Soviet agriculture chief Viktor Nikonov will visit the United States next week, meeting with President Reagan and then touring American farms and agricultural industries, U.S. officials said yesterday.

Nikonov, 58, a voting member of the ruling Politburo and a protege of Soviet leader Mikhail Gorbachev, is the highest-ranking Soviet official other than Foreign Minister Eduard Shevardnadze to visit the United States in recent years.

Elevated to the Politburo in June, Nikonov is a member of the Communist Party secretariat, which oversees internal political matters.

Although his visit will be unofficial, Nikonov will also meet Secretary of State George P. Shultz, Commerce Secretary C. William Verity, Trade Representative Clayton Yeutter, Agriculture Secretary Richard E. Lyng and leaders of the House and Senate.

He is scheduled to tour farms, agribusiness and research facilities in Iowa and Missouri and to visit the world's largest commodity market, the Chicago Mercantile Exchange, U.S. officials said.

He will be accompanied by some 30 Soviet officials, primarily experts in farming and agricultural processing.

A spokesman for House Agriculture Committee Chairman E (Kika) de la Garza (D-Tex.), who is hosting the visit, said several members of Congress from farm states may go with Nikonov to the Midwest.