Original Terra Preta has been around for many thousands of years and until now, no one has been able to recreate it in its original form. The main two approaches to make Terra Preta yourself are the following:
- Composting/ decomposition of biomass
- indigenous microorganisms are introduced with biologically activated charcoal
- pH value depends on the plant charcoal (usually neutral)
- can be applied immediately after maturity
- area must be able to breathe – normal compost pile is too
- can be used as soil and soil conditioner
- Effective microorganisms (EM) are completely superfluous in a well-managed composting and have no chance of survival there.
Fermentation under exclusion of air: Bokashi
- enzymatic conversion (fermentation) of biomass
- with the addition of effective microorganisms (EM)
- acidic pH value (4 – 6)
- must still ripen after conversion, otherwise harmful for many animals and plants
- area must be hermetically sealed
- can be used as a soil conditioner
The production of Bokashi makes sense when we collect our biomass over the winter and then compost it in the spring. With the addition of plant carbon, nutrients are stored and thus increase the quality of the future compost.
The fermentation route works easily, however I have opted for a different, simpler and cheaper route and make Terra Preta in the compost. This is hard to beat in simplicity, since most users have a composter in the garden anyway. Described this way in my free compost guide, in which you can follow the simple production.
We can produce positive effects of Terra Preta with the help of plant carbon, whether with the conventional aerobic composting or with the anaerobic method with the help of EM. My claim is the production of high quality compost – with simple and inexpensive means.
Because the Bokashi cannot be used directly in the bed due to its pH value (about 4 to 5), but it needs a post rotting in the air, this approach is too cumbersome for me.
There are also scientific studies on this. I recommend the final report of the Terra BoGa project of the FU Berlin. In planting trials conducted as part of the Terra BoGa project, “no additional added value could be identified through fermentation”.
Making Terra Preta – This Is How It’s Done!
Making Terra Preta is very simple!
Making Terra Preta yourself is not as difficult and complicated as you probably think. However, the first and most important condition for the production of Terra Preta is space. To do this, you absolutely need a garden or other plot of land with soil on which to build the compost heap.
Right. I make Terra Preta by composting. Quite normal compost with some peculiarities, but understandable and easy for you to follow.
If you make your own compost:
Mix fine-grained plant charcoal with the material to be composted when setting up the compost pile. Include the plant charcoal in thin layers, approximately 40 liters per 1 m³ of composting material.
When using Effective Microorganisms (EM) or Indigenous Microorganisms (IMO), we recommend plant charcoal for Bokashi.
To all conventional composters I can recommend our biologically activated plant charcoal. By the way, we use indigenous microorganisms from our own natural source.
When creating the compost pile, you pile up one cubic meter of green waste. Use 40 liters of plant charcoal for – 1 m³ of fresh compost. The plant charcoal should be sprinkled in layers when you put it on, and then it mixes when you turn it over and through the activity of the compost worms.
For more detailed info, pick up my free compost guide.
For compost in subsequent years, 15 to 20 gallons will suffice, depending on soil type. For sandy soils or heavy clay soils, I recommend continuing to add 40 liters/sq. m. of starting material.
If you already have compost
The biologically activated plant charcoal can also be added to mature compost. Here, too, the proportion of plant carbon in the compost depends on the soil in which the “Terra Preta” is to be used.
Our recommendation is 5 to 10% biologically activated plant charcoal in mature compost at first use. After that, 3 to 5% of plant carbon is sufficient. The plant carbon should mature in moist compost for a few days – better 2 weeks – before being used in the bed!
Please note that too high a proportion of plant charcoal in the soil has a negative effect!
Exact limits are not yet known, but we recommend not to use more than 20% plant charcoal in the garden soil.
If you do not have the possibility to produce compost or if you want to check the statements made here in advance, you can order Terra Preta compost (Terra Anima® humus soil) from us.
For high-yielding soils, the addition of our Terra Anima® Humus Soil is sufficient to improve the soil biology.
Further Information On Composting
I have also tested a wide variety of composters, with sometimes very unsatisfactory results. The compost should have contact with the soil. Please never put the compost on concrete. Also think about manageability when you move your compost.
There are umpteen different types and price ranges of wooden composters alone. I myself have the very basic ones. I always buy two at once and then put them together to make one. They last, depending on the type of wood, at least 3 – 5 years before they rot. Skilled do-it-yourselfers can also make wonderful compost heaps with pallets. The important thing with composters is to make sure that the compost gets as much air as possible.
Metal grate composters have the charm that I can simply unhook the front part and immediately start turning with the shovel. This saves me immense amounts of time that I don’t have to spend disassembling the composter first.
The best way to do this is to download my free composting guide. In it I describe the requirements, the structure and the steps to go through to “harvest” a good and mature Terra Preta in the end. In it you will also be able to read the background why I do not recommend thermal and rapid composters. In them I have measured very high rotting temperatures.
I myself build windrows that are about 1 meter high (capacity 1 cubic meter), this is space-saving and the plant charcoal comes in suitably as a 40 liter bag. 1 cubic meter of green waste gets a bag of 40 liters of activated plant charcoal mixed in.
Addition of vegetable carbon
The main ingredient is green compost made from plant residues. You know this from your compost. The last thing to add is all the soil organisms that should make your compost terra preta. These are essentially contained in the activated plant charcoal (the most important additive), but also penetrate to some extent through the soil.
Theoretically, you could also take the charcoal from the hardware store, however, I advise against this supposed move because you are not doing yourself any favors. Why?
Vegetable charcoal differs from regular barbecue charcoal in the way it is made and in the amount of pollutants it contains. Barbecue charcoal is produced inexpensively using whatever materials are available. What materials these are, you will not be told for sure. Tests by institutes show that conventional barbecue charcoal and charcoal have very high levels of PAH pollutants. Even if the pollutant content of the charcoal is partially degraded by the soil organisms in the compost, I am of the opinion that the one or the other euro saved is not worth the risk to health.
Please note that too much plant charcoal in the soil has a negative effect!