was not to promote soy as the oil of choice for biodiesel.  Since in the Midwest most farmers grow corn and soybeans so the number of acres going into each crop depends on the relative profit between the two crops.  If the price of soybeans remain low the number of acres of corn will increase dramatically, however if the demand for soy oil goes up the price of soybeans will go up to buy soybean acres.

As far as which crop is best for biodiesel production, I have no idea which is best, but I suspect it will take all the crops to make a dent in the diesel market.

I have never grown sunflowers, canola or palm trees, so I really can't really comment on the relationship of these crops to corn or each other.  However, as corn becomes more drought tolerant I would expect corn to compete for acres in the areas sunflower and canola are grown.

Also in the future, when conversion of cellulose to ethanol becomes more efficient, we will have another cash crop to compete for corn, soybean, sunflowers, and canola acres.