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IA/MN/WI | That sample simply tells you that you don't need synthetic fert.
If you start taking 0-24" samples consistently, all you need to do is multiply the ppm by 4 and that give you available nutrient at the time of the sample. So you have 195lbs of available Phos at the moment. Doesn't even include what will cycle in season in the top 12", or all the Phos still decomposing in your residue....
Coops don't push deeper samples because they would sell less fertilizer... same reasoning behind why they don't recommend pulling nitrate tests before side dress.
It's standard practice in the Dakotas to take 0-6" and 6-24" cores for all fertilizer recs. I can't understand at all why this agronomic practice isn't done in the rest of the Midwest. Sometimes you will find a coop that uses 0-8" samples. | |
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24 inch soil samples
