What is living soil?
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Soil science
What is living soil?
Most of what happens when you feed a plant in open ground happens before the plant is involved at all.
Living soil is soil that holds a working population of bacteria, fungi, protozoa, nematodes and earthworms, enough organic matter to keep that population fed, and the structure to let air and water move through it. The organisms do the work of turning organic inputs into forms a root can actually take up. Feed the soil properly and it releases nutrients on a timetable set by soil temperature and biology, rather than one set by whoever is holding the watering can.
That is the principle behind no-dig beds, mulching, and every fertiliser that lists ingredients rather than salts. It is also why our two granular blends behave the way they do: they are food for the soil first, and the plant second.
The short version
Soil biology converts organic inputs into plant-available nutrients. No biology, no conversion.
Release speeds up as soil warms, which is roughly when plants want more anyway.
What to feed it
All Purpose 4-4-4 through the growth stage, from spring onwards.
Bloom 2-8-4 once buds set and fruit starts to swell.
What is actually down there
More than most people assume. A 2023 review in PNAS estimated that soil is home to 59 ± 15% of all species on Earth, which makes it the most biodiverse single habitat we know of.1 Fungi are the most soil-bound group of the lot, with around 90% of species living there.
Almost none of that population feeds your plants directly. What it does is eat. Nitrogen locked inside a plant protein is no use to a root until something has broken it down to ammonium or nitrate. Phosphorus held in a rock mineral stays held until fungal and bacterial acids prise it loose. Organic matter binds into crumbs only because fungal threads and bacterial glues hold the particles together, and those crumbs are what let a bed drain in November and still hold water in July.
The plant is last in the queue, and the queue is the point.
Why living soil changes how you feed
Miller and Geisseler measured nitrogen mineralisation across 55 agricultural soils at 5, 15 and 25 °C over a ten-week incubation.2 They found a Q10 averaging 2.87, with a range of 2.67 to 3.15. In plain terms, a 10 °C rise in soil temperature almost tripled the rate at which organic nitrogen became available, and the response held regardless of region, texture, pH or organic matter content.
That number explains something most gardeners notice without naming. A granular organic feed scattered on cold March soil does very little for a fortnight, then starts working properly once the soil gets into double figures. Plant demand climbs on much the same curve, so a feed that releases with temperature is broadly in step with what the plant is asking for. A soluble salt feed is not: it delivers on the day you apply it whether the plant wants it or not, and what the plant does not take, the rain takes.
The soil-building side has decent evidence behind it too. Luo and colleagues pooled 690 experiments and found organic amendments raised soil organic carbon by 38% and total nitrogen by 20% compared with mineral-only fertilising, alongside higher microbial biomass and more activity in the enzymes that cycle nutrients.3 Those are farm-scale field trials on arable crops, so read the direction rather than the exact figure for your raised bed. The direction is consistent.
Feeding through the season with 4-4-4 and 2-8-4
Two blends cover most of an outdoor growing year. Both are premium organic fertilisers, handcrafted in small batches in Stockport, plant-based, and multi-input rather than built on one or two ingredients.
Growth stage
4-4-4
Even nitrogen, phosphorus and potassium with calcium, magnesium and sulphur alongside. The feed for spring through the leafy stage.
- Ten organic inputs, slow release, feeds for up to 8 weeks
- Balanced 4-4-4 for beds, borders, veg, fruit, shrubs and containers
- Broken down by soil organisms, so it suits no-dig and mulched beds
- Handcrafted in small batches in Stockport, in compostable packaging
Flower and fruit
2-8-4
Nitrogen dialled back, phosphorus lifted, potassium held steady. Goes on when buds set and fruit begins to swell.
- Eleven organic inputs, slow and steady release
- High-phosphorus 2-8-4, rich in calcium and potash
- Timed for the flower and fruit stage, so growth is not still pushing leaf
- Handcrafted in small batches in Stockport, in compostable packaging
| Use | All Purpose 4-4-4 | Bloom 2-8-4 |
|---|---|---|
| Into a soil or compost mix, before planting | 5–10 g/L | 5–10 g/L |
| Top dressing on established plants | 2–4 g/L | 2–4 g/L |
| Beds, borders and allotments | 100–300 g/m² | 100–300 g/m² |
| How often through the growing season | Every 4–6 weeks. Light feeders every 5–6 weeks, heavy feeders every 2–3 weeks | Every 4–6 weeks. Fruiting vegetables every 2 weeks at 3–4 g/L |
| Roses and ornamentals | Use through the growth stage | 3 g/L, or 60–100 g per plant, every 3–4 weeks |
Rates as published on the product pages. Scatter on the surface and water in for established plantings. On a no-dig bed there is no need to work either blend in; worms and water do that.
