… and that in the short-term carbon through microbial form immobilizes already available N, potentially making less available for plants or loss through leaching.
The belief that adding high-carbon mulch locks up nitrogen may yet have some merit, not necessarily in the mulch, but in the microbes!
Although C input promoted microbial growth and N demand, we did not find indicators of increased N mobilization from SOM polymers, given that none of the soils showed a significant increase in protein depolymerization, and only one soil showed a significant increase in N-targeting enzymes. Instead, our findings suggest that microorganisms immobilized the already available N more efficiently, as indicated by decreased ammonification and inorganic N concentrations. Likewise, although N input stimulated ammonification, we found no significant effect on protein depolymerization. Although our findings do not rule out in general that higher plant-soil C allocation can promote microbial N mining, they suggest that such an effect can be counteracted, at least in the short term, by increased microbial N immobilization, further aggravating plant N limitation.
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
Earthworm mucus increases dissolved carbon 9.8%–37.5% and accelerates mineralization and humification of organics.
Plant worms. Prime carbon. Increase nutrient cycling.
Role of earthworms’ mucus in vermicomposting system: Biodegradation tests based on humification and microbial activity http://www.sciencedirect.com/science/article/pii/S0048969717321022
During vermicomposting, the organic wastes can be recycled into high-value products as mediated by earthworms through gut digestion, burrowing, casting and mucus excretion. However, to date, few studies have been done on the role of mucus in vermicomposting system compared to the effects of the other activities. Hence, this study investigated the potential role of earthworms’ mucus in the decomposition and humification of organic wastes. For this, the mucus of Eisenia fetida was extracted and inoculated into three vermicomposting substrates using cow dung (CD), fruit and vegetable wastes (FVW), and sewage sludge (SS). The results obtained after a 20 day experiment showed that the mucus could accelerate the mineralization and humification rates of organic components. The dissolved carbon showed 9.8%–37.5% increase in treatments containing mucus, higher than those in substrates without mucus. Moreover, the mucus significantly stimulated the microbial activity and bacterial abundance, showing the greatest increases in FVW treatments. In addition, the mucus positively stimulated growth of Proteobacteria, but negatively affected the Firmicutes during decomposition. This result suggests that the earthworms’ mucus significantly accelerated the decomposition and humification of vermicomposting materials, and could even promote microbial activity, growth, and increase community diversity in vermicomposting systems.
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.