An Agriculture Department analysis says the recovery in farm land prices is putting a healthy glow back into the financial complexion of American farmers.

When new figures based on readings as of Feb. 1 are released, they are expected to show the average price of farm land is up nationally for the first time in six years, although there are still areas where land values are lagging.Meanwhile, the department's Economic Research Service says that as stability returned last year to farm real estate, which includes land and buildings, the financial returns to farmers as a share of equity became positive for the first time since 1980.

Equity, the value difference between assets and debts, plummeted 34 percent to $536.6 billion in 1986 from $814.4 billion in 1981.

Land values, the mainstay of farm assets, plunged $256 billion between 1981 and 1986, especially in the Corn Belt and Northern Plains states.

As land values declined, more and more borrowers were unable to pay existing obligations without restructuring their debts or selling their assets, the report said. Even some farms with positive cash flows were considered poor credit risks because of low or negative equity positions.

The report added: An improved land market in the remainder of the 1980s represents an important indicator that the agricultural economy has turned the corner.

One measure of the importance of the land market to U.S. agriculture is the agency's computations on the total return to equity from farm income and real capital gains.

In 1987 when net cash income rose to a record level of $57 billion by USDA estimates, a couple of other things happened. Interest rates declined, and farm debt, which climbed to a peak of $192.7 billion in 1983, began to recede as credit tightened and farmers began paying off at a faster clip.

More than $50 billion was paid off in the next few years, and agency economists think the 1988 debt balance may be whittled further to a range of $128 billion to $138 billion.

Real estate debt of $75 billion to $81 billion in 1988 will be 25 percent lower than in 1984, the report said. Non-real estate debt of $53 billion to $57 billion will be nearly 37 percent less.

Thus, the economists said, the return to farmers on their equity in 1987 averaged 4.4 percent nationally, nearly the average of 4.9 percent a year in the period of 1959-70.

Net cash income is expected to decline this year to a range of $50 billion to $55 billion because of reduced federal supports, as a three-year drop in production expenses comes to an end, and because livestock earnings are likely to decline after two years of growth.

As a consequence, farm returns on equity are forecast to decline, perhaps ranging from no gain at all or an increase of 2 percent. But that Reflects the estimated stable prices for land, the report said.