The carbon cycle of the olive tree

In a healthy ecosystem (e.g. an untouched forest) nature has established an ongoing carbon cycle with a constant supply of dead organic matter (branches, leaves) falling to the ground where it is being transformed back to become new building material and food for all successive plant life.

With a highly specialised crop system like an olive grove, orchard or even veggie garden, we have to work very hard towards generating a carbon cycle. If we‘d only ever extract fruit, veggies or olives and never gave anything back to sustain a carbon cycle, the soil would be depleted of essential organic matter very soon and therefore having a negative impact on the soil and in future crops.

Taking nature as an inspiration, it is important to observe and understand natural processes and then imitate them. The following 5 steps are showing the regenerative techniques we’re currently using to achieve this:

1. SPREADING ORGANIC MATTER

The most abundantly available organic matter is produced by the olive tree itself in the form of leaves and branches.

After pruning the trees, we put all the branches and twigs through a shredder and scatter the wood chips / leaves on the ground along the drip line of the tree.

Along the drip line we’ll find the most active root zone. This is where the microbial activity is highest. The microorganisms that are present in the root zone now colonize the added organic material and thus enter into a nutrient exchange with the root system of the trees. This way, we return the lost biomass (from old leaves or pruned branches) back to the natural nutrient cycle.

(Source: www.santabarbaraca.gov)

Why aren’t we simply burning the pruned branches like everybody else in this region?

Even though shredding the branches and putting them back as wood chips is a much more laborious process, it is also exponentially more beneficial for the health of our soil.

The act of burning organic matter is interrupting the carbon cycle as the carbon material is lost to the atmosphere and therefore can’t be used by the microorganisms to produce more nutrients for new plant growth.
Plus, by adding organic matter to the soil, we’re actively boosting the plant’s ability to store atmospheric carbon dioxide (CO2) in the soil (carbon sequestration) and therefore reducing the impact of CO2 as a greenhouse gas instead of adding more CO2 to the atmosphere by burning precious organic matter.

Shredding olive branches with a woodchipper
Giving back to nature instead of burning it
Adding organic matter (in the form of wood chips) around the drip line of an olive tree

2. PRODUCTION OF BIOLOGICALLY ACTIVE COMPOST (solid)

The production of high quality compost (= full with microbial life, especially fungi) is the basic ingredient for a successful regeneration of any land-based ecosystem.

With the active assistance of the present microbiology in a complete compost, we can re-stabilize even the most depleted soils and bring them back to their full, natural potential.We’re using a hot composting process to do this. It is an aerobic process that needs to be monitored regularly in terms of humidity and temperature.

The compost building process involves layering three different materials:

1. MANURE – with a high nitrogen content, ideally from herbivores such as cows, horses, goats, sheep, rabbits (but chicken manure works, too).

2. GREEN – material with nitrogen content such as green leaves, grass clippings, green stems, kitchen waste, etc.

3. BROWN – carbon material such as dry leaves, dry branches, straw, etc..

By using the right ratio between these materials (normally 10% manure, 30% green and 60% brown) and a good water management of the pile (we want to reach 50% humidity level), we’re able to produce a high-quality compost that contains all the beneficial groups of  microorganisms (especially fungi). These microorganisms are going to build a healthy soil, transform minerals and organic matter in plant available nutrients, and protect the plant from pests and diseases. 

The type of microorganisms can be determined both quantitatively and qualitatively with the help of a microscope in our soil lab. This is important because it means that you always know exactly which microbiology you are working with, as not all microorganisms are useful for every purpose.

Depending on the type of application, the finished compost can now be spread directly onto the garden beds or around the fruit/ or olive trees. This will positively favor plant growth through the microbial activity around the root zone. In contrast to a classic NPK-fertilization process (where usually “only” certain elements such as nitrogen, phosphorus or potassium are added in the form of salts), the compost application has a far more holistic effect, as the microorganisms also provide the plant with all other nutrients and trace elements and protect them from pest and diseases.

Like with the plants, these additional nutrients and trace elements will be able to nourish and heal our bodies in a holistic sense. We’ll be writing more on nutrient-dense food soon, trying to outline how the beneficial microorganisms in the soil do affect the micro-biome in our guts and how important it is today to know where our food is coming from or how it is being grown.

Left: Fava bean grown in regular soil w no compost Right: Fava bean grown in soil w added compost

The image above shows two fava bean plants from our experimental bed in the garden. They were sown at the same time and had about the same height when they were harvested. The picture to the right shows a massively enlarged root ball. Also the growth of the stems (5 instead of 3) speaks for itself.

Left: Fava bean grown in regular soil w no compost
Right: Fava bean grown in soil w added compost

3. PRODUCTION OF COMPOST EXTRACT (liquid extracted from solid compost)

If one cannot produce enough solid compost with the relatively labour-intensive hot composting process (e.g. for larger areas / systems), there is the option of working with compost extract. The solid compost is placed in a textile bag and “swirled” in a large water tank by blowing air into the water from below. This way, the microorganisms present in the solid compost such as bacteria, fungi strands (hyphae), amoeba or nematodes will be transferred into a liquid medium.

