On a CaseIH 16/31 planter it looks like there is an extra seed sensor on rows 3 and 30.

What are these for?

(Pl1 (full).jpg)

(PL2 (full).jpg)

(PL3 (full).jpg)

Pl1 (full).jpg (129KB - 66 downloads)

PL2 (full).jpg (152KB - 68 downloads)

PL3 (full).jpg (116KB - 64 downloads)