Supply vs demand
The fundamental rule in the market is that commodity prices will rise with an increase in demand. This ties in with income and population, the cost of production of the commodity, and the actions of governments and producer organisations.
Production of commodities is influenced by natural factors like weather and crop conditions, cultivation land, trade constraints, subsidies, taxes, and production-related factors like labor patterns, development in farming tools & technologies used.
Cost of production
Commodity production costs include raw materials, labor/wages, research and development, insurance, licensing fees, taxes, and much more. An increase in production costs will have a direct impact of the price of the commodity being produced.
The prosperity of a country indicates the purchasing power of its population. This effect is more obvious in countries that are major producers or consumers. As the economy grows and urbanises, they typically consume a larger amount of commodities.