Soil Engaging Tool Effects on Surface Residue and Roughness with Chisel-type Implements
The site specific nature of optimum tillage systems makes it desirable to provide versatility in tillage performance at a minimal cost. Chisel-type implements are among the most flexible primary tillage machines, largely due to the range in options for soil-engaging tools. The objective of this study was to evaluate surface residue and roughness from a full range of shovels, points, and sweeps on both a disk chisel and a chisel plow operated during fall tillage in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] stubble. Effects of operating speed and depth were also examined. Changing soilengaging tools caused remaining spring residue to range from 44 to 59% in corn and from 22 to 54% in soybean stubble. Residue remaining generally ranked from high to low as follows: low crown sweep ≥ medium crown sweep > chisel point > high crown sweep > concave twisted shovels. Sweep and shovel width had only minor effects on surface cover, but similar soil engaging tools on a chisel plow left about 10% more surface cover than on a disk chisel. Soil engaging tools had less effect on roughness than residue. Twisted shovels left the roughest soil surface and sweeps left the smoothest surface. The chisel point left surface conditions smoother than twisted shovels but often not significantly rougher than sweeps. Shovel and sweep width as well as machine type (chisel plow vs. disk chisel) did not greatly affect surface roughness. Operating speeds of 5 to 9 km/h did not affect surface roughness, but reducing speed to 2.5 km/h increased residue and decreased roughness. Increasing operating depth of a disk chisel decreased surface residue, but had little effect on surface roughness.
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