Feed the soil, then the plant
Two granular blends, made with organic ingredients, handcrafted in small batches in Stockport. Plant-based throughout, in compostable packaging.
- All Purpose Fertiliser 4-4-4 · growth stage, beds and borders, veg and shrubs
- Bloom Fertiliser 2-8-4 · flowering and fruiting, roses and tomatoes
★★★★★ Rated 4.96 out of 5 across 3,543+ reviews and ratings. More on the inputs in what is humic acid and benefits of seaweed fertiliser.
The simplest check on your own soil takes a spade and two minutes. Lift a square from a bed you have been mulching and feeding, and look at what moves. Worms, pale fungal threads through the leaf litter underneath, a crumb structure that breaks apart in your hand rather than slumping into a wet block. That is what you are paying for when you feed the soil rather than the plant.
Common questions
What is living soil?
Living soil is soil that holds a working population of bacteria, fungi, protozoa, nematodes and earthworms, enough organic matter to keep that population fed, and the structure to let air and water move through it. The organisms convert organic inputs into forms a root can take up, which means nutrients are released on a timetable set by soil temperature and biology rather than by watering.
Is living soil the same thing as no-dig?
They overlap but they are separate ideas. No-dig is a method: leave the soil structure alone, mulch from the top, let worms move material down. Living soil is the condition you are aiming for. No-dig is one reliable way of getting there, and it is easier to maintain than to establish, but a dug bed that is regularly fed with organic matter can also be biologically active.
How do I know if my soil is alive?
Lift a spadeful from a bed you have been feeding and look at it. Earthworms, pale fungal threads under the leaf litter, and a crumb structure that breaks apart in your hand are all good signs. Soil that smells sour, slumps into a solid wet block, or turns up nothing living when it is neither frozen nor waterlogged is short of organic matter.
Which Dr Forest fertiliser should I use for living soil?
All Purpose 4-4-4 through the growth stage from spring onwards, at 100 to 300 g per square metre on beds and borders every 4 to 6 weeks, then Bloom 2-8-4 once buds set and fruit starts to swell. Both are slow-release granular blends that soil organisms break down, so they suit no-dig and mulched beds. Scatter on the surface and water in.
Does organic matter really reduce how often I need to water?
A little, over years, and less than most marketing suggests. Minasny and McBratney pooled 60 studies and more than 50,000 measurements and found a 1% increase in soil organic carbon by mass raised available water capacity by 1.16% by volume, which is around 1.16 mm of extra plant-available water per 100 mm depth of soil. The stronger arguments for feeding soil biology are nutrient cycling and soil structure.4
Why does organic fertiliser seem to do nothing in early spring?
Because release depends on soil temperature. Across 55 soils, Miller and Geisseler measured a Q10 for nitrogen mineralisation averaging 2.87, meaning a 10 °C rise in soil temperature almost tripled the rate at which organic nitrogen became available. Cold March soil releases slowly. The same application works properly once the soil reaches double figures, which is roughly when plants start asking for it.
Sources cited
- Anthony, M.A., Bender, S.F. & van der Heijden, M.G.A. (2023). Enumerating soil biodiversity. Proceedings of the National Academy of Sciences 120(33): e2304663120. doi:10.1073/pnas.2304663120
- Miller, K.S. & Geisseler, D. (2018). Temperature sensitivity of nitrogen mineralization in agricultural soils. Biology and Fertility of Soils 54: 853–860. doi:10.1007/s00374-018-1309-2
- Luo, G., Li, L., Friman, V-P., Guo, J., Guo, S., Shen, Q. & Ling, N. (2018). Organic amendments increase crop yields by improving microbe-mediated soil functioning of agroecosystems: a meta-analysis. Soil Biology and Biochemistry 124: 105–115. doi:10.1016/j.soilbio.2018.06.002
- Minasny, B. & McBratney, A.B. (2018). Limited effect of organic matter on soil available water capacity. European Journal of Soil Science 69(1): 39–47. doi:10.1111/ejss.12475
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