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Coles County, Illinois | My soil samples are taken on a grid. That data is used by the fertilizer company (FS) to generate a 4 year VRT plan. The plan doesn't apply fertilizer the same rate over the whole grid and switch to another rate for the next grid. A soil type map and CEC map is over-layed and the grid samples are used to calibrate the rates with an adaptive curve. Topographical data must be incorporated as well but that over-lay isn't exposed in the report (plan). I have a field that has my highest soil sample levels 500' away from my lowest sample. The reason is the slope between the two. Poor drainage/dark soil is in the bottom with the high test values. Well drained but light soil is on the hill with low test values. The light soil has good K levels but poor P values. So as the sprader is going up the hill the DAP rate gradually goes from 0 to 450 lbs/acre. The rate change is not lineral as the rate changes more quickly on steeper portion of the slope. Compounding the issue would be the width of the spreader pass. Going straight up the hill could be manageable. Spreading along the side of a hill would get into so many calculations as to overwhelm anyone. | |
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Variable Rate Fertilizer is driving me nuts
