Residual Effects of Deep Tillage vs. No-Till on Corn Root Growth and Grain Yield

Tillage pans occur in many coarse-textured soils and must be ripped by a form of deep tillage to maximize yields. This study compared the longevity of slits produced by subsoiling and slit-till (both to 16 in.) to a no-till treatment, and related slit longevity to corn (Zea mays L.) grain yield and root development. The soil was a Typic Kandiudult with a tillage pan. Both deep tillage treatments were last performed in 1989; this study was conducted from 1990 through 1992. Roots were examined at tasselling each year, and in 1992 thin sections were examined to determine the effects of the tillage slits on root penetration. Corn grain yields were not significantly different among the three tillage treatments in any of the 3 yr. Concentrations of roots in soil profiles did not differ significantly among treatments and roots extended to depths > 40 in. Root observations indicated that the tillage slits affected root development 2 yr after tillage was performed. Residual effects of both subsoiling and slit-tillage on root growth could be seen for up to 2 yr after tillage was imposed, but the effects were gone by the third year. The residual effects of tillage did not affect yield in any year.