Composting Michael Rowell Composting is the accelerated decomposition of organic waste to produce a stable useful soil amendment This is not composting Simple decomposition or rotting produces a useful mulch but it is of limited nutrient value ID: 203328
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Slide1
Basic CompostingMichael Rowell
Composting is the accelerated decomposition of organic waste to produce a stable useful soil amendment Slide2
This is not composting
Simple decomposition or rotting produces a useful mulch but it is of limited nutrient value Slide3
Composting blends organic residues together and manages the decomposition to optimize the value of the product as a soil amendment.It can be a mulch
Improve water holding capacity
Help in water conservation
Help to suppress weed growth(perhaps)
It is a slow release fertilizer
Nitrogen, potassium, phosphorus, sulphur, calcium & magnesium
Micronutrients
It is a microbial inoculantAddition of beneficial microbes
It may be free of weed seeds and pathogensSlide4
Methods of Composting
Commercial windrows
Aerated barrel
Compost worms
Compost tea
Bokashi
system
Compost BinsSlide5
Making a compost binCheapest to make it out of wood2x4 for frame; 1x6 for sidesTreated or untreated? Cedar, fir, spruce etc.
Size (at least 1m x 1m x1m)
Essential for pile to be well insulated
Two Bins better than one
One for active compost
One for mature compost
Good aerationSlatted system to allow passive air circulation
Easy to mix contentsVariable baffles in front, leverage with forkSlatted top (optional)Block excess rainfall with polythene sheet
Drainage or no drainageSolid or open at bottomSlide6
We could compost anything that is biodegradable
“
All organic things produced by living things are biodegradable, some more easily so than others
Easy
Juicy fruits, grass clippings, non-waxy leaves, many dairy & fish products; many meat products; animal manure
Moderate
Finely shredded wood, corn cobs, hedge trimmings; straw & tougher plant stems; light cooking oils; cardboard, paper and cotton & many other natural fibres
Difficult
Bones, leather, feathers, hair, nut shells, pine cones, waxy leaves, wood, grease, natural resins, coal, heavy fats and oils.Slide7
What things are not biodegradable?Items that were never living and many synthetic substances made by humans
Metals and alloys
:
Iron, aluminum, lead, gold, steel, copper
Minerals
:
Rocks, sand, lime, ash, shells, diatomaceous earth, talcum powder, diamonds, pearls
GlassInorganic Chemicals: Bleach, battery acid, inorganic fertilizers, baking soda, table salt etc.
Many synthetic products: Plastics, glue, rubber, pigments, pesticides
[some synthetic organic products biodegrade slowly because their chemical structures have some similarities to natural products] Slide8
Things to avoid or treat with caution?Slow to decompose Grass sod, conifer needles and cones
Waxy leaves, leather, bones
Fatty food residues
Potentially toxic
Rhubarb leaves, walnut leaves (toxins in leaves)
Charcoal (toxic combustion residues)
Be careful
Wood ashes (high pH)
Plant seeds (remain viable)Biosolids
(may contain hazardous residues)Fish products (smell)Nuisance
Weed seeds and
propagative
parts
Diseased plants
Meat & high fat residues (smell & attract scavengers)
Pet and human excrement (risk from odour and pathogens)Slide9
Example of a compost pile started in mid summerPhase 1 (week 1 & 2) Easily degradable things decomposed quickly by microbes that produce a lot of heat as a by-product. Insulation of pile maintains heat and these microbes die off.
Phase 2
(week 3 and 4)
Decomposition at high temperature by specialist microbes. Hot enough at 50-55C to kill weed seeds and many pathogens.
Phase 3
(weeks 5 to 12)
Temperature decreases and other slower growing organisms come in to degrade residues from phase 2 and other resistant residues.
