Soybean futures on the Chicago Mercantile Exchange have reached a four-year low due to the prospect of a record crop in Brazil and proposed changes in U.S. biofuels policy, causing a drop in soybean oil prices. The decline in soybean prices is also attributed to expectations of a large harvest in South America. In contrast, wheat futures on the Chicago Mercantile Exchange remained steady, despite lower Russian wheat production estimates, due to larger crops in Australia and Argentina. The exact size and purchase prices of a durum wheat purchase by Algeria's state grain agency remain unclear.