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.

Compost tea is made up of extracts of fermented water leached from composted materials.^[1] Composts can be either aerated or non-aerated depending on its fermentation process.^[2] Compost teas are generally produced from adding one volume of compost with four to ten volumes of water, and occasional stirring to release microbes.^[2] There has been debate about the benefits of aerating the mixture.^[1] 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.^[2] Aerated compost tea brews faster and generates more microbes, but has potential for human pathogen regrowth.^[2] 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.^[1] They have also been shown to have a suppressive effect on plant pathogens.^[3] 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.^[2] 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.^[2] 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.^[2]

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. ^[4]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.^[5] 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.

The temperatures generated by compost can be used to heat greenhouses, such as by being placed around the outside edges.^[6]

Compost extracts are unfermented or non-brewed extracts of leached compost contents dissolved in any solvent, including water. ^[2]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.

Composting can destroy some pathogens or unwanted seeds, those that are destroyed by temperatures above 50 °C (122 °F). 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.^[7]

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.^[8] 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.^[8] The microbiota, or the community of microbes, and enzymes present in compost extracts also have a suppressive effect on fungal plant pathogens. ^[9] Compost is a good source of biocontrol agents like B. subtilis, B. licheniformis, and P. chrysogenum that fight plant pathogens.^[8] However, sterilizing compost, compost tea, or compost extracts have a reduced effect on pathogen suppression.^[8]

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:

• Bacteria- The most numerous of all the microorganisms found in compost. Depending on the phase of composting, mesophilic or thermophilic bacteria may predominate
  • Mesophilic bacteria both get compost to the thermophilic stage, and cure it afterwards, which makes the fresh compost more bio-available for plants.^[10]
  • Thermophilic bacteria do not reproduce and are not active at (−5 to 25°C), normal temperatures^[11] yet are found throughout soil, becoming active once breakdown of organic matter -by mesophilic bacteria- increases temperatures.^[10] They have been shown to enter soils via rainwater.^[10]Overall, they are present so broadly because of many factors including their spores being resilient.^[12]Thermophilic bacteria then thrive from (40-60°C), and only large-scale composting -such as windrow composting- operations generally exceed (60-65°C), beyond which point many beneficial microorganisms will die.^[10]
• Actinobacteria- Necessary for breaking down paper products such as newspaper, bark, etc.
• Fungi- molds and yeast help break down materials that bacteria cannot, especially lignin in woody material.
• Protozoa- Help consume bacteria, fungi and micro organic particulates.
• Rotifers- Rotifers help control populations of bacteria and small protozoans.

In addition, earthworms not only ingest partly composted material, excreting worm castings, but also continually re-create aeration and drainage tunnels as they move through the compost.