As the Senate gets ready to debate billion-dollar revisions in irrigation land and water laws, kingpins of California agribusiness are pouring money into the Carter and Connally presidential campaigns.

Within a three-day period last week, Rosalynn Carter and Republican candidate John B. Connally were feted by San Joaquin Valley growers and allies, many of whom crossed party lines to contribute.

The future of their rich farm empire, heavily subsidized by low-cost federal irrigation water, is directly tied to congressional action and administration policy on revisions of the 1902 Reclamation Act.

Mike Roos of Los Angeles, state coordinator for the Carter-Mondale campaign, said the meaning of the generosity of the agribusiness contributors was clear. They want to buy influence, he said.

"Water is the most central thing in that area. It is paramount. And those people will speak to anyone who has a voice in government," Roos said.

"They want to influence the direction of policy and contributions is one way to do it," Ross added, although he insisted their contributions would have no effect on Carter administration policy.

"Money is raised rather peculiarly in California," he said. "Basically, you raise money where you can get it - and that is especially so in the valley. I'm not surprised that the same people would attend different events."

Typical of the blurring of partisan lines was the appearance at a Connally luncheon last Thursday of Fresno Democratic operative Joe Meredith, who arranged Mrs. Carter's Tuesday reception. He said he went to the Connally affair as a nonpaying guest.

The financial reports are not yet in from the Carter-Connally sallies into the irrigated farm country, but two events for Mrs. Carter produced well over $25,000 for e Carter-Mondale campaign.

Mrs. Carter was feted in Fresno last Tuesday at the home of a Republican cotton merchant. The next day in Palo Alto, Democrats and Republicans kicked in as much as $500 each to shake her hand.

In Fresno, at least one farmer told Mrs. Carter that the changes reformers want to make in the Senate's proposed revision of the Reclamation Act of 1902 are not needed.

According to press pool reports, Mrs. Carter told the farmer, Frank Coelho, that she was acquainted with the controversy over the law and that it was being looked into - although the meaning of that was not explained.

Mrs. Carter's host in Palo Alto was Walter Shorenstein, a real estate magnate who has been involved in recent efforts by big-money interests to dilute the Senate legislation.

Shorenstein; R. J. Landis, chairman of the Del Monte canning company; bankers, farm and cattle executives and others with a stake in the outcome of the legislation met three weeks earlier in San Francisco with Sen. Alan Cranston (D-Calif.) to discuss exemptions they were seeking.

The state chamber of commerce, which sponsored the meeting, reported in its 4uly 13 newsletter that Cranston was "obviously anxious" to have agribusiness support in his reelection campaign next year. Cranston aides denied the chamber's report that he would back the exemptions.

Connally's hosts last Thursday were Paul and Octavia Diener and John Harris, Republicans whose holdings of federally irrigated farmland could be diminished if the proposed legislation were enacted.

The Dieners were among a group of Fresno-area agri-business leaders - Republicans and Democrats - who contributed more than $50,000 to the Democratic National Committee in another Meredith-sponsored venture that brought them to Washington in January for a presidential reception at the White House.

Their interest then, as now, was the administration's position on S. 14, expected to reach the Senate floor in debate in September. The bill would revise the 1902 act, which has been violated systematically for decades.

The old law put a 160-acre limit per person on federally irrigated land holdings and was the basis for the program that irrigated millions of acres of land in 17 western states, providing enomous tax subsidies along the way.

Large landholders in the West, particularly in California and Arizona, have put intense pressure on Congress to go slow in revising the law and establishing acreage limitations that would curtail their operations.

The "reform" bill reported out last month by the Senate Energy and Natural Resources Committee at the direction of Sen. Frank Church (D. Idaho) would exempt vast areas of federally irrigated land from coverage.

Interior Secretary Cecil D. Andrus, conceding he had been caught unaware by the committee, last week launched an unusual attack on the bill that Church, his longtime Idaho politicial ally, had pushed through subcommittee and full committee.

Andrus wrote senators to outline his objections to the "grievous violence" the committee did to the reclamation program and to attack the bill's exemptions.

Andrus detailed several amendments that he and Sen. Gaylord Nelson (D-Wis.), an adamant critic of existing reclamation practices, intend to propose on the Senate floor.

The secretary called together last Friday a group of labor, consumer, church and rural-interest representatives to enlist their support in the effort to amend the committee's bill.

An administration official, commenting over the weekend on the lobbying and campaign-money gestures, acknowledged the impact of the pressures.

"What does all this mean to the general public?" he said. "It means pressure on bureaucrats and elected officials. Political pressures. It is the politics of water - money, big money, big names."

In the case of the empires of the West, controlled by a relatively few individuals and corporations, the legislation is a dire threat. Federal tax subsidies on irrigation water, running as high as $1,700 an acre in some cases, could be reduced or eliminated.

So far, an Andrus assistant said, there has been no White House attempt to alter the secretary's strong stand against the Church bill. CAPTION: Picture 1, ROSALYNN CARTER; Picture 2, JOHN CONNALLY...both are feted by farmers seeking influence in battle against Senate water bill.