President Carter has ordered aides to give him options this week for dealing with spreading Midwest strikes that have paralyzed inland grain movements in some areas and joepardized food exports.

Grain exports dropped 25 to 30 percent between early August and early September despite unprecedented orders from abroad.

Agriculture Department officials said they were studying whether this was a normal seasonal decline or was related to problems that have caused the worst disruptions in grain transportation in years.

Of primary concern to the administration is a 15-day strike by 2,500 members of the Brotherhood of Railway and Airline Clerks against the bankrupt Rock Island Railroad. The Rock Island line moves 7 percent of Midwest grain and provides exclusive service to 1,680 grain elevators.

At a Cabinet meeting Monday, Carter ordered the secretaries of agriculture, transportation and labor to come up with options for returning grain movements to normal. The officials are scheduled to meet today or tomorrow with presidential adviser Stuart E. Eizenstat to work out a final set of proposals.

Officials said yesterday that the president could declare an emergency, set up a special board and order a 240-day cooling-off period during which strikers would return to work.

However, such a step would damage the president's political standing with organized labor, some elements of which reportedly already are interested in the presidential candidacy of Sen. Edward M. Kennedy (D-Mass).

On the other hand, a prolonged export jam could badly damage the president's position in such states as Iowa and could also worsen the nation's trade balance.

Talks here between the railroad and the union under auspices of the National Mediation Board failed yesterday to make any headway toward ending the strike. The bankrupt railroad has refused the union's demand for a pay increase retroactive to Jan. 1, 1978.

The strike spread in the last few days to members of the United Transportation Union, which represents train operators other than engineers.

UTU workers in Hutchinson, Kan., reportedly refused to switch Rock Island trains operated by railroad managers to tracks of the Santa Fe for the trip west.

In addition to these problems, striking grain handlers at the Great Lakes ports of Duluth and Superior have blocked the loading of grain ships there since July 6. The union rejected a contract offer this week by the Continental Grain Co. The two Lakes ports handle about 10 percent of U.S. grain exports. Government officials said yesterday that pressure was mounting from grain companies and farm organizations for the president to declare an emergency and order the Rock Island strikers back to work.

"The Midwest is in a critical situation, with everything pushed to the limit," said Williard Clarkson of Agri Industries, a Des Moines-based cooperative with many elevators situated on the Rick Island line. "We have 80 elevators that are closed -- and not taking in grain from farmers -- and millions of dollars are going down the tube."

Clarkson said a 25-car train that was filled with corn before the strike has moved 30 miles in the last 20 days. He said the cooperative is late on commitments to deliver its monthly quota of 11 100-car trainloads of grain to international grain companies on the East Coast.

"I've been in the business for 30 years and I've never seen anything like this before," he said.

The blockage of grain movements occurs shortly before Midwest farmers prepare to harvest what may be the largest corn crop in history. Unless the system can be unjammed by October, farm officials say, some corn could rot in the fields.

A further uncertainty is whether the Rock Island line, which serves the grain export ports of Chicago, Houston and Galveston, will have the money to resume full-scale operations after the strike.

If the railroad has to halt operations, the Interstate Commerce Commission has authority to direct other railroads to take over its tracks and serve its customers. The federal government is required, under those conditions, to cover any losses and to pay the operating railroads a commission.

In addition to the problems of the Rock Island, another grain handler -- the Milwaukee Road -- is also in bankruptcy and seeking to cease service immediately on 6,400 of its total 9,200 miles of track.

"The state of Iowa simply cannot sustain the loss of two railroads," warned a state official in Des Moines last week.