DEPARTING D.C. School Superintendent Floretta D. McKenzie has surprised some observers with her school system budget for fiscal year 1989. Practically all the new funding proposed in the $459 million request is devoted to higher salaries for teachers. That sends an important message. Hiring and keeping the most competent new teachers will be the school system's priority.

The starting salary for new teachers in the city's schools this year was $1,984 to $2,884 lower than in other Washington area school districts. The best pay available to D.C. teachers -- about $39,500 -- was even lower in relation to neighboring school systems. In the Montgomery County schools, the best paid teachers earn about $44,500. In Fairfax County, the figure this year was $50,000.

Of equal importance is the fact that an average of 19 people apply for each teaching vacancy in the Fairfax County public schools. An average of 10 people apply for every teaching position offered by Arlington County. The D.C. public schools receive only four applications for every teaching post that must be filled. That's particularly disturbing when one considers the fact that the city's schools -- with the area's oldest teaching staff -- will have to hire more new teachers than any other area school system.

In Fairfax, large pay increases were tied to the area's first merit pay plan for teachers. Only the best teachers will receive the highest wages. Less accomplished teachers will receive no raise at all, and the worst will be fired. The city's school system has no pay for performance plan for teachers, and it needs one. Better wages must be accompanied by better teaching. That's the essential trade-off.