Bacteria feeding nematode
Microarthropod
Microarthropod
Fungi hyphae

After a short time, the extract can be applied directly or used for irrigating a garden or an olive grove (i.e. fed into an irrigation system).

Depending on the amount of organic matter in the soil, the added microorganisms will settle there and thus favour the soil building process and the nutrient uptake of the plants.

4. PRODUCTION OF COMPOST TEA  (liquid extracted from solid compost)

The brewing process of compost tea is more time-consuming ( 24h / 48h) because, in this case, we need to add food to encourage microorganisms to reproduce in the liquid medium. The application of compost tea pursues a different goal than the administration of compost extract. Sprayed directly onto the plant, the compost tea forms a protective layer (a so-called biofilm) on the stem/leaf surfaces of the plant and protects it from pests and diseases, especially on leaves and fruits. With a sufficiently high ratio of beneficial fungal biomass, compost tea serves as a natural fungicide, i.e. it can prevent or cure most types of fungal infestation on leaves.

On our farm, we use both compost extracts and compost teas – both in our gardens and olive groves.

Brewing of compost tea with adding seaweed to encourage fungal growth
Once the brew is finished, we fill it into transportable 25L containers to wheelbarrow it one by one to its destination

Like with solid compost, the same rule of thumb applies to both types of liquid compost (compost extract & compost tea):

A complete beneficial micro-biome provides the soil with the right biology responsible for building healthy soils and that will in return generate healthy plants. This way, we increase the natural resilience of the plants, so it can resist diseases better and is consequently less likely to be attacked by pests.

Inoculation of organic matter with beneficial microorganisms

5. REPEAT POINTS 1-4 REGULARLY

As long as an ecosystem is not stabilized, i.e. as long as it cannot provide itself with all the necessary nutrients or defend itself against diseases, we must repeat the application of organic matter and solid or liquid composts. In our case, we need to fix many years of conventional agriculture practices where the use of toxic chemicals and the lack of soil management were the “normal”.

The good news is that we can regenerate damaged soils in a relatively short period of time if we manage to support and imitate the cycle of life properly.

SUMMARY

If you wish to bring your own soil back to its full potential, it is imperative to first spend some time observing the place, its topography, the water flow, its current vegetation and more to draw the right conclusions for your long-term treatment of the land.
We will write more about the observing process / how to read a landscape in another article. For now, let us subsummize the main “ingredients” for a healthier micro-biome and therefore a richer soil:

1. SPREADING ORGANIC MATTER

We’re helping nature by imitating / speeding up the natural process of decay and regrowth

2. PRODUCTION / APPLICATION OF BIOLOGICALLY ACTIVE COMPOST (solid)

We’re actively “producing” the right set of beneficial microorganisms and adding them to our gardens or fruit trees to improve soil and plant health

3. PRODUCTION OF COMPOST EXTRACT (liquid)

We’re multiplying these beneficial microorganisms to improve soil health on a bigger area

4. PRODUCTION OF COMPOST TEA (liquid)

We’re actively re-producing a particular set of microorganisms (i.e. fungi) for a specific purpose, mainly for protecting plants against pests or disease

5. REPEAT POINTS 1-4 REGULARLY

While a single application of organic matter / compost is good – a regular and recurring application of organic matter in combination with the right set of microorganisms will work wonders!

More fruit trees – Creating a food forest!

New trees for the future food forest

This amazing piece of land has provided us with medicinal herbs, fruits, and all sorts of edible plants. Most of them have been planted a long time ago by the previous owner; Teresa Fiorenza, a gentle old lady that probably has lived through hard times during and after World War II. Thank you for that, Teresa!

We are blessed with a variety of perennial plants and trees such as loquat, artichokes, mulberries, dates, peaches, plums, apricots, almonds, figs, pears, apples, kakhi, jujube, pomegranates, walnuts, hazelnuts, lemons, oranges, mandarins, cedro and bergamot. What a treat to eat fresh produce directly from a tree or pick from the land…!

But it doesn’t stop there.

Continuing Teresa’s legacy and following our own path towards being self-sufficient, we started planting a selection of new trees around the house (such as the sub-tropical Moringa Oleifera and Ceratonia siliqua / Carob, some fig and oak).

Young carob sapling

“The best time to plant a tree was 20 years ago. The second best time is now.”

― Chinese Proverb

In the previous orchard, we added two varieties of apricot, two varieties of apple, quince, flat peach (Prunus platycarpa), regular peach, mulberry and plum.

Alongside a cliff in a more shaded spot, we have planted white/red/black currant, red gooseberry, blueberry and raspberry.

In the flatter part of our future food forest, we utilize swales, a landform in the shape of a trench and berm running along contour (points of the same altitude) to catch as much rainwater for the trees and plants as possible. In our case we probably should call them semi-swales, as they’re interrupted and not perfectly along the contour line.

Aerial view of food forest area, showing potential water collection in swales (in blue)

Tree planting

View of the future food forest with freshly dug swales

We dug holes in the “hill” side of the swale, about 40-50cm deep / wide. A large enough hole for the roots to grow bigger before they’ll eventually hit native soil (which is usually more compacted). Each tree will receive more rainwater, as the ditch of the swale will help infiltrate all the surface water into the root zone.

