Iowa corn and soybean prices are down slightly this month and are significantly lower than this time last year. May corn was at $3.40 a bushel, down a nickel from April. In May of 2009, corn was at $4.06 a bushel. Soybeans went down 15-cents in May from $9.35 in April. One year ago beans were at $10.60 a bushel. Relatively low oil prices combined with favorable weather in many parts of the state are two likely reasons for the declines.