What is Aegir Sea Shell Grit, and Why Is It Used in bokashi composting systems ?
Aegir is a natural product made from finely ground sea shells, primarily composed of calcium carbonate (CaCO₃). It functions as a pH buffer—that is, it helps moderate fluctuations in acidity during the fermentation or composting process.
In bokashi systems, whether anaerobic or aerobic, maintaining the right pH range is crucial to supporting beneficial microbes. Without regulation, certain materials—especially nitrogen-rich green waste like grass clippings, hedge trimmings, or soft garden debris—can lead to extreme pH shifts, usually becoming too acidic or occasionally too alkaline. These shifts can suppress microbial activity, slow fermentation, cause odours, or even lead to putrefaction rather than proper breakdown.
🧪 Why Are pH Swings a Problem?
Bokashi fermentation depends on a balanced microbial community, including:
Lactic acid bacteria (LAB) – thrive in mildly acidic environments (pH ~3.5–6.5)
Yeasts – prefer a slightly acidic to neutral pH
Phototrophic bacteria – need more stable pH conditions to remain active
In aerobic systems: aerobic bacteria, actinomycetes, and even some fungi join in, many of which prefer near-neutral pH
If the pH drops too sharply (as it often can with green waste), these beneficial microbes may go dormant or die off, allowing less desirable organisms to take over (e.g., those that produce foul odours, pathogens, or degrade the quality of the final compost).
⚖️ How Aegir Helps
By gradually releasing calcium carbonate into the mix, Aegir sea shell grit:
Buffers excess acidity without neutralizing it completely (which would stop fermentation)
Supports a broader range of beneficial microbes
Helps retain nitrogen by preventing overly alkaline conditions where ammonia volatilization could occur
Contributes trace minerals and calcium, which improve the nutrient profile of the final product when applied to soil
🧤 Anaerobic vs Aerobic Bokashi: How pH Regulation Works in Each
Let’s look at how Aegir functions in both systems.
1. Anaerobic Bokashi (Traditional System)
Carried out in sealed systems, excluding oxygen
Relies on fermentation, not decomposition
Dominated by Effective Microorganisms (EM), especially LAB
pH naturally drops during fermentation (to ~3.5–4.0)
If pH drops too quickly or too far, LAB may stall, and yeasts or phototrophs may be suppressed
Aegir’s Role: In this system, Aegir prevents excessive acidification and helps keep the microbial balance intact. This is especially useful when fermenting green waste, which breaks down rapidly and can spike acidity. The result is stable fermentation, no foul odours, and a more uniform end product for composting or soil application.
2. Aerobic Bokashi (Hybrid/Fermentative Composting)
Used in open or semi-open systems (e.g., piles, windrows)
Especially common in larger-scale or municipal green waste management
Combines fermentation with aerobic microbial activity
Generates some heat, and oxygen is present
pH may rise due to ammonia formation, or drop due to organic acid production
Challenges in Aerobic Systems:
Rapid microbial activity can cause wild pH fluctuations
Acidic conditions suppress aerobic microbes, slowing composting
Alkaline conditions (from high N content) can cause ammonia loss
Aegir’s Role: In aerobic contexts, Aegir helps stabilize pH swings in both directions. It provides a buffering action that keeps the system within a microbial “comfort zone.” It also minimizes nutrient loss—especially nitrogen—and improves the overall quality and mineral balance of the compost.
