Validation and ordering test for an formula of soil tillage draft force, extended to the dependence on soil moisture

The article presents results regarding a possibility of extending Goriacikin's soil tillage draft force formula. The extension tries to include in the formula the influence of soil moisture. Some comments are made on the problem of optimum working moisture of the machines intended for soil works. Similar extension procedures are suggested for other formulas of the soil draft tillage force. For a first verification of the results, reference is made to several works in the literature, which present experimental data that include the behaviour of soil tillage draft force to soil moisture.