Compost (pron.: /ˈkɒmpɒst/ or /ˈkɒmpoʊst/)
is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Compost is a key ingredient in organic farming. At the simplest level, the process of composting simply requires making a heap of wetted organic matter (leaves, "green" food waste) and waiting for the materials to break down into humus after a period of weeks or months.

Modern, methodical composting is a multi-step, closely monitored process with measured inputs of water, air and carbon- and nitrogen-rich materials. The decomposition process is aided by shredding the plant matter, adding water and ensuring proper aeration by regularly turning the mixture. Worms and fungi further break up the material. Aerobic bacteria manage the chemical process by converting the inputs into heat, carbon dioxide and ammonium. The ammonium is further converted by bacteria into plant-nourishing nitrites and nitrates through the process of nitrification.

Compost can be rich in nutrients. It is used in gardens, landscaping, horticulture, and agriculture. The compost itself is beneficial for the land in many ways, including as a soil conditioner, a fertilizer, addition of vital humus or humic acids, and as a natural pesticide for soil. In ecosystems, compost is useful for erosion control, land and stream reclamation, wetland construction, and as landfill cover. 

Green Thumb Composting
My personal version of how to build and maintain green thumb compost.

Home Composting
Compost is one of the most valuable resources for beautifying your landscape, and it is virtually free. Vegetable scraps, egg shells, leaves, grass clippings, and the branches you trim are some of the things you can use to make compost. Finished compost is dark and has a pleasant smell. It is produced when organic matter, such as garden, lawn, and kitchen waste, is broken down by bacteria and fungi. Making your own compost is probably the simplest way to make high quality compost and save money. It's really not as complicated as you may think: .

Compost can be made in either a pile or bin, depending on the amount of material for composting and the needs and size of your garden. A compost pile should be a minimum of one cubic yard. The pile may be enclosed using bricks or timber. Leave an access area or work space at the front of the pile for turning the compost and cover it with a lid or piece of carpet to retain heat and provide protection from rain.

Bins should be open at the top and bottom. The top needs a tight-fitting lid. The other end is placed in contact with the soil to allow earthworms to enter. These little gardeners speed the decaying process by loosening the compost and allowing air to enter and circulate. Avoid placing the bin or pile too close to houses. Consider placing it directly on level soil in a garden bed.

Two bins or piles allow material to accumulate in one while composting in the other. The pile should be protected from hot sun and heavy rain to prevent excess drying or moisture, which prevent effective composting.

Compost works best if you add a balanced mixture of rapidly decomposing "green" material (see below). and "brown" material, which decomposes slowly (see below). These can be added in any order.

Once you have a mixture of materials, cover with a layer of soil, add some water and a lid to keep the heat in and speed the rotting process.

Composting matter should feel damp, but if waterlogged it will smell, attract flies and be inefficient. Control the moisture level by adding absorbent materials such as sawdust, newspaper, straw or dry manure.

Turning the pile with a fork will speed decomposition. The more frequently the material is turned, the faster it will decompose. Care should be taken to make sure that all material is turned into the inner, hottest part of the pile where weed seeds and pathogens are destroyed. If the pile is turned regularly, the compost should be ready for use in a month or two. Your compost can sometimes be smelly when you turn it, so set up your compost away from your neighbours! The pile may be left unturned, but the process could take an extra six to twelve months.

Compost is ready to use when it has a crumbly appearance, an earthy smell and identifying what things were is difficult!

Key Elements of Composting:
Water - Keep the compost just damp. Too much water will ruin your compost.
Balance - Add a mix of green and brown materials to make a well balanced compost.
Air - Turn the pile over every few weeks or every 5 to 6 days if using a bin.
Size - A compost pile will mature quickest if it is at least one cubic yard.
Microorganisms - These help break down the compost material. They come from the soil or old compost you add and from the earth on which the compost pile is built.

The Best Mix in Compost:
All compostable materials are either carbon or nitrogen-based. Building a healthy compost pile is simple: maintain a working balance between these two.

Carbon - Referred to as browns, carbon-rich matter (peels, thin branches, stems, dried leaves, bits of wood, bark dust or sawdust, shredded brown paper bags, coffee filters, conifer needles, egg shells, hay, peat moss, wood ash) gives compost its light, fluffy body.

Nitrogen - Referred to as greens, nitrogen or protein-rich matter (food scraps, manures, leafy materials like lawn clippings and green leaves) provides raw materials for making enzymes.


Manures

Manure is a excellent amendment to any soil. Manure is a source of many nutrients including: nitrogen, phosphorus, potassium and many others. Nitrogen is often the main nutrient of
concern for most crops.

Type of Garden Best Type of Manure Best Time to Apply
Flower cow, horse early spring
Vegetable chicken, cow, horse fall, spring
Root Crops chicken, cow, horse fall, spring

Dairy Cow Manure: Dairy manure is the preferred manure for most gardeners. It is not as hot as other manures and more forgiving if accidentally applied when too fresh. It is preferred over horse and steer manure but may be harder to acquire. Though cow manure has lower nutrient levels than other manures, it is this that makes it safer to use in larger quantities. It should be aged like other manures.

Horse Manure: Horse manure is about half as rich as chicken manure, but richer in nitrogen than cow manure. It is considered a "hot" manure. Horse manure often contains a lot of weed seeds, it is best to compost this manure before use, or add to the garden in the fall.

