Compost

organic farm in Washington Composting is an aerobic method of decomposing organic solid wastes, so it can be used to recycle organic material. The process involves decomposing organic material into a humus-like material, known as compost, which is a good fertilizer for plants. Composting organisms require four equally important ingredients to work effectively: Composting is most efficient with a carbon-to-nitrogen ratio of about 25:1. Hot composting focuses on retaining heat to increase the decomposition rate, thus producing compost more quickly. Rapid composting is favored by having a carbon-to-nitrogen ratio of about 30 carbon units or less. Above 30, the substrate is nitrogen starved. Below 15, it is likely to outgas a portion of nitrogen as ammonia. Nearly all dead plant and animal materials have both carbon and nitrogen in different amounts. Fresh grass clippings have an average ratio of about 15:1 and dry autumn leaves about 50:1 depending upon species. • Thermophilic bacteria do not reproduce and are not active between , yet are found throughout soil. They activate once the mesophilic bacteria have begun to break down organic matter and increase the temperature to their optimal range. Thermophilic bacteria thrive at higher temperatures, reaching in typical mixes. Large-scale composting operations, such as windrow composting, may exceed this temperature, potentially killing beneficial soil microorganisms but also pasteurizing the waste. Physical decomposers • Ants create nests, making the soil more porous and transporting nutrients to different areas of the compost. • Mesophilic phase: The initial, mesophilic phase is when the decomposition is carried out under moderate temperatures by mesophilic microorganisms. 2 to 8 days • Thermophilic phase: As the temperature rises, a second, thermophilic phase starts, in which various thermophilic bacteria carry out the decomposition under higher temperatures (.) • Cooling phase (also called Mesophilic II) • Maturation phase: As the supply of high-energy compounds dwindles, the temperature starts to decrease. Semicomposting is the degradation process that handles volumes of organic waste lower than that recommended for composting and therefore does not present a thermophilic stage, because mesophilic microorganisms are the only responsible ones, for the degradation of organic matter. Hot and cold composting – impact on timing The time required to compost material relates to the volume of material, the particle size of the inputs (e.g. wood chips break down faster than branches), and the amount of mixing and aeration. Such short processes involve some changes to traditional methods, including smaller, more homogenized particle sizes in the input materials, controlling carbon-to-nitrogen ratio (C:N) at 30:1 or less, and careful monitoring of the moisture level. Cold composting is a slower process that can take up to a year to complete. It results from smaller piles, including many residential compost piles that receive small amounts of kitchen and garden waste over extended periods. Piles smaller than tend not to reach and maintain high temperatures. Turning is not necessary with cold composting, although a risk exists that parts of the pile may go anaerobic as it becomes compacted or waterlogged. Pathogen removal Composting can destroy some pathogens and seeds, by reaching certain temperatures. Dealing with stabilized compost – i.e. composted material in which microorganisms have finished digesting the organic matter and the temperature has reached between – poses very little risk, as these temperatures kill pathogens and even make oocysts unviable. The temperature at which a pathogen dies depends on the pathogen, how long the temperature is maintained (seconds to weeks), and pH. Compost products such as compost tea and compost extracts have been found to have an inhibitory effect on Fusarium oxysporum, Rhizoctonia species, and Pythium debaryanum, plant pathogens that can cause crop diseases. Aerated compost teas are more effective than compost extracts. Compost is a good source of biocontrol agents like B. subtilis, B. licheniformis, and P. chrysogenum that fight plant pathogens. • Aspergillosis • Farmer's lung • Histoplasmosis – a fungus that grows in guano and bird droppings • Legionnaires' disease • Paronychia – via infection around the fingernails and toenails • Tetanus – a central nervous system disease Oocytes are rendered unviable by temperatures over . == Environmental benefits ==

Compost adds organic matter to the soil and increases the nutrient content and biodiversity of microbes in soil. Composting at home reduces the amount of green waste being hauled to dumps or composting facilities. The reduced volume of materials being picked up by trucks results in fewer trips, which in turn lowers the overall emissions from the waste-management fleet. == Materials that can be composted ==

