Higher grain prices are likely in the coming months after the lower-than-hoped-for crops in the Northern Hemisphere this year, commodities experts indicated in interviews conducted yesterday. The Soviet Union this week virtually admitted that its harvest was very disappointing, while drought in the United States cut production this summer.

World consumption of grain is expected to exceed production by about 2 percent this year, according to John Schnittker, a former Agriculture Department official and now an agricultural consultant. This is despite historically high levels of grain production. World production in the 1980-81 crop year probably will be the second-higher ever, Schnittker said.

But increased demand for grain -- largely because of a rise in the amount used for meat production -- means that there still will be upward pressure on prices. This will be greatly increased if there is a poor harvest in the Southern Hemisphere producers, such as Australia, Brazil and Argentina.

The Australian crop already is known to be well down from previous years' levels, but this has been taken into account in the figures, Schnittker said. Argentina has just suspended sales of grain futures because of early indications that the wheat crop will be down from an anticipated 10 million tons perhaps to less than the 1979-80 harvest of 7.9 million tons.

U.S. grain exports account for 60 percent of world trade in grains, Schnittker said. On the Chicago market, prices have been moving up over the last few months. The December wheat futures contract was $5.30 a bushel Tuesday, up from $4.25 on June 6. There was a comparable percentage rise in corn prices from $2.90 to $3.62. The soybean November contract has risen from $6.50 on June 6 to 8.70 on Tuesday.

The Russian grain shortage has little effect on the U.S. market, according to Stuart Baird, director of public relations for Cargill Inc., a Minneapolis grain company. The American embargo on sales to the Soviet Union of more than 8 million tons of grain a year means that, unless the administration changes its mind, U.S. exports will not be boosted by the Russian shortage, he said.

But the shortage will increase the pressure on other suppliers of grain to Russia. It will import about 30 million tons of grain altogether this year, Schnittker said yesterday. This is about the same amount as it imported last season.

If the embargo were lifted early next year, the Soviet Union would raise its purchases to 35 million tons, Schnittker believes. The USDA recently estimated the Soviet crop at 205 million tons, well above some other estimates. The target for Russian production was 228 million tons.

Yesterday's formal agreement on a grain pact between China and America will not affect the market much, according to Schnittker, Baird and Clarence Palmby, vice president of Continental Grain Co. in New York.

The agreement formalizes what was happening already, Schnittker said. "It is constructive but not terribly import," he added.

"It is simply telling the world that China is probably going to go on buying from the U.S. at about the same rate as last year," Palmby said yesterday. He said that it is too early to tell whether there will be an overall grain shortage this year but added that "the estimated carryover in the U.S. a year from now does not look that uncomfortable."

However, there could well be "a bit less grain over the next 12 months," he said, which is "not bearish, is it?" Schnittker said that if there is not a bumper crop next year, then there will be a serious problem of rising grain price.

The last two decades have been dramatic changes in grain consumption and trade patterns. The centrally planned economics together -- including China, the Soviet Union and Eastern Europe -- were 99 percent self-sufficient in grains between 1960-63, according to Agriculture Department figures. By the period 1977-79, these countries produced only 93 percent of the grain they consumed.

Eastern Europe boosted its consumption from 64.3 million tons in the rist period to 106.5 million tons in 1977-79. China raised its consumption from 112.3 tons to 225.2 million tons, while Russian comsumption went from 119 million tons to 217.6 million tons.

The United States also has boosted consumption over the 20 years but still was able to export almost 95 percent as much as it consumed in the three years 1977-79.