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!

The vegetable garden – our first big project

Our first big project was the construction of a big veggie garden. With the uncertainties of this new pandemic situation, we figured that it won’t be a mistake to create a slightly bigger garden, just in case we would have to become self-sufficient earlier than we had thought… The capacity of it should be able to feed at least six people or more.

We chose a sunny 500m2 patch that stretches along the steep, forested valley-side down to the river which runs 150 m below. There were just four small olive trees on this terrasse, so we wanted to include them in our garden design as a shade instead of eliminating them. First of all, we had to create a durable fence to keep out the many wild boars that roam these lands. Many people had warned us from these animals that seem to be quite a plague here.

Protection against wild boars

The main reason is that there are no more predators (i.e. wolves) around to keep their numbers at bay. Some locals have another explanation for this phenomenon: The legend goes that some farmer once bound a domestic sow (female pig) and had her impregnated by a wild boar. Later on, part of the offspring apparently managed to escape and therefore combined the original genes with properties from the domesticated mother. While wild boars usually only give birth once a year, these new wild boars (with partly domesticated genes) could now reproduce up to three times a year and get up to twelve young ones at a time!
Whatever the case might be, we soon discovered holes in pre-existing fences in other parts of our land. Following the trails that started at these holes we regularly discovered patches that had been upturned by a troop of wild pigs. So far, the damage luckily has been moderate since they didn’t reach the roots of the olive trees. Let’s hope it’ll stay that way!
Nevertheless, we were warned..

So we dug a trench, 50 cm deep and 30 cm wide and inserted more than 100 hard-wood poles (chestnut), each of them 1 m apart. The poles were secured by hammering granite stones into the soil around them

We continued by filling the rest of the trench with more granite stones and some rubble that the previous owners had dumped somewhere on the land.
After the main fence (150 cm high) was set, we reinforced it with a 1 m high heavy-duty steel-mesh which was buried around 30 cm into the ground.

Our volunteers Angi and Joel completed the job with two nicely crafted gates that would supposedly withstand any attempt by wild boars of ramming it.
After some weeks of hard labor we finally could start with the initial task of creating a veggie garden!

Preparing the beds and soil

The existing soil seemed to be pretty compacted, so we decided to loosen it with digging forks. The first layer was dry leaves and/or cardboard to reduce the weed pressure from below as there was nothing more than thick grass and weeds present.

Luckily, we got a few cubic meters of old soil (supposedly fertile) out of a ruin in town, where a huge fig tree has been growing for decades. The beds were then topped off with a 10 cm thick layer of soil mix (we added old chicken manure that we’ve found in a barrel – unfortunately, it was almost decomposed to soil). After putting the soil mix on the beds, we watered them down to moisten the soil and also the cardboard underneath.

The fun begins

Finally, the fun part could start: Planting the beds! Shortly after our arrival to the land, we had eagerly germinated a big variety of seeds, no matter if they were in season or not. We brought a bunch of seeds with us and we didn’t even know if these varieties would tolerate the much hotter climate here in the south.

We planted tomatoes, basil, peppers, pumpkins, zucchini, cucumbers, strawberries, leeks, salads, onions, carrots, broccoli (which was apparently not the right season – they grew like crazy but went straight to seeding stage), beans, beetroots, chard, corn and many other things would follow as soon as we got more beds prepared. Our volunteer Diego built us a nice broad fork to loosen the soil much easier as you operate it with your whole body, not just with your hands.
We eagerly mulched all the beds around the seedlings to avoid evaporation and to slow down weed growth. Since May was no season to find fresh straw, we had to take what was left over from the previous year (most of it got rained on), so we must have used some moldy bits in our mulch because some plants really didn’t seem to grow for weeks. Only after we had taken it off or have replaced the straw with other mulch (wood chips that we made with our shredder) the beds suddenly showed some increased activity.

Planting carrot seeds between rows of onion seedlings
hügelbed hügelkultur wood

Later on, we added more organically shaped beds, like a spiral with a Fibonacci ratio :), two keyhole beds and a „hügelbed“ or „hügelkultur“ in the shape of a gecko. Most of the beds produced a good yield regarding the little input we gave them and for the first season (spring / summer) we are quite happy how everything developed.

healthy food from healthy garden

Thanks to the amazing cooking skills of Yvonne, we enjoyed countless incredibly yummy vegan meals and dishes.
Besides the luxury of having a passionate cook who always fed us well (and therefore kept us happy), the rest of the gang could concentrate on the other tasks at hand.
Thanks again, Yvonne, for the love and passion you’ve brought to this place!

We also won’t forget Markus’s skills to create incredibly delicious raw food cakes for us (which would easily match those of a 5-star restaurant!) Thank you, too, Markus. You’re a gifted cake-maker (and also maker of useful things like vermicompost bins and much more)

The small house garden

We also created a small house garden which is running along and underneath a pergola-like structure that is overgrown with wine. We also included the pre-existing lemon tree, a loquat tree, a plum tree and a fig tree inside the fence.

These trees will most likely produce much more fruit in the long run, thanks to the irrigation in the surrounding garden. In return, they will help shade the plants from too much sun. The little wooden bench that Mario and Markus have built invites everyone to enjoy little breaks in the midst of a beautiful variety of plants and flowers.

This little bench invites everyone to enjoy little breaks in the midst of a beautiful variety of plants and flowers. If you want to know more about our adventures you can join our community and receive our regular newsletter.

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