BEIJING, April 20 (Reuters) - China’s March soybean imports from Brazil plunged as rain delayed some shipments from the top exporter, but its imports of the oilseed from the United States more than quadrupled. The world’s biggest buyer of soybeans imported 315,334 tonnes from Brazil in March, down 85% from 2.1 million tonnes a year earlier, data from the General Administration of Custom showed. Brazil is the world’s biggest soybean exporter. From the United States, China imported 7.18 million tonnes of soybeans in March, up 320% from 1.71 million tonnes in the previous year. China had stepped up purchases of soybeans and other U.S. farm produce after the two sides signed an initial trade deal in January last year. But buyers of the oilseed have turned to the United States more than usual in 2021, as rains in Brazil slowed the harvest there and delayed exports. China’s total imports of soybeans in March rose 82% to 7.77 million tonnes. Chinese crushers bring in soybeans to crush into soymeal to feed livestock and for cooking oil. They had previously ramped up buying of soybeans amid expectations of healthy demand from the country’s fast-recovering hog herd. But a severe wave of African swine fever in recent months has wiped out at least 20% of the breeding herd in northern China, some estimates show, reducing soymeal demand. Increased use of wheat in animal feed has also curbed soymeal demand, analysts and traders say. (Reporting by Dominique Patton and Shivani Singh; Editing by Himani Sarkar and Rashmi Aich)