I put “Out the Back” fertilizer discs From Schaffert Mfg. on my White 6000 Planter in 2009. We planted corn in wet conditions in southern Indiana and they worked very well. We put down 18 gallons of 32% nitrogen.
A neighbor had a liquid attachment on his JD planter in front of the planter. He had fertilizer and mud all over his planter. My planter stayed clean all season.
I really liked the job the Schaffert Fertilizer Disc did. We will put more fertilizer on this year with the discs.