nuts bushing 59 washers 61 and seal 63 are used to secure the crankshaft 52 to the disc 12 via a hub 65 that is coupled to the disc 12 by fasteners 67 in addition to setting the depth at which the disc 12 cuts into the planting surface the depth gauge wheel 46 keeps the outer surface of the disc 12 generally clear of mud and debris a scraper blade 60 is mounted opposite the depth gauge wheel 46 is designed to remove dirt mud and other debris from the inner surface of the disc 12 the planting unit 10 is designed to separately drop fertilizer and seed into the furrow in a single pass in this regard a fertilizer tube 62 is mounted rearward of the center hub of the disc 12 but forward of the seed boot 16 the seed boot 16 which is mounted separately and to the rear of the scraper 60 generally includes a seed tube 64 and a cutting member 66 that is forward of the seed tube 64 in operation as the disc 12 forms a furrow having a relatively deep fertilizer trench in the planting surface fertilizer is dropped into the fertilizer trench from a.