Steve Baum set out to fashion a baseball bat that had a heart of plastic and a soul of wood.

He may wind up helping to save the soul of baseball, not to mention a lot of timber.

Baum's wood composite bat, a shell of white ash wrapped around a core of foam plastic, preserves the genuine crack of bat meeting ball. But it almost never cracks. Or chips. Or breaks.

It sounds like wood, hefts like wood and, most importantly, reacts with the same dynamics as wood, punishing the batter with a sharp sting if he doesn't meet the ball on the sweet spot.

The bat is the first non-wood bat to win over traditionalists in professional baseball. No one, least of all Baum, wants to see it replace Adirondacks or Louisville Sluggers in major league games. However, as a cost-saving alternative in the minors, the bat has been a smashing success.

With the approval of farm-system directors, several thousand players in Rookie, Rookie Advanced and Dominican summer leagues used the bats in games last season. Many teams also made the bat available to minor-leaguers for practice. The experimet will continue in the upcoming season, and if the universal raves continue, the bat could ascend the ladder into Class-A games in 1995.

"I'm a firm believer in woods bats, but of all the gimmicks and gadgets that have come along, this one works pretty well," says Ken Higdon, major league equipment manager for the California Angels. "I didn't hear any negatives all."

Roy Krasik, supervisor of baseball operations for Major League Baseball, says Higdon's opinion is widely shared. "All the reports from our farm directors came back very favorable," he says. "Eventually we'd like to see the bat used in all of amateur baseball: high schools, Little League, all the way through, so those players would have an easier transition to wood bats."

Baum, 54, an inventor from Traverse City, Mich., is pleased at the bat's reception on the professional level. But, like Krasik, his most fervent wish is to see it replace aluminum in the college and high school ranks, where a handful of programs now train with wood composite bats and use them in exhibition games.

"An aluminum bat is a terrible tool to use to learn to hit a baseball," Baum says. "It eliminates the problem of breakage, but it also eliminates the sting. Kids pick up bad habits, and then major league baseball can't evaluate them. The scouts are going crazy."