Community supported agriculture (CSA) is the practice of farming with a greater than usual degree of involvement of consumers and other stakeholders.

In a CSA arrangement (sometimes referred to as crop-sharing, also, community shared agriculture), a farmer sells shares in the upcoming season's harvest. Each participant contributes an equal amount, and in return receive an equal share. The share price goes toward production and distribution expenses. Consumers share the natural risks with the farmer.

There are many types of CSA arrangement. Some farms are dedicated entirely to CSA, others also sell through on-farm stands, farmers' markets, and other channels. Most CSAs are owned by the farmers, while some offer shares in the farm as well as the harvest. Consumers have organized their own CSA projects, going as far as renting land and hiring farmers. Many CSAs have a few designated people who assist with CSA administration. Some require or offer the option of members providing labor as part of the share price.

Vegetables and fruit are the most common crops. Many CSAs practice organic farming, avoiding pesticides and inorganic fertilizers. The cost of a share is usually competitively priced when compared to the same amount of vegetables conventionally-grown, because the distribution cost is lowered. There is no documented case of the CSA model being applied to meat production. However, related movements like Slow Food have been involved in both meat and dairy production.

Method of distribution is a distinctive feature in CSA. In the US and Canada, shares are usually provided weekly, with pick-ups on at a designated day and time. CSA subscribers often live in towns and cities - local drop-off location, convenient to a number of members, are organized, often at the homes of volunteers. Shares are also usually available on-farm.

CSA is different from buying clubs and home delivery services, where the consumer buys a specific product at a predetermined price. In CSA, members actually participate in farming. By paying in advance, and accepting what the harvest brings, they provide direct financing. Members also assist with distribution by picking up their shares. The idea is to ensure the availability of fresh, local food, by making sure small, independent farmers survive. With a certain assured revenue, up front, the farmer can concentrate more on production, less on financing and marketing. The close consumer-producer relationship also favors good quality.

The concept was developed Japan in the 1960s, where about 25% of the households participate in a CSA (called "Teikei"). CSA also has roots in subscription farming, and the food cooperative movement of the 1970s.

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