TSELINOGRAD, U.S.S.R. (AP) _ Three decades after Nikita Khrushchev dispatched workers to transform Kazakhstan's ''virgin lands'' into the Soviet wheatbasket, drought, erosion and a manpower shortage continue to slow the march toward self-sufficien cy in growing grain.

The 1953 campaign that brought short-term glory, then eventual scorn for the volatile Soviet leader has made a measurable contribution to grain production and development of the vast Kazakh steppe in central Asia.

However, Soviet output of bread grains has been erratic and even in the best years has fallen short of national needs, forcing Moscow to import huge quantities of grain.

Wind erosion and loss of topsoil nutrients caused by poor crop rotation have hurt per-acre yield in Kazakhstan since the late 1950s, after the initial boom in the virgin lands.

Farmers and researchers today still criticize Khrushchev's all-out effort to boost grain production by planting every available acre in the virgin lands without regard for soil conservation.

Like the Dust Bowl-era of the 1930s in the United States, Kazakhstan suffered serious topsoil losses in the late 1950s; farmers in the central Asian republic have been battling to replenish it ever since.

Sub-surface tillage, which leaves much of the uppermost soil layer in place while preparing the ground for seeding, gained popularity after Khrushchev was ousted in 1964 and has done much to preserve topsoil, said Alexander Barayev, head of the National Grain Research Institute and a prominent agricultural researcher for nearly 50 years.

Barayev and other researchers advocated soil conservation during Khrushchev's campaign to open the ''tselina'' - the virgin lands. But Khrushchev pressed for massive plantings, and the country had record grain harvests in the late 1950s. Production in Kazakhstan alone was up by nearly 50 percent from five years earlier.

''Khrushchev had the ability to convince the country to undertake a project it was not fully ready for,'' Barayev said.

The effects of soil erosion and failure to rotate crops began showing over the next few years; by 1962, the republic's grain yield dropped significantly.

Despite soil conservation practiced in the past two decades, the virgin lands have not produced grain on the scale envisioned by Khrushchev. But the program provided an important impetus to Soviet agricultural expansion at a time when the nation was growing quickly, according to Western analysts.

Kazakhstan accounted for only about 2 to 5 percent of Soviet grains in the years before 1953. The republic's share jumped to as much as l8 percent during the late 1950s, then dropped to an average of 10 to 12 percent, which it maintains today.

Severe drought in the grain-growing region of the country was blamed for last year's poor harvest. Kazakhstan harvested 17.5 million tons, compared to a target of 27.5 million, and the nationwide harvest of 170 million tons was nearly 60 million tons below the target figure.

Soviet leader Mikhail S. Gorbachev noted in a speech in June that weather is not the sole culprit in poor harvests. He has called for more efficient use of farmlands and broader introduction of technology.

This winter's heavy snowfall delayed spring planting until May 25. Although there were average rainfalls in May and June, a recent dry spell worried Kazakhstan farmers about the fate of this year's crop and the chances of meeting their goal of 28 million tons.

The monthlong drought prompted the U.S. Department of Agriculture to lower its forecast in July for 1985 Soviet grain production from 195 million tons to 190 million. About the time of the revised forecast, however, rain fell over the Tselinograd region.

The Soviet Union's grain imports from all foreign sources are expected to reach 37 million tons, the Agriculture Department said in June. Although that figure would be well below the record of 55 million tons imported in 1984-1985, it would still rank as the third-largest in Soviet history.

In their campaign to boost production and lower the need for costly grain imports, Kazakhstan's farmers and Moscow's planners apparently are deciding in favor of the familiar Soviet bigger-is-better theory of farming.

The republic plans to increase the amount of farmland by 11 percent before 1990 by reclaiming another 4 million hectares of salinated soil, according to Taufik Mukhammed-Rakhimov, head of planning for the Kazakhstan government. A hectare is about 2.47 acres.

Western agricultural experts in Moscow expressed surprise at the plans to expand in view of Gorbachev's campaign for more efficient use of existing resources as a means of revitalizing the economy.

Mekhlis Suleimenov, deputy director of the grain research center, emphasized that the expansion will be accompanied by greater use of soil conservation techniques on existing farmland to boost the yield per hectare.

In addition to weather problems, virgin land farmers currently face chronic shortages of fertilizers, chemicals, spare parts for farm machinery and a population growth rate that doesn't meet the demand for more workers.