By Scout Nelson
Rising phosphorus (P) fertilizer prices are prompting many producers to reassess nutrient management plans. However, University of Nebraska–Lincoln (UNL) specialists emphasize that reducing phosphorus applications across all acres may not be the most profitable strategy.
Higher prices for diammonium phosphate (DAP), monoammonium phosphate (MAP), and liquid starter fertilizers have increased production costs. Nebraska Extension recommends prioritizing phosphorus applications on fields with low soil-test phosphorus levels while reducing or delaying applications where soil phosphorus is already adequate.
Soil testing remains one of the most effective tools for determining where phosphorus applications are likely to provide an economic return. Producers are generally encouraged to collect soil samples every three to five years and use the results to guide fertilizer decisions.
Research shows phosphorus is often the second most limiting nutrient for corn production after nitrogen. Fields with low phosphorus levels are more likely to respond to fertilizer applications, while fields with sufficient phosphorus reserves may see limited yield benefits from additional inputs.
A long-term University of Nebraska–Lincoln study at the Haskell Agricultural Laboratory evaluated phosphorus management strategies in continuous dryland corn over 16 years. Researchers compared no-phosphorus programs, crop-removal-based applications, and approaches designed to maintain various soil phosphorus levels.
Results showed that eliminating phosphorus applications gradually reduced soil fertility and increased the risk of yield losses. In contrast, maintaining very high phosphorus levels required substantially greater fertilizer investments without consistently increasing yields.
Researchers found that a crop-removal strategy delivered strong economic returns by replacing the phosphorus removed in harvested grain. This approach provided the highest return on fertilizer investment while maintaining competitive corn yields throughout the study period.
Extension specialists caution producers against allowing soil phosphorus levels to fall below critical thresholds. At the same time, they advise avoiding excessive phosphorus applications that can increase costs without improving profitability.
Additional practices can improve phosphorus-use efficiency. Banding phosphorus near the crop row and using variable-rate technology can help place nutrients where they are most needed and maximize fertilizer value.
Manure should also be considered when developing nutrient management plans. Fields with a history of manure applications may already contain sufficient phosphorus reserves, reducing the need for additional commercial fertilizer.
Overall, Nebraska Extension recommends using current soil-test information, targeting phosphorus applications to responsive fields, accounting for manure nutrients, and considering crop-removal strategies to maintain productivity while controlling fertilizer costs.
Photo Credit: gettyimages-songdech
Categories: Nebraska, Crops, Corn