IT HAS BEEN 40 years since James Agee and Walker Evans traveled through rural Alabama to examine the lives of impoverished sharecroppers. Part of what they discovered became "Let Us Now Praise Famous Men," an enduring classic of American journalism. The book comes to mind because recently the American Friends Service Committee in Philadelphia covered much of the same ground. The text and photographs of their recent report on rural housing in Alabama offer a haunting similarity to the conditions of the 1930s and '40s. It is as though the committee had opened a time capsule and found that many families have been trapped in changeless poverty.

In Alabama's 67 counties, 40per cent of all rural homes are substandard. The shacks and shanties - many propped up by stones or bricks, with cracks in the wooden walls - are the last resorts for citizens who may live in counties that have no subsidized public housing rental units, that do not utilize Farmers Home Administration programs, that are left out of the Section 8 HUD programs or have long waiting lists for assistance. For black families, it is often worse: 84 per cent of black-occupied houses lack adequate heating against 54 per cent or all rural residents. Black families live in half of Alabama's substandard houses, but they receive only 39 per cent of Farmers Home Administration loans. "It's kind of tough living here," said a man who shares with eight others a two room house that has neither heating nor plumbing.

These conditions are not limited to Alabama, because no rural area of the county is without unlivable housing. The significance of the committee's 100-page report is that it calls attention to the bleakness of rural housing at a moment when a new administration appears ready to involve itself in a long-term commitment. During his confirmation hearings, Secretary of Agriculture Bob Bergland was candid: "Half of the poverty in the United States is in rural communities. These folks suffer in silence. They do not march. they do not demonstrate. They do not have the attention that many of the problems of the city have been given lately, but they suffer nonetheless. And we need to address that question with some bold imaginative new programs."

Actually, some of the old programs - if given new life - would bring a measure of relief. The committee, for example, points to the FmHA Section 502 loan programs by which families can build their own homes. It tells of 71 homes being built since 1971 in Macon County, with local families providing the labor, loans were provided by FmHA and the technical assistance came from the Tuskegee Institute's self-help housing program.

Self-help homes are not the whole solution to the rural housing emergency, but they are part of it. What is important now is that Mr. Bergland and his specialists in rural affairs seize the opportunity to put all the partial solutions together into a full effort.