|Compost - Compost - is the decomposed remnants of organic materials (those with plant and animal origins). Compost is used in gardening and agriculture as a soil amendment and commercially by the landscaping and container nursery industries. It also used for erosion control, land/stream reclamation, constructed wetlands, and landfill cover. (See Compost uses.)|
|Compost and Composition - Composition The Compost is a concentrate and should be blended with soil and/or other ingredients, typically no more than 30 percent of the total mix. In landscaping and gardening, compost can also be used full strength as a mulch. However, like soil, it should not be heaped up around the woody stems of trees and shrubs, as this encourages insect damage. Compost improves soil structure, increases the amount of organic matter, and provides nutrients. Biodegradation is the means by which organic matter is recycled in its environment. Compost is also used as a seed starting medium generally mixed with a small portion of sand for improved drainage.|
|Humus and Compost - Compost is a common name for humus, which is the result of the decomposition of organic matter. The decomposition is performed primarily by microbes, although larger creatures such as ants and nematode and oligochaete worms (see vermicomposting) contribute to the process. This occurs naturally in all but the most hostile environments, such as within landfills or in extremely arid deserts, which prevent the microbes and other decomposers from thriving.
Composting is the controlled decomposition of organic matter.
Rather than allowing nature to take its slow course, a composter
provides an optimal environment in which decomposers can thrive. To
encourage the most active microbes, a compost pile needs the correct
mix of the following ingredients:
||Decomposition happens even in the absence of some of these
ingredients, but not nearly as quickly and not nearly as pleasantly.
(For example, vegetables in a plastic bag will still decompose, but the absence of air encourages the growth of anaerobic microbes that produce disagreeable odors.)
||Decomposers - All guidelines for building compost piles have the goal of creating the proper environment for a decomposing ecosystem. The most effective decomposers are bacteria and other microorganisms. Also important are fungi, protozoa, and actinobacteria (or actinomycetes, bacteria that are often seen as white filaments in decomposing organic matter). At a macroscopic level, earthworms, ants, snails, slugs, millipedes, sow bugs, springtails, and others work on consuming and breaking down the organic matter. Centipedes and other predators feed upon these decomposers.
||Compost ingredients - Given enough time, all biodegradable material will compost.
However, not all compost feedstocks are appropriate for backyard composting. Most backyard systems will not reach high enough temperatures to kill
pathogens and deter vermin, so animal manures, pet droppings, meat scraps, and dairy products are best left to operators of high-rate, thermophylic systems. Using more sophisticated systems under competent management, composting is also an efficient, cost-competitive, environmentally sound technology to recycle not only animal manures and
bedding, but also the by-products of food production and processing, restaurant grease and cooking oils, and residuals from the treatment of wastewater and drinking water.
Composting will also breakdown petroleum hydrocarbons and some toxic
compounds for recycling and beneficial reuse. The use of composting for
such purposes is most commonly referred to as a form of bioremediation.
The goal in a compost pile is to provide a healthy environment and
nutrition for the rapid decomposers, the bacteria. The most rapid
composting occurs with the ideal carbon to nitrogen ratio of between 25
and 30 to 1 by dry chemical weight. In other words, the ingredients
placed in the pile should contain 25 to 30 times as much carbon as
nitrogen. For example, grass clippings average about 19-to-1 and dry autumnleaves
average about 55-to-1. Mixing equal parts by volume approximates the
ideal range. Commercial-grade composting operations pay strict
attention to this ratio. For backyard composters, however, the charts
of carbon and nitrogen ratios in various ingredients and the
calculations required to get the ideal mixture can be intimidating, so
many rules of thumb exist to guide composters in approximating this mixture.
High-carbon sources provide the cellulose needed by the composting bacteria for conversion to sugars and heat, while high-nitrogen sources provide the most concentrated protein, which allow the compost bacteria to thrive.
