Updates prices, adds background

BEIJING, May 20 (Reuters) - Chicago grain and oilseed futures fell marginally on Wednesday, after a rally in the previous session on China's commitment to buy $17 billion of U.S. farm goods ranging from grains to beef and poultry in the next three years.

The most-active soybean contract on the Chicago Board of Trade (CBOT) Sv1 fell 0.4% to $12.05 a bushel by 0345 GMT. Wheat Wv1 lost 0.7% to $6.62-1/2 a bushel while corn Cv1 dropped 0.5% to $4.73 a bushel.

China has committed to purchasing at least $17 billion of U.S. agricultural products in 2026, 2027 and 2028, the White House said on Sunday.

China's U.S. soybean imports in April more than doubled from a year earlier, as cargoes booked after Beijing resumed purchases late last year gradually arrived at Chinese ports.

The country imported 3.33 million tons of soybeans from the U.S. in April, Chinese government data showed on Wednesday. Soybean imports from Brazil rose 3.3% year-on-year to 4.75 million tons.

China resumed purchases of some U.S. farm goods after an October meeting, fulfilling a U.S.-stated commitment to buy 12 million metric tons of soybeans by the end of February. It has also purchased some U.S. wheat cargoes and large volumes of sorghum.

The USDA reported on Monday soybean inspections for the week ended May 14 at 483,881 tons and for corn inspections at 1,378,770 tons. The U.S. corn crop was 76% planted, as of Sunday, up from 57% a week earlier, it said.

Rains in the U.S. Southern Plains are expected to come too late to aid the parched winter wheat crop, according to analysts.

The USDA rated 27% of the nation's winter wheat in good-to-excellent condition, as of Sunday, in a report issued after trading ended on Monday. That was down one percentage point from a week earlier and the lowest for this time of the year since 1996.