corny MJ

i was just wondering if anyone knows how fast MJ grows compared to corn

well this is what i found for hemp

Its growth rate is so rapid, it is ready for harvest in only 4 months- reaching a height of 6-12 feet, and producing 3-6 tons of dry fiber per acre.
http://www.reusablebags.com/facts.php?id=10

and heres some corn

Under the linear trend, the trend yield for 2006 is 159.9 bushels per planted acre. This would grow to 181.3 bushels per planted acre in 2015. Under the break-point trend, the trend yield for 2006 is 169.1 bushels per planted acre, 9.2 bushels per acre higher. The 2015 trend yield is 200.0 bushels per planted acre, roughly 10 percent higher.
http://www.card.iastate.edu/iowa_ag_review/fall_05/article3.aspx

and heres the bushel conversion
Corn, shelled
56 pounds per bushel Corn, ear
70 pounds per bushel
http://extension.missouri.edu/publications/DisplayPub.aspx?P=G4020

so thats roughly 159.9bushels in 2006 at 70 lbs of corn per bushel
159.9*70=11,193 lbs of ear corn per planted acre

but who knows how acurate these figures are