Anything that grows decomposes eventually; composting simply speeds up the process by providing an ideal environment for bacteria, fungi, and other decomposing organisms such as worms, sowbugs, and nematodes to do their work.
The resulting decomposed matter, which often ends up looking like fertile garden soil, is called compost. Organic discards can be processed in industrial-scale composting facilities, in smaller-scale community composting systems, and in anaerobic digesters, among other options.
This guide focuses primarily on home composting, which is a great way to keep your organic discards out of the waste stream and produce a valuable soil amendment for your own use. Composting is a great way to recycle the organic waste we generate at home. Food scraps and garden waste combined make up more than 28 percent of what we throw away. Not only is food waste a significant burden on the environment , but processing it is costly. With the United States generating more than million tons of municipal waste in and sending two-thirds of that to landfills and incinerators, we spent billions of dollars on waste management.
Composting at home allows us to divert some of that waste from landfills and turn it into something practical for our yards. When compostable waste goes to a landfill, it gets buried under massive amounts of other trash, cutting off a regular supply of oxygen for the decomposers.
The waste then ends up undergoing anaerobic decomposition , being broken down by organisms that can live without free-flowing oxygen. During anaerobic decomposition, biogas is created as a by-product. This biogas is roughly 50 percent methane and 50 percent carbon dioxide , both of which are potent greenhouse gases, with methane being 28 to 36 times more effective than CO 2 at trapping heat in the atmosphere over a century. Although most modern landfills have methane capture systems, these do not capture all of the gas; landfills are the third-largest source of human-generated methane emissions in the United States.
Because our solid waste infrastructure was designed around landfilling, only about 6 percent of food waste gets composted. However, states, cities, and individual businesses and vendors can spearhead zero-waste strategies to increase composting and recycling rates within their jurisdictions and to keep waste from being generated in the first place.
There have been many composting success stories around the country, one notable example being San Francisco. In San Francisco established a large-scale composting program, and by it was able to divert 50 percent of its waste from landfills. By increasing its goals over the years, San Francisco has been diverting more than 80 percent of waste from landfills since That means more than 90, metric tons of carbon emissions are avoided each year—equivalent to the annual greenhouse gas emissions from 20, passenger vehicles.
Compost is an essential tool for improving large-scale agricultural systems. Compost contains three primary nutrients needed by garden crops: nitrogen, phosphorus, and potassium. It also includes traces of other essential elements like calcium, magnesium, iron, and zinc.
Instead of relying on synthetic fertilizers that contain harmful chemicals , composting offers an organic alternative. Irrigation systems are effective but are expensive and time-consuming for farmers to manage. Additionally, water is becoming increasingly difficult to obtain across the country.
How can compost help? Research has shown the water-retaining capacities of soil increase with the addition of organic matter. In fact, each 1 percent increase in soil organic matter helps soil hold 20, gallons more water per acre. By using compost to foster healthy soil, farmers do not have to use as much water and can still have higher yields compared with farming with degraded soil. Consumers are responsible for a staggering amount of wasted food.
NRDC research in three U. According to a report in The Guardian , U. The best way to reduce impacts from food waste is to prevent waste from occurring in the first place, so NRDC works through its Save the Food campaign and other tools to educate consumers on how to shop for, prepare, and store food to minimize waste.
However, even if we do everything possible to decrease food waste, there will still be food scraps that cannot be consumed e. Composting is a great way to recycle those discards instead of tossing them in the trash. Composting can be done both indoors and outdoors and can be as complicated or as simple as you would like.
The best way for you to compost at home depends on several factors:. There are two main types of backyard composting: cold also known as passive composting and hot also called active composting. Cold composting breaks down organic matter slowly, but it also takes the least amount of effort and maintenance.
Anything organic decomposes eventually; cold composting is just letting Mother Nature do her job with minimal intervention on your part. You do not need to worry about the ratio of compost ingredients, aerate regularly, or monitor moisture levels.
Cold composting is the best process if you have little organic waste to compost and not much time to tend to the process, and if you are not in a hurry for finished compost. However, depending on what kind of cold method you use, it can take one to two years before you get usable compost. A cold composting process is primarily anaerobic, meaning that your discards are broken down by microorganisms that thrive in an oxygen-deprived environment. In addition to being slower to break down, cold piles may be smellier or wetter than hot piles.
Hot composting is a faster, but more managed, compost process. This method requires attention to keep carbon and nitrogen in the optimum ratio to decompose organic waste. It also requires the right balance of air and water to attract the organisms that thrive in an oxygen-rich environment.
Under ideal conditions, you could have the final compost product in four weeks to 12 months. If managed correctly, the high temperature of the pile will destroy most weeds, plant diseases, pesticides, and herbicides, plus any bug larvae or eggs. Organisms that decompose organic waste need four key elements to thrive: nitrogen, carbon, air, and water.
