A grim picture of a faltering farm economy, drawn by the National Farmers Union from hearings across the country, was delivered yesterday to the House Agriculture Committee with a forecast of tougher times to come.

The report by NFU President George W. Stone was part of an effort to stir congressional support for emergency legislation aimed at carrying farmers through their worst economic squeeze since the Depression.

The 325,000-member NFU urged adoption of a pending farm-crisis act to limit production and so prop up prices of basic grains and cotton. The House committee has scheduled hearings for next week and approval of the bill is expected. It is a farm counterpart to emergency housing aid also moving through Congress.

Reps. Thomas A. Daschle (D-S.D.) and Kent R. Hance (D-Tex.), chief sponsors of the legislation, contend that it would help farmers out of their economic plight by reducing production and forcing up prices. Their bill has been introduced in the Senate by Sens. J. James Exon (D-Neb.) and Max Baucus (D-Mont.).

Stone said the 1981 farm bill, which, under pressure by the Reagan administration, scaled back traditional agricultural-support programs, "will not bring about the needed recovery in agriculture."

"Simply to continue existing agricultural and interest rate policies will get the nation into deeper trouble--deeper trouble as farmers, deeper trouble as users of credit and deeper trouble as taxpayers," Stone said.

Farm-state Republicans and Democrats from the committee and the congressional rural caucus applauded NFU's report, a compilation of testimony and data from nine regional hearings in March and April.

Rep. Ed Jones (D-Tenn.), chairman of the rural-credit subcommittee, said there was "no way my subcommittee or the rural caucus could have devoted the time and resources required to conduct such a massive review of conditions in rural America."

Rep. E. (Kika) de la Garza (D-Tex.), chairman of the Agriculture Committee, told Stone: "You have documented that the 1981 farm bill didn't work and that it may need corrections."

The report, called "Depression in Rural America," depicted farmers and farm communities in a state of economic and spiritual depression as a result of skyrocketing debt, fast-falling income, rising production costs and continuing high interest rates.

Stone said the depth of the crisis was illustrated simply: In 1981, for the first time in history, the interest paid by farmers exceeded their net income. Nationally, farmers had about $10 worth of debt for each dollar of net income.

Farm income is expected to decline again in 1982, for the third consecutive year, although the administration insists that its voluntary acreage set-aside program will assist in reducing production and bolstering prices on wheat, corn and other basic commodities.

The income picture, along with depressed market prices and lagging export demand, has heightened fears among NFU and other farm groups that many farmers will face foreclosures at the end of this growing season.

The fears were increased a bit this week as the Department of Agriculture reported that in the year ending Feb. 1, the average value of U.S. farmland declined 1 percent. Until the drop, the first in 28 years, many farmers had been able to finance their yearly operations on steadily inflating land values.