President Reagan, continuing his fight for merit pay for teachers, told elementary and secondary school principals at the White House yesterday that even the Soviet Union recognizes the benefit of merit pay as an incentive to get better work done.

The president called for a "renaissance in American education" that will come from a consensus among parents, teachers, students and principals. Reagan said the key to forming the consensus is to "reward excellence."

"I saw something interesting in The Washington Post several weeks ago," the president told the National Associations of Elementary School Prinicpals and Secondary School Principals in the East Room.

"It was a story on how the Soviet leadership is considering ways to get the Soviet economy moving again. Well, one proposal is to depart from the practice of paying Soviet citizens relatively equal wages irrespective of job performance.

"Now if even Yuri Andropov and the Soviet bureaucracy are beginning to realize the need for merit pay," the president said in stern tones, "why can't certain segments of our own educational establishment?"

The president's remarks apparently were aimed at the National Education Association. The NEA has consistently said that while it is open to discussing merit pay proposals it does not know of an objective measure of teachers' performance that could serve as the basis for paying one teacher more than another.

"We simply can't tell the taxpayer that more funds are needed to improve quality when, during the 20-year period between 1960 and 1980, spending on education was shooting up while the college board scores were going down," the president said. "If a 600-percent increase, which is what we had in spending in those 20 years, couldn't make America smarter, how much more do we need?" The president said that what principals can do to improve schools without spending more money is to use updated textbooks, raise graduation requirements and enforce strict discipline.

Also yesterday the president addressed a gathering of the Future Farmers of America in the Rose Garden and told them, "I hope when you go back to your homes you will tell your families and your friends of our confidence that things are getting better. And while you're at it, tell them that the--that a White House source--told you personally that America's farmers are not going to be left out of the good times that lie ahead."

Reagan did not mention the agreement reached Thursday between the Soviet Union or the Payment-in-Kind program, both intended to help farmers recover from what Reagan described as "hard times."

"I know thing have been rough and still are for many farmers," he added.