A soil test can tell you how much phosphorus or potassium is in the soil. But it simply cannot tell you, “Your residual fertility is worth $800 per acre.”
There are several important steps between measuring nutrients in the soil and determining whether some of that fertility may represent residual value for a landowner. That distinction (and the corresponding soil report) matters for anyone considering a Residual Fertility Valuation (RFV), commonly discussed in connection with Section 180.
Here is how Advanced Agrilytics turns soil data into a documented residual fertility value.
Step 1: Start With the Location Specific Soil
Residual fertility is unique to each property, so the soil analysis should start locally.
Advanced Agrilytics uses soil samples collected at specific, georeferenced points across the property. Laboratory analysis measures nutrient levels and soil characteristics at those individual locations.
Why does that matter?
Because fertility can vary considerably within the same field. A few composite samples or a regional average may miss those differences. Point-level sampling provides a much more detailed picture of what is actually in the soil and where it is located.
Step 2: Determine What Productive Soil Needs
This is where a soil report becomes much more than an inventory of nutrients. Finding phosphorus, potassium, calcium, or other nutrients in the soil does not mean all those nutrients represent residual fertility value. Advanced Agrilytics establishes field-specific critical levels based on the soil characteristics measured at each sample point.
Think of the critical level as the baseline. It helps identify the fertility needed to support normal crop production. That baseline is important because residual fertility valuation is not about assigning a dollar value to everything in the soil. It’s about identifying qualifying fertility above what the soil needs.
Step 3: Calculate the Excess
Once the measured fertility and critical levels are established, the difference between them can be evaluated.
For example, imagine a soil sample contains a phosphorus level of 35 ppm and the appropriate critical level at that location is 20 ppm. The residual fertility would be 15 ppm (the difference between 20 and 35).
The analysis focuses on the amount above the critical level. That distinction helps separate the fertility needed for production from the excess fertility that may have been built by previous applications.
In other words: measured fertility – field-specific critical level = potential excess fertility
That calculation happens across the property, nutrient by nutrient and sample point by sample point.
Step 4: Determine What That Fertility Was Worth
Finding excess fertility isn’t the end of the valuation. Next, the valuation of the nutrients at the time the land changed hands comes into play.
Advanced Agrilytics converts qualifying excess nutrients to the appropriate fertilizer compounds and applies documented historical nutrient pricing tied to the relevant month and year of acquisition or inheritance.
That means the valuation is not based simply on today’s fertilizer price or a generic cost per pound. The goal is to establish a documented value appropriate to the property and the time it was acquired, whether today, last month, last year, or 10 years ago.
Step 5: Culminate the Calculations Into an RFV Report
Now the full picture begins to emerge.
Actual soil samples → measured nutrient levels → field-specific critical levels → excess fertility → historical nutrient values → Residual Fertility Valuation
The resulting RFV Report documents the agronomic analysis behind the value, including field boundaries, sample locations, laboratory results, nutrient calculations and mapping that helps show how fertility varies across the property.
That documentation is especially important when the valuation becomes part of a larger tax conversation.
A Soil Test Is the Starting Point, Not the Valuation
This may be the most important takeaway. A soil test measures what is there. A Residual Fertility Valuation determines what portion may represent qualifying excess fertility and establishes a documented value for it.
That requires more than multiplying a soil-test result by a fertilizer price. It requires agronomy, field-specific analysis, historical pricing, and documentation that connects the final value back to the soil itself.
For landowners, that can reveal value they may not have realized came with the property. For accountants and tax professionals, it provides agronomic information to help evaluate potential Section 180 or related tax treatment. And for agricultural real estate professionals, it helps explain why the value transferred in a land transaction may extend beyond what can be seen above ground.
The value may start buried in the soil, the RFV Report helps make it visible.
Advanced Agrilytics provides agronomic analysis and valuation documentation, not tax, accounting or legal advice. Eligibility, filing method and tax treatment should be determined by a qualified tax professional.