Good article on Food Security and potash.

http://potashinvestingnews.com/10409-what-is-food-security.html

According to the Food and Agriculture Organization of the United Nations, food production must double by 2050 in order to feed the global population at that time. However, crop yield growth rates are declining, seed technology is reaching its limits and agricultural improvements are slowing. The bulk of population growth is expected to occur in less developed countries, to boot, where access to the benefits of advanced agricultural technology is even more limited.

Existing arable land is declining as well, making an increased rate of crop yields seem even less likely. The FAO reports arable land per person decreased by 44 percent between 1965 and 2005. Available arable land is largely located in developing countries – of that amount, around 80 percent is in Latin America and Sub-Saharan Africa. According to the FAO, there is almost no spare land in South Asia, the Middle East and North America, which are the regions with the highest rates of population growth.

Growing strain on resources due to population growth is also a factor in food security, particularly in making food available that fits the changing diets of those in developing countries. Rising incomes in some markets are creating an overall improvement in diets, but the addition of more grain and protein puts strain on agriculture. For example, 21 kilograms of grain are necessary to get 1 kilogram of lamb meat, and the ratio is not much more favorable for other non-poultry meats.