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

Comparisons of bulk density between no-till and chisel management systems h ave produced conflicting results in different studies. These conflicting re sults have been due to averaging across large depth increments (up to 30 cm ) and by ignoring traffic patterns when sampling. A few studies have measur ed 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 wi th similar measurements from tilled management systems. The objective of th is study was to compare no-till and chisel management system effects on 2-c m increments of the vertical soil properties both for sites with and withou t controlled wheel traffic in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. The controlled traffic site consisted of Muscatine (Fine-s ilty, mixed, mesic, Aquic Hapludoll) and Tama (Fine-silty, mixed, mesic Typ ic 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 fr om no-till was more dense than soil from chisel plots 61% of the time. Ther e was no significant soil bulk density difference between tillage treatment s for plots without controlled traffic. Results of tillage on residue, orga nic C, and crop yield were inconsistent. Chisel management did not result i n less dense soil than no-till unless traffic was carefully controlled.