The key factors in Bobby Ross' decision to remain as the University of Maryland football coach were the university's decision to expedite improvements at Byrd Stadium and the establishment in writing for the first time of academic guidelines for the recruitment of athletes, Ross said yesterday.

Details of the academic guidelines and a revised plan to add lights to Byrd Stadium next season and spend $11-12 million to modernize it by the 1987 season were discussed publicly by a university official for the first time yesterday.

The stadium improvements will make "life more pleasant for the people who come to our games," Athletic Director Dick Dull said. The modernized stadium will have 52,000-55,000 seats, including 3,000 new seats under cover, Dull said.

Ross' concerns about the university's commitment to stadium improvements and his concern for better communication and written admissions guidelines caused the coach to put off signing a 10-year contract to which he had agreed a year ago and to sign a one-year contract then instead.

Ross insisted yesterday -- and both Dull and a top aide to Chancellor John B. Slaughter agreed -- that no substantive changes are being made in Maryland's admissions policy for athletes. The key element of the guidelines is that Ross can sign any athlete who meets the standards of NCAA Proposal 48.

That rule, to become effective in August, requires a 700 score (out of 1,600) on the Scholastic Aptitude Test and a 2.0 grade-point average (on a 4.0 scale) in a core curriculum of 11 academic courses to be eligible to practice or play as a freshman. The rule may be modified slightly at the NCAA convention next month, but Ross said Slaughter assured him Maryland will adhere to the provisions of Proposal 48.

"To me it's guidelines and it's an equal opportunity," Ross said. "I can assure you this -- that there are players playing in other programs that we turned down for academic reasons."

Under the old NCAA rules, a player was eligible as a freshman if he had a 2.0 grade-point average in all his high school courses.

The Maryland guidelines also provide for the athletic department to receive as many as 15 exceptions a year for all men and women athletes who do not qualify under Proposal 48. Ross has said he would want to use no more than three to five a year, apparently the number of exceptions he currently is allowed.

Athletes who enter as exceptions would go into an Intensive Educational Development program, administered by the academic counseling office and not the athletic department. They would be unable to practice or play as freshmen, even if NCAA rules are subsequently changed.

Dull said this is no change in policy.

A year ago, Ross reached the boiling point when five recruits he signed to letters of intent were subsequently not admitted to school. All five eventually were admitted on a conditional basis for summer school.

Two are currently enrolled at Maryland, but did not practice or play this season because they were in the Intensive Education Program. Two others are attending Maryland's University College and will be admitted to the university proper in January if they have a C average. The other one dropped out after summer school.

"We didn't have specific guidelines. This year we do. The standards are the same as last year," Dull said. "There haven't been any compromises. At least now they're defined, so we can understand them."

Ross said, "The bottom line is that we have gone from generalities to specifics and, yes, I do have the trust (in the Maryland administration fulfilling its promises)."

The university's board of regents will not consider until its Dec. 13 meeting a financing plan for the stadium project that includes private donations and issue bonds still to be authorized by the state legislature. In February, the regents will receive final plans for the stadium improvements.

Dull said he expects to play two or three night games in Byrd Stadium next season.

The rest of the improvements are expected to begin at the end of the 1986 season. In addition to a new press box and 3,000 seats under cover, Maryland will build new restrooms and new concession stands, redo a lot of concrete work and repave the macadam on the stadium concourse.

"It's a positive direction," Ross said. "It's feasible and it's in line with the goals and directions of the University of Maryland and myself . . . It's in line with things that we think will give us an opportunity to compete at the level we're competing at."