One acre of hemp produces as much cellulose fiber pulp as 4.1 acres of trees!!!

[muriel_volestrangler]

19. China, for instance (world's largest producer)

http://www.naturalfibres2009.org/en/fibres/hemp.html

However, the fact that they still produce relatively little is an indication that hemp is not, after all, some wonder-crop. From 1998:

In 1997, world hemp fiber production was about 55,500 metric tons, with China, South Korea and the Russian Federation producing more than 70% of total world supply. None of these countries has ever made industrial hemp cultivation illegal. China, Russia, Ukraine, Romania and the European Union are some of the countries which subsidize hemp production. Although more publicity has been given to revitalized hemp production in the European Union and Canada, these countries remain negligible producers.

Notably, world hemp production has been on the decline, falling from over 300,000 metric tons in the early 1960's to one-fifth that level today. Although there has been a resurgence in interest in industrial hemp (due to the growing world demand for natural fibers and the adoption of more advanced hemp cultivation and processing techniques) production remains stable over the last five years.

www.uky.edu/Classes/GEN/101/Hemp/HEMP98.PDF

(That compares to about 25 million tons of cotton annually worldwide, or 400 million tons or paper and paperwood.