What is compost? What is composting?
Composting has a long history that dates back thousands of years. Ancient civilizations, including the Greeks and Romans, recognized the value of using organic matter to improve soil fertility. The Chinese were also known to have practiced composting as early as 1000 BC, and in Japan, composting was an important part of the traditional agricultural system.
In the Middle Ages, European farmers also used composting to improve soil quality and increase crop yields. In the 18th century, the famous agriculturalist Jethro Tull wrote about the benefits of composting in his book "Horse-Hoeing Husbandry". During the 19th and 20th centuries, many scientists and farmers began to study and experiment with composting methods to better understand the process and improve its effectiveness.
Composting is a complex biological process that involves the breakdown of organic materials through the action of microorganisms. These microorganisms, including bacteria, fungi, and other decomposers, feed on the organic materials, breaking them down into simpler compounds such as water, carbon dioxide, and nitrogen compounds.
Composting typically requires a mixture of "brown" materials, such as dried leaves, wood chips, or straw, which are high in carbon, and "green" materials, such as food scraps and grass clippings, which are high in nitrogen. The mixture needs to have the correct ratio of carbon to nitrogen to provide the right conditions for the microorganisms to thrive. The ideal ratio of carbon to nitrogen is around 30:1.
The composting process involves several stages, each of which is characterized by different types of microorganisms and environmental conditions. The first stage is called the mesophilic stage, during which the temperature of the compost pile rises to between 20 and 45 degrees Celsius. In this stage, bacteria and fungi break down simple sugars, starches, and proteins.
The second stage is called the thermophilic stage, during which the temperature of the compost pile rises to between 45 and 70 degrees Celsius. In this stage, thermophilic bacteria and fungi break down complex organic materials such as cellulose, hemicellulose, and lignin. The high temperatures in this stage also help to kill off pathogens and weed seeds that may be present in the compost pile.
The final stage is called the maturation stage, during which the temperature of the compost pile cools down, and the compost becomes stable and mature. In this stage, the compost is rich in nutrients such as nitrogen, phosphorus, and potassium, and can be used as a soil amendment to improve soil fertility, water retention, and structure.
Starting a DIY Compost
Starting a compost is easy and can be done in a few simple steps:
- Choose a location: Select a dry, level spot in your yard that receives some sunlight but is also shaded to avoid drying out. Avoid placing your compost pile too close to your house or your neighbor's property.
- Decide on a compost bin: You can either purchase a compost bin or build one yourself using materials like wood pallets or chicken wire. If you live in an urban area, consider a vermicomposting bin that uses worms to break down the organic material.
- Gather materials: You will need a mix of "brown" materials (high in carbon) and "green" materials (high in nitrogen) to start your compost pile. Brown materials include dry leaves, wood chips, and shredded newspaper. Green materials include fruit and vegetable scraps, grass clippings, and coffee grounds. Aim for a 3:1 ratio of brown materials to green materials.
- Start layering: Begin by adding a layer of brown materials to the bottom of the compost bin. Then, add a layer of green materials on top. Continue layering until the bin is full or you have used up all of your materials.
- Add water: Moisture is important for the composting process, so water your compost pile lightly after each layer is added. Be careful not to add too much water, which can make the pile too wet.
- Turn the pile: After a week or two, use a garden fork or shovel to turn the pile. This will introduce oxygen into the mix and help the compost to decompose more quickly. Continue to turn the pile once a week.
- Monitor the pile: Check the compost pile regularly to make sure it is not too wet or too dry. A properly maintained compost pile should not smell bad. If it does, it may indicate that it is too wet or there is not enough oxygen.
Carbon to Nitrogen Ratio
To measure and make sure you have a carbon to nitrogen ratio of 30:1, you will need to know the carbon and nitrogen content of the materials you are using to make your compost pile.
One way to determine the carbon to nitrogen ratio of a material is to use a compost calculator or reference chart. These resources provide a list of common organic materials and their carbon to nitrogen ratios, allowing you to estimate the overall ratio of your compost pile.
To ensure a balanced carbon to nitrogen ratio in your compost pile, you can mix brown materials, which are high in carbon, with green materials, which are high in nitrogen. A general rule of thumb is to aim for a mix of about three parts brown materials to one part green materials.
Some common brown materials include dry leaves, wood chips, straw, and shredded paper. Some common green materials include fruit and vegetable scraps, grass clippings, and fresh plant trimmings.
