Fourth is the availability of infrastructure roads and highways, developed waterways, storage facilities, even governance. Certainly, the U.S. has the most highly developed infrastructure for agricultural production in the world. Fifth is the skill level of farmers. Although there are at work forces that are calculated to diminish the importance of this factor, historically this has been a significant explanatory variable for the success of U.S. agriculture. Sixth is the level of trade barriers.
Trade barriers can effectively wall a country off from the rest of the world.
In general, the U.S. has led the battle for demolishing trade barriers and has gradually lowered trade barriers for U.S. products. Finally, the level of competition for land resources. At present rates of conversion, by my calculation in about 340 years, give or take a few years, agricultural land in this country could be all concrete, blacktop and rooftops. Like the much touted and feared spectre of running out of oil resources, this is not likely to happen certainly not any time soon. A reasonably good measure of agricultural competitiveness, in a world of global markets, is the value of land.