Newcomers to Iowa are always amazed at the yearly changes in the heights of fields. The landscape expands from ground level to ten feet tall and back again every year: from frozen bare ground in winter to light green sprouts in late spring to dark green corn in late summer to acre upon acre of dry cornstalks at harvest time. Slow and unwieldy machines take up more than their share of the roads, clouds of black or yellow dust cover the fields in spring and fall, pigs (or are they hogs?) in various colors look out from fences, huge tractors with complicated add-ons lumber through the fields, shiny silos linked with tentacles tower above tidy white farmhouses dwarf ..