Mosaic, the USA's largest phosphate fertiliser producer, started petitioning the US International Trade Commission in June to implement the duties, saying unfairly subsidised imports were causing significant harm to its operations.

The DOC agreed with the complaint and had calculated a subsidy rate of 23.46% for Moroccan producer OCP. In the Russia investigation, the DOC calculated rates of 20.94% and 72.5% for the PhosAgro and EuroChem respondents, respectively, and 32.92% for all other producers and exporters.

Mosaic CEO Joc O'Rourke said the foreign government subsidies had to be addressed to level the playing field in the US market.

"[The] ruling moves a step closer to fair trade and an assurance for US farmers that they will be able to rely on US fertiliser for decades to come," he said.

Scotiabank analyst Ben Isaacson said trade flow had already shifted on the back of the petition, which he said should start to reduce the NOLA [New Orleans, Louisiana] DAP [delivered-at-place] premium versus global parity values.

"The largest catalyst for Mosaic is now behind it, which could trigger marginal selling of a stock that has gone from a COVID-low of US$6.50 to nearly $22 (our target price)," said Isaacson.

Scotiabank maintains a ‘sector perform' rating on Mosaic and a preference for potash over nitrogen and phosphate through 2021.

The DOC is scheduled to make a final determination on the countervailing duties on February 8, 2021, followed by similar action by the International Trade Commission on March 25 and a final order planned for April 1.

In the event, Mosaic shares (NYSE:MOS) powered to a new 12-month high on Tuesday at $23.19, giving it a market value just shy of $9 billion.