Air Force and Army leaders yesterday expressed deep concern about their ability to fill ranks with volunteers.

There is "an alarming deficiency" of volunteers for the armed services, Gen. Lew Allen Jr., Air Force chief of staff, told the Air Force Association convention here.

He said the House's recent votes against requiring young men to register with their draft boards "clearly indicates" that the public does not appreciate the severity of the manpower problem.

Not only is the Air Force unable to sign up the desired number of young people for the enlisted ranks, Allen said, but it is not recruiting as many officers with technical backgrounds as it needs.

Also, continued the Air Force chief, many highly trained enlisted people and young pilots and navigators are quitting the Air Force. He said they become disillusioned as they see benefits eroding.

"The fact is that we have not maintained pay comparability with the civilian sector," said Allen, and "benefits are under attack on virtually all fronts . . . "

Army leaders, in response to shortages of volunteers, decided to relax educational standards in hopes of recruiting more soldiers.

Starting Oct. 1, the Army will drop its requirement that male and female volunteers must have finished at least 10 years of schooling. The volunteers will still be required to score at least 31 on entrance tests.

Gen. Edward C. Meyer, Army chief of Staff, in his first news conference, said Monday that recruiting was his number one problem. The shortage of volunteers, other Army leaders said yesterday, is aggravated by the high dropout rate of people who do enlist.

The Army is expected to end fiscal 1979 on Oct. 1 with a shortage of between 13,000 and 15,000 volunteers.

The Carter administration told Congress in a recent letter that it would use $51.9 million from its fiscal 1980 supplemental request for $2.7 billion to intensify recruiting to make up for shortages of volunteers.

"If active Army recruiting fails in fiscal 1980," the administration wrote Congress, "the All Volunteer Force will not recover for two or more years."

Marine leaders already have decided to settle for 10,000 fewer people in its active duty ranks to free more money for readiness activities, such as repairing tanks and fixing runways.

The Navy, too, has not been able to meet goals for volunteers in fiscal 1979.

If shortages continue to plague the armed services through next year, the drive in Congress to resume drafting people into the military is bound to pick up steam.