Mosaic's Sulfur Curtailment Exposes a Gap in U.S. Fertilizer Policy
Primary lensTrade remedies
Sub-topicPhosphate CVD orders
Evidence base16 records used
Use caseTrade-remedy exposure
The Policy Map Stops Before the Plant Gate
The federal instruments reviewed here act on phosphate fertilizer at two points in the supply chain. They do not reach the point where the largest North American production system is now constrained.
On June 29, the White House declared a fertilizer supply emergency and authorized temporary countervailing-duty relief for Moroccan phosphate fertilizer within the written scope of C-714-001. Effective July 8, Commerce implemented a shipment-specific request channel: an importer or exporter must file in ACCESS, obtain approval for the identified merchandise and intended use, and normally enter it within 60 days of notice. USDA then offered at least $500 million through FIELDS for new or expanded independent domestic capacity.
Both measures can increase finished fertilizer supply. Neither puts affordable sulfur under contract for an incumbent phosphate plant.
That is the gap exposed by Mosaic's August 4 operating record and the August 20 congressional request for a fertilizer supply-chain strategy. Mosaic reported that sulfur availability and affordability drove production reductions, with Faustina fully idled and Bartow operating at 40 percent of its targeted annual rate. The lawmakers pointed to a reported Chinese halt in sulfuric-acid exports and asked USDA and USTR to respond.
For incumbent producer counsel, the immediate decision is narrower than the political request. The public record supports opening a Section 301 evidence build, not filing the petition. It documents the plant constraint but not the operative Chinese measure, the state nexus behind particular purchases, or China's causal share of the U.S. burden.
Counsel should build the sulfur evidence file first.
Plant Filings Establish the Constraint
Phosphate fertilizer does not begin with finished MAP or DAP. The USDA production chain shows phosphate rock reacting with sulfuric acid to produce phosphoric acid, which is then converted into the principal phosphate fertilizers. Mosaic's 2025 Form 10-K describes the same physical dependency: one tonne of DAP requires about 0.40 long tons of sulfur.
The sulfur supply response is also unusual. Most U.S. elemental sulfur is recovered as a byproduct of petroleum refining and natural-gas processing. A phosphate producer cannot call a new sulfur mine into service simply by paying more. Refinery throughput, the sulfur content of feedstock, recovery equipment, transport mode, terminal access, product grade, and contract allocation determine which tons can reach a plant.
Mosaic's filings show the constraint moving from the commodity market into operations. The company said sulfur availability and affordability were the primary challenge in the second quarter. It reported a Q2 sulfur cost of $522 per long ton and Q3 contracts with U.S. Gulf Coast refiners at $705 per long ton. Faustina was completely idled, and Bartow was running at 40 percent of its targeted annual operating rate.
Scale makes that more than a single-company footnote. Mosaic reported that it accounted for about 72 percent of estimated North American annual production of concentrated phosphate crop nutrients in 2025. An input problem at that system can become a regional fertilizer-supply problem even when phosphate rock, plant equipment, and demand remain available.
The filings do not, however, attribute the curtailments solely or primarily to China. They identify global raw-material disruption and contract pricing; the 10-K separately identifies reduced refinery operating rates and geopolitical instability as risk factors. The congressional letter adds a possible foreign cause. It reports Chinese purchases of U.S. sulfur and a May halt in sulfuric-acid exports, but it does not attach the Chinese measure or the transaction records behind the purchasing allegation.
The filings establish an urgent supply constraint, but they do not establish how much of it is attributable to Chinese conduct. The United States both imports and exports sulfur, and gross exports alone do not prove strategic diversion. Grade, location, buyer, price, timing, transport, and the counterfactual domestic allocation all matter.
Where Section 318 and FIELDS Stop
Section 318 operates at the border. The White House proclamation authorized temporary relief for subject Moroccan phosphate fertilizer for no more than eight months, subject to earlier termination of the emergency. Commerce preserved the underlying CVD order and implemented a request channel inside case C-714-001 effective July 8. The order's written scope is dispositive and excludes products including phosphoric acid. Each request must identify the producer, merchandise, HTS number, U.S. price, quantity, entry date, port, transport mode, consignee, destination, and intended use. Commerce approval leads to a shipment-specific CBP instruction, and the merchandise must be used for the approved Section 318 purpose.
That channel can move approved shipments of subject Moroccan phosphate fertilizer into the United States. It does not secure elemental sulfur or sulfuric acid for a domestic phosphoric-acid plant. For an incumbent producer, it may increase supply for customers while leaving the producer's input constraint untouched.
FIELDS looks further ahead. The USDA program can support new facilities, upgrades, equipment, and some working capital and logistics tied to increased output. Its design directs money toward independent capacity. An applicant and its affiliates cannot hold a production share equal to or greater than the fourth-largest participant in the relevant nitrogen, sulfur, phosphate, or potash market. Working capital and logistics cannot be the project's primary use.
