Composting 101 What is Composting? The rapid biological decomposition of organic matter into an...
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Transcript of Composting 101 What is Composting? The rapid biological decomposition of organic matter into an...
Composting 101
What is Composting? The rapid biological decomposition of organic matter
into an inorganic form available for plant uptake
Microorganisms turning organic matter into plant food Nutrient cycling
Breeding of microorganisms or worms This is my approach to composting Our goal in composting: to provide microorganisms with the
food they need to thrive and thus rapidly decompose organic materials while retaining the maximum amount of nitrogen in those materials
Composting 101
Many types of composting
Anaerobic Composting/Digestion Slow process in absence of oxygen or in low
oxygen environment Easy method for small-scale composting Retains nitrogen very well
“Backyard” Composting Small-scale; good for home waste diversion Requires little management
Composting 101
Worm Composting Can be done indoors or on large scale Results in nutrient-rich compost or “castings” Finished compost in 3-5 months or sooner depending on
system Relatively high management needs (harvesting)
“Hot” Composting Method for large quantities of organic matter Rapid decomposition - as little as 4-8 weeks for certain
materials Requires some management to ensure high quality
We will focus on these two methods
Composting 101
So let’s breed some microorganisms…
Composting 101: Hot Composting
Hot Composting Best method for rapidly making large volumes of
compost Heat can destroy weed seeds and pathogens Good for soil fertility and structure building Requires frequent monitoring and turning Process of building pile is important Often benefits from off-farm nitrogen source Works good as soil inoculant Quality of compost depends on:
Quality of feedstock/composting materials Quality of monitoring Effort in preparing pile
Composting 101: Hot Composting
Six key elements to good hot compost (and most other methods as well):
1. Carbon:Nitrogen (C:N) ratio2. Air3. Water4. Surface Area5. Critical Mass of Pile6. Diversity of Materials
Composting 101: Hot Composting
1. Carbon to Nitrogen Ratio Food for the compost pile – must be
balanced Ideal ratio: 24:1
Microorganisms need 24 carbon molecules for every 1 nitrogen molecule they consume
Ratio too wide (e.g., 50:1)? Process is slower
Ratio too Narrow (e.g., 10:1)? Process is faster Nitrogen lost as ammonia
Composting 101: Hot Composting
1. Carbon to Nitrogen Ratio TABLE HERE
Composting 101: Hot Composting
1. Carbon to Nitrogen Ratio How to Balance:
General rule: equal parts browns and greens This shifts depending on how brown or green
Increased surface area in nitrogen materials: Increases decomposition rate Acts like higher N content, but used up quicker
Get familiar with common materials available to you
Composting 101: Hot Composting1. Carbon to Nitrogen Ratio
Essentially, the C:N ratio determines how hot the compost pile will get
The heat is a by-product of microbial activity An indicator of how happy your
microorganisms are Nitrogen is often a limiting factor
Importing nitrogen is crucial for good hot compost
Manure, okara, grass clippings Too much heat = too much N = N loss to
ammonia Also reduces diversity of microorganisms
Composting 101: Hot Composting
2. Air Your microorganisms need air to breathe
Gas exchange is crucial for life Think of your compost pile like your soil
How much air does it need (by volume)? About 20-25%
How do we promote good aeration? Mix pile consistently as you build it Use some woody and fibrous materials to
promote porosity Small twigs (e.g., willow) work very well
Composting 101: Hot Composting
2. Air Even with good porosity air space will
decline Pile becomes more dense as it decomposes –
filling pores Passive aeration tubes can be used to
maintain air flow
How do I reintroduce air into the pile? Usually by turning the pile and mixing the
contents More nitrogen can be added at this point if
needed
Composting 101: Hot Composting
2. Air Air is used to control rate of decomposition
Adding air can increase decomposition rate Removing air slows the process Can be used to help correct high C:N ratio
Air can be added passively or actively Passive:
Building good porosity into the pile using “twiggy” materials
Using perforated pipes horizontally layered in the pile Active:
Physically turning or manipulating the pile Forced air used for in-vessel systems
Composting 101: Hot Composting
3. Water Your microorganisms need water – just like
you Water also softens materials for
decomposition Good porosity allows extra water to drain
away Makes it difficult to over water your pile
Some materials with have a higher water content
Fresh plant matter Other materials will be very dry
Sawdust; leaves; manure
Composting 101: Hot Composting
3. Water Water usually needs to be added to the
pile Add water while building your pile
How much water? 50% water by weight!
