Soybeans tumbled the most in eight months and corn dropped to the lowest price since October after the U.S. reported larger inventories than analysts expected. Wheat reached a five-month low as planting topped forecasts. A record 2009 harvest left corn inventories up 11 percent from a year earlier and the largest for March since 1987, the Department of Agriculture said. Soybean stockpiles were 1.27 billion bushels, 5.5 percent more than the average estimate of analysts in a Bloomberg News survey. Wheat supplies were up 30 percent, as rising global output erodes demand for U.S. grain.