Making Soil in Gbiota Beds

The Gbiota Bed Toolkit – Principles, Not a Single Design

Gbiota beds are a way to make living soil that supports gut-healthy food. There is no single design that works everywhere – a bed in the mountains of Colorado needs a different approach to one in the Queensland tropics – but the fundamental principles are the same.

Over the years I have worked with:

• Contour beds fed by a creek and small dam in wet, windy Melbourne
• Large wicking beds up to 50 m long in dry Gin Gin using all household grey and black water
• Gbiota beds in Bundaberg using mains water and community dams, surrounded by wildlife

Different climates, soils and crops (deep-rooted alfalfa versus shallow baby greens) all require tweaks – but they share the same core: breed beneficial soil biology and manage moisture correctly.

Basic Principles of Gbiota Soil Making

Breeding Beneficial Biology

The main purpose of a Gbiota bed is to breed beneficial biology – for both the soil and our gut. We deliberately create conditions where “good bugs” out-compete harmful biology.

Key points:

• Do not rely on inert potting mix alone – it doesn’t feed biology.
• Soil life needs real food: organic matter, minerals, moisture and oxygen.
• If you don’t feed the friendly bugs, they die and problem biology takes over.

Raw Materials – What to Add

To breed soil biology you need a balanced “menu” for microbes and worms.

Core ingredients:

• Food waste & soft organics (kitchen scraps, green waste) – fast-decomposing, ideal microbe food
• Hard organics (branches, prunings) – slow carbon, builds long-term soil structure
• Nitrogen source (e.g. chicken manure) – fuels decomposition
• Buffer (e.g. dolomite) – balances acidity from manures
• Mineral mix / rock dust – broad spectrum minerals and trace elements for plants and people
• Filler soil or clay – helps moderate nutrient strength and improve texture

Avoid Killing Plants with Osmosis

If nutrient levels in the soil are too concentrated, osmosis works against you: instead of water moving into plant roots, it is sucked out of them and the plants die.

• Build rich mixes – but always balance them with soil, clay or other fillers.
• When in doubt, dilute – you can always add more nutrition later.

Inoculants – Starter Biology

Food and minerals are not enough – you also need starter biology (inoculants):

• Virgin, undisturbed soils often already contain diverse beneficial microbes and fungi.
• Degraded soils usually need help: compost, vermicast, worm eggs, quality microbial products.
• Once established, biology will continue breeding as long as you keep feeding and watering correctly.

Moisture and Air – Controlling the Bug Environment

Most soil life is very sensitive to moisture and oxygen. Too wet and you get smelly anaerobic conditions; too dry and biology slows or dies.

Gbiota beds aim for “Goldilocks moisture”: not too wet, not too dry, just right for aerobic life.

Moisture Level is Critical

Different creatures thrive at different moisture levels – ants and beetles in hot dry soils, frogs in damp locations. Microbes are similar: some prefer wet, some moderate, some dry.

Conventional wicking beds often run too wet, growing slimy, smelly algae and encouraging the wrong biology. A well-managed Gbiota bed maintains a moderately moist, well-aerated zone where beneficial biology can dominate.

How Water Moves in Soil – Why It Matters

Understanding how water moves helps you design beds that stay in the healthy moisture zone.

Gravity & Hydraulic Flow

Water flows down under gravity and sideways when it meets resistance – this sideways movement is hydraulic flow.

• Water applied at the top moves down until it hits a barrier (clay layer, liner, compacted zone).
• It then spreads sideways, filling pores until it finds a path down or out.

Wicking

Wicking occurs when water climbs into hydrophilic (water-loving) soil particles. Moisture rises from a saturated zone up into drier soil above until it reaches a maximum height, then stops.

Important points:

• Fine, well-aggregated soils wick better than coarse gravels.
• There is always a moisture gradient – saturated below, progressively drier above.
• Wicking does not go on forever; it reaches a limit.

Evaporation and Condensation

In many “stone-filled wicking beds”, moisture above the stone layer is actually supplied by evaporation and condensation, not true wicking. Water evaporates from the surface, condenses on cooler surfaces above and re-enters the soil.

This can work, but it is less efficient and harder to control than a true wicking system with fine soil or media.

Osmosis

Osmosis is the movement of water from a weaker solution to a stronger one across a semi-permeable membrane – the basic mechanism plants use to take up water.

• If the soil solution is too strong (over-fertilised), water moves out of roots and the plants wilt and die.
• Balanced mixes keep osmotic pressure in the right range for plant uptake.

Tensile Strength of Water

Water can transmit tension like a rope. In trees, evaporation from leaves literally pulls water up from the roots, thanks to water’s tensile strength.

In soil, this means moisture is constantly in motion – pulled by plants, evaporation and pressure differences.

The takeaway: none of these mechanisms on their own guarantee “Goldilocks moisture”. For that, we use partial flood and drain.

Compost Tea, Flood and Drain – The Goldilocks Trick

As a child, my job was to dunk pots into a tank of “chicken-manure tea”. Each pot was:

• Fully saturated in the brew
• Then lifted out and allowed to drain, pulling in fresh air

The result was soil that was evenly moist and well aerated – exactly what biology loves. That experience underpins Gbiota bed design today.

