Abstract In the past, investigators of rotary tillage tools have concentrated their efforts in developing relationships between the power requirement and operational parameters of tillers. Many researchers have developed empirical force and torque prediction models without giving due consideration to the strength properties of soil. In the absence of proper soil-tool behaviour equations, the designers of rotary tools have relied on these empirical approaches. In recent years, the authors have proposed the first theoretical model for two-dimensional soil failure by a rotary powered blade. The presently available state-of-the-art ideas on rotary tilling force prediction models has been presented in this paper.