Seeing Spots: Probing Deeper Into Yield Loss

Between the Fencerows

How we look at soil to evaluate yield problems

Published on: November 20, 2013

Last week I described to you some of our process in evaluating yield loss. Now, that the naked eye evaluation is complete, if I was unable to make a definite determination, I move on to the soil.  Is the fertility OK?  How is the lime?  Are ratios in line with recommendations?  Are the micro nutrients sufficient?

Coupling soil test results with visual observation from the plants can confirm a diagnosis.

Going deeper into soil examination, poorly performing soybeans may have had a high level of soybean cyst nematode infestation.  Sending a sample to the lab can confirm this.  If you planted a cyst-resistant variety, maybe it is time to send a sample off for type testing.  We have seen a race shift in the last five years and now plant Peking varieties or PI88788 varieties with Votivo.

Soil and stalk samples can show if your corn crop ran out of nitrogen. One- and two-foot samples will show what nutrients are leftover.  As a bonus, they will give what residual nitrogen may be left for the next crop.

We have also been able to determine that some continuous corn fields have nematode infestations as well, though those samples were taken in the spring and summer.  Identifying these problem fields allows us to choose to rotate crops or use other measures, such as nematicides.

While you're taking soil samples, you may stumble across another yield robber: soil compaction.  What caused the compaction?  Is this farm new to you?  Is there a history of farming wet?  Can tillage be done to remedy this?  Would different practices fit this farm better?  Can a cover crop be part of the solution?

The purpose of all this work is simply to improve soil health, make better decisions, and increase the bottom line.  Sometimes a spot simply remains an anomaly; however, many times corrective measures will lead to a better overall farming experience.