Compost

Compost ( or ) is made by decomposing organic materials into simpler organic and inorganic compounds in a process called composting. This process recycles various organic materials otherwise regarded as waste products. A good compost is rich in plant nutrients and beneficial organisms.
Compost is used to improve the soil fertility in gardens, landscaping, horticulture, urban agriculture and organic farming. The benefits of compost include providing nutrients as fertilizer to the crop, acting as soil conditioner, increasing the humus or humic acids content of the soil, and introducing beneficial colonies of microbes in the soil, which help in suppressing pathogens. The natural interaction of the soil, plant roots and nutrient / microorganisms of compost improves the soil structure. An improved soil structure will increase the soil water retention ability and control soil erosion. Compost can be used for land and stream reclamation, wetland construction and landfill cover.
At its simplest level, composting requires gathering a mix of 'Greens' and 'Browns'. Greens are materials rich in nitrogen such as leaves, grass, and food scraps. Browns are more woody materials rich in carbon-like stalks, paper, and wood chips. The materials are wetted to break them down into humus, a process that occurs over a period of months. Most organic standards demand at least a 60 days composting process, however, composting can also take place as a multi-step, closely monitored process with measured inputs of water, air, and carbon- and nitrogen-rich materials. The decomposition process is aided by shredding the plant matter, adding water, and ensuring proper aeration by regularly turning the mixture when open piles or "windrows" are used. Fungi, earthworms and other detritivores further break up the organic material. Aerobic bacteria and fungi manage the chemical process by converting the inputs into heat, carbon dioxide, and ammonium.
Fundamentals.
Composting is an "aerobic method" (meaning that it requires the presence of air) of decomposing organic solid wastes. It can therefore be used to recycle organic material. The process involves decomposition of 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:
Certain ratios of these materials will allow microorganisms to work at a rate that will heat up the compost pile. Active management of the pile (e.g., turning) is needed to maintain sufficient supply of oxygen and the right moisture level. The air/water balance is critical to maintaining high temperatures until the materials are broken down.
The most efficient composting occurs with an optimal carbon:nitrogen ratio of about 25:1. Hot container composting focuses on retaining heat in order to increase the decomposition rate thus producing compost more quickly. Rapid composting is favored by having a C/N ratio of ~30 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, but amounts vary widely, with characteristics noted above (dry/wet, brown/green). Fresh grass clippings have an average ratio of about 15:1 and dry autumn leaves about 50:1 depending upon species. Mixing equal parts by volume approximates the ideal C:N range. Few individual situations will provide the ideal mix of materials at any point. Observation of amounts, and consideration of different materials as the compost pile is built up over time, can quickly achieve a workable technique for the individual situation.
Microorganisms.
With the proper mixture of water, oxygen, carbon, and nitrogen, microorganisms are able to break down organic matter to produce compost. The composting process is dependent on microorganisms to break down organic matter into compost. There are many types of microorganisms found in active compost of which the most common are:
In addition, earthworms not only ingest partly composted material, excreting worm castings, which is separate from but can happen in compost, but also continually re-create aeration and drainage tunnels as they move through the compost.
Phases of composting.
Under ideal conditions, composting proceeds through three major phases:
Hot and cold composting - impact on timing.
The time required to compost material relates to the volume of material, the size of the inputs (eg. wood chips break down faster than branches) and the amount of mixing or aeration - usually by turning the pile. Generally, larger piles will reach higher temperatures and remain in a thermophilic stage for days or weeks. This is referred to as hot composting and is the normal method for large-scale (eg. municipal) composting facilities and many agricultural operations.
A process often referred to as the 'Berkeley method' produces finished compost in eighteen days, but it requires the assembly of a least a cubic meter of material at the outset, and requires turning every two days after a four-day initial phase. Many such short processes involve a few changes to traditional methods, including smaller, more homogenized pieces in the compost, controlling carbon to nitrogen ratio (C:N) at 30 to 1 or less, and monitoring the moisture level more carefully.
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 waster over extended periods. Piles smaller than approximately a cubic meter have trouble reaching and maintaining high temperature. Turning is not necessary with cold composting, however, there is a risk that parts of the pile may go anaerobic as they get compacted or water-logged.
