Using cone index as indication of soil strength, empirical equations are developed in accordance with soil mechanics theory to relate soil strength or
properties to tillage tools draught. A common five tillage tools in Saudi Arabia were
tested on sandy loam soils arid their empirical draught equations are developed.
Chisel, moulldbaord,:and field cultivator equations comprise a quasi-static component
dependent on cone index and a dynal"(1ic component function of specific weight,
operating speed. 'While, for disk plough and. tandem disk harrow, the draught
equation compromises three components, nameddepth, operation and penetration
dependent on tillage depth, speed .and soil penetration resistance. The cone index
equation provides a method of predicting tillage draught directly from soil properties
and operational parameters. the object of t~is research was to relate tillage draught
to soil strength and operational parameters in sandy loam soils, at AI-Qassim arid
area, 'Saudi Arabia. '