What is living soil?

By Joe, Founder of Dr Forest · August 2026 · Edited 7 Oct 2026 · 7 min read

Most of what happens when you feed a plant in open ground happens before the plant is involved at all.

Living soil is soil you keep covered, rich in organic matter, dig as little as possible, and feed with organic fertilisers rather than soluble salts — so bacteria, fungi, protozoa, nematodes and earthworms stay working. Those organisms turn organic inputs into forms a root can take up, on a timetable set by soil temperature and biology rather than by whoever is holding the watering can.

The same idea sits behind no-dig beds, mulching and organic fertilisers. It is also why our two granular blends behave the way they do: soil life has to break them down before the plant can use them.

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 A large share of the world's fungi live in soil. So do most of the small worms.

Very little of that life feeds your plants on purpose. It feeds itself, and the plant gets what is released along the way. 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. Soil forms crumbs largely because fungal threads, roots, worms 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 only gets fed once soil life has broken things down, which is why organic feeding is slow and steady.

Why living soil changes how you feed

Miller and Geisseler measured how fast organic nitrogen became available to plants in 55 Californian farm 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 until the soil warms to about 10 °C, which in much of the UK is often not until April. 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 nitrogen the plant does not take can wash out in heavy rain.

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 These were farm trials using manure, compost and straw at farm rates. That is far more organic matter than a bag of granular feed adds, so most of the soil-building comes from compost and mulch. A granular feed tops up the nutrients.

Feeding through the season with 4-4-4 and 2-8-4

Two blends cover most of an outdoor growing year. We make both by hand in small batches in Stockport.

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.

Related: All Purpose Fertiliser 4-4-4 · Bloom Fertiliser 2-8-4 · what is humic acid · "seaweed fertiliser guide" (`/blogs/the-dr-forest-blog/seaweed-fertiliser-guide`)

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.

The same principle sits behind our organic fertilisers that feed the soil: mostly blends that soil life breaks down, with a few single minerals for a known shortage.

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 usually short of organic matter, air, or both.

Which Dr Forest fertiliser should I use for living soil?

All Purpose 4-4-4 through the growth stage from spring onwards — typically about 100 g per square metre every four to six weeks on beds and borders; reserve around 300 g/m² for a one-off charge on a new or tired bed. Then Bloom 2-8-4 once flower buds form. 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. Exact bands and feeder groups live on the product pages — follow those if this page and the bag ever disagree.

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

1. 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
2. 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
3. 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
4. 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