Some ingredients with higher carbon content:
There are two primary methods of aerobic composting:
Most commercial and industrial composting operations use active composting techniques. This ensures a higher quality product and produces results in the shortest time (see compost windrow turner). The greatest control, and therefore the highest quality, is generally achieved by composting inside an enclosed vessel which is monitored and adjusted continuously for optimal temperature, air flow, moisture, and other parameters. See In-vessel (also en-vessel). Home composters use a range of techniques varying from extremely passive composting (throw everything in a pile in a corner and leave it alone for a year or two) to extremely active (monitoring the temperature, turning the pile regularly, and adjusting the ingredients over time) and combinations of both. Some composters use mineral powders to absorb smells, although a well-maintained pile seldom has bad odors.
|Microbes and heating the pile -
An active compost heap, steaming on a cold winter morning. The heap is kept warm by the exothermic action of the bacteria as they decompose the organic matter.
||An effective compost pile is kept about as damp as a well wrung-out
sponge. This provides the moisture that all life needs to survive.
Bacteria and other microorganisms fall into a variety of groups in
terms of what their ideal temperature is and how much heat they
generate as they do their work. Mesophilic
bacteria enjoy midrange temperatures, from about 20 to 40 °C (70 to 110
°F). As they decompose the organic matter, they generate heat, and the
inner part of a compost pile heats up the most.
The heap should be about 1 m (3 ft)
wide, 1 m (3 ft) tall, and as long as is practicable. This provides a
suitable insulating mass to allow a good heat build-up as the material
decays. The ideal temperature is around 60 °C (140 °F), which kills
most pathogens and weed seeds and while providing a suitable
environment for thermophilic
(heat-loving) bacteria, which are the fastest acting decomposers. The
centre of the heap can get too warm, possibly hot enough to burn a bare
hand. If this fails to happen, common reasons include the following:
||Other ingredients - Some users like to put special materials and activators into their compost. A light dusting of agricultural lime (not on the animal manure layers) can curb excessive acidity that can slow down the fermentation. Seaweed meal can provide a ready source of trace elements. Finely pulverized rock (Rock dust - Rock flour) can also provide needed minerals, as opposed to clay (which is trace mineral-poor and/or leached rock dust).
The animal manure part of compost source materials can be collected by composting toilets (in this case, human feces). However, such compost is usually not used as a fertilizer for plants that are directly edible (e.g., salad crops). Most composting toilets do not allow for the thermophilic activity needed to completely kill off the pathogens and bacteria.
However, there is research that shows that if these high temperatures
are reached, there is no danger of contamination, and the resulting
compost can be safely used on food crops.
||Aerated Static Pile
||High fibre composting
||In-vessel (also en-vessel)
||Spent mushroom compost
||List of environment topics
||Instructional Videos on Composting:
Step-by-step guide on how to make your own compost, how to turn and mix
your compost, and how to make a compost container yourself
|| Start Composting - Beginner's Composting
|| The Compost Bin - Learn about Composting
||Compost Composting in Quebec
||Make A Large Compost Bin Out Of Waste Wood
||Lesson Plans and Composting
||Projects for Schools
|| Home Composting
|| Master Composter
||Cornell Composting--Science and Engineering
||How to Begin a Compost Pile
||The Humanure Handbook
||The Compost Froup composting community and forums
|| Midwest Bio-Systems
||Composting in your garden
||Klickitat County, Washington. Online calculator to help composters with their C:N ratios.
||Canada Composting Council
||Carolinas Composting Council
||European Compost Network
||Georgia Composting Association
||Ireland, Composting Association
||Italian Composting Association
||Michigan Composting Council
||Mid-Atlantic Composting Association
||(NY) Organics Recycling and Composting Council
||Oregon,Composting Council of
||Pennsylvania Composting Association
||(UK) Community Composting Network
||(UK) Composting Association
||US Composting Council
||Vermont,Composting Association of
||Washington Organic Recycling Council
||What is Compost ? Composting just happens !
Look at the Science behind our eyes.
Organic material breaks down over time. Making compost is a
controlled or managed version of the natural process. By concentrating the activity
in one place and balancing food, air and water - composting happens faster.
||Composting Systems: There is no one best system for managing compost. Instead, there are many ways, each offering advantages and benefits. Systems can range from mulching leaves on a
path to gathering a batch of organic matter for a three-week hot compost. To
determine which system is most appropriate for you, consider such factors as how
much time you want to devote to composting, how much garden space is available, how
much organic waste you have and how much money you want to spend.
Practical applications of composting science information. It outlines what to compost and three composting systems: yard composting in a container, mulching and composting with worms.
|The systems and instructions are intended to be a guide. They may be followed more
closely at the beginning and less closely as you learn and do more composting yourself.
