The Dave Matthews [ tickets ] Band will cap their sold-out summer tour with a featured performance at the 12th edition of Farm Aid. The show, announced last week by Farm Aid co-founders Willie Nelson, Neil Young and John Mellencamp, will take place Sept. 12 at the Nissan Pavilion near Washington, D.C.

The day-long concert will also feature performances by Trisha Yearwood [ tickets ], The Mavericks, Sawyer Brown, Susan Tedeschi and Steve Earle along with sets by Nelson, Young and Mellencamp.

In a written statement, Nelson spoke of a rising need to put pressure on lawmakers to reform farm policies. ''We're bringing this lineup of committed musicians to Washington to entertain folks, but also to remind them that right now family farmers are gripped in a struggle to survive.''

A series of rallies across the country, staged by the Campaign to Reclaim Rural America organization, took place on the same day as the concert announcement.

''Farmers are mad and they should be. Farm policy has failed them,'' Nelson said. ''Farm Aid stands with them, and we'll be in Washington in September to keep pushing for changes that will guarantee the survival of family farms.''

Democratic Senators are asking this week for President Clinton's endorsement of a $10 billion emergency aid package for farmers, who have seen grain prices plummet since the passage of the Republican-authored ''Freedom to Farm'' law in 1996. The legislation eliminated government restrictions on what farmers could plant and removed most farm subsidy payments, which often protected farmers from price downturns.

Farm Aid officials say the organization has granted $14.5 million to more than 100 farm organizations, churches and service agencies since it was founded in 1985. The concept grew from a statement made by Bob Dylan on stage at the 1985 Live Aid Concert, which benefited Ethiopian famine victims. Six week's after Dylan opined that it would be great to do something for the struggling family farmer in America, the first Farm Aid concert was underway before a crowd of 80,000 in Champaign, Ill, with Dylan among the performers. Farm Aid concerts did not take place in 1988, 1989 or 1991.

The concert will be televised nationally on CMT, which also broadcast last year's concert.

Tickets, priced from $65 to $27.50, are currently on sale locally via the numbers (703) 573-SEAT, (202) 432-SEAT or (410) 481-SEAT and nationally via the Cellar Door Concerts web site.