Abstract: A soil moisture measurement system is incorporated in an agricultural implement, for measuring soil moisture during operation of the implement. The soil moisture measurement system includes a sensor or input unit mounted to a subsoil portion of the implement, e.g. to the shank portion of a tillage implement. The soil moisture measurement system may be in the form of a time domain reflectivity (TDR) system. The operator can adjust the depth of the soil-working portion of the implement to attain a desired degree of soil penetration according to soil moisture conditions for seeds to be planted within the soil. Depth adjustment can be accomplished manually by the operator, or automatically by virtue of a depth control unit interconnected with the implement.