According to an Interfax report, Russia's agricultural minister said that starting tomorrow and through June 1, Russia will halt wheat, corn, rye and barley exports.

Now, Russia isn't growing or harvesting anything right now so these are supplies from last year.

Despite all that, precipitation levels are extremely low in most of Europe and grains prices are already sky high. Russia may be trying to secure its own supplies. China also has a year of wheat supplies in storage.

That's not the case in much of the world. High prices could lead to famines and food insecurity in much of the developing world. That will likely be exacerbated by sky-high fertilizer prices and could be worsened if Ukrainian planting is disrupted.

Late yesterday, Argentina also halted all its soy exports in part due to drought. Food inflation is coming.

To add to this, here's a note from BofA Securities:

“Perhaps the most “ominous” message from our fertilizer panel at our Global Agriculture & Materials conference was the potential impact of the conflict in Eastern Europe on global crop production. Russia and Ukraine are critically important to global crop supply, representing 29%, 19%, and 13% of global wheat, corn, and vegetable oil trade, respectively. As for fertilizer, Russia alone makes up 20% of the global potash market – a key component for fertilizer, with Belarus making up another 18%. Thus global crop prices are expected to remain elevated, supporting farmer economics in some regions and extending the agriculture cycle, but potentially leading to a significant supply shortage. Combining higher prices with less supply, US Chemicals analyst Steve Byrne raises his price objectives on Buy-rated fertilizer stocks – CF, NTR and MOS; while Alex Jones, covering European Chemicals, upgrades K+S to a Buy. Countries in LatAm could benefit too given many export food and energy and in a much broader note assessing regional impact from the conflict, the team raises LatAm GDP growth modestly. "