Fertilizer is best thought of as 3 separate products, limited by either nitrogen, phosphorous, or potassium. Plants need all 3 of them to grow.

Your article is primarily about nitrogen fertilizers, which is usually made by processing fossil fuels. It's possible to make nitrogen fertilizers without fossil fuels, but that's more expensive, so the fossil fuel methods dominate.

Canadian production of potash (potassium compounds used for fertilizer) is a different product, with different supply chains.

Phosphorous production is dominated by China and Morocco (with some significant production by United States, Russia, Jordan, Saudi Arabia) so that's not really in either discussion about fertilizer shortages or trade wars now.