More interesting is this report, which
analyzes the impact of growing four crops--corn, soy, wheat, and cotton, which account for 70% of farmed acres in the Unites States--from 1987 to 2007. One key finding is that the amount of land required to grow a certain amount of food has fallen. Because of yield gains, for example, it now takes 37% less land to grow a bushel of corn than it did in 1987. In addition, the rate of soil loss per amount of grain or cotton grown has declined between 30% and 70%. This is due mainly to the adoption of no-till farming, in which the fields are not plowed multiple times for weed control. Less plowing means less soil blows or washes away.The post also mentions two key factors: First, because it was prepared by 17 authors from agricultural and environmental backgrounds, it is bi-partisan. Second, greater efficiency for a given crop does not mean that a given crop is better than another crop, i.e., it is still unsustainable to grow corn for ethanol when corn displaces a lower-impact crop.
The analysis, led by agronomist Stewart Ramsey of the consulting firm Global Insight, also finds that the amount of energy spent on farming has fallen by 40% to 60%, probably because farmers who plant genetically modified crops are driving tractors less frequently to spray pesticides and herbicides. Irrigated water use dropped by 20% to 50%, the report found, and carbon emissions fell by about 30%. Wheat was the only crop of the four surveyed that did not post big gains in efficiency. More water is being used, and an increase in application of nitrogen fertilizers has meant an increase in energy use and climate impacts per bushel.
Bottom Line: Knowledge and efficiency are good. Now let's stop stupid policies (ethanol).