The House yesterday passed a $50.4 billion agriculture spending bill for 1991 that will terminate crop insurance for farmers on Oct. 1 unless the legislation is changed later in the session.

Members of the policy-making House Agriculture Committee admitted they were stunned by the action when it was initially taken by the House Appropriations Committee on Friday. They were unable to regroup by yesterday when the measure went to the House floor. The final vote was 335 to 86 for passage.

During a testy floor exchange, Rep. Glenn English (D-Okla.) called the appropriators' action "arbitrary," but Rep. Jamie L. Whitten (D-Miss.), who is chairman of the House Appropriations Committee and its agriculture subcommittee, shot back that the program had cost taxpayers $1.23 billion since 1985 and was benefiting relatively few farmers.

"I could give you a book full" of reasons for killing the program, Whitten told English, who is chairman of the subcommittee in charge of farm credit matters in the Agriculture Committee.

Underlying the dispute is broad farmer dissatisfaction with the crop-insurance program. Soybean farmers across the South, and particularly in Whitten's state of Mississippi, have voiced complaints about tight requirements and other problems, and only 18 percent of corn and soybean farmers signed up for the government insurance from 1986 to 1988. Costs exceeded premiums by $2.3 billion since 1980. The program covers weather damage, pest destruction and other losses, but many farmers continue to depend instead on government disaster-relief payments, which Congress authorized on three occasions in the 1980s.

Whitten's spending bill withstood five amendments to reduce it by varying percentages. Among them was an amendment to reduce it by a symbolic $19.90. It failed 214 to 175.

The votes attested to the power of Whitten and to the agriculture bill's benefits for almost every district in the nation. Rep. Harris W. Fawell (R-Ill.) noted that the bill even contained an allocation for "District of Columbia agricultural services." Next year's measure contains $19 billion for the food stamp program, $2.35 billion to feeding poor pregnant and nursing women and their infants and $50,000 for research into blight on nut-bearing filbert trees.

As the House nears the end of its initial round of appropriations work, the Senate Appropriations energy and water subcommittee drafted a $20.9 billion bill which, like the House version, provides the full $318 million sought by the administration for the atom-smashing Superconducting Super Collider (SSC) to be built near Dallas.

Subcommittee Chairman Sen. J. Bennett Johnston (D-La.), in one of the strongest statements to date for the SSC, urged the administration to continue seeking foreign participation to offset costs but added that the project was worth doing even without such participation.

In a written statement, Sen. Lloyd Bentsen (D-Tex.) praised the subcommittee action and said he would work to prevent cuts in collider funding in any White House-Congress budget summit agreement.

Last-minute maneuvering yesterday by subcommittee member Sen. Harry M. Reid (D-Nev.) salvaged an additional $10.4 million for Nevada, whose Yucca Mountain has been selected as a national respository for spent nuclear power plant waste. Although permits to start the site planning are held up in lawsuits, Johnston offered an olive branch to the state in the form of increased grants to the University of Nevada, the Nevada legislature and county governments.

Another subcommittee member, Sen. James A. McClure (R-Idaho), succeeded in redirecting $10 million initially earmarked for development of a nuclear space engine to research on a new generation of commercial reactors underway at Argonne National Laboratory and the Idaho National Engineering Laboratory, the latter in McClure's state.