Steve Fields, one of eight nonunion umpires hired by major league baseball during its umpires' strike of 1979, has been fired by the National League.

A spokesperson for the NL office, which confirmed that Fields was the first unpire to be fired in five years, said that Fields was released because of "low performance ratings" and "failure to show improvement."

"I'm totally disgusted," Fields, 41, of Alexandria said. "I'm definitely planning to file a lawsuit against major league baseball.

"I feel like baseball used me when they needed me (during and after the umpires' strike), and now they're discarding me because it suits their purposes," said Fields, who, after seven years in the International League, was the senior umpire (11 years) in the minors when called up in 1979. "I've given baseball 14 years of my life and now I've got nothing to show fot it.

"They called me seven weeks ago, out of the blue, and, in a five-minute phone call, said, 'Your ratings are down... You're fired... So long.' Well, I think I know what the reason really is. Baseball's afraid of another umpires' strike this spring, so they decided to throw a bone to the umpires' union. Something to appease them. I'm the bone."

Last fall, Fields became a center of controversy when he was in a spectacular late-season rhubarb with the Philadelphia Phillies over whether Larry Bowa tagged second base on a double play. Fields symbolized the breach between union unpires and the nonunion umpires with whom they refuse to speak; Fields got little or no assistance from other crew members during the long argument.

"That incident made me a conspicuous target," Fields claimed.

Major league umpires are rarely fired for lack of competence, the last such case being NL umpire Art Williams in 1977. The NL office declined comment on Fields' threatened suit.

"We plan to file suit by the end of the month so we can try to get injunctive relief for Steve," said Fields' lawyer, R. W. Fraley of Fayetteville, Tenn. "We're still in the early stages of investigating this matter, but I think he's got a cause of action along 'right-to-work' lines."

Has Fields had any contact or encouragement from baseball since his firing?

"I got a Christmas card from Bowie Kuhn," he said.