Depth-incremental soil properties under no-till or chisel management

Comparisons of bulk density between no-till and chisel management systems have produced conflicting results in different studies. These conflicting results have been due to averaging across large depth increments (up to 30 cm) and by ignoring traffic patterns when sampling. A few studies have measured 2-cm depth increments for soil from tilled plots, but few, if any, have measured 2-cm incremental soil properties from no-till and compared them with similar measurements from tilled management systems. The objective of this study was to compare no-till and chisel management system effects on 2-cm increments of the vertical soil properties both for sites with and without controlled wheel traffic in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. The controlled traffic site consisted of Muscatine (Fine-silty, mixed, mesic, Aquic Hapludoll) and Tama (Fine-silty, mixed, mesic Typic Argiudoll) soils, and the site without controlled traffic had Downs soil (Fine-silty, mixed, mesic Mollic Hapludalf). We collected soil samples in 2-cm increments to the 30-cm depth. On controlled traffic plots for the 0- to 2-cm increment, soil bulk density from no-till plots was less than from chisel plots for half of the cases, but for the 6- to 18-cm depths, soil from no-till was more dense than soil from chisel plots 61% of the time. There was no significant soil bulk density difference between tillage treatments for plots without controlled traffic. Results of tillage on residue, organic C, and crop yield were inconsistent. Chisel management did not result in less dense soil than no-till unless traffic was carefully controlled.