Potential sources of compostable materials, or feedstocks, include residential, agricultural, and commercial waste streams. Residential food or yard waste can be composted at home, or collected for inclusion in a large-scale municipal composting facility. In some regions, it could also be included in a local or neighborhood composting project. Organic solid waste microorganisms. The two broad categories of organic solid waste are green and brown. Green waste is generally considered a source of nitrogen and includes pre- and post-consumer food waste, grass clippings, garden trimmings, and fresh leaves. Brown waste is a carbon source. Typical examples are dried vegetation and woody material such as fallen leaves, straw, woodchips, limbs, logs, pine needles, sawdust, and wood ash, but not charcoal ash. Products derived from wood such as paper and plain cardboard are also considered carbon sources. Human excreta Human excreta, sometimes called "humanure" in the composting context, can be added as an input to the composting process since it is a nutrient-rich organic material. Nitrogen, which serves as a building block for important plant amino acids, is found in solid human waste. Phosphorus, which helps plants convert sunlight into energy in the form of ATP, can be found in liquid human waste. Solid human waste can be collected directly in composting toilets, or indirectly in the form of sewage sludge after it has undergone treatment in a sewage treatment plant. Both processes require capable design, as potential health risks need to be managed. In the case of home composting, a wide range of microorganisms, including bacteria, viruses, and parasitic worms, can be present in feces, and improper processing can pose significant health risks. In the case of large sewage treatment facilities that collect wastewater from a range of residential, commercial and industrial sources, there are additional considerations. The composted sewage sludge, referred to as biosolids, can be contaminated with a variety of metals and pharmaceutical compounds. Insufficient processing of biosolids can also lead to problems when the material is applied to land. Urine can be put on compost piles or directly used as fertilizer. Adding urine to compost can increase temperatures, so can increase its ability to destroy pathogens and unwanted seeds. Unlike feces, urine does not attract disease-spreading flies (such as houseflies or blowflies), and it does not contain the most hardy of pathogens, such as parasitic worm eggs. Animal remains Animal carcasses may be composted as a disposal option. Such material is rich in nitrogen. Human bodies == Composting technologies ==

Industrial-scale composting In-vessel composting Aerated static-pile composting Windrow composting Other systems at household level Hügelkultur (raised garden beds or mounds) The practice of making raised garden beds or mounds filled with rotting wood is also called in German. It is in effect creating a nurse log that is covered with soil. Benefits of Hügelkultur garden beds include water retention and warming of soil. Buried wood acts like a sponge as it decomposes, able to capture water and store it for later use by crops planted on top of the bed. Composting toilets Related technologies • Vermicompost (also called worm castings, worm humus, worm manure, or worm faeces) is the end product of the breakdown of organic matter by earthworms. These castings have been shown to contain reduced levels of contaminants and a higher saturation of nutrients than the organic materials before vermicomposting. • Black soldier fly (Hermetia illucens) larvae are able to rapidly consume large amounts of organic material and can be used to treat human waste. The resulting compost still contains nutrients and can be used for biogas production, or further traditional composting or vermicomposting • Bokashi is a fermentation process rather than a decomposition process, and so retains the feedstock's energy, nutrient and carbon contents. There must be sufficient carbohydrate for fermentation to complete and therefore the process is typically applied to food waste, including noncompostable items. Carbohydrate is transformed into lactic acid, which dissociates naturally to form lactate, a biological energy carrier. The preserved result is therefore readily consumed by soil microbes and from there by the entire soil food web, leading to a significant increase in soil organic carbon and turbation. The process completes in weeks and returns soil acidity to normal. • Co-composting is a technique that processes organic solid waste together with other input materials such as dewatered fecal sludge or sewage sludge. • Small-scale and organic farms can also produce aerobic compost piles for crop bed preparation using a "turned pile" technique in which piles are formed with the appropriate ratios of nitrous, carbonous, and neutral materials, checked with a temperature gauge, and turned by-hand at weekly intervals. == Uses ==

Agriculture and gardening On open ground for growing wheat, corn, soybeans, and similar crops, compost can be broadcast across the top of the soil using spreader trucks or spreaders pulled behind a tractor. It is expected that the spread layer is very thin (approximately ) and worked into the soil prior to planting. Application rates of or more are not unusual when trying to rebuild poor soils or control erosion. In countries such as Germany, where compost distribution and spreading are partially subsidized in the original waste fees, compost is used more frequently on open ground on the premise of nutrient "sustainability". In plasticulture, strawberries, tomatoes, peppers, melons, and other fruits and vegetables are grown under plastic to control temperature, retain moisture and control weeds. Compost may be banded (applied in strips along rows) and worked into the soil prior to bedding and planting, be applied at the same time the beds are constructed and plastic laid down, or used as a top dressing. Many crops are not seeded directly in the field but are started in seed trays in a greenhouse. When the seedlings reach a certain stage of growth, they are transplanted in the field. Compost may be part of the mix used to grow the seedlings, but is not normally used as the only planting substrate. The particular crop and the seeds' sensitivity to nutrients, salts, etc. dictates the ratio of the blend, and maturity is important to insure that oxygen deprivation will not occur or that no lingering phyto-toxins remain. Compost can be added to soil, coir, or peat, as a tilth improver, supplying humus and nutrients. It provides a rich growing medium as absorbent material. This material contains moisture and soluble minerals, which provide support and nutrients. Although it is rarely used alone, plants can flourish from mixed soil that includes a mix of compost with other additives such as sand, grit, bark chips, vermiculite, perlite, or clay granules to produce loam. Compost can be tilled directly into the soil or growing medium to boost the level of organic matter and the overall fertility of the soil. Compost that is ready to be used as an additive is dark brown or even black with an earthy smell. and the possible tie up of nitrogen by incompletely decomposed lignin. It is very common to see blends of 20–30% compost used for transplanting seedlings. Compost can be used to increase plant immunity to diseases and pests. Compost tea Compost tea is made up of extracts of fermented water leached from composted materials. Composts can be either aerated or non-aerated depending on its fermentation process. Compost teas are generally produced from adding compost to water in a ratio of 1:4–1:10, occasionally stirring to release microbes. and soil-borne diseases. Community composting Community composting uses organic materials sourced from a local community. Sites used for compost piles include educational institutions or community gardens. Community composting programs may be involved in community education. The compost generated is used locally. Each community composting operation is generally smaller than a commercial composting operation. Other Compost can also be used for land and stream reclamation, wetland construction, and landfill cover. The temperatures generated by compost can be used to heat greenhouses, such as by being placed around the outside edges. == Regulations ==