It's important to always remember that composting happens - that it will just take
longer without management.
||Making Compost - A Simple Summary
||How to Compost - information about composting fundamentals for those interested in an introduction to how composting should be done. In addition, a set of composting questions and answers provide information about how to tell if compost is finished, how to use compost, and how compost benefits the soil.
||As a composter, you can put as much effort as you like into your composting system, but at its heart composting is really a very simple process that needs only minimal maintenance. Once you understand the basics, you will need to choose a bin system and build or purchase it (of course, binless compost piles can work just fine as well). With an understanding of the fundamentals, a spot set up for composting, and a few ingredients, you'll be ready to build a compost pile.
|Good composting is a matter of providing the proper environmental conditions for microbial life. Compost is made by billions of microbes (fungi, bacteria, etc.) that digest the yard and kitchen wastes (food) you provide for them. If the pile is cool enough, worms, insects, and their relatives will help out the microbes. All of these will slowly make compost out of your yard and kitchen wastes under any conditions. However, like people, these living things need air, water, and food. If you maintain your pile to provide for their needs, they'll happily turn your yard and kitchen wastes into compost much more quickly. Keep in mind the following basic ideas while building your compost piles:
||AIR - Composting microbes are aerobic -- they can't do their work well unless they are provided with air. Without air, anaerobic (non-air needing) microbes take over the pile. They do cause slow decomposition, but tend to smell like putrefying garbage! For this reason, it's important to make sure that there are plenty of air passageways into your compost pile. Some compost ingredients, such as green grass clippings or wet leaves, mat down very easily into slimy layers that air cannot get through. Other ingredients, such as straw, don't mat down easily and are very helpful in allowing air into the center of a pile. To make sure that you have adequate aeration for your pile and its microbes, thoroughly break up or mix in any ingredients that might mat down and exclude air. You can also turn the pile to get air into it, which means completely breaking it apart with a spade or garden fork and then piling it back together in a more 'fluffed-up' condition.
||WATER - Ideally, your pile should be as moist as a wrung-out sponge to fit the needs of compost microbes. At this moisture level, there is a thin film of water coating every particle in the pile, making it very easy for microbes to live and disperse themselves throughout the pile. If your pile is drier than this, it won't be very good microbial habitat, and composting will be slowed significantly. If your pile is a great deal wetter, the sodden ingredients will be so heavy that they will tend to mat down and exclude air from the pile, again slowing the composting process (and perhaps creating anaerobic odor problems). If you are using dry ingredients, such as autumn leaves or straw, you'll need to moisten them as you add them to the pile. Kitchen fruit and vegetable wastes generally have plenty of moisture, as do fresh green grass clippings and garden thinnings. Watch out for far-too-soggy piles in wet climates (a tarp may help to keep rain off during wet weather). In dry climates, it may be necessary to water your pile occasionally to maintain proper moisture.
||FOOD - In broad terms, there are two major kinds of food that composting microbes need. |
Brown Color Materials: are dry and dead plant materials such as straw, dry brown weeds, autumn leaves, and wood chips or sawdust. These materials are mostly made of chemicals that are just long chains of sugar molecules linked together. As such, these items are a source of energy for the compost microbes. Because they tend to be dry, browns often need to be moistened before they are put into a compost system.
Green Color Materials are fresh (and often green) plant materials such as green weeds from the garden, kitchen fruit and vegetable scraps, green leaves, coffee grounds and tea bags, fresh horse manure, etc. Compared to browns, greens have more nitrogen in them. Nitrogen is a critical element in amino acids and proteins, and can be thought of as a protein source for the billions of multiplying microbes.
|OTHER THINGS TO CONSIDER -
If you live in a cold climate, your compost pile will probably go dormant in the winter. No problem -- it'll start back up again when the springtime thaw comes.
