The war did not have a big effect on the food crisis that occurred in the world, the war only meant that the countries involved could no longer make maximum use of agriculture so that it affected production which made it difficult for local people to get food. However, what is currently frightening is that almost the entire world is being hit by extreme climate change, so the entire world is very worried about the food crisis.
What if that war-mongering country is a major exporter of a specific food? In this case Russia is one of the major exporters of worlds wheat and the war makes it difficult to keep running a safe transit. No other country will take the risk of importing goods from a country that is at war. The country that was dependent on importing wheat from russia will have to look for other alternative or they will face food shortages.
Yes, maybe people in rural areas can still survive and have the opportunity to work on the available land to support life. But another obstacle they face is the difficulty of obtaining fertilizer materials and the price is very high, so the current conditions are very difficult for all residents, both in villages and in cities. The government of course always thinks about this thoroughly, but the impact of climate change and conflict situations between countries makes this crisis difficult to overcome.
Earth's soil is naturally fertile if you are not living on a rocky mountain. We use fertilizers to increase food production, but without their use, we can still grow crops. There are other better alternatives, like compost fertilizer, which can be produced by using natural ingredients that are available in our surroundings. The only difficulties the villagers will be facing is with their communication or transportation. In a war, the most affected sector will be transportation, which is essential for importing any goods from outside the villages.