The value of Utah's farms and ranches has fallen $700 million in the past 12 months, according to an annual report from the Utah Agriculture Statistics Service and the Utah Department of Agriculture.

The report says Utah agricultural land was valued at $5.5 billion in 1987 and is valued at only $4.8 billion this year. Utah land has dropped steadily in value in the past few years, from $7 billion in 1984.Many real estate and agriculture experts say Utah farm land, like agricultural land across the nation, was overvalued in the early 1980s because of double-digit inflation through much of the middle and late 1970s. The land has fallen in value as a result of the farm crisis and the sharp drop in the inflation rate.

Utah also has 100 fewer farms this year than last year - down to 13,600 - and 100,000 fewer acres being used for farm and ranchland - from 11.4 million in 1986 to 11.3 million in 1987 - according to the report.

The dwindling number of farms reflects the history of the nation's agricultural industry. Farm numbers around the country are decreasing.

Farm numbers for Utah peaked in 1940 at 28,500, when off-farm employment was scarce. Since the 1960s, when urban growth began to have a noticeable effect on farmland values, the number of farms in Utah has fallen steadily, mostly because of weather problems, low commodity prices and falling land values.

The size of farms has increased in most areas of the United States, but not in Utah, where average farm size has decreased steadily, from 1,000 acres in 1975, to 831 acres in 1987.

Utah rose from seventh to sixth place in the nation in sheep and lamb inventories last year, according to the report; climbed from 19th to 15th place in commercial cattle slaughtered; rose from 23rd to 18th in the nation in commercial apple production; and stayed in third place in mink pelts and apricot production.

The state fell from second to third place nationally in tart-cherry production, slipped form sixth to seventh place in sweet cherries and dropped from seventh to eighth nationally in summer-storage onions.