JAPAN ACTIVELY BOUGHT U.S. CORN LAST WEEK - TRADE Japanese feed and starch makers actively bought U.S. Corn last week, C and F basis, for July/September shipment in view of bullish freight rates following active inquiries by the Soviet Union, trade sources said. Some said the makers were seen buying some 30 pct of their requirements, estimated at about three mln tonnes for the three-month shipment period. "Belief is growing that freight rates will not decline sharply from current high levels even in the usually sluggish summer season because the Soviet Union's chartering is seen continuing five to seven months from April," one source said. The sources said Japanese trading houses were seen covering a total of 500,000 tonnes of Chinese corn for shipment in May to October. But they are believed to have not yet sold most of the corn to end-users in anticipation of further corn price rises in the world market. Supply from Argentina and South Africa for July/September is still uncertain. But the sources forecast supplies from Argentina may fall to 400,000 to 500,000 tonnes from an anticipated 800,000 in calendar 1987 and from South Africa to 700,000 to 800,000 tonnes from an estimated one mln in light of tighter export availability.