Partial Flood and Drain with a Leaky Dam

Modern Gbiota beds use the same principle, but automated:

1. A sump tank sits below bed level, filled with compost tea or nutrient-rich water.
2. A pump on a timer pushes water into an Ag pipe along the base of the bed.
3. A soil dam in the pipe prevents immediate drainage, so the base of the bed floods up to dam height.
4. Once the level reaches the dam, water flows out through the drain and returns to the sump.
5. When the pump stops, water drains back, leaving the soil moist but not waterlogged and drawing in air.

This pulsing flood-and-drain cycle creates:

• Even moisture through the root zone
• Regular oxygen renewal for soil biology
• Minimal waterlogging and reduced risk of “pongy” anaerobic slime

Example: Bundaberg Gbiota Bed System

Climate and Water Strategy

I now live in Bundaberg, in the dry tropics. We can have months without rain, then heavy falls from cyclones. On a normal suburban block, there isn’t room for a tank large enough to cover the whole dry season, so I use a hybrid rain + mains water system.

Daily Supply Tank

My Gbiota beds cover about 50 m². In this climate, they need roughly 200 L per day. To manage this safely:

• A 200 L tank is filled daily using a mains water timer (runs ~20 minutes).
• A float valve stops filling if rainwater has already filled the tank.
• Because the valve only runs briefly each day, a failure while I’m away can’t flood the whole yard.

Dealing with “Mr Murphy” and Magpies

Murphy’s Law always applies. In my case, a local magpie learned to peck the timer button, randomly changing the settings. A simple bag over the controller fixed that. A fly-swatter cable-tied to the float valve acts as a damper to stop oscillation.

Experimental Beds and Sump Size

I set up multiple bed types linked to a common sump and pump:

• 1.7 m wide beds with a single pipe across the full width
• Narrow beds under 1 m wide with individual pipes
• One bed without a plastic liner (pipe buried directly in soil)

Growth was similar, but the unlined bed returned less water, suggesting lower water efficiency for shallow-rooted crops. My soil is duplex – silty clay over heavy clay – which naturally holds water deeper.

Initial sump sizing used a simple rule of thumb: 1 L of water per m² of bed. For a 50 m bed, I chose a 60 L tote box. In practice:

• The pump’s built-in float and stand meant not all 60 L were usable.
• The sump was too small for a full pulse, so I added extra pumps on staggered schedules.

Later designs use about 6 L per m² of bed, allowing a single daily pulse with comfortable margin.

Using Gbiota Beds to Grow Soil

Switching from “Growing Vegetables” to “Growing Soil”

Originally these beds grew vegetables (especially baby greens). With the development of Gbiota boxes, my main aim became growing soil – turning organic waste into rich, biologically active topsoil to fill the boxes.

Separating Hard and Soft Organics

I split compost inputs into:

• Hard organics – branches, coarse prunings (slow to break down, 6+ months)
• Soft organics – kitchen scraps, green waste, restaurant waste (decompose in weeks)

Both go into compost bins initially. Hard material hosts worms, soldier fly larvae, beetles and more – all unpaid workers creating structure and biology.

Trench Method – Feeding the Bed

I prefer open beds connected to the surrounding soil so soil life can freely move in and out.

To feed the bed:

1. Dig a trench down to the Ag pipe, leaving undisturbed soil on each side.
2. Add manure and mineral mix to the trench base.
3. Backfill to soil level.
4. Spread soft organics (food waste) on top to form a ridge.

This ridge decomposes quickly, feeding microbes and worms while the harder material below breaks down over months.

Plants as Soil Makers

Plants are essential partners in soil building:

• Roots exude sugars that feed microbes and mycorrhizal fungi.
• Roots physically push through soil and, when they die, leave channels and pores.

On top of the organic ridge I spread a thin layer of good quality soil (from previous cycles) and seed a cover crop or food crop.

Germination Strategy

Germination in wicking or Gbiota beds can be tricky – too wet and seeds rot, too dry and seedlings die. What works best for me is:

• Use a fine germination mix: sieved soil + well-rotted compost + minerals.
• Cover seeds lightly and water frequently until roots reach the moist zone below.

Once roots reach the active zone, growth is rapid. Self-seeding plants like lettuce and amaranth often prove how well the system works.

Filling Gbiota Boxes

The goal is to harvest topsoil from the ridge once it has transformed into rich, crumbly, microbe-rich soil. I use this to fill Gbiota boxes.

Soil from used Gbiota boxes eventually becomes denser. I return it to the bed ridges as a top layer, where biology and roots refresh its structure. The soil cycles through bed and box repeatedly.

High-Tech vs Natural Composting

There are sophisticated composting systems with tightly controlled biology and temperatures. These are useful, but my preference is to copy nature:

• Use organic waste as raw material.
• Rely on the full soil community – worms, insects, microbes, fungi – to process it in situ.
• Let plants, roots and soil life build deep, stable structure over time.

Technical Support

There is no single “1–2–3” manual that fits all climates, soils and crops. This article explains the principles and patterns behind Gbiota beds so you can adapt them to your own conditions.

If you are setting up Gbiota beds and want help tailoring them to your site, I offer technical support and am happy to comment on specific situations.