What would you say the best soil building plants would be? Lets say we start with Comfrey, Nettles and Yarrow... what other plants would you put in this category?

Sounds like you're leaning towards perennial?

Yeah, apologies, should have written that, I my mind it was implied. Definitely looking for perennial plants.

Dandelion, chamomille. I would say cannabis, but there are some restrictions with that, and it's not perennial.

Also, Mulberry leaves are edible when young and concentrate calcium, potassium, and phosphorus. It makes a great tree for coppice/pollarding to make berries easier to pick and get bushy tender leaf growth through most of the year.

Basswood (linden, lime in UK) also has edible leaves which concentrate calcium, magnesium, nitrogen, potassium, and phosphorus.

Those ones aren't herbaceous, obviously, but they can be pruned as shrubs.

soil building,

well that might mean leaving things in the soil..such as a green manure crop, or something like diakon rotting in the soil. I've been told that sweet potato is, and I'd say swiss chard.

Rhubarb is a good "leaf crop" like comfrey..and horseradish is too, but not where you will be moving soil around..

Some of my current favorites for my region

Lupine - N-fixer, deep roots, insectiary,pretty, self sows
Sorrel - deep root, lots of leafy mulch, edible, easy to divide and stuff roots


Cant resist mentioning the woody pioneers.
Alder - Fast growing, N-fixer, good fuel and tool wood, OK mushroom wood,
Cottonwood - coppices well, N-fixer, medicinal buds, OK mushroom wood, grows from livestakes, lots of big leaves
Blue eldberberry - grows faster than red elder or the e-coast or eurasians, insectiary, grows from cutting, berries OK, coppices well

I think of my soil building plants as real sacrifice plants, I am looking for easy cheap establishment and rapid biomass. both leaves and for hugelbeet. They are always getting hacked and chopped.

Id have to testify to sweet potatoe. They did an amazing job on some mild to nasty clay. I poured mulch onto them a few times over a few years. When I finally pulled them out, some 3 years later, the soil was truely improved to a gorgeous deep loam, easy friable. Highly impressed.

Soil building through use of herbaceous plants ... I am very interested in the topic. I've managed to work out a strategy for improving my soil, but it doesn't involve plants (it consists of growing potatoes under very thick mulch / sheet compost for a season or two, then shifting the remains of the mulch onto the next lot - a travelling compost heap, as it were).

However, from the various contributions in this thread so far I haven't been able to distill a strategy for using the herbaceous plants that some of you guys mentioned, other than cutting down their foliage & using it as mulch / adding it to compost. Is there any other way? Talking specifically about the deep-rooted herbaceous perennials - comfrey, dandelion, horseradish (of which I have plenty on my plot) - how do we use these?

I've heard hypotheses that their deep root system may make nutrients more available in the top layers of the soil, but the problem is, some plants that would benefit most from these nutrients may not be very happy near the lush foliage of horseradish or comfrey.

L_

Good replies here! For my region and soils, I would have to add buckwheat, radish, and clover - they seem to always have a place in raised beds, food forest, and oldfield...

Levente Andras wrote:

However, from the various contributions in this thread so far I haven't been able to distill a strategy for using the herbaceous plants that some of you guys mentioned, other than cutting down their foliage & using it as mulch / adding it to compost. Is there any other way? Talking specifically about the deep-rooted herbaceous perennials - comfrey, dandelion, horseradish (of which I have plenty on my plot) - how do we use these?

I've heard hypotheses that their deep root system may make nutrients more available in the top layers of the soil, but the problem is, some plants that would benefit most from these nutrients may not be very happy near the lush foliage of horseradish or comfrey.

L_

The plants just being there help. In a polyculture orchard fruit trees are definitely going to like comfrey, dandelion and horseradish which all benefit the tree with minerals accessible via their decomposing leaves, and root systems that don't compete with the tree's roots... much better than grass which competes with the tree's roots and doesn't supply much nutrition. These are all great answers, I've never had good luck with Lupine before though, I don't know why. I've tried several kinds. I'm thinking Dock (rumex) - bigger leaves then the Sorrel part of rumex- might be a good one too... but I'm really interested in the long term ones that grow a lot of biomass and get the most bang for your buck in smaller areas.

Holy hell, my property is a carpet of dandelion blossoms this week.

Makes me glad I never do anything to deter them. The old garden plot that the previous owners kept is very spent soil, and is now a mess of dandelions and clover... couldn't have planted it better myself.

I marvel at nature, most times.