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Eastern Shore of MD | I am with workonjunk with on N management saying that it is an extremely dynamic system that is hard to predict what N is needed. We do side dress in fact the last 2 years we have done an early side dress on knee high corn and a late one at 6 -7' tall corn. This past year we compared 3 approaches to N management and in general got 3 vastly different answers; I remember the first field that I went into to do the late side dress the recommendations varied from 0# additional N needed up to 170# needed with the 3rd approach being in the middle. Talk about something that will really make you scratch your head and wonder what to do next!
Having said all that we have found that we can produce 220-260 corn with only about .55-.60 #N/bu on 3-5 CEC soils. However, we do have poultry manure and cover crops in the system and we are pretty certain that history is affecting our Nitrogen use efficiency. We also can not explain why in some fields we are getting an economic yield response to N applied over the .55 - ..60lb/bu and some fields we saw no yield response to adding the extra N. I kind of find myself questioning everything that I thought I knew about N management.
These are the 3 approaches we used last yr to manage N:
Adapt N - computer modeling program from Cornell
Pre side dress Nitrate Test
Green Seeker
My opinion at this point is that Green Seeker has probably been the most accurate approach to this point.
Trying to figure this stuff out is what keeps farming interesting to me.
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How to know when to side dress corn
