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WC Mn/Dakotas | Removal is all fine and dandy as a summary or report card at the end of the year. However it tells you nothing about specific needs or quantity demands at specific stages.
If you remove 36 lb of nutrient in a crop and the soil can produce (or capable of releasing) 12 lbs in a year (6 months thawed and accumulating gdu, may thru oct) but growing season is the middle 4 months and 75% is required in late july and aug, you have to apply to cover the peak period and tie up, not the avg.
The avg would be 2lbs per month, but that is not reality.
If mineralization doesnt happen until soil temps reach 65 degrees, almost nothing is mineralized until mid june. Some is needed in may and early june, you need to apply a form that is available in may and june conditions.
Then if crop matures in mid sept, the nutrients that become available in end of sept and oct dont do the crop any good either. So really you can only figure available nutrients from mid june to mid sept (3 months worth, not six) So maybe you get 8lb credit from soil total for the crop, not the full 12.
If daily nutrient demand in late july and aug is greater than daily naturally released or capable of diffusing, you have to apply enough to cover that deficit.
If you figure you need 20lbs (or whatever) and a certain percent of what you apply gets tied up, you need to apply enough more so 20lb will be plant available.
There are lots of variables like these that are chemistry and biological related realities. Not getting around those temperature, moisture, ph, cec, o.m. type factors. Dont have to understand them all to grow a crop because you can often apply more to over compensate. If you want to run more economically, then you do need to understand or work with a specialist who does.
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Nitrogen requirement for corn
