Organic lawn management

Organic lawn management is the practice of establishing and caring for an athletic turf field or garden lawn and landscape using organic horticulture, without the use of manufactured inputs such as synthetic pesticides or artificial fertilizers. It is a component of organic land care and organic sustainable landscaping which adapt the principles and methods of sustainable gardening and organic farming to the care of lawns and gardens.
Techniques.
A primary element of organic lawn management is the use of compost and compost tea to reduce the need for fertilization and to encourage healthy soil that enables turf to resist pests. A second element is mowing tall (3" - 4") to suppress weeds and encourage deep grass roots, and leaving grass clippings and leaves on the lawn as fertilizer. 
Additionally, fertilize in the fall, not the spring. Organic lawns often benefits from over seeding, slice seeding and aeration more frequently due to the importance of a strong root system. Well-maintained organic lawns are often drought-tolerant. If a lawn does need watering it should be done infrequently but deeply.
Other organic techniques for caring for a lawn include irrigation only when the lawn shows signs of drought stress and then watering deeply - minimizing needless water consumption. Using low volume sprinklers provides more penetration without runoff. Lawnmowers with a mulching function can useful in reducing fertilizer use by allowing grass clippings and leaves that are cut so minutely that they can settle into the grass inconspicuously to decompose into the soil.
Organic pesticides.
Organic land managers may use registered pesticides approved under the National Organic Program in their lawn care programs. These pesticides are generally derived from natural materials and are minimally-processed. Alternatives include the use of beneficial insects and natural predators such as nematodes to prevent infestation of lawns with pests such as crane fly larvae and ants. Pesticides are not always used in organic lawn care because proper organic care can keep pest populations below action thresholds, such as preventing fungal infections using physical maintenance techniques such as effective mowing and raking. 
Organic fertilizers.
Synthetic (inorganic based) fertilizers are made in chemical processes, some of which use fossil fuels and contribute to global warming. They also greatly increase the amount of nitrogen entering the global nitrogen cycle which has a serious negative impact on the organization and functioning of the world's ecosystems, including accelerating the loss of biological diversity and decline of coastal marine ecosystems and fisheries. Nitrogen fertilizer releases N2O, a greenhouse gas, into the atmosphere after application. Organic fertilizer nitrogen content is typically lower than synthetic fertilizer.
Biodiversity.
Organic lawns contribute to biodiversity, by definition, when they contain more than one or two grass species. Examples of additional lawn and grasslike species that can be encouraged in organic lawns include dozens of grass species (eight for ryegrass alone, sedges, mosses, clover, vetches, trefoils, yarrow, ground cover alternatives, and other mowable plants). Biodiversity increases the functioning and stress tolerance of ecosystems. Lack of biodiversity is a significant environmental issue brought up by the use of lawns with grassroots groups emerging to promote this method of lawn care. Certain low-growing grass species can also eliminate the need for mowing, thus also being environmentally friendly. Clover is often mixed with grasses for its ability to fix nitrogen into the soil and fertilize the lawn.
Locations with organic lawns.
Highgrove House estate, Gloucestershire, England - In 1996, Prince Charles had transitioned the Highgrove House estate's farm and gardens to organic management. 
Harvard University, Massachusetts, USA - In 2009, the New York Times reported on Harvard University's decision to use organic management on all their grounds, which was championed by President Drew Gilpin Faust and implemented by landscape director Wayne Carbone. The New York Times noted: "Thanks to these efforts, the university has reduced the use of irrigation by 30 percent, according to Mr. Carbone, thus saving two million gallons of water a year. And the 40-year-old orchards at Elmwood, which have been treated with compost tea, are recovering from leaf spot and apple scab, two ailments that had afflicted them."
Takoma Park, Maryland, USA - Residents Catherine Cummings and Julie Taddeo began a campaign in 2011 to restrict lawncare pesticide use in Takoma Park, Maryland. City council members Seth Grimes and Tim Male quickly got behind the effort and drafted Takoma Park's Safe Grow Act of 2013, leading to the city council's enactment of the law, which went into effect March 1, 2014.
Ogunquit, Maine, USA - In 2014, Bill and Judy Baker and other residents convinced the Ogunquit Town Council to pass a strict pesticide ban requiring organic land care on both public and private property.
Montgomery County, Maryland, USA - In 2015, Julie Taddeo and Catherine Cummings and Safe Grow Montgomery colleagues campaigned to get Montgomery County, Maryland to adopt a pesticide ban that required organic lawn management throughout the county on both public and private property. Montgomery County Council President George Leventhal (D-at-large) wrote and introduced Bill 52-14, based on Takoma Park's 2013 legislation. The county council enacted Bill 52-14 that October. The ban was challenged in court by local lawn care companies and pesticide industry lobbying group Responsible Industry for a Sound Environment (RISE). In 2017, the ban was overturned by a Circuit Court, and the ruling was appealed. In 2019, a Maryland appeals court upheld the ban.
Irvine, California, USA - In 2016, Nontoxic Irvine led by Laurie Thompson, Ayn Craciun, Kathleen Hallal, Kim Konte and Bob Johnson with help from City Councilor Christina Shea convinced the City Council to adopt an organic ordinance requiring organic land care on all city property. 
Carlsbad, California, USA - In 2017, Nontoxic Carlsbad campaigned to get the city to adopt an ordinance requiring organic land care on all city property.
Portland, Maine, USA - In 2018, Portland Protectors led by Avery Yale Kamila and Maggie Knowles convinced the Portland City Council to adopt an organic ordinance requiring organic land care on all public and private property.
Gardens of Vatican City, Rome, Italy - In 2019, Rafael Tornini, head of the Garden and Environment Service of the Vatican, announced the 37 acre Gardens of Vatican City had been transitioning to organic management since 2017.