Key Takeaways

• Prioritize low-testing fields. Use current soil tests to target phosphorus applications where a yield response is most likely, and consider reducing or postponing applications where soil-test P is already high.

• Avoid costly extremes. Long-term Nebraska research found that eliminating P increased yield risk, while maintaining excessively high soil-test P required substantially more fertilizer without consistent yield gains.

• Consider crop-removal strategies. Applying P based on crop removal produced the highest return on fertilizer investment in a 16-year Nebraska dryland corn study.

• Improve fertilizer efficiency. Evaluate banding, starter fertilizer and variable-rate applications based on field needs, and account for manure-derived phosphorus before purchasing additional fertilizer.

With phosphorus (P) prices still rising, the most profitable P program this coming season is not necessarily smaller but more targeted: Protect yield on low-testing fields and cut back where soil-test P is already high. 

According to DTN, average retail prices during Sept. 21–25, 2026, were $926 per ton for diammonium phosphate (DAP), $970 per ton for monoammonium phosphate (MAP) and $701 per ton for liquid 10-34-0 starter. Those prices were up about 2.4%, 5.2% and 5.3%, respectively, from the same week in 2025 (Quinn, 2026).

Comparing products on a cost-per-pound-of-P₂O₅ basis also helps. Ignoring the nitrogen they supply, the September 2026 prices work out to about $0.93 per lb P₂O₅ for MAP (11-52-0), $1.01 for DAP (18-46-0) and $1.03 for 10-34-0. Crediting the nitrogen in each product narrows these differences somewhat (Figure 1).

After nitrogen, phosphorus is the nutrient most likely to be deficient for profitable corn production in Nebraska. However, the economic benefits of applying P depends strongly on how much plant-available P is already in the soil. UNL recommendations therefore rely heavily on soil testing to identify fields where a crop response is most likely.  For more information, see the Nebraska Extension NebGuide EC117, “Nutrient Management Suggestions for Corn” (Iqbal et al., 2023).

For producers trying to manage fertilizer costs, the goal should not be to cut P uniformly across all acres. The better strategy is to prioritize fields and management zones with low soil-test P, maintain adequate P where yield could be at risk and reduce or postpone applications where soil-test P is already high.

Start With Soil-Test Phosphorus

Nebraska Extension generally recommends collecting soil samples from the surface 0–8 inches every three to five years to determine P, K and micronutrient needs. Several laboratory tests can be used to estimate soil P availability. EC117 recommendations are primarily calibrated to Bray-1 P, but results from Mehlich II, Mehlich III or Olsen P tests can be converted for use with those recommendations. To estimate a Bray-1 P equivalent, multiply the Mehlich II, Mehlich III or Olsen P result by 0.9, 0.85 or 1.5, respectively. Calcareous, high-pH soils are common in central and western Nebraska. On thse soils, Bray-1 can underestimate plant-available P, so the Olsen test is the better choice.

EC117 uses different critical soil-test P levels depending on the previous crop. For corn following corn, the critical Bray-1 P level is approximately 20 ppm, compared with approximately 15 ppm for corn following soybean. Yield increases from added P are unlikely above these critical levels, and no P is recommended when Bray-1 P is greater than 25 ppm for corn following corn or 20 ppm for corn following soybean. 

That makes soil testing especially valuable when DAP and MAP are near or above $900 per ton. Low-testing acres deserve priority because inadequate P can limit crop productivity. Where soil-test P is already well above the critical range, producers have more flexibility to reduce or postpone P applications this year.

What 16 Years of Nebraska Research Tell Us

A 16-year University of Nebraska–Lincoln (UNL) study at the Haskell Agricultural Laboratory near Concord evaluated P fertilization strategies in continuous dryland corn grown on a Nora silt loam soil from 2000 to 2015. The soil initially averaged about 16 ppm Bray-1 P. Treatments included no P, P applied according to previous crop P removal, and maintaining soil-test P near 15, 30 or 45 ppm (Patel et al., 2024).

The results demonstrate both the risk of applying too little P and the cost of maintaining unnecessarily high soil-test P. In the no-P treatment, Bray-1 P fell from about 16 ppm near the beginning of the study to approximately 8 ppm by the end, showing that continued crop removal without P replacement eventually draws down soil fertility.

