THIS IS A LOW-LYING land of bog, pond, and moss where the Baltic plain runs down to the cold northern sea. Teutonic knights, Danes, Swedes, Nazis and Russians have fought and died to control the soil, but few permanent marks of their conquests remain. Instead, under the scudding autumn cloud, the most visible and enduring sign of endless human toil to be seen here are large stone piles in the middle of fields, piles built up through the years as peasant farmers plucked rocks from their furrows to raise grain and hay to feed herd and family.

Soviet collectivization of individual farms began here in the years after World War II. It met stiff resistance from the Estonians but now is complete. A recent guided tour of one of the farms, near their provincial city 60 mile southeast of Tallinn, the capital, gave a glimpse of what the Soviets extol as the better way of doing things.

The "Ninth of May" collective, named for the date of the Nazi capitulation in 1945, was founded 30 years ago and now combines nine small collectives totaling 24,700 acres, of which 12,000 are under cultivation. Millions of rubles have been invested in the farm, and the snug cowbarns and comfortable four and five-room cottages of some of the "kolkhozniks" are reason enough for the officials to want to show it off to foreign journalists.

According to Endel Leiberg, the collective farm director, "there were no tractors, no machinery of any kind, no electricity" when the collective was formed. Now there are 120 tractors, enough harvesters and 60 trucks available for the farm. "There are twice as few people as 30 years ago, but we produce four times as much," he said proudly.

TWELVE HUNDRED PEOPLE live on the farm, including 700 collective members, 400 of whom are counted as workers. Ninety-nine percent of the families are Estonian. "There is one Russian family and their children speak Estonian," said Leiberg, who is himself Estonian. There are 100 private houses and three apartment buildings for the families. A family that masses 4,000 rubles $5,500 can apply for a private house.

A visit to the house of Lambit Yoesalu, a 52-year-old truck driver and Communist Party member, disclosed a snug five-room house for which he paid 3,500 rubles down and a monthly "mortgage" of 33 rubles. He and his wife, Elve, 49, have a combined income of 400 rubles a month, so the monthly housing charge is no budgetary strain. Yoesalus is one of 50 Communist Party members on the farm, and officials said there is no preference given them in housing.

Leiberg's wife, Helga, runs the farm school, consisting of eight grades and 161 children. Of 17 pupils who finished the eight grade, 11 went on to secondary schools (Estonia requires 11 years of public schooling for most children, as opposed to 10 years elsewhere in European Russia). Of those who go to secondary schools, about 19 percent go on to a higher institute or unversity, an average Mrs. Leiberg said she is "happy with." Instruction is in Estonian, but Russian is taught as a second language. Mrs. Leiberg, who is Estonian, was clearly more comfortable in Estonian than in Russian.

Crop, milk and meat yields cited by the farm officials indicate that the "Ninth of May" collective is about twice as productive as collectives in European Russia, according to official figures. "Maybe we work harder," said Leiberg with a smile.

IN TALLINN one night recently, a group of chiefs of traffic police from the Soviet Union and other East Bloc countries gathered in the 15th century city hall to hear a concert given in their honor by a 13-member musical group that specializes in medieval and Renaissance religious and court music.

The policemen, blocky men with short hair and the unmistakable look of police anywhere, listened intently and applauded with appreciation at the performance of the group of shaggy-haired, mustachioed men in their long tights, brocade tunics and lace-trimmed shirts. That Tallinn officials would schedule such a concert for such an audience says something about the drive for culture in the city.

The state-supported group, "Hortus Musicus, "concentrates its repertoire in the Renaissance, according to its leader, Andres Mustonen. They found most of the music in the Lenin Library, he said. The concert that night included 15th and 16th century Italian court music, as well as a complete selection of choral music from the mass, including the Pater Noster and the Agnus Dei.

The musicians used harpsichord, sackbut, viola da gamba, several recorders and other instruments that could have come straight from the 16th century woodcuts.

"Hortus Musicus" means "garden of music" in Latin, and Mustonen says he chose the name because of its "traditional meaning and richness." The group has toured the Soviet Union for the past four years and made five records. He said interest in Renaissance and baroque music is growing among the nation's youth.

"We like the spirit of music of the Renaissance, which is especially good for people of our time, because there is a tension and clarity in it which does not coincide with 20th century music," Mustonen said.

That such a group should be based in Tallinn, with its medieval walls and European tradition as a Hanseatic League city, seemed particularly appropriate.

CITY OFFICIALS have spent more than 50 miles rubles and have set aside an equal sum to restore and rebuild the old town of Tallinn, an area of 90 acres surrounded by the remains of two medieval walls and containing several hundred buildings that date from the Middle Ages. The target date for completing the restoration is timed to coincide with the Olympic yachting races, which will be held here. A huge seaside yacht center is rising a few miles from downtown in Pirita, and the usual Soviet exhibition of economic achievement is filled with well-designed Olympic souvenirs, from yachtsmen's nylon windbreakers to cocktail coasters.

Few of the souvenirs can be found in local shops - it is said they are being stockpiled for 1980.

EACH SUMMER HERE for the past few years, a handful of Estonians has quietly used vacation time to work on an oral history of one of this Republic's most sensitive past chapters: the 20 years between 1920 and 1940 when Estonia was recognized by the world as an independent and sovereign country.

The amateur historians, numbering perhaps a few dozen in a population of 1.4 million, will never see the fruits of their labor officially published or recognized here since their views are at variance with official Soviet histories of the time.

The Soviet version is that Estonia voluntarily joined the Soviet Union in a successful workers' uprising in 1917-18, but that repressive reactionary nobility and bourgeois, stiffened by British Naval units and volunteers from Western nations, installed a reactionary boureols government that kept power through 1940. Soviet occupation and annexation of Estonia in 1940 is officially considered "restoration" of legitimiate Souviet power.

THE YEARS OF SOVIET power have seen an enormous buildup of Russians, attracted by Estonia by its higher living standards. Although imperial Russia ruled Estonia from the early 1700s to 1917, by the late 1930s only about 8 percent of the population was Russian. Since 1940, this has changed radically. The Russian population now makes up 32 percent of the country, 43 percent in Tallin and continues to climb.

One reason is that the Russians seem more willing to take unpleasant jobs, such as oil shale mining near Narva in eastern Estonia. There, in large open-pit mines, oil-bearing shale is mined. The oil distilled and burned at pit-head electric stations, producing a substantial part of Estonia's electricity and allowing the tiny republic .2 percent of the entire Soviet land Mass to export electricity.

"Russians are expanding along the Narva-Tallian railroad. It's like in America," one Estonian said. "It's the railroad veruss the Indians."