Ask an Agronomist

October 4, 2010 09:50 AM

Q:To manage soil compaction in a 30"-row setup, which is better—a wider tire (520/85r46 at 8.5 psi) or a narrower tire (480/80R50 at 10.5 psi)? Is it better to have less ground pressure closer to the row or a little more ground pressure further away from the row?

A: Tire inflation pressure is the primary factor affecting surface soil compaction. By selecting large, low-pressure tires, you can reduce compaction. Adding duals can help as well. Even though you are closer to the row with the wider tire, the impact of down force is less since the tire runs with lower pressure.
Q: How well do seed firmers work? They say you don’t need them, and I think they affect seed spacing.

A:There are two things to keep in mind when running seed firmers. First, be sure your planter is running level. Place a level on the main toolbar and have someone walk alongside while you are planting to ensure the bubble stays in the level position. You can make adjustments by raising or lowering your hitch height. If your planter is not running level, you could have problems with seed firmers. The second thing is to pay attention to moisture conditions if you are running an in-furrow fertilizer with your seed firmer. You do not want soil to build up on the firmer. In fit soil conditions, this should not be a problem, but there is a low-profile seed firmer available.
As long as the planter is running level in the field and wet conditions and in-furrow fertilizer are not causing soil to build up on the firmer, we have been very successful running seed firmers. We have seen good improvement in the uniformity of planting depth. Remember, a ¼" variation in planting depth can often be the difference between growing a good ear and a nonharvestable ear. 

You can e-mail Darrell Smith at

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