The application window closed on August 17. Many capital projects may still require engineering, permitting, construction, commissioning, and feedstock contracting, with timing dependent on the project type. The program may diversify domestic supply over time. It is not an emergency sulfur-purchase facility for a dominant incumbent.
Critical-minerals policy has a similar boundary. The final 2025 list added phosphate and potash, but not sulfur. That designation helps organize federal monitoring and industrial policy around the mineral. It does not create a sulfur allocation rule, an export control, or a plant-restart fund.
The policies address different products on different timelines.
Current Federal Reach
Federal tool
What it reaches now
What remains outside
Section 318 Moroccan relief
Approved shipments of subject Moroccan phosphate fertilizer within C-714-001 and for the approved Section 318 use
Sulfur delivery to domestic plants
USDA FIELDS
New or expanded independent U.S. capacity
Primary working capital and emergency procurement for a dominant incumbent
Critical-minerals policy
Phosphate and potash designation
Sulfur as the conversion reagent
Executive Order 14387 DPA direction
Adequate supply of elemental phosphorus and glyphosate-based herbicides
No express sulfur or phosphate-fertilizer continuity program
BIS short-supply rules
License requirements for commodities currently controlled under 15 CFR Part 754
Elemental sulfur and sulfuric acid are not currently subject to those requirements
Section 301
Investigation and potential trade action against an identified foreign act, policy, or practice
Domestic allocation and a petition record still missing core evidence
USDA can finance agricultural capacity, USTR can investigate foreign conduct, Commerce and BIS administer export controls, and refiners and gas processors generate most domestic sulfur. The federal instruments reviewed here do not connect those authorities to near-term sulfur continuity for incumbent phosphate production. Import relief, industrial finance, and foreign-practice enforcement therefore leave the present procurement gap unresolved.
Section 301's Filing Gate Is Evidence
Section 301 can reach conduct that does not look like a conventional tariff, but its mandatory and discretionary branches differ. Under 19 U.S.C. 2411(a), an unjustifiable foreign act that burdens or restricts U.S. commerce can trigger mandatory action. Under section 2411(b), an unreasonable or discriminatory act must burden or restrict U.S. commerce, and USTR must also determine that U.S. action is appropriate. An interested person may petition USTR, and USTR has 45 days to decide whether to initiate an investigation.
The petition rules make the current evidence gap concrete. Under 15 CFR 2006.1, a petitioner should provide the foreign law or regulation where possible, identify it with the greatest possible particularity if a copy is unavailable, identify the foreign country or instrumentality and affected product, show the actionable burden on U.S. commerce, state the trade volume involved, and describe the methodology used to calculate that burden.
The reported Chinese sulfuric-acid halt could fit that architecture. An official export prohibition, licensing rule, customs instruction, or unpublished administrative direction could be the challenged practice. USTR has confronted Chinese raw-material export quotas, licenses, minimum export prices, and failures to publish measures before.
No operative Chinese measure appears in the public record cited here. The record does not establish the issuing authority, legal basis, covered tariff lines, duration, exceptions, or licensing procedure for the reported May halt. The House letter establishes the allegation and request for action, not the foreign measure.
The same discipline applies to purchasing. A state-linked company buying sulfur at a high price is not, by itself, proof of government direction or an actionable plan. A petition framed as export targeting would need to identify the assisted enterprise or industry, the coordinated government plan, and how that plan improved export competitiveness. A petition framed around an export restriction would need to prove the restriction and its effect.
Those theories should not be blended into a single claim. Aggressive purchasing, state ownership, an export halt, and a downstream fertilizer policy are different facts with different proof requirements.
Why Filing Now Is Tempting
Delay has a cost. Plants are already curtailed. Section 318 may increase competition from approved subject merchandise while incumbent capacity remains idle. Filing a petition would force USTR to make a public threshold decision within 45 days and could give the producer a formal place in the interagency record.
The rules also recognize that petitioners may not possess every foreign-government document. They ask for information reasonably available and permit the petitioner to identify a measure with as much particularity as possible. Investigation can uncover evidence private parties cannot obtain.
Those timing advantages do not cure the present filing defects.
The 45-day decision is not an extended discovery period. In 2022, USTR declined to open a Section 301 investigation into alleged Mexican seasonal-produce export targeting because it could not conclude within the statutory period that an investigation would be effective. It pursued other work with USDA instead. A sulfur petition built from multiple global shocks faces the same effectiveness question.
Filing now would spend the first statutory decision on a record that does not yet identify the foreign measure with precision or isolate its commercial effect. The better course is a short, dated evidence build. If the missing links can be documented, file. If they cannot, ask for a different instrument rather than treating Section 301 as an emergency procurement program.
The Sulfur Petition File
Petition element
Current public record
Filing gate
Foreign act, policy, or practice
Congressional description of a reported restriction
Open
Government or instrumentality nexus
China is identified, but the administering body and direction behind specific purchases are not
Open
Product definition
Elemental sulfur, sulfuric acid, phosphoric acid, and finished phosphate can be separated
Largely ready
Burden on U.S. commerce
SEC filings document cost and curtailment
Partial
Causation
No public allocation among Chinese conduct and other supply shocks
Open
Trade volume and methodology
No petition-ready public calculation
Open
Requested action
No defined response tied to the alleged practice
Open
The pre-filing file needs five parts.
