Filling up the two seed hoppers, one to supply its own set of 12 rows, on a 24-row planter only takes a few minutes. The two tanks for seed sit side-by-side. Hence the name – a central fill planter. The seed travels to various rows, all the way out to row 12 on each end, via a vacuum metering system.
The biggest disadvantage to a central-fill planter is all the weight that winds up on the center four rows underneath where the seed rides. Precision Planting experts began noting to customers at meetings last fall that it was an issue worth addressing if you wanted to maximize whole-field yield. Pictures of extreme cases indicate that the four middle rows where the wheels carrying the planter and the tractor wheels run can exert extra pressure, resulting in corn that shows signs of soil compaction, especially in a dry year. In years with plenty of rainfall, the effects of soil compaction may be masked and not as obvious.
There are various ways to address the issue. One farmer we visited runs a tracked tractor which he believes gives him more flotation to begin with. Then they equipped his newest planter with wider, dual tires in the center section under the tanks where the central-fill seed tanks are located. The tires are actually duals on each side. Each pair of duals mounts to an extender that separates and spread out one dual from the other on each side.
Compared to original equipment where the weight was carried on narrow tires, this is a big advancement, farmers say. The idea is to spread out the weight over more soil to deflect the risk of deeper soil compaction caused by pressure when the tanks are full on narrow, conventional tires. This may not be the answer for everyone, but at least some farmers believe it's a step in the right direction.