As you build your compost pile, you can use a compost thermometer to monitor the internal temperature of the pile. A well-maintained compost pile should reach a temperature of at least 130°F (54°C) during the thermophilic stage, which is when the bulk of the decomposition occurs. If the temperature is too low, it may indicate a lack of nitrogen in the pile, while a temperature that is too high may indicate an excess of nitrogen.
By monitoring the carbon to nitrogen ratio and temperature of your compost pile, you can ensure that your composting process is effective and efficient, and that your compost will be a high-quality soil amendment for your garden or landscaping.
Avoiding Anaerobic Conditions
To avoid going anaerobic during composting, it is important to maintain adequate levels of oxygen in the compost pile. Anaerobic conditions occur when there is not enough oxygen in the pile for aerobic bacteria to thrive, and instead, anaerobic bacteria take over, producing unpleasant odors and slowing down the composting process.
- Build a properly sized pile: A compost pile that is too small will not retain enough heat to maintain aerobic conditions. A pile that is too large, on the other hand, may compact and limit airflow. Aim for a pile that is at least 3 feet high and 3 feet wide.
- Add the right mix of materials: The ideal compost pile contains a mixture of "brown" materials (high in carbon) and "green" materials (high in nitrogen). Avoid adding large amounts of high-moisture materials like food waste, which can create anaerobic pockets.
- Turn the pile regularly: Turning the pile with a pitchfork or compost aerator once a week will introduce fresh oxygen and help to distribute moisture and heat evenly throughout the pile.
- Monitor moisture levels: Compost needs moisture to decompose, but too much moisture can create anaerobic conditions. Aim for a moisture content of around 50% (the consistency of a wrung-out sponge). If the pile is too dry, add water; if it is too wet, add more brown materials.
- Use a compost thermometer: Measuring the internal temperature of the pile regularly will help you to know when to turn the pile and ensure that it stays in the aerobic range (between 130°F and 160°F).
What can I put in compost?
- Fruit and vegetable scraps
- Coffee grounds and filters
- Tea leaves and tea bags
- Eggshells
- Grass clippings
- Dry leaves and plant trimmings
- Shredded newspaper and cardboard
- Wood chips and sawdust
- Hay and straw
- Houseplants and flowers
- Nut shells (except for walnut shells, which can contain a chemical that inhibits plant growth)
- Cotton and wool rags
What not to put in compost?
- Meat, dairy, and fatty foods: These materials can attract rodents and other pests, as well as create unpleasant odors.
- Oils and grease: These materials can also attract pests, as well as make it difficult for other materials in the compost bin to break down properly.
- Bones: Bones take a long time to break down and can attract pests.
- Diseased plant material: Plant material that is infected with a disease or pest should not be added to the compost bin, as it can spread the problem to other plants.
- Weeds that have gone to seed: Weeds that have gone to seed should be avoided, as they can spread and create more weeds in your garden.
- Cat and dog waste: Pet waste can contain harmful bacteria and should not be added to the compost bin.
- Charcoal ash: Ash from charcoal can contain chemicals that are harmful to plants.
- Synthetic chemicals or treated wood: These materials can contain toxins that can contaminate your compost and harm your plants.
- Large branches or logs: These materials take a long time to break down and can make it difficult to turn the compost.
Benefits of Composting
- Reduces Landfill Waste: When food scraps and yard waste are thrown into the trash, they take up valuable space in landfills. Composting these materials instead reduces the amount of waste that ends up in landfills, which can help reduce greenhouse gas emissions and extend the lifespan of landfills.
- Improves Soil Quality: Compost is rich in nutrients and helps improve soil quality by providing essential nutrients to plants and improving soil structure. This can result in healthier plants, better yields, and reduced need for synthetic fertilizers.
- Reduces Water Use: Compost helps soil retain moisture, which can reduce water use in the garden. This is particularly important in areas with limited water resources or during drought conditions.
- Controls Erosion: Compost can help prevent erosion by improving soil structure and reducing runoff. This can help protect water quality and prevent soil from washing away.
- Reduces Greenhouse Gas Emissions: When organic materials break down in landfills, they can produce methane, a potent greenhouse gas. Composting these materials instead can help reduce greenhouse gas emissions.
- Compost can be used as an alternative to synthetic fertilizers. Unlike synthetic fertilizers, which can leach into waterways and harm the environment, compost provides a slow-release source of nutrients that are released over time as the organic material breaks down
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