Chicken Manure: Chicken manure is the richest animal manure. Chicken manure is considered "hot", it is best to compost this manure before use. Otherwise, it will burn any plants it comes in contact with.

Sheep & Goat Manure: Sheep or goat manure is another "hot" manure. It is somewhat dry and very rich. Manure from sheep and goats fed hay and grain will be more potent than manure from animals that live on pasture. It is best to compost this manure before use or add to the garden in the fall.

Rabbit Manure: Rabbit manure is even higher in nitrogen than some poultry manures and it also contains a large amount of phosphorus--important for flower and fruit formation.

Seaweed: (many gardeners refer to Seaweed as a manure) With beach access available, this is a fairly easy manure to obtain at no cost. Seaweed is an excellent source of calcium and potash. Prior to using seaweed though, wash it thoroughly to remove the salt. Dig it directly into the soil or compost it.

Manure Tea: Manure tea can be used for periodic feedings as a fertilizer or very diluted and used every time you water. Do not allow undiluted manure tea to come into direct contact with foliage. To make manure tea, simply place a shovel or two of manure in a large container (5 gallon bucket) filled with water, and after a week or so, strain out the manure. To make the straining process a little easier, you can tie the manure in a burlap bag before placing it in the water (like a giant tea bag).

Green Manure: Green manure is a crop that is grown then plowed into the soil or otherwise left to decompose for the purpose of soil improvement. These crops return more nutrients to the soil than they use to grow. Examples of cover crops used for green manure include soybeans, clover, rye, and others. Green manure does not mean raw manure.

IMPORTANT: Do not use cat, dog, pig or human feces (manure) in composts or gardens it can spread disease and parasites into the garden, and eventually you or your family members. Use of human and pig manure or feces is used in commercial agriculture, but has usually been processed prior to application to kill parasites and diseases (how effectively, we are not sure and would not use it). Never use fresh manure (hot), since it contains soluble nitrogen compounds and ammonia that can burn plants and interfere with seed germination. Manure that is well composted or has aged for at least six months is best - a year or more is even better but hard to find. When added to the compost pile, manure will speed the composting process.



Things you can compost!

Materials Carbon or Nitrogen Details
Alfalfa meal and hay
Algae, seaweed and lake moss
Nitrogen
Good source of nutrients and minerals.
Apple pomace (cider press waste)
Ashes (wood, not coal)
Neutral
Use only wood ashes since coal ashes can be toxic to plants. Use sparingly as a pest deterant.
Beverages, kitchen rinse water
Neutral
Help keep the pile moist, but don’t over do it.
Buckwheat straw or hulls
Cardboard
Carbon
If you have lots of this, consider recycling it. Otherwise, shred into small pieces in pile.
Cat litter (unused!)
Clover
Cocoa hulls
Coffee grounds (and filters)
Nitrogen
Great source of nitrogen and worms love coffee grounds!
Cornstalks, corn cobs A little tricky, so shred and/or break down and mix well into pile.
Cottonseed hulls
Cowpeas
Dog food
Nitrogen
Dryer lint
Carbon
Yum, lint. Make sure you moisten it a little before you add it.
Eelgrass
Egg shells
Neutral
These break down slowly, so make sure to crush these before adding.
Feathers
Nitrogen
Flowers
Fruit peels (not limes)
Grape pomace (winery waste)
Grass clippings
Carbon
Make sure they are not too wet and mix with dry leaves for best results.
Hair
Nitrogen
Good source of nitrogen. Make sure you scatter, so it doesn’t clump.
Hay
Nitrogen
The best kind is hay that is not suitable for livestock and is starting to decay on its own. Make sure it is dry and weathered.
Hedge Clippings
Hops (brewery waste)
Kelp (seaweed) Good source of potassium (perfect for growing potatoes!). Use sparingly or sprinkle kelp meal in to get your pile cooking.
Leather (leather waste)
Nitrogen
Leaves
Nitrogen
Manure from herbivores (cow, horse, pig, sheep, chicken, rabbit)
Nitrogen
Newspaper
Carbon
Nut shells
Oak leaves
Carbon
Oat straw
Sawdust and wood shavings
Carbon
Paper
Peanut hulls
Peat moss
Pine needles and cones
Carbon
Tea leaves
Vegetable peels and scraps
Vetch
Weeds
Carbon
Wheat straw


Things you should NOT compost!

Materials
Carbon or Nitrogen
Details
Ashes (coal or charcoal)
n/a
May contain materials that are toxic to plants.
Cat droppings/litter
n/a
These may contain disease organisms and should always be avoided for composting.
Colored paper
Dog droppings
n/a
Same as cats.
Lime
n/a
Acidity can kill composting action.
Meat, fat, grease, oils, bones
n/a
Do not break down, can coat materials and “preserve” them, can attract pests.
Nonbiodegradable materials
Toxic materials


University of Missouri Article on Composting
A good article on composting, bin designs and other information.

Composting Article from Ohio State University
Another good article on composting, Good images showing various bin designs and composting instruction.

Article on Manure from the University of Minnesota Extension Service
A very good article on manure and how it works in your garden. This page contains basic information about what manure does in the soil and why manure nutrient content varies so much from garden to garden.