April 23, 1983

Despite a sharp jump in food costs, consumer prices inched up only one-tenth of 1 percent in March, the Labor Department reported today. Prices of most things other than food declined or rose only slightly, and even the recent rapid rise in medical costs slowed. For the first three months of this year, the Consumer Price Index has risen at an annual rate of only four-tenths of 1 percent and is up only 3.6 percent in the last 12 months. The overall price level in the index is now below where it was in October, the first time since 1956 that prices have been lower than five months before.

The State Commissioner of Education refused yesterday to approve Deputy Mayor Robert F. Wagner Jr. as Chancellor of the New York City public school system. The surprise decision by the Commissioner, Gordon M. Ambach, left the largest school system in the country without a permanent chief administrator and threw into doubt when a new Chancellor could be chosen by the seven-member Board of Education. Mr. Ambach said Mr. Wagner lacked the necessary educational requirements for the post and did not have enough educational administrative experience to warrant a waiver. The 39-year-old Deputy Mayor was named Chancellor by the board two weeks ago, but needed the waiver to serve because he does not meet all the formal requirements for the post as they are stated in state education law. The decision was a blow to Mayor Koch, who for weeks had held fast to his choice of Mr. Wagner for the post despite strong opposition from black and Hispanic leaders. The Board of Education selected Mr. Wagner by 6 to 1.

The West German magazine Stern said today that it had discovered 60 volumes of previously unknown handwritten diaries of Hitler and would begin publishing them Monday. The weekly magazine did not say how or from whom it had received the diaries, which it said were written from 1932 to 1945. But it said ''internationally renowned handwriting experts and historians'' had studied the diaries and two volumes of other writings it said related to the flight to Britain in 1941 of Rudolf Hess, Hitler's deputy, and judged them genuine. Other experts said that they doubted that all of the documents could be genuine. These experts have not seen the documents, but have studied the field for years.

President Reagan announced tonight that he was ending the ban on negotiations of a long-term grain agreement with the Soviet Union. He had imposed the ban last year out of concern for the political situation in Poland. Mr. Reagan said he was taking the step ''to reaffirm our reliability as a supplier of grain'' to the Soviet Union. Administration officials explained that the decision came after it became clear that the refusal to talk about a long-term agreement was discouraging the Soviet Union from buying more grain this year.

Farmers here in the ''black muck'' basin on the New York-New Jersey border say they have lost $8 million in damage to their crops and lands from a week of flooding, and more rain is forecast for the weekend. Early crops of onions and lettuce were wiped out when the Wallkill River overflowed and inundated 5,000 acres of some of the richest farmland in the United States. Farther east in Dutchess County, farmers said that damage from the rains that started a week ago was slight, but that the weather had prevented them from planting corn and other crops at their normal times, increasing the chance of frost damage in the fall. Farmers on Long Island and in Connecticut and in lower New Jersey also reported losses. A delay in planting because of the heavy rains, rather than damage to crops, is proving to be the main problem in New Jersey and Connecticut, according to state agriculture officials.