We have used single disc 2X2 fertilizer openers on a John Deere planter for 20+ years. 3-4 years ago I had a bearing go out on one row. It was going to rain that night, so to finish the field I removed the fertilizer opener and extended a piece of tube to dribble the 28% and 10-34-0 mix on top behind the closing wheels, same rate - just dribbled on top. When the corn got about 10-12" tall I could see which row had the fertilizer dribbled on top, they were yellower and shorter. It was on a highway neighbors even asked if I had a row stopped up.  Those same rows stayed shorter till it tasseled out. I didn't yield check it, probably should have, but the next time I have a bearing out I will stop and fix it. I can't believe people even think about dribbling fertilizer on top, if its too much trouble to do it right, plant beans!