New issues usher in agriculture secretary. WINDS OF CHANGE BLOW A MODERATE COURSE

In agriculture, issues can change almost as quickly as the weather. And they have changed dramatically in the last two years. When Clayton Yeutter, the new secretary of agriculture, takes office next month, he will find a policy climate that is far different from the one his predecessors operated in.

Grain surpluses? They are suddenly gone, largely because of this year's drought. The farm crisis? Most farmers' finances have improved so much that the plight of those who remain in trouble has been virtually ignored.

But the new policy climate is not likely to be easier, only different.

``Clayton's got a full platter,'' says Bob Frederick, legislative director of the National Grange. ``He didn't walk away from anything.''

The most pressing domestic issue for agriculture is the budget.

Spending on farm programs soared to a record $26 billion in the mid-1980s as policymakers scrambled to stabilize the agricultural economy. Now that farmers are on the mend, there are strong pressures to curb farm spending. According to the dictates of the Gramm-Rudman deficit-reduction law, which sets targets for federal spending, farm programs will have to be cut by some $3 billion.

The other new domestic issue is the environment.

A whole raft of challenges, such as pesticide contamination of water, soil erosion, and food safety, are likely to play a bigger role in the next Congress, says Ross Korves, an economist with the conservative American Farm Bureau Federation.

The overwhelming international issue in agriculture is trade.

And here, the policy climate is unlikely to change. Currently the US trade representative, Yeutter is likely to continue the hard-line stance that the Reagan administration has taken with the European Community. The EC and the US have battled for four years over whether to eliminate subsidies (the US view) or manage output (the European view). So far, negotiations have yielded very little.

Overall, the conservative policy directions pursued by the current secretary of agriculture, Richard Lyng, are expected to continue under Yeutter. Yeutter may even be a little more aggressive in promoting free-trade agriculture than Mr. Lyng was, says Bill Lesher, an agricultural consultant and former Agriculture Department official.

This continuity of conservative thinking at the top may lead to policy changes of progressive farm groups, which have supported up to now government programs that would tightly regulate farm production. In an important speech last week, Alan Bergman, president of the North Dakota Farmers Union, officially abandoned support for such a plan.

``We must be willing to recognize that President-elect Bush has rejected mandatory supply-management programs and that this door is closed, at least for the next four years,'' he told delegates at the union's convention in Bismarck, N.D.