Maize is harder to grow, or at least harder to grow well. Crop yields vary tremendously across the hundreds of countries where grown but the disparity is more notable for corn. For rice and wheat, the country with the 15th highest yield in these two crops is netting over 60 percent of the yield achieved in the number one highest yield country. However, for maize the country down at number 15 for yield is achieving just 35 percent of the yield of the highest per hectare output country. This is a skewed view since any country can achieve a high yield if cost of production is ignored. Some of the countries with the highest yields produce on relatively few hectares and are not exporters. Achieving a very high average yield across a large land...