Systems, methods and ap-paratus are provided for determining the depth of atrench opened by anagricultural planter. Sensors are provided for detecting the position of aground-engaging elementof the planter such as a gauge wheel or seed firmer of a row unit of theplanter. Apparatus andmethods are provided for installing such sensors onto a row unit of theplanter. Systems, methodsand apparatus are provided for controlling downpressure on a row unit based onthe trench depth.Methods are provided for mapping trench depth measured by the depth sensors.