A common misunderstanding about compost piles is that they must be - hot - to be successful. This just isn't true. If you have good aeration and moisture, and the proper ingredient mix, your pile will decompose just fine at temperatures of 50 degrees Farenheit or above. |
Hotter piles will decompose a bit faster, however. One way to understand why this is so is to realize that the heat in a hot pile is the result of the collective body heat of billions of microbes that are busy digesting the ingredients in the pile. Generally speaking, a hotter pile means more microbes or conditions that allow the microbes to have faster metabolisms, and therefore a faster composting process. If you'd like to keep your pile as warm as possible, consider the following: For a pile to get hot and stay hot for a long period of time, the typical minimum size for the pile is one cubic meter (a cube one meter, or about three feet, on a side). A pile this size has plenty of mass in which those billions of heat-generating microbes can live, yet is also large enough that the center of the pile is well-insulated by the material surrounding it. Smaller piles just cannot insulate themselves well enough to remain hot for long, if at all. You can also provide additional insulation to a pile by stacking bales of hay or straw, or bags of dry autumn leaves, around your bin system. Some people even used stacked hay bales to make bin systems (this kind of bin will slowly compost itself, of course).
|Composting Questions and Answers
||When is my compost finished? - Finished compost is dark in color and has an earthy smell (like the smell of soil). Usually, it's difficult to recognize any of the original ingredients, although bits of hard-to-decompose materials (such as straw) sometimes can be seen. There is no single point at which compost is finished -- it's a bit more subjective than that. For many outdoor garden applications, for instance, it can be fine to use compost that still has a few recognizable bits of leaves or straw -- it will finish rotting in the soil. If you plan to use compost in seed-starting mixes, though, you're best off having a well-finished compost, because seedling roots may be attacked by decomposer microbes if the roots contact unfinished compost.
||How can I use my finished compost? Well-finished compost looks so fine that I'm tempted to eat the stuff sometimes. However, there are several more common ways that compost can be used, on gardens, lawns, landscapes, and houseplants
See our section of Uses of Compost for additional information.
||COMPOST AS SOIL AMENDMENT: Many people put compost into their garden soil by digging it in prior to spring planting. The image shows a potato harvest by apprentices at the UCSC Farm and Garden in 1990. Due to the use of copious amounts of compost, the potato beds yielded about one pound of potatoes per square foot, or about 1000 pounds total from these four beds, each 80 feet long.
||Others actually - do - their composting in the soil, by burying kitchen wastes and other materials in trenches in the garden. Compost can also be used as a 'top dressing' on the soil during the growing season -- in this case it is added in around the bases of plants, where irrigation and soil animals will slowly incorporate it into the soil. On lawns, many people sprinkle/broadcast sifted compost as a top dressing in the spring -- I have been doing this on a 'problem area' of a lawn for several years, in an attempt to improve the soil there for better grass growth. It is also fine to top-dress houseplants occasionally with small handfuls of finished compost.
||COMPOST AS MULCH: Compost can be left on the surface as a mulch around landscape and garden plants. This is essentially the same as a 'top dressing' application, described above, but mulches are typically meant to cover all of the soil around the plants that get mulched. Mulches protect the soil from erosion. The also save water by shielding soil from the drying effect of the wind and sun. As they decompose, mulches add nutrients to the soil, and if composed of small-enough particles, worms may slowly eat the mulch and incorporate it into the soil.
||COMPOST AS TEA: Compost tea is made by combining equal parts of compost and water and letting it sit for a while. The liquid can help to provide a 'quick boost' to ailing houseplants or young seedlings and transplants (I recommend diluting it quite a bit for use on seedlings). Stu Campbell, in Let it Rot, says that the same compost - make several batches of tea. When you're finished making compost tea, use the mucky dregs as a mulch in the garden or landscape.
||How does compost benefit the soil? - Compost does several things to benefit the soil that synthetic fertilizers cannot do. First, it adds organic matter, which improves the way water interacts with the soil. In sandy soils, compost acts as a sponge to help retain water in the soil that would otherwise drain down below the reach of plant roots (in this way, it protects plants against drought). In clay soils, compost helps to add porosity (tiny holes and passageways) to the soil, making it drain more quickly so that it doesn't stay waterlogged and doesn't dry out into a bricklike substance. Compost also inoculates the soil with vast numbers of beneficial microbes (bacteria, fungi, etc.) and the habitat that the microbes need to live. These microbes are able to extract nutrients from the mineral part of the soil and eventually pass the nutrients on to plants.
||Compost Compost FAQ
||Compost Directory, Science, Use,