Soil Management

By Christy Caplan

That post-harvest period often reveals the season’ s hidden costs: nutrient removal, compaction, uneven residue, drainage trouble, exposed ground, and early signs of erosion. Left unaddressed, those issues can reduce nutrient efficiency, weaken soil structure, and make spring fieldwork more difficult and expensive. When managed well, however, fall can become one of the most important opportunities to protect long-term productivity.

Why Fall Matters More Than It Seems

After harvest, fields are finally open enough for growers to see what really happened during the season. Wheel tracks, ponded areas, residue bunching, and low-performing zones are easier to spot now than when spring workloads pile up. It is also the moment when fertility has changed: nutrients have left the field with grain, forage, or removed residue, and the soil’ s balance may no longer match crop needs.

Anthony Bly, SDSU Extension soils field specialist, says nutrient removal depends heavily on what was harvested and

After crops come off, growers have a short but important window to assess nutrient loss, soil condition, and the field factors that could shape next spring’ s success.

how.“ Nutrients are removed when crops, grain, or forage are removed,” Bly says.“ Phosphorus is primarily removed in the grain. Potassium is primarily removed when forage or crop residues are removed. For forage crops like alfalfa, higher amounts of phosphorus are removed too.”

That shift matters because bare or compacted ground is vulnerable heading into winter. Exposed soil is prone to erosion from wind and rain. Compacted zones limit infiltration and root growth. If residue is mismanaged, growers may create new challenges for nutrient cycling or spring planting. Good fall management is about more than correcting a deficiency. It is about improving resilience, reducing risk, and giving next season a better start.

Test Before You Treat

Before making fertility or field management decisions, growers need a clear picture of current conditions. Soil testing remains one of the most useful tools in the post-harvest window, especially when done early enough to guide fall applications.

Soil sampling is the best tool for monitoring soil Phosphorus( P) and Potassium( K) levels.“ Using your local university recommendations that are based on long-term, multi-location research is the best approach.” He cautioned against relying solely on simple crop removal math for P and K planning.

“ University research has shown that using the crop removal approach for P and K usually results in soil P and K levels eventually increasing above recommended levels,” Bly says.

“ Yield goal is‘ not the yield you want, but the yield you can get,’” Bly continues.“ Correct yield goal determination is based on past yield history for the field, zone, or grid.” Beyond the lab

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