Symphytum officinale, Common Comfrey, is one of the best dynamic accumulators.
This is a term that I first came across in Dave Jacke’s book, Edible Forest Gardens. In brief, it is the idea that certain plants (often deep-rooted ones) will draw up nutrients from the lower layers of the soil, and these nutrients will be deposited in the plants’ leaves. When the leaves fall in autumn and winter and are broken down, those stored nutrients are then incorporated into the upper layers of the soil where other plants will benefit from their deposition.
This is a natural method of increasing soil fertility. It is likely one of the ways that forest ecosystems continue to thrive and remain stable with minimal external inputs.
This is also a great Permaculture tool. By observing nature, we can mimic nature, and we can have great results with minimal effort. As I always say, Permaculture is about design!
We can sustainably and naturally increase our land's soil fertility by using dynamic accumulators. It can be done with almost no work, other than planting or sowing seed, and allowing nature to do what it naturally does on its own.
We can expedite the process a bit, and increase our work a bit, by cutting back fast growing plants to encourage more frequent plant growth during the growing season. For instance, chopping a bunch of mature leaves off fast growing Comfrey will provide high nutrient green mulch. We can drop them where they fall or redistribute them to other locations that are low in nutrients.
There are a number of other ways to incorporate dynamic accumulators. I'll be addressing these in an upcoming article.
The tiny flowers of Stellaria media, Common Chickweed, a dynamic accumulator that has a lot of Permaculture benefits... poultry food (hence the name), ground cover, and dynamic accumulator!
The science of dynamic accumulators is an area of botany with very little research to date. We know it is true, but unfortunately not a lot of time has been spent studying the concept of dynamic mineral accumulation, so we only have research on a few plants. Hopefully with time, we will be able to add substantially to this data.
Here is a list of well studied dynamic accumulators that can be used in a Temperate Climate. The nutrients that they provide are abbreviated in bold:
- Sugar Maple, Acer saccarum K, Ca
- Maples, Acer spp. K
- Yarrow, Achillea millefolium K, P, Cu
- Chives, Allium schoenoprasum K, Ca
- Black Birch, Betula lenta K, P, Ca
- Birches, Betula spp. P
- Shagbark Hickory, Carya ovate K, P, Ca
- Hickory, Pecans, Carya spp. K, Ca
- German Chamomile, Chamaemelum nobile K, P, Ca
- Chicory, Cichorium intybus K, Ca
- Flowering Dogwood, Cornus florida K, P, Ca
- Horesetails, Equisetum spp. Ca, Co, Fe, Mg
- Beeches, Fagus spp. K
- European Beech, Fagus sylvatica K, Ca
- Strawberry, Fragria spp. Fe
- Wintergreen, Gaultheria procumbens Mg
- Licorices, Glycyrrhiza spp. P, N
- Black Walnut, Juglans nigra K, P, Ca
- Walnuts, Juglans spp. K, P
- Lupines, Lupinus spp. P, N
- Apples, Malus spp. K
- Alfalfa, Medicago sativa Fe, N
- Lemon Balm, Melissa officinalis P
- Peppermint, Mentha piperita K, Mg
- Watercress, Nasturtium officinale K, P, Ca, S, Fe, Mg, Na
- Silverweed, Potentilla arserina K, Ca, Cu
- White Oak, Quercus alba P
- Black Locust, Robinia pseudoacacia K, Ca, N
- Sorrels, Docks, Rumex spp. K, P, Ca, Fe, Na
- Salad Burnet, Sanguisorba minor Fe
- Savory, Satureja spp. P
- Chickweed, Stellaria media K, P
- Comfreys, Symphytum spp. K, P, Ca, Cu, Fe, Mg
- Dandelion, Taraxacum officinale K, P, Ca, Cu, Fe
- Basswood, Tilia Americana P, Ca, Mg
- Linden (Lime in the UK), Tilia spp. P, Ca
- Clovers, Trifolium spp. P, N
- Stinging Nettle, Urtica dioica K, Ca, S, Cu, Fe, Na
- Vetches, Vicia spp. K, P, N
- Violets, Viola spp. P
Ca = Calcium
Co = Cobalt
Cu = Copper
Fe = IronK = Potassium
Mg = Magnesium
N = Nitrogen (in this case, these plants are nitrogen fixers)
Na = SodiumP = Phosphorus
S = Sulfur