Bonsai Soil Tests: Part 2: Freeze-Thaw Cycles
Scientists at Caltech and USC have discovered a way to speed up the slow part of the chemical reaction that ultimately helps the earth to safely lock away, or sequester, carbon dioxide into the ocean. Simply adding a common enzyme to the mix, the researchers have found, can make that rate-limiting part of the process go 500 times faster.
On paper, the reaction is fairly straightforward: Water plus carbon dioxide plus calcium carbonate equals dissolved calcium and bicarbonate ions in water. In practice, it is complex. “Somehow, calcium carbonate decides to spontaneously slice itself in half. But what is the actual chemical path that reaction takes?” Adkins says.
Studying the process with a secondary ion mass spectrometer (which analyzes the surface of a solid by bombarding it with a beam of ions) and a cavity ringdown spectrometer (which analyzes the 13C/12C ratio in solution), Subhas discovered that the slow part of the reaction is the conversion of carbon dioxide and water to carbonic acid.
“This reaction has been overlooked,” Subhas says. “The slow step is making and breaking carbon-oxygen bonds. They don’t like to break; they’re stable forms.”
Armed with this knowledge, the team added the enzyme carbonic anhydrase — which helps maintain the pH balance of blood in humans and other animals — and were able to speed up the reaction by orders of magnitude.
Key to speeding up carbon sequestration discovered | EurekAlert! Science News
That makes me wonder about the chemical limitation of carbon sequestration in soils.
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.
- •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
Do Bacteria Live On Meteorites?? | SimplyScience by Kristie Tanner
Kristie summaries a paper that can be found here
Much more interesting than I thought it would be. The iron and sulphur makes me think about the amount of energy those elements provide to form reactions that sustain life(scroll down for pictures), and how differing amounts of those elements may influence the colonization.
I’m also reminded of the sea monster at the bottom of the carbon food chain where there’s little oxygen and energy is scarce.
To the other extreme where oxygen is rich and where historically moisture rich microbes respire excess carbon from soils.
Why So Many Meteorites Come From The Same Place
Urban soils at the scene of construction where subsoil has been brought to the surface, mixed or that have had the topsoil removed and construction materials like sand, stone, brick etc. embedded in them can pose a challenge to regenerate. Stabilising these soils such that rain and flood doesn’t cause erosion is also an important task.
To help understand what contributes to soil aggregate formation and the stability of these soils researchers studied the “Interactive effects of compost, plants and earthworms on the aggregations of constructed Technosols” and found increasing amounts of compost needed increasing amounts of plants or earthworms to make a difference.
Aggregation is an important physical process to study during the early formation of Technosols. It is known to be influenced both by the organic matter content and soil biota. Constructed Technosols represent good models to test the importance of these factors since their composition can be easily manipulated by mixing different proportions of parent materials and introducing soil organisms. In this study, we performed a 5 month mesocosm experiment, using excavated deep horizons of soils (EDH) as mineral material mixed with green waste compost (GWC) at six different proportions (from 0 to 50%) in the presence or absence of plants and/or earthworms. After 21 weeks of incubation, aggregation was characterized by: 1) determining the size fraction and morphology, 2) measuring the distribution of organic carbon (OC) in each fraction and 3) testing the aggregate stability. Results showed that organisms accounted for 50% of soil aggregation variance while green waste compost (GWC) was responsible for only 5% of the variance. The percentage of total variance of OC distribution in aggregates explained by organisms, GWC, and the interaction of the two was similar (28%, 22% and 26%, respectively). The effect of GWC on structural stability was negligible (2%) compared to that of organisms (70%). The effect of earthworms combination with plants was complex: plants had a dominant effect on the distribution of the size of aggregates by disrupting earthworm casts, but earthworms had a dominant effect over plants for aggregate stability under fast wetting only when the percentage of compost was low. This study underlines the importance of considering the interaction of the organic matter and soil biota: in this case, increasing compost proportion in a Technosol has significant effects on aggregation only in the presence of plants or earthworms.
Solvita Field Soil Respiration
Bacterial cells in carbon-rich media (purple and blue) grow twice as big as those in carbon-poor media (green). New research shows they can grow big, however, only if they can make fats with the carbon.
Fat (lipids) limits how big bacterial cells can be. “If you prevent cells from making fat, they’re smaller, and if you give them extra fat or allow them to make more fat, they get bigger,” said Levin, professor of biology in Arts & Sciences. “Fat makes cells fat.”
“If we hit the cells with an antibiotic that targets fatty-acid synthesis, we really saw a significant drop in cell size” Vadia said.
Also, by turning up FadR, a transcription factor that activates expression of the fatty-acid synthesis genes, the cells got bigger.
“It doesn’t seem to matter what the lipids are, really,” Levin said, “provided you have enough of them. We found we could give the cells oleic acid, a fat found in avocados and olive oil, to supplement diminished fatty-acid synthesis and as long as the added fatty acid got into the membrane, the cells could recover.”
A little place for my stuff | EurekAlert! Science News
Hydrogenation: transform liquid oil into solid fat
Olive Oil Did WHAT to my Triglycerides??!!?? (Pt 2)
From left to right; water, HCl, formic acid, acetic acid, butyric acid, lactic acid, citric acid.
A new study reports a newly discovered biological pathway that is activated in times of drought. By working out the details of this pathway, scientists were able to induce greater tolerance for drought-like conditions simply by growing plants with acetic acid, found in vinegar.
Example of an Addition Soil Formation Process – Formation of a Forest Floor
“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 matterwas 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.
How is carbon stored in the soil?
No doubt I’m bound to use the word humus to confuse myself and others too, just a heads up then… 🙂
Lakes in Jeopardy!