Composting




Benefits and Uses of Compost
What to Compost
What not to Compost and Why
Composting Methods
Compost Pile Temperature
Particle Size
Build a Pile
Managing a Compost System
Finishing/Curing
How to Use Compost


All composting requires three basic ingredients:

Browns - This includes materials such as dead leaves, branches, and twigs.
Greens - This includes materials such as grass clippings, vegetable waste, fruit scraps, and coffee grounds.
Water - Having the right amount of water, greens, and browns is important for compost development.

Your compost pile should have an equal amount of browns to greens. You should also alternate layers of organic materials of different-sized particles. The brown materials provide carbon for your compost, the green materials provide nitrogen, and the water provides moisture to help break down the organic matter.
 

Benefits and Uses of Compost 1

Compost offers many benefits to the landscape and garden. For example, compost:
 Improves soil tilth condition, and structure;
Increases the soil's ability to hold water and nutrients;
Supports living soil organisms;
Helps dissolve mineral forms of nutrients;
Buffers soil from chemical imbalances;
May provide biological control of certain soil pests;
Helps return organic materials to the soil, and keeps them out of landfills and waterways.
Compost can be used as a mulch, a liquid "fertilizer", or incorporated into the soil or potting mixes.
 

What to Compost 2
 
Fruit and Vegetables
Eggshells
Coffee grounds and filters
Tea bags
Nut shells
Shredded newspaper
Cardboard
Paper
Yard trimmings
Grass clippings
Houseplants
Hay and straw

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What not to Compost and Why 2
 
Black walnut tree leaves or twigs
- Releases substances that might be harmful to plants

Coal or charcoal ash
- Might contain substances harmful to plants

Dairy products (e.g., butter, milk, sour cream, yogurt) and eggs*
- Create odor problems and attract pests such as rodents and flies

Diseased or insect-ridden plants
- Diseases or insects might survive and be transferred back to other plants

Fats, grease, lard, or oils*
- Create odor problems and attract pests such as rodents and flies

Meat or fish bones and scraps*
- Create odor problems and attract pests such as rodents and flies

Pet wastes (e.g., dog or cat feces, soiled cat litter)*
- Might contain parasites, bacteria, germs, pathogens, and viruses harmful to humans

Yard trimmings treated with chemical pesticides
- Might kill beneficial composting organisms

 

* Check with your local composting or recycling coordinator to see if these organics are accepted by your community curbside or drop-off composting program.

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Composting Methods 1

Cold or "Slow" Composting
Hot or "Fast" Composting
Using Earthworms

Cold / Slow Composting is for people who have more carbon (brown) material than nitrogen (green) material, and are not concerned about a slow composting rate, a desire for weed seed destruction, or a need for plant disease suppression.
There are four ways to Cold/Slow compost: Sheet Composting, Trench Composting, Cold Bin Composting and Heap Composting.

Sheet Composting involves top-dressing organic material on the soil surface and allowing the materials to decompose without further manipulation. As the materials decompose, compost filters slowly into the soil below. Leaves, wood chips, and other mulches are examples of sheet composting.

Trench Composting is a relatively straight-forward method of composting directly in the soil. This method does not require a bin. Simply dig a trench 8 inches deep in the garden area, fill with 4" of kitchen scraps and backfill with soil.
After a few months, the material will have decomposed sufficiently for planting above the compost trench. For large amounts of material, consider roto-tilling the material into the soil, and waiting a season before planting.

Cold Bin Composting. Simply fill your compost bin halfway with browns and bury kitchen scraps in the bin. After a month or so, start layering kitchen scraps and thoroughly covering with browns and a little soil. Keep adding material throughout the year. As the bin fills up, start a second compost bin. After a year or so, the material in the first bin will have decomposed enough for most landscape uses. Start harvesting from the bottom of the pile. With Cold Bin composting, bury or cover new material with browns. Exposed food will attract pests.

Heap Composting. You do not have to have a bin to have a compost system. A compost heap can be created anywhere in your yard, it's simply a collection of compostable materials placed in a designated area. However, bins help keep the compost neat and tidy, and may help you exclude pests if they are a problem.

Hot / Fast Composting will yield the fastest rate of composting and best control of weed seed and plant pathogens. Hot composting is also the most intensive method and requires several elements to succeed, including:

A minimum of 1 cubic yard of material to start the pile
A blend of greens and browns (C:N Ratio)
Proper moisture content
Frequent turning to provide aeration
Particle size of less than 2" - 3"

Using Earthworms. Many people know the value of worms in their garden. Worms are great decomposers, especially red-wigglers and African night crawlers. If you generate only kitchen and table scraps, or if you live in an apartment, composting with worms (officially called "vermicomposting") is the way to go.

Vermicomposting, Florida's Online Composting Website ext. link
Vermicomposting from the University of Nebraska Extension pdf

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Compost Pile Temperature 1

Compost pile temperature is a function of the biological activity within the composting system, and, to some extent, its exposure to the sun. When microbes flourish, they will raise the pile temperature through their metabolism, reproduction, and conversion of composting materials to energy.
The main reason to be concerned about pile temperature is that maintaining a minimum pile temperature of 131°F for 3 days is desirable to destroy weed seeds or plant pathogens. To establish this highly efficient biological system requires the proper food balance (a mixture of nitrogen and carbon rich materials), sufficient pile size (approximately one cubic yard), oxygen and adequate moisture content (moist but not soggy).
 

