How much biodiesel can be produced from an acre of hemp?

I’ve done quite a bit of biofuel research, and when looking at hemp fuel, I have found consistently different numbers… I’ve seen as low as 39 gallons per acre (Wikipedia, but the source was not cited for that data). “The Great Book of Hemp” shows that if you include the stalks in the processing, one acre (assuming 5-10 tons of dried stalk per acre) would be able to produce 500 gallons of biofuel. I guess like a lot of the other things, and it would depend a lot on the strains being grown and the care given to the crop–I’ve heard a lot of “tricks” folk use to encourage higher seed yield. I suppose there are also variants in the way the biofuel itself is created, which could also change the answer to this question.