Pathogen removal.
Composting can destroy some pathogens or unwanted seeds, those that are destroyed by temperatures above . 
Dealing with stabilized compost - i.e. composting material that has gone through the phases where micro-organisms are digesting the organic matter and the temperature inside the composting pile has reached temperature up to 50-70 °C - poses very little risk as these temperatures kill pathogens and even make oocysts unviable. People turning the compost should wear gloves and a breathing mask as that material contains pathogens that can make humans sick. The temperature at which a pathogen dies depends on the pathogen, how long the temperature is maintained (it can take seconds to weeks), and even pH.
Compost products like compost tea and compost extracts have been found to have an inhibitory effect on "Fusarium oxysporum", "Rhizoctonia" sp., and "Pythium debaryanum," plant pathogens that can cause crop diseases. Since the inhibitory effects of compost products are a result of their microbial population and its diversity and stability, aerated compost teas are more effective than compost extracts. The microbiota, or the community of microbes, and enzymes present in compost extracts also have a suppressive effect on fungal plant pathogens. Compost is a good source of biocontrol agents like "B. subtilis", "B. licheniformis," and P. "chrysogenum" that fight plant pathogens. However, sterilizing compost, compost tea, or compost extracts have a reduced effect on pathogen suppression.
Diseases that can be contracted from handling compost.
People turning the compost when it has not gone through its phases where temperatures of +50 °C are reached, must wear a mouth mask and gloves to protect themselves from diseases that can be contracted from handling compost, s.a.
Oocytes are made unviable thanks to the phase where the temperature reaches temperatures of +50 °C.
Materials that can be composted.
Potential sources of compostable materials, or feedstocks, include residential, agricultural and commercial waste streams. There is not a linear relationship between the source of a given feedstock and the method that it is composted. For example, 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.
There are two broad categories of organic solid waste: green waste and brown waste. Green waste is generally considered a source of nitrogen and includes pre- and post-consumer food waste, grass clippings, garden trimmings and fresh leaves. Animal carcasses, roadkill and butcher residue can also be composted and these are considered nitrogen sources. 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 (not charcoal ash). Products derived from wood such as paper and plain cardboard are also considered carbon sources.
Food waste can be an important feedstock depending on the region. For example, residential food waste is collected as a separate waste stream in some municipalities, and will then be included in large municipal recycling facilities. In other areas, food waste may be part of the regular waste stream and the only option for composting will be backyard or community programs.
Animal manure and bedding.
On many farms, the basic composting ingredients are animal manure generated on the farm as a nitrogen source, and bedding as the carbon source. Straw and sawdust are common bedding materials. Non-traditional bedding materials are also used, including newspaper and chopped cardboard. The amount of manure composted on a livestock farm is often determined by cleaning schedules, land availability, and weather conditions. Each type of manure has its own physical, chemical, and biological characteristics. Cattle and horse manures, when mixed with bedding, possess good qualities for composting. Swine manure, which is very wet and usually not mixed with bedding material, must be mixed with straw or similar raw materials. Poultry manure also must be blended with carbonaceous materials - those low in nitrogen preferred, such as sawdust or straw.
Human excreta.
Human excreta can be added as an input to the composting process since it is a nitrogen-rich organic material. It can be either composted 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 there are potential health risks that 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 and therefore 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.
Uses.
Compost can be used as an additive to soil, or other matrices such as coir and peat, as a tilth improver, supplying humus and nutrients. It provides a rich "growing medium" as absorbent material (porous). This material contains moisture and soluble minerals, which provides support and nutrients. Although it is rarely used alone, plants can flourish from mixed soil, 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.
Generally, direct seeding into a compost is not recommended due to the speed with which it may dry and the possible presence of phytotoxins in immature compost that may inhibit germination, 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 at cotyledon stage or later.