Particle Size 1

Smaller materials have more surface area available for microbes to attack. Therefore, reducing the particle size of raw materials will increase the speed of the composting process. Size reduction also reduces the volume of the compost pile, thereby saving space.
It is a good idea to chip or mulch small limbs and twigs to a size of 2-3 inches before composting.
Particle size can be too small. For example, sawdust sized and wet materials can decrease aeration, reduce the rate of composting and perhaps cause anaerobic conditions leading to odor problems.


Build a Pile 1

Sandwich Method: Layer compost materials/ingredients into the composting system using a balance of Green and Brown materials. Over time, you will develop a unique "recipe" for your composting system.

Cross Section of Layering in Compost Bin
Fig. 1 Cross Section of Layering in Compost Bin 


Mix-it! Method: If you are using a "no-turn" method, or if you want to speed up the composting process, try the Mix It! Method. Simply
mix up the green and brown materials before adding them to the compost system. This prevents the moist greens (grass clippings, for example) from forming compact layers that may restrict the flow of water and oxygen through the pile.
Add the mixture to the compost system in 4" batches. Water each batch so that the moisture is evenly distributed. It's really difficult to
get water into the whole pile after the pile has been built, so add water as you build the pile.

You can add fresh materials to an actively (or passively) composting pile. One way to add materials to an existing pile is to add them as you mix or turn the pile. Burying new materials in the pile also works well. Eventually, you will want to start a second batch of compost for adding fresh materials. This will give the first batch of compost time to stabilize and mature.

The materials you add will supplement the existing food base. If you add more greens, the effect will be adding nitrogen and potentially speeding up the composting process, increasing moisture, and/or heating up the pile. If you add more browns, the effect will be increasing carbon, and potentially slowing the composting process, drying out the pile, and/or reducing pile temperature.

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Managing a Compost System 1

Monitor Smell: Turn if there are any odors. Add "browns" if odors persist. Use a brown layer on top of compost pile. Why? It will absorb odors and discourage flies. Your family, friends, and visitors will appreciate it.

Monitor Moisture: Add moisture as you BUILD the pile. Add moisture as you TURN the pile. If too wet, turn (without adding more water).

If still too wet, add dry "browns" to pile while turning. Why? Because microbes require moisture to survive, but too much moisture will create odor problems and slow the composting rate.

Monitor Temperature: If you are using a hot composting method: Turn if the pile is less than 100°F. Turn if the pile is more than 150°F
Why? Because the Thermophilic bacteria prefer temperatures in the 105-140°F range, and these microbes are the fastest at converting raw materials to compost.
If the compost pile exceeds 155°F, or so, it may be too hot for the bacteria population to thrive. At higher temperatures the heat may actually kill off part of the population. If this happens, the temperatures will fall off and the populations will slowly rebuild.

Mixing and Turning Compost: The compost pile should be mixed and/or turned periodically, depending on how quickly and completely you want your compost to breakdown. Turning is also the first line of defense for any problems that may occur during the composting process. You can use a pitchfork, shovel or specialized tools for this purpose.
Turning has many benefits, including: Adds Oxygen. Helps Destroy Undesirables. Reduces odor problems. Breaks up clumps and layers.


 Finishing/Curing 1

Many people wonder how to create finished compost if they are always adding materials to the compost bin. The secret is to make composting a batch process. After a while of composting in one bin, set the compost aside to finish the composting process for "curing" period. Curing or "finishing" is the process of allowing materials in the compost system to finish the composting process at lower temperatures. Earthworms and other invertebrates will assist with this process. Make sure the compost is moist and aerated during the curing period, which can be as short as one month or as long as a year or more.
While one batch of compost is curing, you can start a second composting bin for your active composting process. In this manner, you can make your compost and use it too!


How to Use Compost 1

Compost as Soil Amendment: Use compost as a soil amendment to increase the organic matter in the soil. Organic matter is critical for plant development and growth (see benefits of compost). Tropical and subtropical soils are notorious for their lack of this material. Whereas temperate soils may have up to 50% organic matter, sub-tropical soils typically have 1% or less. Compost can help raise organic matter in soils.

Compost as Mulch: The forest floor is a natural composting system in which leaves are mulch on the soil surface, and then gradually decompose, recycling nutrients and conditioning the soil. Likewise, yard debris such as leaves, grass clippings, or shredded branches can be used as mulch in the landscape and allowed to compost on the soil surface. Over time, the mulch will compost in place.

Compost as Potting Mix: Compost can be used as an excellent potting soil for your container nursery. Compost offers good water retention qualities and some basic nutrients. However, gardeners should use only fully decomposed (called "finished") compost as a potting mix. Container grown plants need a potting soil that retains moisture, but is well drained. Most gardening enthusiasts blend compost with coarse sand, perlite, vermiculite, etc. to make optimal planting media.

Compost as Tea: Compost tea is a method of using your compost nutrients for indoor plants, potted plants with no room for additional soil, and foliar applications (spraying on plant leaves).
To make compost tea, follow this procedure: Step 1 - Fill a woven bag (e.g., burlap) with finished* compost. Step 2 - Place the bag in a barrel or bucket of water. Step 3 - Let sit an hour. Step 4 - Remove the bag. Step 5 - Use the resulting liquid, "compost tea" to water plants. Step 6 - Empty the contents of the bag into the garden and use as compost mulch or soil amendment.



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Bibliography

1 "The Compost Happens Tutorial." sarasota.ifas.ufl.edu. N.d. Web. 28 May 2014.
2 "Composting at Home." epa.gov. N.d. Web. 28 May 2014.

Photograph

Fig. Cross Section of Layering in Compost Bin. N.d. sarasota.ifas.ufl.edu. Web. 28 May 2014.

Published 28 May 2014 LR. Updated 16 May 2015 LR
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