The world "is facing the moment of truth from Malthusian pressures," Jean Mayer, professor of Nutrition at the School of Public Health, said last night.

Mayer, speaking before 275 people at a Medical School forum, cited that three factors have let to recent concern about the world food supply: bad harvests in several major crop-producing nations of the world; the aggresive buying policies of the Soviet Union; and the poor 1974 crop here in the United States. The three events have resulted in a drop in the world grain supply of 50 million tons, he said.

"The world produces about 1200 million tons of cereals every year. It takes about 25 million additional tons every year just to stay level," he said. "So you see that the 28 million tons the Soviet Union purchased was an enormous factor in the existence of the world reserves," he said.

Petro-chemicals, Mayer noted, are needed both to power irrigation, as well as use as fertilizers. The Association of Oil Producers increased oil prices was "the straw that broke the camel's back," Mayer said.

"All in all the situation is bleak," Mayer said. Long-run measures he cited included an increased investment in agricultural improvement, which requires large amounts of capital. "I will feel confident when I see one tenth of the capital invested in armaments used for agricultural improvements," he said.