What soils need to make them highly productive and to keep them so, and how their needs may be supplied are problems which are met constantly on the farm to-day. To enable every Iowa farmer to solve these problems for his local conditions, a complete survey and study of the soils of the state has been undertaken, the results of which will be published in a series of county reports.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 2—Pottawattamie County Soils" (1918). Soil Survey Reports. 4.