Soil Reacting Forces for Disks from Field Measurements
ABSTRACT FOR single-acting, tandem and offset disk harrows, the disk angle can often be adjusted as much as 10 to 25 deg whereas the usual range is 30 to 40 deg for the one-way disk harrow. A field experiment was conducted with a single disk and a multicomponent sensor using a split-plot factorial design, with two tilling sites in the main plots and the disk angle, depth and speed in the subplots. The results indicate that a small disk angle should be used unless it is necessary to improve pentration, reduce skewing or both for the one-way disk harrow; to improve penetration, increase the uniformity of tilling depth or both for the tandem or offset disk harrow. For either implement the minimum depth should be used which is consistent with adequate culti-vation. The draft of the one-way disk harrow and the draft per unit width of cut is such that the former is maximum at 35 deg whereas the latter is maximum at 45 deg. The location of the resultant of the soil reacting forces indi-cates that a soil body affected the geometry of the tool.