The Tree of Life aka "dynamic accumulator"
A key aspect of these plants is that they need to grow wild (as you'll soon find out why if you keep reading). Obviously for most of us here, comfrey is one of the plants we should be strongly looking at for these reasons.
Cannabis (like her cousin Nettles) is a "Bio-Dynamic Accumulator" plant. The function of “B.D.A.’s” on the Planet Earth is to move in and colonize barren, waste, and disturbed soils. Cannabis has a deep tap root up to 16’ long and miles of secondary roots, that retrieve lost minerals and nutrients from the sub-soils and returns them to the surface as humus from the rotting cannabis leaves when they fall. Hence its value in the compost pile. Its extensive root system breaks up compacted soils for the reintroduction of micro-organisms and topsoil species (like earthworms) and leaves miles of channels in the soil from its decomposed roots when they die, allowing air and water to penetrate, restoring vitality and "Tilth" to the soil!
I have many times found “volunteer” cannabis plants growing vigorously and producing excellent quality buds with absolutely no help from humans at all! Consider this when fertilizing, especially soil grown plants in raised beds or open ground. Every year at the start of the growing season, I amend with 4” of compost with a bit of rotted cow manure mixed in … that’s it! I have been known to boost flowering with molasses water and it is good to water with this when first establishing a new bed or planting hole to stimulate the growth of beneficial bacteria and micro organisms. But the lady realty does all the work here and sometimes (often) a lighter hand is a kinder hand! Observe your plants everyday and you will be sensitive to their needs and ready to respond if things get out of balance. And try the “less is better” approach when fertilizing, it is my opinion that many of us spend inordinate amounts of time and money of nutrients, perhaps expecting a miracle in a bottle effect (step right up folks and see the most amazing elixir known to man, cures gout, rheumatism, rickets, fever and ague, all while strengthening the blood and restoring hair growth!!!) Funny thing here is that many of the snake oil elixirs sold by traveling medicine shows were cannabis based! But I digress! Daily attention and understanding of plant dynamics and habits will go father to yielding a bountiful crop than spending countless $$$ on nutrients!
Extremophile organisms can live miles below the earth surface. There are a lot of bacteria between the surface and 15-20 feet, and certainly more at that extreme depth. It is an astonishing feat of survival what some of these often single celled animals do to survive. And one of the cool things about plant root systems is they expand and grow based on a need to do so seeking water, nutrients, and these compounds in high organic content soils. By the time a single acre of hemp/cannabis is 70 days old it will have established approx 32,000 miles of roots.
Dynamic accumulators are plants that gather certain micronutrients, macronutrients, or minerals and store them in their leaves. These plants can be used either for detoxifying soil or for gathering a certain nutrient or mineral from an area. For instance, clovers will mine great quantities of nitrogen out of the air via a symbiotic relationship with bacteria. These bacteria convert gaseous nitrogen into a form available to the clover, and exchange this nitrogen for exudates/sugars given by the clover. When the clover dies or is cut down, the green matter breaks down and releases the nitrogen into the soil.
These plants become rich in a certain substance and can then be cut down. This can be used as a fertilizer or as part of a fertilizer mix for other plants that may be deficient in those particular nutrients. The use of a nitrogen dynamic accumulator, such as a clover patch, could potentially replace nitrogen-rich fertilizers. These types of plants play an important role in many permaculture guilds.
Microbiologist Kristine Nichols of the University of Maryland showed that grasses like switchgrass, blue grama, Indian grass not only send down deep roots but increase glomalin levels and arbuscular mycorrhizal fungi. These fungi help "glue" the soil together, make it coherent, and shuttle biologically available nutrients from soil to plant. Some land reclamation companies are now using arbuscular mycorrhizal fungi and triticale to accomplish a similar end, and most likely Orchard grass (especially in combination with chicory and clover), and yacon, Jerusalem artichoke, chicory and many other plants will also eventually be shown to increase glomalin. Whatever that mysterious quality of "fertile" and "fertility" turns out to be in the soil, it must have something to do with these processes.
The plants with function as dynamic accumulators are often traditionally regarded as companion plants. In those cases, a plant such as yarrow or alfalfa growing near other plants, or in some cases being used as a green manure or cover crop, will show benefits to other plants due in part to the nutrients selected and exchanged. Among the accumulator plants of broadest nutrient variety are dandelion, plantains, watercress, comfrey, and kelp. Under good soil and growing conditions, certain plants may extract higher levels of nutrients than others, with consistency, although removing those nutrients from that soil can create a void in availability. Therefore, composts made with accumulator plants should also be reintroduced to those same growing areas upon compost completion.
Good luck and good grows, even more reason to grow cannabis organically.
Source: Seamus O' Blarney's Fine Medicinal Herbs