The 2007 crop was the 22nd year for the survey.  It is interesting that the average protein was 35.3±1.49 and oil was 18.7±0.89 for the crop years 1986-2007.  The 2007 protein and oil values are similar to the 22-year survey average.  During this period average soybean yields have increased by about 25 percent, meaning that farmers are increasing soybean yields without altering composition.

soybean composition-historical summary
Seth L. Naeve and James H. Orf.  2007.  Quality of the United States Soybean Crop: 2007.   www.ussoyexports.org/

Comparative Soybean and Soybean Meal Quality
Quality of soybeans and soybean meals (SBM) from non-US and US origins were compared in a series of studies at Iowa State University.  They reported that US soybeans were lower in protein than Brazilian soybeans, but higher than Argentine soybeans.  The crude protein disadvantage of US soybeans was offset by higher concentrations of the essential amino acids in the lower protein soybeans.  The US soybeans were lower in oil content compared to South American meals.
Quality of soybeans by origin
They reported that the SBM of U.S. origin was more consistent, had higher digestibility (by KOH solubility) and lower fiber, and was a better source of essential amino acids compared to SBM of other major export origins (Argentina, Brazil and India).   While the protein content was higher for the SBM from Brazil, the percentage of total digestible amino acids was highest for the SBM from the US and China.  The US SBM had the highest total of five amino acids essential for both poultry and swine feed uses which when coupled with higher digestibility, would give US meal an advantage in rations formulated using digestible amino acids.