The Senate Finance Committee has scheduled voting sessions next week on some 75 narrow-interest changes in the tax code that together could add as much as $5 billion to the $39.4 billion tax-cut bill it approved last month. a

The tax breaks would benefit a broad array of industries and situations ranging from railroads, oil products and intercity bus lines to makers of cigars and artificial fish bait and owners of trees killed by Dutch elm disease.

The panel also is expected to consider a plan by Sen. Spark Matsunaga (D-Hawaii) to allow a special windpower energy tax credit for those who use sailboats in a trade or business.

If the proposals all were enacted the drain on the Treasury ultimately would reach $15 billion to $20 billion by 1985. Cost estimates have not been completed yet for all the measures.

The list of 75 amendments is being circulated among committee members in advance of next week's session. The panel also is expected to take up several trade and tariff items and proposed changes in federal revenue-sharing. s

The new amendments may prove a stumbling-block to efforts by Chairman Russell B. Long (D-La.) to push the tax-cut bill through the Senate before the November election.

Long is hoping to win Senate approval in time to press the House to draft similar tax-cut legislation this year. House leaders are opposed to any tax bill this year, but may go along if the Senate passes one.

The 75 amendments were culled from an original list of 161 narrow-interest tax-break provisions introduced by Finance Committee members. Still more possible amendments are expected on the floor.

In a drafting session last month, Long won bipastisan agreement to withhold narrow-interest amendments temporarily to clear the basic tax-cut bill promptly.

Congressional observers have been warning for months that any major tax-cut legislation would become a "Christmas tree" before the November elections. The Finance panel traditionally loads its bills with narrow-interest measures.

This time:

Sen. David F. Durenberger (R-Minn.) wants to provide cash grants to railroads that do not have enough earnings -- and therefore tax liability -- to take advantage of a tax credit for investing in new property. Cost by 1985: $68 million.

Sen. David L. Boren (D-Okla.) would exempt more so-called stripper, or small, oil wells from the recently enacted crude-oil tax. Congress already has provided favorable treatment for many of these wells.

Sen. H. John Heinz (R-Pa.) wants to liberalize the tax deferral now allowed for special export companies. The original tax break was enacted in 1971, when exchange rates made U.S. goods uncompetitive.

Another plan by Heinz would reduce the federal excise tax on large cigars. Cost: $9 million by 1985.

Sen. Malcolm Wallop R-Wyo.) would ease the excise tax on fishing equipment by redefinining artificial bait. Treasury cost: uncertain.

A Durenberger proposal would allow casualty-loss deduction of trees killed by Dutch elm disease. The change would cost $30 million in fiscal 1981, dropping to $21 million by 1985.

Matsunaga has suggested extending the investment tax credit for purchase of horses used for work or breeding. The amendment would cost $6 million in fiscal 1981, rising to $21 million by 1985

Other amendments would provide special tax writeoffs for the Tillamook, Ore., YMCA; Erie Lackawanna Railroad, Manhattan Bowery Corp., New Yorker magazine, Watertown (Wyo.) Daily Times and the Glide, Ore., sewer system.

And still other proposals would include housewives returning to work under the employment tax credit for the needy, exempt childrens' homes that hold royalties from the crude-oil profits tax, and reduce the excise tax on tires.

There also are amendments that would cut estate and gift taxes; provide a tax credit for electric cars; benefit artists and theatrical producers; exempt farm vehicles from taxes, and exempt intercity bus lines from gasoline taxes.

Other proposals would benefit the Broadmoor resort hotel in Colorado; Jane M. Cathcart of Virginia, on the sale of her home; employees of Sun Oil Col. in Marcus Hook, Pa., and owners of spacecraft.

Along with these proposals, the committee also may vote again on a plan by Sens. Daniel P. Moynihan (D-N.Y.) and Bob Packwood (R-Ore) to allow taxpayers who do not itemize to claim deductions for charitable contributions. Cost to the Treasury: $3.6 billion.

A $500 million-a-year proposal by Sen. Bill Bradley (D-N.J.) would provide breaks for state and local governments that have chosen to pay Social Security taxes for their employees.