This won’t be news to the one person following this blog but researchers have now quantified the result of composting biochar.
Researchers found that dissolved organic substances played a key role in the composting of biochar and created the thin organic coating.
“This organic coating makes the difference between fresh and composted biochar,” Kappler said. “The coating improves the biochar’s properties of storing nutrients and forming further organic soil substances.” Hagemann added that the coating also developed when untreated biochar was introduced into the soil — only much more slowly.
Rather than composting I prefer soaking my biochar in organic liquids like aged urine (nitrogen and phosphorus), worm tea (plant growth hormones), and compost/extracts.
Preparing Prickly pear
“Not much organic matter yet, but there will be.”
Glastonbury Permaculture Garden
Grow Do It World Tour 2017
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