Whenever I speak to university and high-school audiences the subject of hemp is high on the list. It seems that many young people have been convinced that we should stop cutting trees and use hemp instead. All in the name of saving forests and preserving biodiversity. Hogwash! While hemp makes perfectly good paper and cloth, it is an exotic annual farm crop that requires land to grow, land that could otherwise be growing trees. Most of the statements made about its superiority to trees are myths with no basis in fact.

Here is an excerpt from an advocate of hemp. He is trying to put a good face on it but there is just no getting around the fact that hemp uses more nutrients than most other crops. It requires heavy fertilization or four-year rotations.

"Hemp grows best on rich and fertile, neutral or slightly alkaline, well-drained clay-loam or silt-loam soils in which the subsoil is fairly retentive of moisture. Although hemp makes heavy nutrient demands on the soil, research conducted at Canadian experimental farms during the 1930s showed that hemp takes less from the soil than wheat or corn when taking into account that up to 70 per cent of the nutrients absorbed by the plants are returned to the soil, in particular with the large numbers of falling leaves and through the retting process. Cleaning or mechanical stripping of the leaves and flowers in the field also allows for maximum nutrient recycling. However, prior to the nutrient recycling, hemp extracts more nutrients per hectare than grain crops, removing about two to three times as much nitrogen, three to six times as much phosphorus, and 10 to 22 times as much potassium per hectare, owing to fast biomass production.

Therefore, to achieve an optimum hemp yield, at least twice as much nutrient must be available in an easily assimilable form as will finally be removed from the soil by the leaf-free harvest. Fertilizer rates vary depending on soil type, end use of the plant and crop rotation. A three-year, but preferably a four-year rotation, such as cereals, clover for green manure, corn, hemp and then back to cereals is recommended to help maintain soil fertility."

Source: Government of Canada, Agriculture Canada: Report on Hemp, Bi-Weekly Bulletin, December 16, 1994 Vol. 7 No. 23, by Gordon Reichert.

It is clear from this that hemp is very demanding on soils and will require both heavy fertilization and long fallow periods between crops.