Solid-Seeded Soybean Cultivar Response in Three Tillage Systems

Soybean [Glycine max (L.) Merr.] production in conservation-tillage systems probably will continue to increase for economic and environmental reasons. Cultural practices, including cultivar selection, must be reevaluated for use in conservation-tillage systems. This study was conducted to determine if tillage intensity influences soybean cultivar performance. Field studies were conducted on Piano (fine-silty, mixed, mesic Typic Argiudolls) silt loam soils at Arlington and Janesville, WI, from 1983 through 1985 to compare solid-seeded (8-in rows) soybean performance in three tillage systems using 12 cultivars commonly grown in the northern Corn Belt. Tillages were established in the fall of 1982 following corn (Zea mays L.) harvest and included: (NT) drilling soybeans directly into corn stubble; (RT) para plowing and no secondary tillage, and (CT) moldboard plowing and complete secondary tillage. Corn was the previous crop in all environments and the three tillage systems were maintained the same for corn as for soybean. Averaged over six environments, residue cover averaged 85% for NT, 66% for RT, and 7% for CT. Soil temperatures were 4 to 5°F lower with NT and RT and soybean emergence averaged 12% less than in CT when averaged over 3 yr. Soybean yields using NT and RT averaged 2 bu/acre less than in CT when averaged over all environments. In two of six environments, yields did not differ among tillage systems. Cultivars differed for all characteristics evaluated, and in most cases there was a cultivar × environment interaction. Relative cultivar yield differences, however, did not change significantly among tillages in any environment. The highest yielding cultivars in CT were the highest yielding in both of the reduced tillage systems. Selecting cultivars using yield performance data from CT evaluations should identify the best yielding cultivars for use in NT and RT.