Planting hole

To help these young trees, we added several layers of seasoned compost in between the native soil. The goal with adding our own compost is to inoculate native soils with a most diverse microbiology (beneficial microorganisms and beneficial fungi).

This is the main reason why we have established our Soil Lab. With the help of a microscope we’re able to assess the quality of our own compost and soils, mostly to identify all beneficial or non-beneficial microorganisms that are part of the Soil Food Web.

This way, we’ll simply make better decisions. In the case of planting trees we have utilized a seasoned compost with more fungi than bacteria biomass because trees are lifeforms of a later stage in evolutionary succession. Therefore, trees need nitrogen in the form of ammonium NH4. Fungi are responsible for converting nitrogen into ammonium – that’s why trees prefer fungi dominated soils over bacteria dominated soils.

Adding a rich mix to the planting hole (seasoned compost and topsoil)

Before setting the saplings into their holes, we carefully decompacted the root balls once they were out of their pots to prevent girdling.

Loosening the root ball is important for the development of the roots

What is “girdling”:


When plants grow in nursery containers, their roots hit the wall and begin to grow in a circle. By loosening the root ball and therefore breaking the circling pattern of the roots, the plant will most likely not keep growing circular. We also dug square holes in the hopes that some roots will eventually hit a „corner“ to easier break the threshold between hole and native soil.

Finally, we’ve hammered three fence posts into the ground around each sapling, (making sure not to sever the root ball). Once the summer drought hits this land and the drip irrigation system is on, wild pigs will smell the water immediately (as there is not much water around in summer). They’ll confuse any wet swale for a conveniently prepared pig bath tub and by happily rolling themselves around in it, they might eventually damage or even uproot small trees. Let’s hope this safety measure will protect the saplings from any boar activity!

Creating a “food forest
or “edible landscape

What is a food forest?

A food forest, also called a forest garden, is a diverse planting of edible plants that attempts to mimic the ecosystems and patterns found in nature. Food forests are three dimensional designs, with life extending in all directions – up, down, and out. A food forest does not have to be re-planted year after year. Once it is established, it is generally very resilient.

Source: Resurgent Circles – Seeding Eden (modified by us)


Generally, we recognize seven layers of a forest garden – the overstory (canopy layer), the understory (smaller trees), the shrub layer (bushes), the herbaceous layer (grasses, medicinal plants, etc.), the ground cover layer (perennials like clover, etc.), the root layer (root vegetables) and the vine layer (climbers). Some people also like to recognize an eighth layer, the mycelial layer (mushrooms). Using these layers, we can fit more plants in an area without causing failure due to competition.

The food forest area is marked with a red dotted line

A food forest must be organic. Forest gardens depend heavily on a healthy ecosystem and cannot be sprayed with herbicides or pesticides or have non-organic fertilizers applied. A healthy ecosystem will take several years to establish itself, especially in a city or open farm area. We have to be patient and let nature take care of itself (while providing the necessary food, water, and habitat for all the components of the ecosystem, otherwise they won’t come).

Food forests are a new farming concept in our area, but they have been used for thousands of years in other parts of the world.

Adding some seasoned high-fungal compost to an orange tree

A well-designed forest garden has many benefits:

  • Planting densely and using ground covers to shade soil and suppress weeds is returning more yield on a given surface area.
  • Utilizing nitrogen-fixing (i.e. leguminosae, etc.) and nutrient-accumulating plants (i.e. comfrey, etc.), “chop-and-drop” techniques, and returning wastes to the land will create healthy soils instead of having to buy and add commercial fertilizers.
  • Planting a diverse array of plants will attract beneficial insects to pollinate the fruit crops and keep pest populations from exploding and causing damage.
  • By utilizing several ground-shaping techniques we are able to keep rain water on the site.
  • Depending on the topography, designing for specific placement of plants helps create windbreaks and micro-climates.
  • Placing emphasis on trees, shrubs, perennials, and self-seeding annuals, the overall amount of work is greatly reduced.

In his book “Gaia’s Garden”, Toby Hemenway recommends some of the following soil-building plants for orchards/food forests: 

FunctionSoil building plants
Nitrogen fixersAlder, autumn olive, bayberry, black locust, broom, butterfly pea, cattail, chamomile, chives, collards, common milkweed, false indigo, goumi, licorice, sea buckthorn, wild lilac, wisteria, wild lupine, sweet pea, bladder senna
Annual nitrogen-fixing cover cropsAustrian winter pea, bell bean, crimson clover, Fava bean, Fenugreek, Garbanzo bean, vetch, black-eyed peas, cowpeas, lablab, pinto beans, soybeans, Sunn Hemp
Nutrient accumulatorsAlfalfa, lamb’s quarters, primrose, purslane, stinging nettle, yarrow, sunflower, dogwoods, horsetail
Soil buildersRapeseed, Sudan grass, and crotalaria
Resources: “Gaia’s Garden” by Toby Hemenway