JACKSON (AP) — Mississippi Agriculture Commissioner Lester Spell said Wednesday he won’t seek a fifth term, opening the field for one of the eight statewide offices voters will fill in 2011.

    Spell, 67, announced the decision Wednesday to his staff and to The Associated Press before sending a letter to supporters.

    ‘‘Because next year, 2011, is an election year, I wanted to make my intentions known now so that potential candidates for this office have ample time to make campaign plans,’’ Spell said in a written statement.

    Spell was a veterinarian and Riceland mayor before he was elected agriculture commissioner in 1995.

    He was first elected statewide as a Democrat. He switched to the Republican Party in 2005, saying his ideas about government efficiency were a better match with the GOP.

    Spell reduced the size of the state Department of Agriculture and Commerce by about one-third during his tenure, making many of the cuts soon after he took office in January 1996.

    During his tenure, the department created a ‘‘Make Mine Mississippi’’ program to promote agricultural products that originate in the state. Spell also lobbied legislators to enact a catfish labeling law to let consumers know the origin of the fish they’re buying. In 2009, the department persuaded legislators to enact a country-of-origin labeling law for most fruits, vegetables and meat sold in Mississippi grocery stores.

    Including Spell, at least three of the eight statewide offices won’t have an incumbent seeking re-election during Mississippi’s 2011 elections. Republican Gov. Haley Barbour is limited to two terms and can’t run again. Republican Lt. Gov. Phil Bryant is running for governor, leaving that job open.

    Two statewide officials — Democratic Attorney General Jim Hood and Republican Insurance Commissioner Mike Chaney — have announced they’re seeking re-election.

    Treasurer Tate Reeves and Secretary of State Delbert Hosemann, both Republicans, haven’t revealed their plans.

    During the 2007 campaign, Spell was challenged by Rickey Cole of Ovett, a former state Democratic Party chairman who said Spell should have blocked development of a beef processing plant that operated only a short time in Oakland before closing in November 2004 and leaving 400 people without jobs. The failure of the state-backed plant cost taxpayers at least $55 million and led to criminal convictions of private developers.

    ‘‘He’s a veterinarian. If you’ve got a sick cow or a sick horse, he can probably help you. But he’s proven he doesn’t know very much about economic development,’’ Cole said of Spell in 2007.

    Spell and the Mississippi Development Authority director were co-chairmen of the Land, Water and Timber Resources Board, which approved seed money for the beef plant. In doing so, the board cited a 2001 feasibility study by Mississippi State University Extension Service estimated the plant could have $139.8 million economic impact in the state.

    ‘‘If this project had sound management and oversight, it would have been a benefit to Mississippi,’’ Spell said in 2007.

    On Wednesday, Spell praised the Agriculture Department employees, who oversee a wide variety of services, from operations of the Mississippi State Fair to inspection of gasoline pumps. He said he wants to spend more time with his family.

    ‘‘At the end of this term I’ll be 69, and I am thankful to God for His goodness to me, and grateful to the many people of this great state who gave me the privilege of serving in this office,’’ he said.