China will suffer another poor grain harvest this year, putting more strain on its industry and living standards and increasing its interest in help from the United States, according to experts traveling with U.S. Agriculture Secretary Bob Bergland.

Members of the U.S. delegation winding up a tour of China here indicated yesterday that Peking can expect an increase of no more than a 10 million tons over 1977's disappointing 285-million-ton estimated crop. Such a small increase over what was considered a bad year will cut into China's plans for rapid modernization of its entire economy and perhaps have significant impact on trade with the United States.

Bergland reached agreement with the Chinese for an exchange of three agriculture delegations each next year to trade seeds, pest control methods and livestock breeding techniques.

The Chinese did not discuss adding to their already considerable purchases of U.S. grain this year, delegation members said, but the disappointing harvest leaves open the possibility of more American grain sales, particularly if Canadian and Australian grain stocks again run low.

Bergland and other delegation members said the Chinese were particularly interested in discussing farm machinery, with an emphasis on tiling tools.

"They are shopping, and they are interested in U.S. equipment," Bergland said. Interviewed while touring a botanical garden on the outskirts of this major southern Chinese city, Bergland said: "We didn't come here to sell grain, but to open up relations and we've done that."

He said the upcoming exchanges of agricultural delegations and agricultural students, discussed here are the initial fruits of the first government-to-government information exchange worked out this year between Peking and the Carter administration.

China's difficulty in feeding its 900 million people - still the central economic problem of the Communist government has led Peking to broadcast some of the bluntest attacks in years on its own farming methods.

"The average amount of grain per capita has long remained at around 800 pounds, which is scarcely sufficient to meets the needs for food grain, seeds, fodder and the needs of grain for marketing and industrial purposes," the official People's Daily has said."Industrial crops are insufficient to meet the daily growing demands for economic construction and the people's living."

Experts with the Bergland party said a severe drought in east central China has stunted this year's crop. Official Chinese reports said the dry spell in Anhwei Province is the longest in 20 years, and a similar drought in Kiangsu Province "had no parallel in the past 100 years."

To make up the difference and provide the living standards necessary to encourage Chinese workers to keep producing, Peking has purchased 3.2 million metric tons of U.S. wheat and 1.3 million tons of U.S. corn.

The more than $500 million needed to pay for this must come out of foreign exchange the Chinese had hoped to use to buy modern arms, vehicles and steel-making equipment they cannot produce themselves. The Chinese noted to the Bergland delegation, as they often do in their own press, the difficulties of feeding 20 percent of the world's population with only 7 percent of the world's arable land.

There are no reports of starvation although in some areas where harvests have failed the peasants have had to subsist on fast-growing sweet potatoes, which they do not like.

Bergland said the Chinese are trying to improve harvests by terracing barren hillsides and irrigating infertile stretches of northeastern and western China. They are also trying to increase their yield per acre, already one of the highest in the world, by improving seed varieties and pest control techniques and using more fertilizer. The mechanization that they hope will also help them requires hard cash, however, since many equipment sellers are unwilling to be paid in crops as the Chinese would prefer.

The Chinese press is full of articles, unheard of in the days before the death of Chairman Mao Tse-tung, encouraging peasants to grow their own pigs and vegetables and sell the goods privately. Stimulating private enterprise, the official press argues, will increase morale and bring an overall increase in agricultural production, even if some people earn more than others.

This means putting aside, at least temporarily, such favorite Mao models as the Tachai production brigade. Visitors are still brought to Tachai and shown its methods of collective production without private vegetable plots or private pigs, but the press does not talk so much about the famous brigade now.

New Chinese Communist Party Chairman Hua Kuo-feng has set a goal of 400 million metric tons of grain annually by 1985. This means a 4.5 percent annual increase, at least double the rate in recent years, but necessary if the country is to move ahead of its roughly 2 percent annual population increase.

Rupert Cutler, assistant secretary of agriculture for conservation, research and education, said the Chinese under the agreement completed here Sunday night will send three delegations of about eight members each to the United States next year, with three similar U.S. delegations coming to China.

The two sides will exchange information and materials on disease and pest-resistant seeds each developed, on biological methods of pest control, such as insect-eating wasps, and on methods of artificial insemination of farm animals. Delegations in later year will expore subjects such as soil testing, pasture management and forestry.