hobby when he retired. There are differences in the particulars of lawn maintenance and appearance, such as the length of the grass, species (and therefore its color), and mowing. Environmental concerns Greater amounts of chemical fertilizer and pesticides are used per surface area of lawn than on an equivalent surface of cultivated farmland, and the continued use of these products has been associated with environmental pollution, disturbance in the lawn ecosystem, and increased health risks to the local human and wildlife population. It has also been estimated that more herbicides are applied per surface of lawn than are used by most farmers to grow crops. In response to environmental concerns, organic landscaping and organic lawn management systems have been developed and are mandated in some municipalities and properties. In the United Kingdom, the environmental group Plantlife has encouraged gardeners to refrain from mowing in the month of May to encourage plant diversity and provide nectar for insects. Other concerns, criticisms, and ordinances regarding lawns arise from wider environmental consequences: Lawns can reduce biodiversity, especially when the lawn covers a large area. Traditional lawns often replace plant species that feed pollinators, requiring bees and butterflies to cross "wastelands" to reach food and host plants. Lawns promote homogenization and are normally cleared of unwanted plant and animal species, typically with synthetic pesticides, which can also kill unintended target species. They may be composed of introduced species not native to the area, particularly in the United States. This can produce a habitat that supports a reduced number of wildlife species. Lawn maintenance commonly involves use of fertilizers and synthetic pesticides, which can cause great harm. Some are carcinogens and endocrine disruptors. They may permanently linger in the environment and negatively affect the health of potentially all nearby organisms. The United States Environmental Protection Agency estimated in 2012 that nearly of active pesticide ingredients are used on suburban lawns each year in the United States. There are indications of an emerging regulatory response to this issue. For example, Sweden, Denmark, Norway, Kuwait, and Belize have placed restrictions on the use of the herbicide 2,4-D. It has been estimated that nearly of gasoline are spilled each summer while re-fueling garden and lawn-care equipment in the United States: approximately 50% more than that spilled during the Exxon Valdez incident. The use of pesticides and fertilizers, requiring fossil fuels for manufacturing, distribution, and application, has been shown