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 one volume of compost with four to ten volumes of water, and occasional stirring to release microbes. There has been debate about the benefits of aerating the mixture. Non-aerated compost tea is cheaper and less labor intensive, but it has been associated with phytotoxicity and human pathogen regrowth, though further studies have refuted those findings. Aerated compost tea brews faster and generates more microbes, but has potential for human pathogen regrowth. Field studies have shown the benefits of adding compost teas to crops due to the adding of organic matter, increased nutrient availability and increased microbial activity. They have also been shown to have a suppressive effect on plant pathogens. Compost tea is also found useful in suppressing soil-borne diseases, but its efficacy is influenced by a number of factors, such as the preparation process and the environmental conditions where the compost tea is brewed and used. The disease-suppressing qualities of compost tea depend on how long it is fermented, which differs according to the different types of source compost and the method of fermenting used. Adding nutrients to compost tea can be beneficial for disease suppression, although it can trigger the regrowth of human pathogens like "E. coli" and "Salmonella."
Compost tea is a mixture of nutrients and aerobic bacteria, fungi, nematodes and other microbes that live in finished compost. It takes time to separate these organisms from compost, which is why compost tea is made by steeping compost in water for a day or more.To create compost tea, you'll need compost and it can be locally acquired or natively constructed, as long as it's totally completed the process of fertilizing the soil. Completed manure has a sweet smell. The measure of fertilizer required fluctuates relying upon the measure of tea you're preparing. For a 5-gallon group, you'll need around 4 cups of manure. A group in a 25-gallon garbage bin will require around 20 cups of manure. Keep away from fertilizers that contain creature excrement, as it might hold e-coli microscopic organisms. Albeit the tea-production cycle should execute e-coli, it's smarter to be protected than sorry.
Regardless of the compost tea machine you are using, the source compost is the number one driver of the final compost tea quality. No matter how well engineered the compost tea machine is – whether carefully homemade or commercially produced, or how highly complex your food resources may be – the final compost tea product is heavily dependent on the source compost quality.
Compost tea contains a considerable amount of soluble mineral nutrients that are readily available for plant uptake that facilitate crop growth and yield.
Compost Extract.
Compost extracts are unfermented or non-brewed extracts of leached compost contents dissolved in any solvent, including water.Compost extracts are easily made and can even be brought forth with no mechanical intervention. Bubbling can be used to separate the microbes from the compost or a simple massaging technique.
Heat source.
The temperatures generated by compost can be used to heat greenhouses, such as by being placed around the outside edges.
Commercial sale.
The term "compost" can also refer to potting mixes which are bagged up and sold commercially in garden centers and other outlets. This may include composted materials such as manure and peat, but is also likely to contain loam, fertilizers, sand, grit, etc. Varieties include multi-purpose composts designed for most aspects of planting, John Innes formulations, growbags, designed to have crops such as tomatoes directly planted into them. There are also a range of specialist composts available, e.g. for vegetables, orchids, houseplants, hanging baskets, roses, ericaceous plants, seedlings, potting on etc.
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.
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.
Composting technologies.
Industrial-scale.
Examples.
Large-scale composting systems are used by many urban areas around the world.
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 "hügelkultur" 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 "hügelkultur" bed.
Related technologies.
There are other processes used to break down organic matter that do not rely on aerobic decomposition:
History.
Composting as a recognized practice dates to at least the early Roman Empire, and was mentioned as early as Cato the Elder's 160 BCE piece "De Agri Cultura". 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. The advantage of this method is that little working time or effort is required from the composter and it fits in naturally with agricultural practices in temperate climates. Disadvantages (from the modern perspective) are that space is used for a whole year, some nutrients might be leached due to exposure to rainfall, and disease-producing organisms and insects may not be adequately controlled.
Composting was somewhat modernized beginning 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 frequent citations for propounding composting within farming are for the German-speaking world 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 1950–1958 to set up a large humus organization in the fight against erosion and soil degradation.
In the English-speaking world it was Sir Albert Howard who worked extensively in India on sustainable practices and Lady Eve Balfour who was a huge proponent of composting. Composting was imported to America by various followers of these early European movements by the likes of J.I. Rodale (founder of Rodale Organic Gardening), E.E. Pfeiffer (who developed scientific practices in biodynamic farming), Paul Keene (founder of Walnut Acres in Pennsylvania), and Scott and Helen Nearing (who inspired the back-to-the-land movement of the 1960s). Coincidentally, some of the above met briefly in Indiaall were quite influential in the U.S. from the 1960s into the 1980s.