Mary Kay Thatcher, a lobbyist for the American Farm Bureau Federation, remarked in a story in The Hill last week that change in farm policy is evolutionary, not revolutionary.

Groups striving to change the government farm support program should take her words to heart as another five-year farm bill completes its odyssey through Congress. Judging by the House bill approved in July and the Senate bill hitting the floor this week, the new farm bill will not make huge changes in the way farmers are supported.

This has made many people unhappy, including the Bush administration, which has threatened to veto both the House and Senate bills, even though this could be a political risk given the importance of the legislation to the Midwest, home to several battleground states. The administration does not think the bill includes enough reform, and argues that further limits should be placed on payments to rich farmers.

Religious, environmental and anti-poverty groups as well as taxpayer watchdogs agree. They say more of the dollars targeted to traditional crops should be shifted to nutrition, food stamps and conservation. Debate along these lines will play out all week on the Senate floor.

In all likelihood, however, a new farm bill will include some key changes in policy that will reflect years of lobbying by specific interest groups. The changes may be termed as relatively small — evolutionary — such as an increase in funding for conservation in the Senate bill. But they suggest the lobbying fights of the past year will set the table for further farm bill tinkering in the future.

Most notably, growers of fruits and vegetables appear to be on the verge of winning significant support for the first time. The bill approved by the House last summer includes $1.6 billion to help growers of tomatoes, oranges and other so-called specialty crops market their products overseas, among other things. This is a significant victory from 2002, when specialty crop-growers were disappointed with the results of that year’s farm bill.

Specialty-crop producers won this assistance by aligning themselves with nutrition groups and other interests. They all argued that the nation should have a farm bill that better reflected nutritional needs, and this meant dollars for green beans instead of corn syrup used in sodas.

The alliance between specialty-crop producers and other groups fell apart over differences on the House bill. Fruit and vegetable producers were happy with their increased funding, but activist groups argued that it still gave too much in traditional payments to so-called row crops, including cotton, rice, other grains and corn.

Still, the alliance produced a small but meaningful change, and suggests further tweaks can be made — though possibly not for another five years, when Congress takes up another farm bill. Then, as now, its choices will not be describable as natural selection, but they will amount to evolution.