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Soil penetrometer could come in handy when checking for compaction

A soil penetrometer would be an expensive mixing rod to stir chemicals — they’re not cheap. It might tell you how hard it is to push into a bale, but it won’t tell you what nutrients are inside. And you might find it tricky to pull water samples with a device that features a solid metal rod.

However, a soil penetrometer is useful for checking for soil compaction, notes Gary Steinhardt, Purdue University soils specialist. Once soils soften up and conditions return to normal, it should be possible to pick up hard layers a few inches under the surface. The rod meets resistance when you push through layers.

You can even quantify how much resistance you find, but only relatively speaking. More expensive models have numbers on a dial at the top of the rod. Some less expensive models simply have color coding, such as green for no compaction, yellow for caution and red for compaction. It’s best to worry about how one spot compares to another, Steinhardt says.

Since it was dry last fall, soil compaction might seem like a non-issue. However, it was extremely wet during the ’09 harvest and wet during the latter half of the ’10 planting season. Since it turned dry in mid to late summer in many areas, the signs of soil compaction showed up, affecting corn yields most.

Just because you didn’t add further compaction this past fall doesn’t mean it won’t be an issue in 2011, the specialist says. Freezing and thawing over one winter won’t break down many layers, especially deeper layers. The less freezing and thawing, the more winters it takes to see benefit. In severe cases, effects from soil compaction can be seen for several seasons.

That’s most likely in corn when early summer is dry. Soil compaction adds to already stressed conditions. Soybeans tend to show less effect from compaction, he concludes.

This article published in the January, 2011 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.