There are process and product guidelines in Europe that date to the early 1980s (Germany, the Netherlands, Switzerland) and only more recently in the UK and the US. In both these countries, private trade associations within the industry have established loose standards, some say as a stop-gap measure to discourage independent government agencies from establishing tougher consumer-friendly standards. Compost is regulated in Canada and Australia as well. EPA Class A and B guidelines in the United States were developed solely to manage the processing and beneficial reuse of sludge, also now called biosolids, following the US EPA ban of ocean dumping. About 26 American states now require composts to be processed according to these federal protocols for pathogen and vector control, even though the application to non-sludge materials has not been scientifically tested. An example is that green waste composts are used at much higher rates than sludge composts were ever anticipated to be applied at. U.K guidelines also exist regarding compost quality, as well as Canadian, Australian, and the various European states. In the United States, some compost manufacturers participate in a testing program offered by a private lobbying organization called the U.S. Composting Council. The USCC was originally established in 1991 by Procter & Gamble to promote composting of disposable diapers, following state mandates to ban diapers in landfills, which caused a national uproar. Ultimately the idea of composting diapers was abandoned, partly since it was not proven scientifically to be possible, and mostly because the concept was a marketing stunt in the first place. After this, composting emphasis shifted back to recycling organic wastes previously destined for landfills. There are no bonafide quality standards in America, but the USCC sells a seal called "Seal of Testing Assurance" (also called "STA"). For a considerable fee, the applicant may display the USCC logo on products, agreeing to volunteer to customers a current laboratory analysis that includes parameters such as nutrients, respiration rate, salt content, pH, and limited other indicators. Many countries such as Wales and some individual cities such as Seattle and San Francisco require food and yard waste to be sorted for composting (San Francisco Mandatory Recycling and Composting Ordinance). The USA is the only Western country that does not distinguish sludge-source compost from green-composts, and by default 50% of US states expect composts to comply in some manner with the federal EPA 503 rule promulgated in 1984 for sludge products. There are health risk concerns about PFASs ("forever chemicals") levels in compost derived from sewage sledge sourced biosolids, and EPA has not set health risk standards for this. The Sierra Club recommends that home gardeners avoid the use of sewage sludge-base fertilizer and compost, in part due to potentially high levels of PFASs. The EPA PFAS Strategic Roadmap initiative, running from 2021 to 2024, will consider the full lifecycle of PFAS including health risks of PFAS in wastewater sludge. == History ==

Composting dates back to at least the early Roman Empire and was mentioned as early as Cato the Elder's 160 BCE piece . Traditionally, composting involved piling organic materials until the next planting season, at which time the materials would have decayed enough to be ready for use in the soil. Methodologies for organic composting were part of traditional agricultural systems around the world. Composting began to modernize somewhat in the 1920s in Europe as a tool for organic farming. The first industrial station for the transformation of urban organic materials into compost was set up in Wels, Austria, in the year 1921. Early proponents of composting in farming include Rudolf Steiner, founder of a farming method called biodynamics, and Annie Francé-Harrar, who was appointed on behalf of the government in Mexico and supported the country in 1950–1958 to set up a large humus organization in the fight against erosion and soil degradation. Sir Albert Howard, who worked extensively in India on sustainable practices, and Lady Eve Balfour were also major proponents of composting. Modern scientific composting was imported to America by the likes of J. I. Rodale – founder of Rodale, Inc. Organic Gardening, and others involved in the organic farming movement. == See also ==