In this paper a study is carried out to develop a mathematical model to predict resisting forces exerted on the single shank during cutting the earth based on the blade geometry parameters, operating conditions and soil parameters. A computer program "SHANK" was made on the basis of this analytical study using a professional mathematical package. A verification was held to the mathematical model using published experimental data resulted from cutting sand using narrow blades and the accompanied operating conditions, tool geometry and soil properties. The comparison between the published results and those predicted by "SHANK' showed that this model can be applied to predict resistance forces exerted upon the single shank during cutting the earth with an acceptable deviation putting into consideration the highly nonlinear behavior of soil.