Earthworm Burrows Create Microbial Hotspots with 4-20x The Nutrients

A new study of earthworm burrows finds:

Earthworm burrows provide not only the linkage between top- and subsoil for carbon and nutrients, but strongly increase microbial activities and accelerate soil organic matter turnover in subsoil, contributing to nutrient mobilization for roots.

Rolling in the deep: Priming effects in earthworm biopores in topsoil and subsoil


•Mechanisms regulate microbial activities in biopores vs. bulk soil, topsoil vs. subsoil.
•Earthworms homogenize SOM quality in topsoil and subsoil.
Priming effect in earthworm burrows was 4–20 times higher than in bulk soil.
•Biopores and bulk soil showed higher priming effect in subsoil than topsoil.


Priming effect is the change of soil organic matter (SOM) decomposition due to the addition of labile carbon (C) sources. Earthworms incorporate organic matter into their burrow-linings thereby creating preferred habitats for microorganisms, but the roles of such burrows in priming effect initiation is unknown. Here we study the mechanisms driving SOM decomposition in top- and subsoil biopores and additionally in the rhizosphere. Given the topsoil was newly formed after ploughing 10 months prior to sampling, we hypothesized that (1) SOM accessibility, enzyme activities and efficiency of enzymatic reaction (Ka) are main drivers of different priming effect in biopores vs. bulk soil and rhizosphere, subsoil vs. topsoil and (2) the production of microbial enzymes in biopores depends on microbial community composition. To test these hypotheses, biopores formed by Lumbricus terrestris L. and bulk soil were sampled from topsoil (0–30 cm) and two subsoil depths (45–75 and 75–105 cm). Additionally, rhizosphere samples were taken from the topsoil. Total organic C (Corg), total N (TN), total P (TP) and enzyme activities involved in C-, N-, and P-cycling (cellobiohydrolase, β-glucosidase, xylanase, chitinase, leucine aminopeptidase and phosphatase) were measured. Priming effects were calculated as the difference in SOM-derived CO2 from soil with or without 14C-labeled glucose addition.

Enzyme activities (Vmax) and the catalytic efficiency (Ka) were higher in biopores compared to bulk soil and the rhizosphere, indicating that the most active microbial community occurred at this site. Negative correlations between some enzymes and C:N ratio in bulk soil are explained by higher content of fresh organic C in the topsoil, and the corresponding C and nutrient limitations in the subsoil. The positive correlation between enzyme activities and Corg or TN in biopores, however, was associated with the decrease of C and TN with pore age in the subsoil. In the subsoil, priming effect in biopores was 2.5 times higher than bulk soil, resulting from the favorable conditions for microorganisms in biopores and the stimulation of microbial activities by earthworm mucus. We conclude that earthworm burrows provide not only the linkage between top- and subsoil for C and nutrients, but strongly increase microbial activities and accelerate SOM turnover in subsoil, contributing to nutrient mobilization for roots.

Related: Restoring Construction Soils with Compost, Earthworms and Plants – Permie Flix

Grow straight deep taproots in compost holes

Have you ever noticed how when you mow regularly you get more pioneer weeds appearing with a strong taproot? Do you have poor heavy clay or stony soil that your back doesn’t fancy digging much? Are you just starting out and don’t yet have enough compost to no dig like the experts? And are you searching for a more holeistic approach to your gardening?

Why do all the hard work yourself when you can be like the weeds!

Well now you can with this one weird stick!

Angela’s Kitchen Garden

But that’s not all! Call now and we’ll include this set of augers for those whose soils are like concrete.


And, if you’re one of the first 100 callers we’ll include 200 buckets to hold your compost for only 50c extra!*


*each, shipping and handling not included, may come with extra frosting.