The Farmers Home Administration will make extra efforts to be lenient in extending credit and loan aid to farmers during the farm economy's current "cloudy times," Agriculture Secretary John R. Block said yesterday.

Block and Undersecretary Frank Naylor Jr., who oversees the FmHA, acknowledged that the farm economy is under stress--severe stress in some areas--but argued that the overall picture is not as bad as generally believed.

Some national farm leaders say agriculture has reached "depression" levels, with massive foreclosures and liquidation sales in prospect, and commodity prices projected to remain low this year.

Farm debt is about $200 billion on a $1 trillion asset base, but net farm income in 1980 and 1981 adjusted for inflation was the lowest since 1933.

Block trotted out representatives of three private agricultural lending groups to help him make the case that the farm economy is suffering from temporary credit and cash-flow problems, but is not at a level of collapse.

Representatives of the American Bankers Association, the Independent Bankers Association of America and the Farm Credit Administration agreed with Block's assessment. They said their member banks will be particularly lenient in helping farmers through the current squeeze.

The farm credit system holds about 32 percent of the farm debt, commercial lenders hold about 24 percent and the FmHA holds 11 percent. The rest is held by individuals and others, such as insurance companies, according to the USDA.

FmHA clients are generally thought to be under the most stress. They are farmers who cannot get commercial credit.