CBOT soybean futures closed lower as optimism about increased Chinese purchases of U.S. soybeans faded. According to a survey of analysts by the National Oilseed Processors Association (NOPA) ahead of its report on Friday, U.S. soybean crush in April may have slowed due to seasonal maintenance and repairs at several processing plants, despite strong crushing margins.Meteorologists said Argentina is expected to see dry and cool weather in May and June, which will help accelerate the country's soybean harvest, after weeks of rain delayed farmers' fieldwork. The Rosario Grain Exchange estimates Argentina's soybean production for the current marketing year at 50 million metric tons.