Compost

Community-level composting in a rural area in Germany

Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by decomposing plant and food waste, recycling organic materials, and manure. The resulting mixture is rich in plant nutrients and beneficial organisms, such as bacteria, protozoa, nematodes, and fungi. Compost improves soil fertility in gardens, landscaping, horticulture, urban agriculture, and organic farming, reducing dependency on commercial chemical fertilizers.[1] The benefits of compost include providing nutrients to crops as fertilizer, acting as a soil conditioner, increasing the humus or humic acid contents of the soil, and introducing beneficial microbes that help to suppress pathogens in the soil and reduce soil-borne diseases.

At the simplest level, composting requires gathering a mix of "greens" (green waste) and "browns" (brown waste).[1] Greens are materials rich in nitrogen, such as leaves, grass, and food scraps.[1] Browns are woody materials rich in carbon, such as stalks, paper, and wood chips.[1] The materials break down into humus in a process taking months.[2] Composting can be a multistep, 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 in a process using open piles or windrows.[1][3] 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 ions.

Composter made from a hollow log

Composting is an important part of waste management, since food and other compostable materials make up about 20% of waste in landfills, and due to anaerobic conditions, these materials take longer to biodegrade in the landfill.[4][5] Composting offers an environmentally superior alternative to using organic material for landfill because composting reduces methane emissions due to anaerobic conditions, and provides economic and environmental co-benefits.[6][7] For example, compost can also be used for land and stream reclamation, wetland construction, and landfill cover.

  1. ^ a b c d e "Reduce, Reuse, Recycle - US EPA". US EPA. 17 April 2013. Archived from the original on 8 February 2017. Retrieved 12 July 2021.
  2. ^ Kögel-Knabner, Ingrid; Zech, Wolfgang; Hatcher, Patrick G. (1988). "Chemical composition of the organic matter in forest soils: The humus layer". Zeitschrift für Pflanzenernährung und Bodenkunde. 151 (5): 331–340. doi:10.1002/jpln.19881510512. ISSN 0044-3263.
  3. ^ "The Science of Composting". Composting for the Homeowner. University of Illinois. Archived from the original on 17 February 2016.
  4. ^ "Do Biodegradable Items Degrade in Landfills?". ThoughtCo. 16 October 2019. Archived from the original on 9 June 2021. Retrieved 13 July 2021.
  5. ^ "Reducing the Impact of Wasted Food by Feeding the Soil and Composting". Sustainable Management of Food. US EPA. 12 August 2015. Archived from the original on 15 April 2019. Retrieved 13 July 2021.
  6. ^ "Composting to avoid methane production". www.agric.wa.gov.au. 15 October 2021. Archived from the original on 9 September 2018. Retrieved 16 November 2021.
  7. ^ "Compost". Regeneration.org. Retrieved 21 October 2022.