As small grains come out of the field, mid to late September is a good time to sample for soil nitrate-N and start to make plans for the next crop. Early fall tends to be much drier than the typical spring making soil samples easier to acquire and more accurate.
Ron Gelderman, a professor and soil specialist at the South Dakota State University Extension, advises taking samples before tillage offers the best result. "Each year we have questions on when is the best time to soil sample these fields for the next crop. Our long-term soil test results indicate by mid to late September the residual nitrate-N test has stabilized, on average, and is fairly constant until late April when it begins to increase again. So a soil test anywhere in this time period after small grains provides a good estimate of residual N and what is needed for fertilizer N for the next crop, says Gelderman."
So as harvest ramps up across the Midwest, take the time to sample for nitrate-N while conditions are right to get the most accurate data you can. Arm yourself with a true picture of what is happening in your soil so you can make thoughtful, educated decisions for next year's crop.
Click here for the full article from SDSU Extension.