Since all compostable materials contain carbon, with varying amounts of nitrogen, composting successfully is just a matter of using the right combination of materials to achieve the best ratio of carbon to nitrogen and maintaining the right amounts of air and water to yield the best results.
The ideal carbon-to-nitrogen ratio for a compost pile is 25 to 30 parts carbon for every 1 part nitrogen. If your pile has too much carbon-rich material, it will be drier and take longer to break down. Too much nitrogen-rich material can end up creating a slimy, wet, and smelly compost pile. Fortunately, these problems are easily remedied by adding carbon-rich or nitrogen-rich material as needed. A higher nitrogen-to-carbon ratio is most commonly found in fresh organic material often referred to as greens.
Having plenty of greens in your compost pile makes sure the decomposers can grow and reproduce quickly. Some household greens you can add to your home compost pile are fresh grass clippings, food scraps, and coffee grounds. Carbon acts as a food source for decomposers , helping to keep them alive while they break down waste.
Typical browns you can add to a compost pile include dead leaves, branches, twigs, and paper. To achieve the best carbon-to-nitrogen ratio in your home compost, a rule of thumb is to put in two to four parts brown materials for every one part green materials. Oxygen and Water Finally, like any other living organism, decomposers need oxygen and water to survive.
To ensure a faster home composting process, you will need to make sure your compost system has the right amount of air and water. Right now most food and yard waste is sent to landfills. There, without the proper environment to be composted, they rot, releasing methane and carbon dioxide in the process.
Organic matter in landfills is the 3rd leading human-related cause of methane emissions in the U. By diverting your compostable waste from the landfills and back into the soil, you actually decrease the methane and carbon outputs of your local community. Methane gas is a greenhouse gas that is conservatively 28x more potent than CO2 in warming up the planet.
Public interest nonprofit U. PIRG released a report on composting in the U. Compost is home to a variety of friendly beneficial microbes that plants need around to absorb nutrients. To keep these friends around, plant roots will release carbohydrates from their roots to attract and feed the microbes under the soil. Where do the plants get this tasty party snack? They take CO2 from the air and water from their roots and through photosynthesis, turn it into carbohydrates, or sugars!
Together these sugars and the microbes who enjoy them create humus—not another party snack, but the part of the soil that retains soil-structure, nutrients and moisture. Thanks to the ecology that compost promotes, carbon once in the atmosphere can be stored underneath healthy soil where it will be kept with the proper regenerative farming techniques!
Trash is expensive…or at least the transportation and storage of it is. Composting has been shown to decrease landfill costs on a local level.
Just think about how much money we could save as a society if more businesses and local governments enacted composting programs! Here in the U. Composting transforms what literally would have been thrown into the trash into an incredibly valuable resource, one that will generate more food and revenue. By completing the food cycle, garbage becomes black gold.
By using compost, farmers and gardeners spend less money on expensive fertilizers and pesticides, water, and irrigation and can use that hard-earned cash for expanding their production capacities. This means more crops to sell and more money to be made. Want to do more to support your local farmers? Shop locally! This will keep you in tune to the needs of your local farms, and more than just helping farmers, your produce is guaranteed to be fresher and tastier! Volunteering is another great way to get involved.
Many farmers are so grateful for extra sets of hands and will probably send you home with some of the harvest. At home, composting can give you a much clearer idea about what you are throwing out and can begin to shape your grocery lists and consuming habits to help you save food and money!
Through composting, you may just spend less money on your garbage service bills too! Composting plants have been shown to create more jobs than other disposal facilities, such as landfills or incineration sites! These new, green jobs are vital in creating a carbon-neutral future and in making the U.
Our landfills are filling up. Not to add to your list of concerns, but the U. We could save a ton of space and time by composting our organic waste, instead of sending it to the landfills.
Due to erosion and the widespread use of chemical fertilizers and pesticides, soil across the country has lost much of its nutrient content. If the soil lacks essential nutrients, so does the food that grows there. Depleted soils have led to less nutrient-dense foods. Composting adds nutrients and fosters the growth of beneficial microorganisms, insects and earthworms.
It also helps to minimize wind and water erosion both by holding onto moisture in the soil and by encouraging healthy root growth. Overall, compost makes major contributions to soil health, increasing the chance of plant success. Spreading compost on crops minimizes the need for chemical fertilizers, the U. Environmental Protection Agency says. Compost not only provides the basic nutrients supplied by chemical fertilizers -- nitrogen, potassium and phosphorus -- it also provides a wide array of trace minerals and other nutrients not available in chemical fertilizers.
Less use of chemical fertilizers reduces their associated environmental problems, including water pollution. Nitrogen from these fertilizers causes algae blooms in lakes and the ocean, radically altering the coastal ecosystem.
Chemical fertilizers also leach into groundwater and contaminate drinking water wells.
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