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Thursday, May 31, 2012

Nitrate Testing

We always do some PreSidedress Nitrate Testing (PSNT) to determine nitrogen losses and need for sidressing.  This article in No-till Farmer is an interesting one to read.  Note that different states have different ways of doing the test and different ways of interpreting it.  The real trick is to get a representative sample.  Because the nitrogen is in bands after application, some method is needed to get a sample where some of the sample has nitrogen in it and some does not.  Depth is also important.  Nebraska likes 2 or 3 foot deep samples, because their soils at least in part of the state are pretty sandy.  We sample one foot deep.  Some are recommending trying to sidedress strips to see what happens.  That Guess method does not take into account that plants may have not reached existing N when you apply the extra N.  The Guess method also does not take into account that the corn may respond just as much to the aeration as to the N.  The problem I see is that it is a tricky test to sample for and there are not enough professionals out there to do it for everyone. 

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