Sunday, April 27, 2014

Corn Stand Counts and Avoiding Compaction, Crusting, and Poor Seed to Soil Contact

Problems start to arise out in the field when a drive by of the field shows uneven emergence.  Our goal is always to have uniform stand of corn that is healthy.  Unfortunately, if a corn stand consists of gaps or crowded plants, research has shown there could be an 8 to 20 percent yield decrease.  So, let’s say you take some stand counts in your field and find that there is an issue with corn emergence.  You first will want to investigate what is causing the problem, so the same problem does not happen again.   Could it be a planter, pest, or seedbed issue?

Taking a Corn Stand Count can be made a little bit easier with the following University of Illinois Extension website: http://extension.cropsci.illinois.edu/fieldcrops/production/corn_stand_count/

 What could cause a poor corn stand?
  • Poor Soil to Seed Contact
  • Soil Moisture, Soil Compaction
  • Soil Crusting
  • All of the Above?


When it comes to a uniform corn stand, try to shoot for good soil to seed contact, which means the soil should be closely packed around the kernel.  Issues with soil to seed contact can arise when there is “seed to clod”, “seed to rock”, “seed to air”, or “seed to residue to contact” instead of soil to seed contact.  Poor soil to seed contact can be blamed on soil tillage in wet conditions (clods), poor soil conditions (rocks), open planter furrow (air), or trash in furrow during a no-till situation when soils are too wet (residue).  

Picture via RLNielsen, Purdue depicting poor soil to seed contact which was taken from
 http://www.agry.purdue.edu/ext/corn/news/articles.02/clods-0607.html

As many of us already know, compaction can restrict emergence and promote leafing out underground, so Burrus advises against planting corn when soils are too wet.  Too much pressure of the planter closing wheels can also compact the seed furrow. Sidewall compaction can be a problem when planting occurs in wet soil conditions and the weather remains dry during corn germination.  This type of compaction will not only prevent corn emergence, but also the elongation of the seedling.   

I really like this picture taken from http://pubs.ext.vt.edu/424/424-053/424-053.html (Virginia Cooperative Extension) that shows corn root growth limited by soil compaction (left) and healthy roots from noncompacted soils (right).

Soil surface crusting can also inhibit corn germination.  It can be a problem when major tillage occurs prior to planting and then a significant amount of rainfall is received before emergence of corn, sometimes in cool conditions.  

Another good picture from RLNielsen, Purdue that shows corn leafing out underground due to crusted surface soils, and this picture was taken from http://www.agry.purdue.edu/ext/corn/news/timeless/Corkscrews.html


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