This knowledge is in the papers that guides South African drug law regarding cannabis please read this excerpt and tell me we don't have a solution to world hunger issues or at least some try at cheap low cost staple food that would put Jungle Oats out of business...
"The cannabis plant is a weed that requires little care. It grows well almost everywhere and thrives well in temperate regions. It resists pests and therefore requires no pesticide. It develops deep roots, and when its leaves fall off, they produce minerals and nitrogen, which are returned to the soil. It can be planted in the same soil for up to 20 years in a row without any noticeable depletion of the soil.
The seed serves as food. Gruel, which resembles oatmeal, can be prepared from the seed. The leaves of the plant contain much roughage, while the seeds are a good source of protein and oil without saturated fat, thus reducing the risk of heart attack."
You can pick this document cannabis prohibition is based upon to shreds.
So many wholes they never wanted it to become public knowledge.