A study of data collected from interviewing 43 farmers in Iowa shows large variations in machinery costs for producing com and soybeans in 1997/98. The aim of this study is to determine why some farmers are able to produce these crops with half the costs of machinery per acre and per bushel than others. There is nevertheless a trend for larger-acreage operations to have lower unit costs. On the other hand the smaller equipment set eg four-row, operated on a larger area, usually had lower unit costs than a larger set eg eight-row on fewer acres. Low correlation coefficients were indicative of the wide data spread. The study is on-going. Two graphs of preliminary results follow for com .