The art of composting is really an art of living, a conscious decision to give back to the earth that which we take.
"In our every deliberation, we must consider the impact of
our decisions on the next seven generations."
The Iroquois Indian's Great Law of Peace
A compost pile is really a teeming microbial farm! Microorganisms, such as bacteria and fungi, are naturally present on food and yard trimmings added to the pile. These organisms decompose organic materials into rich, earthy-smelling organic matter. Earthworms, centipedes, beetles, millipedes and other organisms are also involved in the decomposition process.
There are many different methods of composting. The type and amount of material you have to compost, and the amount of time you can devote to it, will determine the system that is best for you.
Bacteria & Fungi
Hot composting is the quickest method and is good for composting large amounts of material. This method depends on heat loving and heat generating bacteria. In order for these bacteria to thrive, the pile should be of correct size, have the proper temperature, and have the proper balance of food, water and air. If these conditions are met, the microorganisms will raise the temperature of the pile to 140 degrees Fahrenheit or more, hot enough to burn your hand! The heat from this rapid decomposition is enough to kill most weeds and disease-causing organisms.
The slow composting method is largely the same but is for people who can devote less time and attention to the process. Decomposition takes longer because conditions aren't optimal for the fast-acting, heat-loving bacteria. Bacteria and fungi that function at mild temperatures are the primary decomposers here.
Materials to Use
Just about anything that was once alive can be composted. All living things are made up of large amounts of carbon (C) combined with smaller amounts of nitrogen (N). The microorganisms in your compost pile will work quicker if fed a diet of 30 parts carbon to 1 part nitrogen (30:1).
It helps to think of materials high in nitrogen as "greens," and carbon-rich materials as "browns." Grass clippings, manure, food scraps, and fresh garden trimmings are examples of greens. Dry leaves, straw, wood chips, nut shells, and sawdust are examples of browns. A good guide to get the right balance of greens to browns is to use roughly half browns and half greens when building your pile.
A pile that is too high in browns will stay cool and sit a long time without breaking down. A pile too high in greens can get slimy and have a foul odor.
GREENS (nitrogen-rich materials)
- Grass clippings
- Green weeds
- Garden trimmings
- Coffee grounds
- Kitchen scraps
BROWNS (carbon-rich materials)
- Dry leaves
- Straw, twigs
- Wood chip
- Corn stalks
- Dry weeds
- Nut shells
Materials Not to Use In Compost:
- Meats, fats, oils, dairy
- Large branches or logs (unless shredded)
- Plastics or synthetic fibers
- Manure from carnivorous (meat eating) animals
- Diseased plants or plants suffering from severe insect attack
- Weeds with seeds
- Invasive plants and weeds (Ivy, succulents, Bermudagrass, morning glory)
- Plants that have been treated with herbicides
- Charcoal ashes
Preparing the Materials
The more surface area the microorganisms have to work on, the faster the materials will decompose. Chop up large kitchen scraps into smaller pieces. Cut or bruise yard trimmings with a shovel or machete, or put them through a chipper or shredder.
Some materials may be run over with a rotary lawn mower. The harder or the more woody the tissues, the smaller they need to be chopped.
Click here for instructions on how to make bins
Backyard composting can be done in homemade bins, store-bought bins, or in an open pile without a bin. The ideal size of the pile or bin is one cubic yard (3' x 3' x 3'). Multiple piles or bins are recommended for different stages of composting.
The benefits of using a bin are they can help the pile retain moisture, they help to achieve the optimum pile dimensions, and some people find them more attractive than an open pile. An open pile, on the other hand, is cost-free and is very easy to turn.
Homemade bins can be constructed out of many materials such as wire mesh, scrap wood or pallets, a combination of wood and wire, or concrete blocks. A barrel composter can be built out of a 55 gallon barrel, with holes and a loading door cut out. Enclosed containers should have slits for air to enter. Bins can have one, two or more compartments for compost in different stages of decomposition.
There are many pre-made compost bins on the market. Plastic bins with lids help the contents of the bin stay damp, reducing evaporation by recycling water that condenses on the interior of the lid. Plastic bins should be thick and durable so they won't crack in the sun.
Place the pile or bin in a shady location out of the wind to reduce evaporation, and locate it over soil so water can drain down and decomposing organisms can come up. Consider locating an open pile in the corner against a block wall - this gives you two "sides" and will help reduce water loss.
A cubic yard is the minimum size of a hot compost pile.
Finished compost should look dark, should crumble easily in your hand and have a fresh, earthy smell.
In a HOT compost pile, enough materials are added to create a 3' x 3' x 3' pile all at once. Piles smaller than 3 feet cubed will have trouble holding heat, while piles larger than 5 feet cubed don't allow enough air to reach microorganisms at the center.
Alternate layers of green and brown materials. Begin with a thick layer of coarse, bulky material, such as sunflower stalks or flowers, to allow air to circulate in the pile. Then layer greens and browns and mix the layers together.
When adding food scraps, try to place them in the active center of the pile, and always cover them with a thick layer of dry materials to avoid attracting flies or critters.
Spray the materials with water as you build the pile. Continue mixing greens and browns until the pile is 3-4 feet high, and then do not add more materials.
