What are the basics of composting?

Answer 1

== == The basics are simple, but it is a bit of an art to get one to heat fast and finish quickly. These hot piles are active composting. However, there is evidence that a slow pile produces more humus, which is the goal, so passive composting is another option.

Active Composting

The pile is effectively built out of two elements, carbon-C and nitrogen-N. It is the balance between these two in the presence of invertebrates, fungi, and bacteria that allows an exothermic reaction to occur and produce the final decomposition. Yard and kitchen scraps are layered with manures or dirt to achieve a carbon to nitrogen ratio that is close to 30:1.

See the "C:N ratio Compost Guide" link below for C:N ratios.

Green ingredients include grass clippings, weeds, kitchen scraps, coffee grounds, seeds, fresh soft green prunings, seaweed, and animal manure (sheep, poultry, horse, rabbit and cow).

Brown ingredients include dead leaves, straw, hay, wood shavings or chips, egg cartons, and newspaper.

Particle size also affects the availability of carbon and nitrogen. Large wood chips, for example, provide a good bulking agent that helps to ensure aeration through the pile, but they provide less available carbon per mass than they would in the form of wood shavings or sawdust. Too much carbon prevents the pile from heating.

Monitoring the Pile

Ideally one uses a thermometer with readings from 0 degrees to 200 degrees Fahrenheit and that is long enough to read well into the pile to determine when to turn the pile. If you have layered the carbon to nitrogen to the ideal 30:1, the pile will shortly begin to heat up. There will be a steady rise in temperature for a day or two. Normally the pile will continue to rise until it reaches 120 to 149 degrees Fahrenheit. Keep on monitoring the temperature. If it stays up, fine. If it drops, turn again. Once it no longer rises in temp after being turned, it is complete. Note this is predicated on being able to balance the carbon or 'browns' to the nitrogen or 'greens'. Also, the particle sizes being added matter. If possible, all material should be run through a chipper to mix and reduce the size. This makes turning much easier, too.

Smell is the best method of managing a pile if you do not have a thermometer.

# If it smells fresh like turned soil, it is working properly. # If you get it too wet, it will begin to decompose anaerobically and produce hydrogen sulfide, the rotten egg smell. The best thing is to turn it and get air in. Possibly layer in fresh dry ingredients to absorb excess moisture. # If the pile has an ammonia odor, you have too much green material (grass clippings, food scraps, green plant material) and not enough brown (dry leaves, woody prunings, pine needles, dried out plants, sawdust). Add more brown material or a shovel of soil and turn it. # If you see ants, then the pile must be too dry. Everything should be moist, but there should be nothing dripping. If you piled it too dry, its own heat dried it or the summer weather dried it, then you must turn it rewetting the layers as you go. # If it just sits there with no smell and won't heat up, you have too many browns. Too much carbon prevents the pile from heating. Go to a coffee shop and get some coffee grounds: any grain, seed or meal is a good source of nitrogen. Add some grass clippings in thin layers ,or get a neighbor to donate kitchen scraps.

What can be added with proper handling

Meat and dairy products are high in fat. They can cause an unpleasant odor if added to a passive pile or poorly-managed active compost pile. For a hot, well-turned, enclosed compost pile, meat and dairy wastes are not a problem. However, it is best to run the wastes through a blender or food processor to reduce their size and speed their decomposition.

Fat, oil, & grease, known as FOG, can be added in small amounts.

Fat, oil, and grease have a high C/N ratio (90:1); if applied to compost, they may affect the availability of N, due to N immobilization during its decomposition by nitrifying bacteria. The same is true of any high carbon ingredient such as wood chips. So FOG is best added in small quantities when turning the pile so they are well blended with other moist green material.

Wood ashes, which are highly alkaline (high pH), are good for sandy, acidic soils (low pH). However, the fine particle size of ash tends to plug the pores of clay soils leading to water penetration and drainage problems. Some thought may be needed before using these in compost.

What should never be added

Feces either from your pet or human carry diseases and parasites, as well as cause an unpleasant odor.

Diseased garden plants can infect the compost pile and influence the finished product.

Invasive weed spores and seeds (buttercups, morning glory, quack grass) can survive the decomposition process and spread to your desired plants when you use the finished compost.

Glossy, colored paper has inks thata are toxic to the soil microorganisms.

Pesticide-treated plant material are harmful to the compost foodweb organisms, and pesticides may survive into the finished compost.

Eucalyptus leaves and bark have allelopathic effects that impact nutrient cycling and prevent some seed germination.

Treated lumber will not break down.

Poison ivy is a potent source of urushiol even after a year and a half (to sensitive individuals).

Walnut shells contain juglone, a naturally occurring chemical that is released by all parts of black walnut trees and can have a toxic effect on many vegetables and landscape plants.

Compost invertebrates

During the early stages of the composting process, flies bring bacteria that are useful to the decomposition. Flies lay eggs in compost, and then the flies and their larvae feed on the decaying vegetation until it heats up. Flies do not survive thermophilic temperatures the bacteria and fungi digestion creates. If flies become a problem, cover food scraps with a little soil from the garden.

Slugs and snails generally feed on living plant material, but they will attack fresh garbage and plant debris and will therefore appear in the compost heap. (Better there where you can find and kill them than in the garden. If they are a problem dump them in soapy water - not antibacterial - until they are dead; then compost them. Soap is a phosphorus source.)

In small-scale, passive compost piles, soil invertebrates aid the decomposition process. The compost should have many kinds of worms, including earthworms, nematodes, red worms and white potworms. They will invade the pile from the soil or through drain holes if you have an enclosed bin. A cool pile is still decomposing with bacteria and invertebrates working slowly towards creating humus.

Besides worms, you will see many other creatures like sow bugs or springtails. All the creatures that move in are there because they like dead stuff. Bugs, big and little, are what make the decomposition happen.

Together with bacteria, fungi, and other microbes, these organisms make up an energy pyramid with primary, secondary, and tertiary level consumers. The base of the pyramid, or energy source, is made up of organic matter including plant and animal residues.

See "Cornell Invertebrates" and " Digital Seed Composter", below, for information on invertebrates of the compost pile.

Passive vs Active Compostinghttp://www.extension.org/pages/Passive_Composting_of_Manure

http://www.msue.msu.edu/objects/content_revision/download.cfm/item_id.207912/workspace_id.-30/OC0353%20Cold%20Passive%20Composting.pdf/

Compost uses

Use compost as a mulch or top dressing. Work it into new beds, and amend holes dug for new plants. Mix it with vermiculite and sand to make your own potting mix. Last, make compost tea.

See "Compost Tea" link below for how to make compost tea.

The reason we need to add organics to soil is to create humus. Good top soil contains approximately equal parts sand, silt, and clay. These give soil its texture and are about 95% of soil solids. Organics give it structure and should be 5-7%. How the soil aggregates or forms crumbs affects how air and water move through the soil. The organic portion of the soil determines this. Crumb structure should allow soil volume to roughly double. The solids take up about 50% of the space, leaving voids between for water and air to circulate; water occupies about 25% and air about another 25%.