It's a system to provide people with sufficient food, that takes into consideration environmental awareness and conservation, economic feasibility, and community support. Read this well written description 
here:
The Sustainable Agriculture Club has been around for several years and runs a community garden on Adelphi Road near the Archives branch. The Garden Club is a brand new group that runs an organic urban garden right on-campus outside St Mary's Hall. Both groups are SGA recognized and have separate budgets and projects. However, the groups have overlapping membership and collaborate extensively.
We manage two gardens and some shared greenhouse space, run an on-campus composting program, and we hold educational events throughout the year.
Other ideas and goals that have been tossed around are doing guerrilla gardening by reclaiming unplanted spaces, starting gardens in our own yards, developing a more extensive on-campus composting system, creating a tool library collective, connecting other members of the local community, advocating low-impact development projects such as greenroofs or rain gardens,, etc.
Anyone can participate in our community garden. All active members are allowed their own plot in our garden to grow what they like. All tools and most materials are provided by the group budget. There are also several group plots that will be used for things such as permaculture forestry, a berry patch, and larger crops like pumpkins, watermelons, etc..
The garden at St Mary's will holds weekly workdays to maintain the garden. Anyone is welcome to join and help with landscaping, planting, etc..
Discussion Board to see what folks are thinking about and to leave your own ideas about what we should be doing!The absolute best way to stay in touch is to join the UMD Gardening Listserve.
umd_sustag-subscribe@yahoogroups.com. You will see announcements about work days and updates on this listserv.