In one to three days, the temperature in the pile should rise considerably - a sign that the microorganisms are busy!
After a few days to a week, the temperature will drop, a sign that conditions are less optimal for the decomposing organisms, and the pile needs to be turned and moistened again.
Turning releases heat and brings in fresh oxygen to the microbes. If a moveable compost bin is being used, remove it and place it next to the pile, and move the compost into it with a pitchfork. Similarly, if you are using an open pile turn the material over into a new pile. You can also just "fluff" the pile with a pitchfork to add oxygen. If you're using more than one bin, fork the compost into the next bin. As you turn it, move the drier outer materials to the active center of the pile.
Limiting moisture the biggest mistake that people make! The composting material should be as moist as a well wrung-out sponge. This is rather wet, especially in our dry climate. If you've got an automatic irrigation system, consider hooking your compost pile up with a micro spray head. A layer of straw, plastic or carpet scraps on top of the pile helps keep its outer edges moist. But don't go overboard. If the pile is soggy or emits a foul, ammonia-like odor, it is too wet. Add dry ingredients, fluff the pile, and let it dry out.
Once you've turned and watered the pile, you've made the conditions good once more for the microorganisms, and the temperature should rise again, though probably not as high a temperature as the initial buildup. This process should be repeated several times, turning about once every 7-10 days, until the temperature ceases to rise significantly.
At this point most of the readily-available nutrients have been consumed by the microorganisms, and you should have a dark, rich compost, with very little of the original materials recognizable. Most batches of finished compost will have some materials that haven't broken down enough. A sifter with a 1/2" mesh is good for screening out these materials, which can then be returned to the compost pile or used as mulch.
Its best to let the sifted compost sit for a week or two for final "curing" before use. Don't let it sit too long though, especially where it will dry out, or it can lose many of its valuable nutrients and qualities.
In a SLOW compost pile, materials are added as they are generated, rather than all at once, and the high temperatures of a hot pile may not be reached. The pile should be turned as often as possible, ideally once a week. Don't worry though, the materials in your pile will eventually compost even if never turned. Turning merely speeds up the process.
Continue adding materials to the bin, mixing the greens and browns, until it is full. The materials will reduce significantly in volume as the composting process takes place. If the pile is never completely turned, the compost on the bottom of the pile will mature first. Some bins have a bottom opening to harvest this finished compost. Others require the bin to be pulled up over the mature compost for harvesting.
If you don't have a "continuous feed" system, where you are regularly adding materials to the top and pulling the mature compost out of the bottom, it is best to have more than one composting bin or pile. This way you can eventually stop adding materials to one bin and allow everything to decompose until finished.
Benefits of Compost
In loose sandy soils, compost helps to bind unconsolidated particles together to retain water and nutrients that would normally wash right through. Added to a clay or silt soil, compost breaks up the small tightly bound particles, allowing water to drain and air to penetrate.
Compost is considered a soil conditioner, rather than a fertilizer, but it can contain a good range of plant nutrients. Of special importance are the micronutrients present in compost. They are needed in small doses by plants, yet micronutrients are often absent from commercial fertilizers. Additionally, the naturally occurring nutrients in compost are released slowly at a rate which the plants can use best.
Soil improved with compost holds more moisture (100 pounds of humus can hold 195 pounds of water).
Compost helps to build good soil structure, reducing erosion.
Compost can help plants overcome soil pH levels that are either too acidic or too high alkaline.
Beneficial Soil Life
The rich soil life in compost, such as redworms, centipedes, sow bugs, bacteria, and others, helps to control diseases and pests that might otherwise overrun a more sterile soil lacking natural checks against their spread.
Reduces Dependence on Energy-Intensive Chemical Fertilizers
The chemical system of gardening and agriculture depends extensively on the use of nonrenewable energy reserves which are increasingly tied to geopolitical issues. Using compost and organic gardening practices will help us achieve energy independence.
- Spread compost 1-4 inches thick over the garden area and work into the top 4 inches of soil. Add twice a year, ideally a month before planting.
- Once or twice a year, loosen the top few inches of soil in your annual and perennial beds and work into it an equal quantity of compost.
- Use as a mulch, 2-3 inches deep around plants, to prevent water loss through evaporation and to smother weeds.
- Every spring, use an aerator on your lawn and then spread a mixture of fine finished compost and bonemeal.
- Sift compost and add to household potting mixes. To rejuvenate the soil in indoor plant pots, scratch an inch or so of compost into the surface twice a year.
- Use sifted compost in seed germinating mixes. Sandy soil has quick drainage and is low in nutrients. Clay soil can store many important nutrients, but is difficult for roots and water to penetrate.
"The nation that destroys its soil destroys itself."
Franklin D. Roosevelt
Store kitchen scraps in a container with a tight-fitting lid until ready to add to the compost bin.
Composting Demonstration Gardens
Visit the following demonstration gardens to see composting bins and learn more:
Ojai Community Demonstration Garden
415 Ventura Street
Conejo Valley Botanic Garden
Conejo Community Park
Dover & Hendrix Avenues.
Cornucopia Community Garden
Telephone Rd, between Johnson & Ramelli