Measure record: the original Chinese instrument or authenticated evidence of an unpublished instruction, issuing authority, legal basis, HS coverage, effective date, duration, exceptions, licensing terms, and customs implementation.
Government nexus: official ownership and control records, policy directives, financing, procurement instructions, or communications showing that the conduct is attributable to a foreign government or instrumentality.
Trade and transaction record: monthly sulfur and sulfuric-acid flows by destination, port, quantity, value, grade, and transport mode, plus tenders, bids, contract awards, supplier communications, freight offers, and storage constraints.
Burden and causation model: sulfur requirements by facility, inventory, attempted substitutes, curtailed output, idle costs, customer effects, and a counterfactual that separates the alleged Chinese practice from refinery throughput, shipping disruption, freight, maintenance, and other buyers.
Remedy memorandum: the action USTR should seek, why it addresses the challenged practice, and why it is more likely to improve sulfur availability than a tariff on unrelated goods.
Commercially sensitive material should be organized in public and confidential versions from the start. Keep elemental sulfur and sulfuric acid separate, use a single mass unit, and connect Gulf Coast constraints to facility data rather than national annual averages.
Why This Is New
The June 26 Traverse Analysis, The Soybean Demand Story Has a Fertilizer Cost Problem, mapped fertilizer costs, Hormuz exposure, acreage pressure, and the live phosphate CVD orders. The records since then present a different problem: shipment-specific import relief and future independent capacity do not reach Mosaic's current sulfur constraint.
The earlier Chinese raw-materials matter was a WTO dispute, not a Section 301 precedent, and it began with a stronger public record. USTR had identifiable quotas, licensing requirements, minimum export prices, and publication failures to plead. Here, the alleged market effect is visible before the reported May instrument. Counsel's first trade-law task is to locate the measure and connect it to a quantified U.S. burden.
What Incumbent Phosphate Producer Counsel Should Do
Counsel should open one controlled sulfur file now and preserve tenders, unsuccessful bids, counterparty communications, freight quotes, terminal constraints, curtailment decisions, and customer-allocation records while they remain contemporaneous.
It should seek the original Chinese measure or document an unpublished instruction through exporter notices, rejected declarations, licensing correspondence, customs treatment, and sworn accounts. USTR should be briefed on the missing evidence and the possibility of government-to-government confirmation. Counsel should separately brief USDA on the agricultural consequences, while treating any domestic short-supply control as a separate Commerce and BIS question.
Filing should be authorized only when four items can withstand hostile review: the measure, the government nexus, the attributable burden calculation, and the remedy memorandum.
Benchmarks to Watch
A Chinese primary record identifying a sulfuric-acid restriction, licensing rule, customs instruction, or implementing authority.
Monthly Chinese exports under heading 2807 and U.S. elemental-sulfur exports under heading 2503, aligned to destinations, ports, quantities, values, and the alleged May start date.
Mosaic's plant restart rates, sulfur contract prices, delivered volumes, and next phosphate-production guidance for Faustina and Bartow.
USDA FIELDS awards identifying the supported input, facility, output, and operating timeline.
A Section 301 petition, USTR self-initiation, Commerce monitoring action, or BIS proposal addressing sulfur supply.
Public Section 318 approvals and CBP instructions showing whether the Moroccan channel is producing actual entries, not merely legal availability.
Caveats
The reported May Chinese sulfuric-acid halt remains reported. Failure to locate a public instrument does not prove that no administrative instruction or customs practice exists. It means the public record does not yet support describing it as a confirmed formal export control.
Mosaic's SEC filings establish a plant constraint and company-reported cost. They do not assign a causal share to China. The congressional claim that a Chinese buyer outbid Mosaic is not supported by a public contract or transaction record located for this review.
FIELDS eligibility is determined by USDA. The market-share rule and the program's capital design make it a poor fit for emergency procurement by a dominant incumbent, but this Analysis does not claim a company-specific agency determination.
Section 301 is leverage against foreign conduct, not a domestic allocation order. Even an initiated and successful case would not guarantee that sulfur reaches a curtailed plant. The requested remedy must be tested against that physical limit.
Section 318 relief applies only to approved subject merchandise within C-714-001 and for the approved emergency-relief use. Misuse can trigger seizure, penalties, or both.
Filing Decision
Section 318 moves approved shipments of subject Moroccan phosphate fertilizer within C-714-001 and for the approved emergency-relief use. FIELDS offers at least $500 million for independent capacity. Near-term sulfur procurement for incumbent plants remains outside both programs.
A China-focused Section 301 case is worth preparing only if counsel can establish the measure, government nexus, attributable burden, and effective remedy. Until then, the sulfur evidence record is the next file.
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