At the other extreme, maintaining very high soil-test P required substantially more fertilizer. Over 16 years, the 45-ppm treatment received about 1,304 lb P₂O₅/ac (569 lb P/ac), compared with 893 lb P₂O₅/ac (390 lb P/ac) for the 30-ppm treatment. The crop-removal treatment received 664 lb P₂O₅/ac (290 lb P/ac), while the 15-ppm treatment received 536 lb P₂O₅/ac (234 lb P/ac). That averages about 82, 56, 42 and 34 lb P₂O₅/ac per year, respectively. 

However, those higher P inputs did not consistently increase yield. Across all 16 years, corn yields (at 15.5% moisture) averaged approximately 126 bu/ac for the 45-ppm treatment, 121 bu/ac for the 30-ppm treatment, 123 bu/ac for the crop-removal treatment and 119 bu/ac for the 15-ppm treatment, compared with 112 bu/ac with no P. Yields did not differ significantly among the P-fertilized strategies (Figure 2). Because the study was conducted in continuous dryland corn, responses may differ in irrigated, higher-yielding or corn-soybean systems.

Grain P concentrations were higher in the 30- and 45-ppm treatments than in the crop-removal and 15-ppm treatments, but this additional P uptake did not consistently translate into higher grain yield. The study described this as luxury P consumption. 

Do Not Let Soil P Fall Too Low

The same study also showed that completely eliminating P is not a sustainable cost-saving strategy.

In normal years, the no-P treatment yielded about 9% less than treatments receiving P. During wet years, the yield reduction was about 12%. Under those wet conditions, the crop-removal strategy also produced about 8% greater yield than maintaining soil near 15 ppm Bray-1 P, even though yields did not differ significantly when averaged across all 16 years (Figure 3). These results illustrate why cutting P across the entire farm simply because fertilizer is expensive can create yield risk, particularly where soil-test P is near or below the critical range. The better approach is to distinguish between fields where P can safely be deferred and fields where P is needed to protect productivity.

Crop-Removal P Performed Well Economically

The long-term study also compared the economic performance of the different P fertilization strategies.

Across the 16-year period, applying P according to previous crop removal produced the highest return on investment at 4.9x, compared with approximately 3.6x for the 15-ppm strategy, 3.1x for the 30-ppm strategy and 3.0x for the 45-ppm strategy (Figure 4). Return on investment was calculated each year by dividing the value of the yield gain over the no-P treatment by the cost of the P applied, using that year's corn and fertilizer prices.

Maintaining soil-test P near 45 ppm produced the largest yield gain and net return in normal years, but it required about twice as much P as the crop-removal strategy. Averaged over all 16 years, net returns were similar for the 45-ppm and crop-removal strategies (about $36 and $34 per acre per year), so the extra yield from building soil-test P did little more than pay for the extra fertilizer. Because higher P prices raise the cost of building soil-test P more than the cost of replacing crop removal, the crop-removal strategy should retain its return-on-investment advantage at today's prices.

For producers facing today's fertilizer prices, the finding is important: more soil-test P is not automatically more profitable.

Use Current Nebraska Recommendations to Set the Rate

EC117 combines soil-test P with crop removal to help maintain adequate fertility without unnecessarily building soil P. For corn following corn with Bray-1 P below 20 ppm, the recommended P₂O₅ rate based on corn grain removal is:

P₂O₅ rate (lb/ac) = 0.33 × corn grain yield (bu/ac)

When corn stover is also removed, add 4 lb P₂O₅ per ton of stover to the recommended rate.

For example, a 200-bu/ac yield goal for corn following corn on a field testing below 20 ppm Bray-1 P calls for about 66 lb P₂O₅/ac, or roughly 127 lb/ac of MAP (about $62/ac at $970 per ton).

For corn following soybean, EC117 bases the rate on the P removed by the previous soybean crop: P₂O₅ rate (lb/ac) = 0.88 × soybean grain yield (bu/ac). For example, after a 65-bu/ac soybean crop, the rate is about 57 lb P₂O₅/ac. 

If all fertilizer P for the rotation is applied before corn, the recommended rate accounts for P removed by both crops: P₂O₅ rate (lb/ac) = 0.33 × corn yield (bu/ac) + 0.88 × soybean yield (bu/ac).

When Bray-1 P is between approximately 20 and 25 ppm for corn following corn, or 15 and 20 ppm for corn following soybean, EC117 recommends applying about 50% of the crop-removal P rate and retesting the soil after four years. This partial rate is meant to slow the decline in soil-test P rather than to produce a yield response this year. No P is recommended when Bray-1 P exceeds 25 ppm for corn following corn or 20 ppm for corn following soybean. 

