If there is a supply glut of a staple food, the prices of food in general, even not of that type tends to driven downward - because to some extent foods are interchangeable. Similar to how an overabundance of residential skyscrapers has a downward effect on the price of less attractive homes. There's a lot of history on food shortages and prices that can be found with a cursory level of searching. Each person can only eat so much in a day.