Phase 4 (fall and over winter) Maturation of compost as reactions slow and carbon dioxide production drops to a lower stable rate (ready for use in spring).Slide10
Making Good Compost: The 5 Golden Rules1: Get the correct balance of residues
2: Increase the surface area
3: Keep it moist
4: Mix frequently to aerate
5: Big enough pile to keep it hotSlide11
The 5 Golden Rules1: Get the correct balance of residues
Greens + Juicy + browns (high nitrogen + high energy + high carbon)
Will allow fast composting with a “hot phase”
Start with a full bin if possible; composting results in a big loss in massSlide12
The 5 Golden Rules2: Increase the surface area
Fibrous plant matter & paper
Chop
Shred
GrindSlide13
The 5 Golden Rules3: Keep it moist
Add more water than you would give plants
Microbes work in water films
Keep it as wet as a wrung-out face cloth
If it is too wet it may get smelly & leach nutrients
If it is too dry the microbes will not work wellSlide14
The 5 Golden Rules4: Mix frequently to aerate
Fast composting needs huge amounts of oxygen
Mix and turn frequently after the first two weeks to add more oxygen
Aerate even during the maturing phase
Mixing moves dryer material at the edges into wetter centre of the pileSlide15
The 5 Golden Rules5: Big enough pile to keep it hot
The pile must be well insulated if you want to keep it hot
This means quite a large pile
A hot pile = fast reactions + killing weeds & pathogens
Other things to consider:
Give it a boost:
Add some high nitrogen residues (alfalfa meal, manure)
Two piles are better than one: Separate the active composting phase from the slow maturing phase. Slide16
.
green
juicy
brown
mix... mix...mix
water.... water
water.... water
High temperature phase
Moderate temperature phase
Cooling phase
Long maturing phaseSlide17
Examples of the three categories of composting materialsGreen (high nitrogen/fresh vegetation; living)
Grass & hedge clippings
Vegetable leaves, bean & pea vines
Juicy
(moist; high sugar, starch &
hemicellulose
)
Kitchen waste, surplus fruit & vegetables, apple cores, potato peelings
Brown (high carbon/low nitrogen, cellulose-rich; dead)
End of season plant residuesPaper , cardboard, wood chips, twigsCorn cobs and stemsAutumn leaves
Making a balanced mix of “greens”, “juicy” and “browns” will ensure that you have a prolonged hot phase which will be hot enough to kill most weed seeds and pathogens.
Slide18
Who does the work?Primary consumers of residues; directly digest carbohydrates, fats, proteins and even fibrous matterMainly bacteria and fungi
Secondary consumers
; small soil animals and other microorganisms that eat primary consumers
Chop, grind and move materials.
Earthworms, nematodes, mites,
springtails, protozoa, rotifers
Tertiary consumers
; eat the secondary consumersCentipedes, mites, beetles, antsSlide19
Problems My new composter does not workSlow compostingBad Smells
It’s slimySlide20
Problems My new composter does not work
New compost piles often take a while to “condition” with the correct microbes
Add small amounts of soil layered in with compost to add microbes
Mix in compost from another active pile
Make sure you are following the 5 golden rules. Slide21
Problems Slow compostingToo Dry
Not enough “greens”; boost with something high in nitrogen
Too much fibre (corn stalks, tough stems, cardboard, sawdust etc.)
Weather too cold (4-10C slow: 11-18C medium: 20C+ fast)Slide22
Problems Bad Smells (ammonia, hydrogen sulphide, mercaptans
, acrid organic acids)
Too much high nitrogen residues (meat, dairy products, blood meal, fresh manures)
Unwanted animals using your pile as a bathroom
Too wet; you are making an alcoholic beverage or silage not compost
It’s slimy
Too much green and juicy residues relative to the brownsSlide23
SummaryChoose the right type of composter for your needsPile, bin, barrel, red worms, apartment sized systems
Follow the 5 Golden rules
Right mix; increase the surface area; water, aerate & mix; keep it hot
Avoid buying unnecessary products
Magic activators, special microbes, power mixers and shredders and other gimmicky hardware
Take heed of the climate
Composting is a biological process; below 4C everything takes a rest.
Use the product wisely
Make sure you have not added anything hazardousDo not add too much ; e.g. Maximum of 1 part compost to 3 parts soil