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RPM Soils, LLC

Tuesday, April 19, 2011

Nitrogen by CEC

We have been hearing from some good farmers that they like to apply only 10 times the CEC in nitrogen units.  The logic being that the soil can only hold so many nutrients on the exchange complex.  We definitely like to see a certain level of nutrients such as calcium, magnesium, and potassium on the exchange complex.  We also need to determine liming requirements according to the CEC.  The  reason we look at CEC is that it determines the soil's ability to absorb positive ions.  I have recently sampled some fields where the higher CEC areas needed lime but other areas did not.  The reason being that the field was being limed according tot he lower CEC areas needs.  So you can see that CEC does affect application of nutrients.  However, Dr. Fabian Fernandez   says that there is nothing to the notion of applying nitrogen according to CEC    Well professors have been wrong before, but this leads me to believe that it may not be a critical practice.  Split applications have also become popular, and this practice fits those ideas. There might be merit in split applications because at least on of those tends to be sidedress which puts down N when the crop needs it. 

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