SOVIET OIL PRODUCTION fell last year, the first decline in a generation. It must have been a profoundly unpleasant shock in a country that, like the United States up to the early 1970s, was accustomed to a steadily rising supply. There have already been repercussions. In the past couple of months the ministers of oil and of electric power have, as the Soviets say, retired.

The immediate cause of the trouble seems to be the inadequate maintenance that is common in Soviet industry. Perhaps improved management, under a new oil minister, can put Soviet oil protion back on that rising curve -- for a time. But somewhere ahead of them lies a more intractable limit. Although Soviet resources are enormous, the geology of Siberia has important similarities to that of North America. Development of the oil fields here started several decades earlier than there, and it seems likely that Soviet production will follow the same general pattern as in this country. American oil production peaked in 1970, and fell in the following years. Despite the enormous price increases, the supply of American oil hasn't risen. It has only stopped falling, and now seems to be stabilized at roughly 8 percent below the level of 15 years ago. Simply holding that level is requiring a gigantic effort by the oil industry, with high capital investment. There have been slight gains in producrs, but those gains have been won only by a dramatic expansion of drilling. The number of oil wells drilled in this country last year was more than 41,000 -- a record, and more than double the rate in the late 1970s.

Soviet ability in this technology is not to be underestimated. For more than a decade they have produced more oil than any country in the world, and they have done it in a region with an unfor- giving climate. Several years ago they surpassed the United States to become the world's leading producer of natural gas as well. But to hold the present output steady is going to require an increasingly strenuous exertion there, as it does here.

The United States responded to the constraints on its domestic oil production, in the 1970s, by increasing imports. The Soviets aren't likely to do that. One reason is that they now depend on exports of oil for most of their foreign exchange earnings. The Soviets may now be approaching a time in which the struggle to maintain oil production joins their agricultural system as a source of perennial strain in their economy.