Northeast Research and Demonstration Farm
Soybean planting date studies of various types have been conducted at this site since 1976. Earlier tests included later planting dates (May through mid-June), differing variety maturities, and comparisons with starter fertilizer and Ridomil fungicide soil treatments. Research reports on these studies can be found in previous annual progress reports with the last summary in the 2001 and 2009 reports.
Iowa State University
Pecinovsky, Kenneth T. and Mueller, Daren S., "Soybean Planting Dates in Northeast Iowa" (2012). Iowa State Research Farm Progress Reports. 93.