OK. I wasn't looking too hard for the data, but here's what I came up with (BTW this was in year 2001):
According to
this site and after doing some conversions, you get about 12 082 092 000 liters of oil each day.
Density of petroleum is somewhere around 0.85 kg/L, so that comes out to be 10,269,778,200 kg or about 10,270,000 tons of oil per day.
Now since they don't really give info (or I just couldn't find anything) on how much oil we get from 100 pounds of plants, I'll say that it's 50 pounds (once again if someone knows the number, please tell me).
So then, we need about 20,500,000 tons of plants daily. That is quite a lot. I really doubt that we can grow and harvest that much in a day.