Build Soil Organic Matter with Brown-rot Fungi

Spatial Heterogeneity of SOM Concentrations Associated with White-rot Versus Brown-rot Wood Decay. – PubMed – NCBI

The brown-rot fungal wood decay resulted in higher concentrations of soil C and N and a greater increase in microbial necromass (i.e., 1.3- to 1.7-fold greater) than the white-rot fungal wood decay. The white-rot sets were accompanied by significant differences in the proportions of the bacterial residue index (muramic acid%) with soil depth; however, the brown-rot-associated soils showed complementary shifts, primarily in fungal necromass, across horizontal distances. Soil C and N concentrations were significantly correlated with fungal rather than bacterial necromass in the brown-rot systems. Our findings confirmed that the brown-rot fungi-dominated degradation of lignocellulosic residues resulted in a greater SOM buildup than the white-rot fungi-dominated degradation.


Plant roots 5x more likely than leaves to turn into soil organic matter

Plant roots are five times more likely than leaves to turn into soil organic matter for the same mass of material.

This among other findings from Stanford researchers.

Improving how land is managed could increase soil’s carbon storage enough to offset future carbon emissions from thawing permafrost, the researchers find. Among the possible approaches: reduced tillage, year-round livestock forage and compost application. Planting more perennial crops, instead of annuals, could store more carbon and reduce erosion by allowing roots to reach deeper into the ground.

Soil holds potential to slow global warming | Stanford News

Humification Theory [Rant]

“Soil organic matter (SOM) derives from dead plant parts in the litter layer”
“A fraction of SOM persists because it can resist decomposition.”
“The process which converts litter into resistant or “recalcitrant” soil organic matter
was called humification”
The product of humification = presumably ‘stable’ organic matter = is called humus

I don’t believe in humification theory. There, I’ve said it. I cringe every time I hear the word humus.

Biochar isn’t even that stable in soil. Unless it’s buried where oxygen doesn’t reach it deep deep in the profile. Something fungi can do with it by embedding it inside soil microaggregates where it won’t be oxidized or access by other organisms. But carbon cycling in soils doesn’t stop there.

I’m not the only one that questions it. Here is a video summary of a paper by Johannes Lehmann and Markus Kleber from 2015, and there are others I’m too lazy to link to.

How is carbon stored in the soil?
Thomas Fester

Here are some slides from a talk about the paper, a talk I wish I could find, and the scientific paper from Nature.
However even Johannes Lehmann the co-author of the paper uses the word humus in the following talk on soil carbon two years ago around the time the paper was released. It’s so engrained in people and our language that I believe it will be around long after the “stable” humus is.


No doubt I’m bound to use the word humus to confuse myself and others too, just a heads up then… 🙂

New Slow-release Nitrogen Calcium Phosphate Fertilizer


Researchers have used nanoparticles to create a a fertilizer that releases nutrients over a week, giving crops more time to absorb them (ACS Nano 2017, DOI: 10.1021/acsnano.6b07781).

They attached urea molecules to nanoparticles of hydroxyapatite, a naturally occurring form of calcium phosphate found in bone meal. Hydroxyapatite is nontoxic and a good source of phosphorous, which plants also need.

In water, the urea-hydroxyapatite combination released nitrogen for about a week, compared with a few minutes for urea by itself. In field trials on rice in Sri Lanka, crop yields increased by 10%, even though the nanofertilizer delivered only half the amount of urea compared with traditional fertilizer.

Slow-release nitrogen fertilizer could increase crop yields | Chemical & Engineering News

They should call it UreaCa! Geddit?

Alternately you could just use fresh plant litter or cover crop residues that leach nitrogen over two weeks and also feed soil microbes carbon. Or faba bean that will release it over three years[1] and build soil carbon so eventually you don’t need to add any.

[1] Carbon and Nitrogen Release from Legume Crop Residues for Three Subsequent Crops
Abstract | Digital Library

[2] Formation of soil organic matter via biochemical and physical pathways of litter mass loss : Nature Geoscience : Nature Research

Soil Priming – Let’s Get This Party Started.


The priming effect, i.e. the increase in soil organic matter (SOM) decomposition rate after fresh organic matter input to soil, is often supposed to result from a global increase in microbial activity and competition due to the higher availability of energy released from the decomposition of fresh organic matter.

However a new study suggests that:

The chemical structure of added compounds on the priming effect is much larger than the effect of energy-content.


Different substrates resulted in different priming effect but appeared to stimulate the growth of similar bacterial groups. This suggests that the added compounds stimulate different enzyme systems within similar bacterial taxa.

Priming of soil organic matter: Chemical structure of added compounds is more important than the energy content