We participated in a multi-location, multi-year trial with about ~20 data points. No difference in yield.

A few things we do to mitigate any potential 'issues':

1. We still run 12 hoses off our manifold, and send 2 to each double tube mole knife. Each knife's hoses are located opposite to one another on the manifold to try to offset uneven distribution caused by an unlevel manifold caused by hills/slopes/mounting.

2. We have built a hitch off-set to keep our wagon off of the 2 knife slots that they would normally run on. BTW, we off-set it to the left to keep the wagon on the road when the tractor is dodging on-coming traffic.

3. Our observation is that if the summer turns dry, having half as many slots to open and dry out is a good thing. Wet or dry, having half as many knives in the ground is a good thing - we side-dress 12 rows of ammonia with a JD 4440 - @ ~.3 gal/ac fuel.

Luke    aka Ken SWOnt