Q. Franz Metternich. Alfons Knauf. Otto Sels. Ernest Bonnstetter. Which one is the old Iowa name?

A. Bonnstetter. Ernest's father emigrated to America from Germany early this century and settled in Iowa. Son, like father, is a farmer - but with a difference. This second generation German-American works for a new breed of German farmers in Iowa: absentee owners.

Bonnstetter raises corn on Kossuth County farmland owned by the family of Prince Franz Albrecht Metternich-Sandor von Ratiborund Corvey. His wife, Princess Isabelle, is a direct descendant of the 19th century Austrian statesman. Together with her sister, Countess Marie Christine WoIff-Metternich, and her husband, they purchased 2,125 acres for $3.5 million two years ago.

The Metternichs are among a growing number of foreigners buying property in the United States. Although there are no statistics to document the sources of offshore capital, a number of real estate specialists believe West Germans are leading the parade.

Prosperity at home, continued decline of the dollar against the mark, German tax laws favoring investment, decrease in available German land and steady appreciation of U.S. property values with no fear of expropriation - all these factors combine to spur German interest in U.S. real property.

The Lehndorff Management Group of Hamburg, which is the largest seller of American real estate to Germans, began investing in the United States in 1968. Today it manages $650 million worth of property (representing $258 million in German assets) in the U.S. and Canada.

Institutional Investor reports that Lehndorff operates through limited partnerships sold through West German banks, which raise about $2 million in new capital each month, as well as through public and private investment vehicles.

Like Canadians and Britons, other large investors, Germans have a preference for income producing properties such as shopping centers and office buildings. (Germans are probably the largest foreign owners in Houston.) But the trend toward ownership of agricultural land is also growing.

As yet, it is but a mole hill in a corn patch. In 1975, according to government figures, 4.9 million acres were owned by foreigners, who held leases on an additional 62.8 million.Now, according to Chicago banks and insurance companies, including Continental Illinois National Bank & Trust Co., one quarter of all U.S. farm sales are being closed by offshore investors.

Lehndorff recently set up an agricultural fund that has invested in 15,000 acres of Midwestern farmland. Reed Oppenheimer expects to put $40 million into farmland for foreign clients, double last year's investment. Continental was forced to abort plans for buying land with tax exempt funds.

But other companies getting into farm funds - primarily but not exclusively for foreigners - include Merrill Lynch, Shearson Hayden Stone, E. F. Hutton, and Smith Barney Harris Upham & Co.

Through these funds, it won't just be the Prince Metternichs who will soon be able to afford a piece of U.S. soil. Europeans, with comparatively little land of their own, have always valued ownership as protection against inflation and financial upheaval.

Although agricultural land has a lower yield than commercial property, appreciation is excellent.

For instance, a typical Iowa farm returns something less than 4 per cent on investment. But between 1972 and 1977 the average price of an acre of land nearly tripled, from $440 to $1,230. The growth between Feb. 1, 1976 and the same day this year was 35 per cent. Top land goes for as much as $3,000 an acre. In Illinois, the increase over last year was 41 per cent.

Public concern over the possibility of wholesale Arab investment was voiced at the time of the oil embargo. Were aliens taking over America? Twenty-nine states already had laws restricting the amount of land foreigners could own, but there was no system for monitoring these limits and determining what nationalities were involved.

In 1975, Iowa was the first, and so far the only, state to pass a law calling for all corporations, partnerships and non-resident aliens owning or leasing agricultural land for farming to report annually to the Iowa Secretary of State.

The first results of that survey eased midwesterners, fears. Less than two hudredths of one per cent of Iowa's farmland was in foreign hands. Of the transactions reported, 80 per cent or 16, were made by Germans.

Thus the Metternich purchase, previously known only to the principals, neighbors and the Kossuth County court house recorder, came to public attention.

Mrs. Bonnstetter declined to answer questions about the family, saying she had been advised not do so by Upper Midwest Management Corp., the firm that operates the Metternich place and employs her husband. It was learned, however, that Midwest and Bonnstetter also operate two other farms purchased last year by Germans. A German broker is said to have made 18 trips to the county to find land for potential buyers.

While the Metternich name is known, those of other beneficial owners are more difficult to trace. For example, the Secretary of State's office received notice of a three-year-old sale involving 1,780 acres in Fayette and Benton counties.

The owners of record were four corporations registered in Lichtenstein. Iowa law requires disclosure of the names of any alien stockholders with more than 10 per cent of a corporation's shares. Three more corporations and done name were listed.

Contacted in Cedar Rapids, the authorized representative for these buyers, attorney James Bradley, declined to discuss the transaction. He did not disclose if he knew the identity or the nationality of the true owners. He would say only that the private corporations had been formed just before the sale.

Leo Lala Jr.'s name and L.D.L. Farms appear in Linn and Wayne county records as the owners of sizeable tracts. At least 1,742 of those acres belong to Otto W. Sels, who owns a soybean processing plant in West Germany. Lala manages their farm. Four other Sels - his wife and three children - are co-owners, a common way of skirting the law prohibiting aliens from owning more than 640 acres apiece.

In Wayne county, Illinois, 11 members of the Knauf family own 3,700 acres (registered as the Skillet Fork Farm Corp.) for which they paid $3 million last year. The Knauf family, headed by Alfons, owns the West German Gypsum Works, with plants all over that country. Farmland in Southern Illinois is being snatched up eagerly today by speculators because some suspect there are coal deposits beneath it.

On July 18, the House passed a bill calling for the USDA and the Commerce Department to work together collecting data on farm ownership. Rep. James A. S. Leach (R-Iowa) is also sponsoring legislation that would add a question on nationality to the agricultural census.