Ignacio Antonio Ciampitti1, Douglas Edward Shoup2, Gary Cramer3, Eric A. Adee4, Gretchen F. Sassenrath5 and Osler Ortez1, (1)Agronomy, Kansas State University, Manhattan, KS (2)Kansas State University, Parsons, KS (3)Agronomy South Central Kansas Experiment Field, Kansas State University, Hutchinson, KS (4)Kansas State University, Topeka, KS (5)25092 Ness Rd., Kansas State University, Parsons, KS
Soybean can be planted over a wide range of planting dates under adequate soil moisture conditions, although germination and emergence could be reduced and delayed in cool soils. Optimum planting time for soybean depends on the genotype, environment, and management practice (G × E × M). Five field studies were conducted during the 2014 growing season across eastern Kansas (Manhattan, Topeka, Ottawa, Hutchinson, and Parsons). This study explored the impact of planting date (early, mid, and late planting times) on yield for modern soybean cultivars from a range of maturity groups (early, medium, and late groups). The primary outcome was that the optimum combination of soybean planting dates and maturity groups was governed by the environment (site) evaluated. Under rained conditions at Manhattan, the mid-maturity group was the highest-yielding at both early and late planting date. The late maturity group out-yielded the other maturity groups at the mid planting date. Under irrigation at Topeka, medium and late maturity varieties maximized yields at the earliest planting date, with yields >4.7 Mg ha-1. Lower yields were observed for the mid-May vs. early planting date, with the exception of the late-maturing group. A synthesis-analysis will be presented utilizing data gathered from the last decade plus the current site-year (2014-2015 growing seasons) of soybean planting date × maturity group research in Kansas.