Pile should be quite wet “As damp as a wrung out sponge” Organic matter will absorb water and allow
pore space to remain for air flow
Composting 101: Hot Composting
4. Surface Area Microorganisms are small – their food
should be too! Increased surface area = easier and faster
dining Chopping up materials greatly increases
decomposition rate – especially high C materials
Materials can be screened after composting to reduce large pieces before adding to soil
Large pieces of OM in soil can tie up nitrogen – especially high carbon materials
Composting 101: Hot Composting
5. Critical Mass of Pile Microorganisms create heat when eating
and they like to stay warm Larger pile = increased insulation 1 metre cube pile is sufficient for good
insulation Larger piles insulate well
Bottom of pile may be anaerobicArea of activity
Composting 101: Hot Composting
6. Diversity of Materials Your microorganisms like a diverse diet
Also results in more diverse microorganisms Diversity of materials = diversity of
nutrients Also makes it easier to balance C:N ratio Dynamic accumulators can be grown
specifically to be added to pile to improve quality and N content
Use large, fast-growing plants that re-grow after cutting
Comfrey Angelica
Composting 101: Hot Composting
6. Diversity of Materials Diversity of materials is not essential to
make compost But it is essential to make good compost
Compare the following compost piles Horse manure and leaves
Horse manure, chicken manure garden waste, comfrey, okara, grass clippings, leaves, sawdust, willow branches
Composting 101: Hot Composting
Other things to consider: The seasonality of composting materials
Carbon materials are prevalent in the fall Nitrogen materials are prevalent in the growing
season What off-farm materials are easily available?
Manures; leaves or other carbon materials Composting of weed seeds, rhizomes and
diseased plants Is it safe? How to do so safely?
Where and how will you compost? Do you have a staging area? Do you have a tractor? Using a bin or windrows?
Composting 101: Hot Composting
Other things to consider: Protect the pile from the weather
To control water level in pile Knowing the C:N ratio of the most common
materials is important in making a good pile Learn how to judge C:N ratio of new materials
Very active soil food web in compost pile Many trophic (feeding) levels Different organisms digest different materials at
different times
Composting 101: Hot CompostingSoil Food Web
Bacteria are primary decomposers of OM Work quickly on diversity of materials Generate heat in compost pile
Fungi also important Only organism that breaks down lignin (found in wood) Thrive in acidic environments Active in latter parts of decomposition
Arthropods Consume OM and each other Work on outside of pile when hot
Worms Consume their weight each day in OM Help aerate compost pile
Composting 101: Hot Composting Soil Food Web Image Here
Composting 101: Hot Composting
The Evolution of a Hot Compost Pile:
Our goal: To build a compost pile, taking into
consideration the six principles of hot composting, that will heat up to a temperature of 55ºC and maintain that heat for up to several weeks
Making a Hot Compost Pile
1. Stockpile materials on farm Materials will start to decompose
2. Import Nitrogen (if required) and build the pile3. Monitor pile temperature4. Turn or aerate pile when temperature has
dropped by 8 - 10ºC Add N if required when turning for first time
5. Turn pile 3-5 times upon cooling6. Let pile cure
Composting 101: Hot Composting
1. Stock pile materials on farm Weeds Leaves
Composting 101: Hot Composting
1. Stock pile materials on farm Weeds Leaves
Composting 101: Hot Composting
1. Stock pile materials on farm Weeds Leaves
Composting 101: Hot Composting
1. Stock pile materials on farm Weeds Leaves
Composting 101: Hot Composting
1. Stock pile materials on farm Weeds Leaves
Composting 101: Hot Composting
1. Stock pile materials from on farm These are organic materials
generated on the farm Weeds Leaves Harvest trimmings
When pile is of sufficient size bring in manure source for hot compost
Composting 101