Systems, methods and apparatus for adjusting the depth of a trench opened by a row unit of an agricultural planter. The row unit includes a trench depth adjustment assembly configured to modify the furrow depth. In one embodiment, the depth adjustment assembly may include a gear box having one or more gears which engage with a gear rack. The gear box may be pivotally connected to a depth adjustment body supporting a rocker that adjusts upward travel of gauge wheel arms. In another embodiment, the depth adjustment assembly may include a depth adjustment arm having a screw receiver that cooperates with a driven screw that adjusts the position of the depth adjustment arm acting on the gauge wheels to adjust trench depth.