Importantly, EC117 notes that if Bray-1 P has already been built above 20 ppm, P application may be reduced or even skipped for a year when fertilizer prices are exceptionally high, although removal-based applications generally should resume within one or two years. 

Starter P: Use It Where It Has the Best Chance to Pay

Liquid 10-34-0 is commonly used as a starter P source. Placing starter fertilizer close to young roots can improve early-season P availability. This can be useful where soil-test P is low or where cool soil conditions limit early P uptake, such as with no-till or early planting. 

However, having a planter fertilizer system does not mean every acre automatically needs the same starter rate. When soil-test P is already high, a starter application may improve early crop appearance without necessarily producing an economic grain-yield response. See more in the CropWatch article, “Starter Fertilizer — When is it Needed?”

The decision to use starter P should therefore be based on soil-test P, field history, placement and expected crop response rather than automatically applying starter because it has traditionally been part of the program. When starter is placed in-furrow with the seed, stay within the rate limits cited in NebGuide G361, “Using Starter Fertilizers for Corn, Grain Sorghum, and Soybeans,” to avoid seedling injury.

Banding Can Improve Short-Term P Efficiency

Phosphorus placement provides another opportunity to stretch fertilizer dollars. EC117 indicates that banded P is generally more efficient in the short term than broadcast P when soil P is low. Under current guidance, producers can apply half the recommended broadcast P rate when fertilizer is banded. 

P can be applied in preplant bands, beside or over the row, in suitable planter placements, through dual placement with anhydrous ammonia, or through strip-tillage systems. Banding does not eliminate the need to maintain adequate long-term soil fertility, but it can help improve fertilizer efficiency when P is needed and fertilizer prices are high. Because the banded rate is lower than the amount of P removed by the crop, using it year after year will gradually lower soil-test P. Check P levels again at the next soil sampling.

Use Variable-Rate P Where Fields Are Variable

Soil-test P often varies substantially within a field because of previous fertilizer and manure applications, historic field boundaries, erosion and deposition, topography and differences in soil properties. A single field-average rate can therefore supply too little P to some acres and more than needed to others.

UNL guidance encourages combining yield maps or management-zone yield data with grid soil-test results to develop variable-rate P prescriptions. For crop-removal approaches, this can help avoid unnecessary P applications in portions of a field where Bray-1 P is already above the response range. 

When P prices are high, identifying those acres becomes more valuable and may justify denser grid sampling or other field mapping.

Account for Manure and Other P Sources

Manure can supply substantial quantities of phosphorus. Fields with a history of manure application may have elevated soil-test P, which can reduce or eliminate the need for additional commercial P fertilizer in the short term. Applying DAP or MAP without accounting for manure-derived P can therefore mean paying twice for the same nutrient.

Use soil testing and manure analysis together to determine how much additional commercial P, if any, is needed. Building soil-test P well above crop needs also increases the risk of P loss in runoff, an environmental reason to avoid over-applying P.

The Bottom Line

High phosphorus fertilizer prices do not mean every field should receive less P. They mean producers have a stronger incentive to put P fertilizer where it is most likely to pay.

Use current soil tests. Protect yield where soil-test P is low. Avoid unnecessarily building already-high soil-test P. Consider crop removal where appropriate, use banding to improve short-term efficiency, evaluate starter P based on actual need, account for manure-derived nutrients, and use variable-rate application where within-field variability justifies it.

Nebraska's long-term research illustrates an important trade-off: allowing soil P to fall too low increases yield risk, but maintaining excessively high soil-test P can require considerably more fertilizer without a consistent yield advantage. 

At current prices, knowing where P is likely to produce a return is increasingly important.

References

• Iqbal, J. (2017, updated 2025). Starter Fertilizer — When is it Needed?, CropWatch, University of Nebraska–Lincoln.
• Patel, S., Shapiro, C., & Iqbal, J. (2024). Long-term comparison of targeted soil test values and crop removal as a phosphorus fertilization strategy in corn. Agronomy Journal, 116(6), 3240–3255. https://doi.org/10.1002/agj2.21677
• Quinn, R. (2026, September 30). Anhydrous Leads Fertilizer Prices Higher, Up 25% From a Year Ago. DTN/Progressive Farmer. 
• Iqbal, J., Ferguson, R. B., Maharjan, B., & Thompson, L. (2023). Nutrient Management Suggestions for Corn (EC117). University of Nebraska–Lincoln Extension.