Understanding Section 180

By Alec Bean, CCA
Last reviewed September 22nd, 2026. How we review

Short answer: Section 180 lets a taxpayer in the business of farming choose to deduct the cost of fertilizer, lime and similar soil amendments in the year they’re paid for, instead of spreading the cost over several years. Many farmland buyers also use it to deduct the part of the purchase price that paid for unexhausted fertilizer the seller applied. That second use rests on limited IRS guidance, and it has to be proven parcel by parcel.

What the law actually says

Section 180 of the Internal Revenue Code is three short paragraphs. In plain terms:

1. Who: a taxpayer “engaged in the business of farming.” That includes owner-operators, tenants and crop-share landlords. A cash-rent landlord qualifies only if they materially participate, and growing timber isn’t farming (Treas. Reg. §1.175-3, applied through §1.180-1(b)).
2. What: amounts paid or incurred during the year to buy or acquire “fertilizer, lime, ground limestone, marl, or other materials to enrich, neutralize, or condition land used in farming,” plus the cost of applying them.
3. Where: “land used in farming” — land the taxpayer or their tenant used for crops, fruit, other agricultural products or livestock, before or at the same time as the expense. Fertilizer used to bring land into farming for the first time doesn’t qualify.
4. How: it’s an election. Claiming the deduction on your return is the election; it covers only that year, must be made by the return’s due date including extensions, and can’t be revoked without IRS consent (§1.180-2).

Read the full text at 26 U.S.C. §180.

Why Section 180 exists

Before 1960, the IRS and the courts treated fertilizer and lime whose benefit lasted more than a year as a capital cost, to be deducted gradually over its period of effectiveness. Farmers had always deducted it in the year they paid for it. Congress passed Section 180 in 1960 to let them keep doing so, by election. If you don’t elect, you can still capitalize fertilizer and amortize it over the period it stays effective (Iowa State CALT).

That history matters, because it’s the foundation of every residual-fertility argument: if fertilizer is a wasting asset that can be written off as it’s used up, then unexhausted fertilizer you bought along with land might be, too.

How land buyers use Section 180: “residual fertility”

When you buy farmland, you allocate the price among what you bought. Land itself can’t be depreciated. Tile, fences and single-purpose buildings can. The residual-fertility approach treats a slice of the price as payment for fertilizer the seller applied that crops haven’t used yet — what the IRS calls the “residual fertilizer supply” — then deducts or amortizes that slice.

No statute, regulation or court case addresses this directly. The main IRS guidance is Technical Advice Memorandum 9211007 (December 1991). The IRS denied the deduction in that case, but it described what a buyer would have to prove (ruling text):

• Presence and extent. Show how much fertility in this soil came from fertilizer the prior owner applied. Comparisons to neighboring or “typical” farms weren’t accepted.
• Exhaustion. Show that this fertility is actually being used up, and over what period.
• Beneficial ownership. You must own the land the fertilizer is part of. (In the ruling, a farm corporation that rented the land from its shareholders couldn’t take it.)

A 1995 IRS audit guide for grain farms repeated the same three points and told examiners to check that values assigned to farm assets are reasonable. It’s out of print and not binding.

One more limit applies: the fertilizer’s slice can’t exceed its share of what you actually paid. If an agronomist’s value plus the land’s value without the fertility adds up to more than the purchase price, the price is split in proportion to those values (U of I Tax School).

What can — and can’t — be counted

Details: What the IRS requires, Pasture and rangeland, Inherited farmland, Land bought in prior years.

Do you qualify?

You’re most likely a fit if you bought (not inherited) cropland this tax year, you farm it or crop-share it, the seller fertilized it, you can get the seller’s application records, and you haven’t applied fertilizer since closing. Renters who buy the ground they already farmed usually can’t count fertilizer they themselves applied and deducted. See Who qualifies for the full decision guide.

What is it worth?

The tax saving equals the defensible fertilizer value times your marginal tax rate. If you later sell while any of that fertility remains, the part of the price attributable to it is ordinary income, not capital gain; if you hold the land until death, that cost generally disappears. On a well-documented parcel the deduction is usually a fraction of what total-nutrient valuations advertise. We walk through a full example, including the downside if a deduction is disallowed, in How much can I save?.

Timing: test before you fertilize

The strongest evidence is a soil test taken at or right after closing, before any new fertilizer goes on, paired with the seller’s records. Once you apply fertilizer, it’s much harder to separate what you bought from what you added. See the Buyer timeline.

The seller’s side

Whatever you allocate to fertilizer, the seller arguably received as ordinary income, not capital gain on land. The IRS can compare both returns. Writing the allocation into the purchase contract is the best evidence you can have. See Seller tax consequences.

Five myths

1. “It’s a loophole nobody uses.” Farmers have deducted unexhausted fertilizer bought with land for decades; what’s new is much larger claims based on all soil nutrients.
2. “The IRS approved it in a 1991 ruling.” The IRS denied the deduction in that ruling.
3. “It’s audit-proof with a good soil test.” A soil test shows what’s there, not where it came from. You also need the link to past applications and proof of exhaustion.
4. “Claim 50–75% to be safe.” A haircut doesn’t create authority; the deduction must match what you can prove.
5. “If Section 180 doesn’t work, depreciate or deplete the nutrients.” Courts have rejected both for soil nutrients.

How Soil Tax Guys approaches it

We value only fertility we can tie to the seller’s applications, using parcel-specific sampling, the seller’s records, crop-removal history and an exhaustion schedule. Our report states what isn’t supported as clearly as what is, so your tax professional can decide. See How our valuation works.

Frequently asked questions

Is Section 180 legal? Yes. Section 180 is permanent law for fertilizer you buy and apply. Using it for residual fertility bought with land is based on limited IRS guidance and isn’t settled.

Can I use Section 180 on land I inherited? Not under Section 180 itself. Heirs may have a separate argument to amortize stepped-up basis; see Inherited farmland.

Do I need the seller’s fertilizer records? They’re the best evidence that fertility came from applications rather than the soil’s natural makeup. Without them, the claim is weaker.

Can I amend an old return? Not to make a Section 180 election — that has to be made on a return filed by its due date, including extensions. Amortization isn’t an election, so it may be claimed on an amended return within the refund window, if you can still prove what was in the soil at purchase. See Land bought in prior years.

Sources

• 26 U.S.C. §180
• Treas. Reg. §1.180-1, §1.180-2, §1.175-3
• TAM/PLR 9211007 (Dec. 3, 1991)
• Tidgren, Considering the Residual Fertility Deduction, Iowa State CALT
• Tidgren & Coutu, Deducting Residual Fertility, USDA webinar, July 2025
• Tidgren & Lashmet, Southern Ag Today, Nov 2025
• McEowen, Deducting Residual (Excess) Soil Fertility, U of I Tax School