* China crushers booked big cargoes beans on good margins earlier * Feed, livestock producers scooped up corn, wheat imports to replace expensive domestic corn * Crush margins under pressure on expected large arrivals of beans (Recasts top of story to add corn, wheat imports; adds details on stocks, crush margins) BEIJING, April 13 (Reuters) - China’s imports of soybeans, as well as grains like corn and wheat, soared in the first quarter, boosted by strong demand from the livestock sector, data from customs showed on Tuesday. Soybean imports almost doubled in March alone year-on-year, according to customs data, as cargoes of beans from top exporter Brazil cleared customs after delays. Meanwhile first-quarter corn and wheat shipments jumped on elevated domestic corn prices amid a supply shortage, the data showed. China, the world’s top soybean buyer, brought in 7.77 million tonnes of the oilseed in March, up 82% from a year ago, according to data from the General Administration of Customs. “Soybean arrivals in Jan-Feb were lower than market expectation due to cargo delay. Some shipments delayed earlier later cleared customs,” said Xie Huilan, analyst with agriculture consultancy Cofeed, speaking after the data release. “More than 5 million tonnes of U.S. soybeans were loaded in January for shipment to China, some of which arrived in March,” Xie said. The customs bureau did not break out monthly figures for corn and wheat for March, usually published in the later half of each month. But it said China brought in 6.727 million tonnes of corn in the quarter, rocketing more than fivefold from the previous year, while quarterly wheat imports more than doubled from a year ago to 2.925 million tonnes. Rains in top exporter Brazil have delayed harvest and shipments of soybeans this year, but cargoes delayed earlier have slowly started to arrive. China’s soybean imports in the first three months of the year came in at 21.18 million tonnes, up 19% from 17.79 million tonnes in the previous year, according to customs data. Chinese crushers previously stepped up purchases of soybeans on good crushing margins as the market had anticipated healthy demand from the country’s fast-recovering pig farming sector. A recent round of African swine fever outbreaks, however, has wiped out at least 20% of the breeding herd in northern China, according to some estimates, curbing demand for soymeal, a major feed ingredient. Soymeal futures traded on the Dalian Commodity Exchange have fallen 10% since they hit record highs in January on worries over demand due to the outbreaks. Soybean arrivals in the coming months were expected to be even higher, industry sources and analysts said. Large arrivals of beans and weaker demand from the pig sector would further pressure crush margins. CNSOY-RZO-MRG China"s national weekly soybean meal inventories as of April 13, were at 797,900 tonnes, up from 477,000 tonnes end of January. CFD-SBMST-NATN Meanwhile, soybean stocks fell slightly to 4.4 million tonnes from levels at the beginning of the year. CFD-SBSTK-NATN (Reporting by Hallie Gu and Shivani Singh; Editing by Kenneth Maxwell)