Educational content only. The information on this page is provided for general informational purposes and does not constitute tax, legal, or accounting advice. Tax treatment depends on your specific facts and circumstances. Consult a qualified CPA or tax attorney before taking any tax position.
The Short Answer
Based on publicly available information, the IRS has not categorically rejected residual fertility deductions as a concept. Historically, scrutiny has focused on documentation quality and methodology rather than the concept itself. Claims with weak soil data, inflated values, or missing methodology create greater exposure. Strong, conservative documentation generally presents a lower-risk profile — but every situation is different. Consult a qualified tax professional before filing.
What Actually Draws IRS Scrutiny
Weak or Missing Soil Testing
Claims without independent lab documentation, or where sampling methodology is absent, give the IRS nothing to verify. If you can't prove the nutrients are there, the deduction has no foundation.
Inflated or Unsupported Nutrient Values
Assigning value to every nutrient on a soil test — including nitrogen, native background minerals, or quantities not tied to actual managed fertility — creates numbers the IRS cannot reconcile with agronomy. Every included nutrient should be justifiable by crop system, lab data, and industry pricing.
Amortization Schedules With No Agronomic Basis
A 1-year or 2-year useful life for phosphorus — a nutrient that can persist in soil for several years under normal cropping — may be difficult to support without strong agronomic justification. Useful life should align with published crop-removal research rather than a number chosen to maximize the deduction.
Missing Methodology Documentation
A report that delivers a deduction number without a traceable chain of evidence — from soil test to nutrient inventory to fertilizer equivalent to purchase-date pricing — gives the IRS no way to audit the math. Every number needs a source.
What Keeps a Claim Protected
Independent Lab Analysis at Standard Depth
Soil sampling by an independent, credentialed lab at 6–8 inch depth using recognized extraction methods (Bray, Mehlich-3, or Olsen depending on region) provides a verifiable starting point that the IRS can check against industry standards.
Conservative Nutrient Selection
Including only phosphorus (P), potassium (K), and calcium/magnesium (as lime equivalent) — and explicitly excluding nitrogen — aligns the report with both the science and the IRS's established standard for multi-year depreciable assets. This is the same standard referenced in PLR 9211007.
University-Backed Useful Life
Exhaustion schedules tied to published crop-removal data from land-grant universities give the IRS a credible, externally-verifiable basis for the amortization period. This is how you satisfy the "exhaustion through use" test from PLR 9211007.
Full Chain-of-Evidence Documentation
An audit-ready report shows the complete path from soil test → nutrient inventory → fertilizer-equivalent conversion → purchase-date market pricing → total deductible value. If a CPA can trace every number from source to conclusion, the IRS can too. That traceability is the deduction's best defense.
Addressing the Iowa State CALT Concerns
The Iowa State Center for Agricultural Law and Taxation has published skeptical analysis of certain residual fertility claims. Their concerns are directed at aggressive, poorly documented claims — not at the general concept of residual fertility as a depreciable asset.
The CALT analysis flagged specific overreach: inappropriate nutrients, unsupported useful-life claims, and deductions that exceed what agronomic data reasonably supports. A conservative, evidence-first approach — independent lab data, only managed P/K/Lime, university-backed exhaustion schedules — is designed to address each of those concerns. Whether it does so sufficiently in your specific situation is a determination for your CPA or tax advisor.
The Controversy in Full Detail
AgronomyPlus covers the full landscape of aggressive vs. conservative approaches, how to defend a look-back analysis, and what the IRS actually looks for in documentation reviews.