amount of soft organic waste, vegetables etc
- liquid is produced which is collected and can be used as a liquid fertiliser
- avoid temperature extremes
- can produce nasty smell
Composting Systems - Cold Frame
- Fresh manure and Straw mixed and laid to a depth of 60cm on the floor of a deep cold frame.
- Wetted and covered with 30cm of good topsoil
- Frame closed and left for a week
- soil gently warms due to microbes decomposing the organic matter below
- Extending the growing season (late winter / early spring)
- Enviromentally friendly
- less risk of pest and disease
- only suitable for low growing crops
- Access to large quantities of Farm Yard Manure
Composting Systems - Comfrey & Nettle Tea
- 500g plus, of nettle or comfrey leaves placed in a cloth sack and submerged in a bucket of water.
- Left for two weeks, resulting liquid can be used a stock solution to be diluted 1:15 and applied as a liquid feed
- Home made soluble liquid feed
- Correct dilution as the stock solution can be highly concentrated
- Produce bad smells
- variable nutrients content
- access to sufficient quantity of leaves
- Organic, inexpensive
- Symphytum officinale (comfrey) high in Pottasium
- Urtica spp. (nettles) high in Nitrogen, Magnesium and Iron
