Maximizing Fertilizer Efficiency Amid Rising Input Costs

Editor’s Note: The “Maximizing Fertilizer Efficiency Amid Rising Input Costs” series is derived from a recent webinar hosted by Advanced Agrilytics, which addresses how growers can achieve greater fertilizer efficiency in our tough farm economy. This first article in the series focuses on improving phosphorus and potassium efficiency.

Rising Input Costs and the Risk of Skipping Applications

As many of our grandmothers used to say when we were children, “Don’t cut off your nose to spite your face!” meaning, don’t make hasty decisions that will have harmful long-term results. Unfortunately, in today’s rough farm economy, many growers are facing pressing, short-term decisions that could have substantial long-term impact on their farm’s profitability.

Input costs remain one of the top challenges for U.S. corn and soybean growers. Fertilizer, especially phosphorus (P) and potassium (K), is one of the biggest annual expenses, and every dollar spent must produce optimum ROI.

But with fertilizer and other key input prices continuing to climb, many growers are contemplating whether to scale back, delay, or even eliminate fall fertilizer applications altogether. While understandable from a cost-control standpoint, cutting back too severely can have long-term consequences for soil fertility, nutrient balance, and ultimately crop productivity. Once soil fertility falls behind, it often takes years, and significant investment, to rebuild.

That’s why our team of agronomy experts recently hosted a webinar on Maximizing Fertilizer Efficiency Amid Rising Input Costs. The focus was clear: rather than abandoning fertilizer applications, growers can get more efficient and more effective with these dollars by targeting inputs where they will generate the greatest return.

At Advanced Agrilytics, we do this by going deeper than field-level averages. Using our proprietary TerraFraming® process, we analyze dozens of sub-acre environmental and agronomic factors that influence nutrient concentration and, more importantly, nutrient availability. Through spatial critical level analysis, we map where phosphorus and potassium levels are below, at, or above critical thresholds and account for differences in soil moisture, topography, and diffusion potential.

The result is a nutrient management strategy that reallocates fertilizer dollars away from acres where additional applications won’t improve yield and directs them toward the acres where those dollars will generate the greatest return. This approach helps growers protect yield potential, maximize ROI, and avoid the productivity risks of “one-size-fits-all” or reduced fertility programs.

Soil Fertility: It’s About More than Concentration

Most of the standard soil test methods in use today were developed in the 1950s–1970s. These tests are designed to measure the concentration of a nutrient in a soil extract.

What these numbers don’t tell us is how much of the nutrient will actually be available to the crop during the season. Availability depends on environmental and soil factors such as:

Soil moisture (controls diffusion of immobile nutrients like P and K).

Temperature (affects mineralization and microbial activity).

Topography and landscape position (affect water holding and erosion risk).

CEC and organic matter (influence retention and release).

That’s why two acres with the same soil test phosphorus can perform very differently: one might have good water availability and strong uptake, while the other, on drier high ground (what we call the water-limited acre), may still be P-limited.

Soil Moisture Powers Diffusion

We know that approximately 90% of P and 80% of K uptake occurs through diffusion, a process heavily dependent on soil moisture. When soil water content drops, nutrient diffusion slows dramatically. One example from the webinar illustrated how available phosphorus at 0.1 ppm changes with soil water:

At 25% soil water by volume, plants had access to ~0.086 lbs. P₂O₅/acre.

At 13% soil water, availability dropped nearly in half, to ~0.045 lbs. P₂O₅/acre.

This highlights why a flat-rate application strategy fails to maximize efficiency.

Spatial Agronomy: The More Efficient Way to Manage Nutrients

Traditional university recommendations set a static critical level of nutrients for an entire field or even a state. But Advanced Agrilytics’ research shows that those critical levels will shift depending on the varying environments affecting nutrient concentration and availability within the field:

Low ground (higher water availability): Crops need less fertilizer because nutrients diffuse more efficiently.

High ground (water-limited acres): Crops need higher nutrient concentrations to make use of limited moisture windows.

By applying a spatial critical level approach, we can optimize fertilizer applications to match each acre’s potential, reducing waste and increasing efficiency.

This spreadsheet ranks a customer’s fields by phosphorus (left three columns) and potassium (right three columns) status using Advanced Agrilytics’ delta to critical level analysis. The highlighted data in the red box shows fields that should be prioritized for phosphorus applications.

Real-World Results for Our Customers

The results speak for themselves. In the example above, a flat-rate program would have applied 150 lbs. of phosphorus across 1,200 acres that were already above critical level. At $900/ton DAP, that would have cost more than $80,000 in unnecessary fertilizer applications. By reallocating those dollars to acres where soil P was below critical level, the grower improved ROI and avoided over-applying where it wasn’t needed.

In this example, we see a similar outcome with potash: a traditional 150 lb./A flat rate application would have wasted more than $40,000 in fertilizer dollars. Instead, this more targeted application strategy allowed the grower to prioritize acres where additional potassium would return the greatest benefit.

Fertilizer Price Trends

Over the past five years, MAP and DAP prices have fluctuated significantly across the Midwest. Illinois retail prices, for example, peaked near $900/ton in 2022–2023, consistent with national benchmarks. Current retail DAP prices in the Midwest remain elevated, generally ranging from $820–$900/ton depending on the state and freight costs.

That volatility underscores why precision in P and K management is essential. Blanket applications risk wasting dollars, which is a mistake no grower can afford to make in these tough economic times.

Moving Toward True Efficiency

At Advanced Agrilytics, we’re helping growers maximize fertilizer efficiency through:

Spatial Analysis: Using Soil Water Index, topography and other data to identify high- and low-potential acres.

Delta-to-Critical Mapping: Showing where P and K levels are below, at, or above optimal levels.

Targeted Fertility Plans: Reallocating fertilizer dollars to the acres with the greatest opportunity for ROI.

Efficiency doesn’t mean cutting fertilizer across the board. It means making sure every dollar invested is working toward yield, rather than wasted on acres that won’t respond.

The Bottom Line

In today’s farm economy, there is no margin for error. Blanket fertilizer programs are too blunt of a tool in a world where margins are razor-thin and nutrient prices remain volatile. By moving to a more predictive, environment-specific fertility strategy, growers can reduce waste, protect yields, and ultimately improve ROI on their P and K investment.

The data proves it: efficiency isn’t just about cutting back; it’s about applying nutrients for optimum efficiency and effectiveness.

Ready to take your nutrient management strategies to the next level? Contact us here.