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Little River, TX | At one time it was all the rage on how AA will kill you ground, turn it to cement &c.
Just to see I put 3,000 lbs of AA into 2 acres of bermudagrass, just to see. There the CEC is a measured 50 meq/100g. That patch was hayed off and each cutting was tested. Results were the nitrogen persisted for 7 full years. Yield never took a hit. The yield increased every year, until year #7.
For this soil and this climate, the 10 lbs of N per unit of CEC is at a minimum valid. From the results here it is conservative. Inadvertent over application has been known to persist for 20 years in pastures.
It is the NH4 that is a cation and attracted to the clay and organic matter's cation sites. It is probably for Ammonium Nitrate fertilizers that the 10 lbs/CEC unit was built on.
Conclusion: the higher the CEC value the more useful a Fall AA application is. With a 20 something CEC added chemistry is not required to retain the nitrogen through the season.
Edited by Hay Wilson in TX 9/13/2009 06:07
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UAN versus ammonia
