A soil apparatus (e.g., seed firmer) having a locking system is described herein. In one embodiment, the soil apparatus includes a lower base portion for engaging in soil of an agricultural field, an upper base portion, and a neck portion having protrusions to insert into the lower base portion of a base and then lock when a region of the upper base portion is inserted into the lower base portion and this region of the upper base portion presses the protrusions to lock the neck portion to the upper base portion.