Oxygenated compost tea

Technical articles - Biodynamics/Homeopathy, Productivity

Organic matter autonomy in vegetable farming Climate resilience Targeted fertilization Soil regeneration NBSOIL

The TCO (Oxygenated Compost Tea) or JCAA (Active Aeration Compost Juice) or also TCA (Aerated Compost Tea) is a liquid rich in organic matter and microorganisms (bacteria, fungi, nematodes,...) extracted from a good quality compost (or vermicompost) that is multiplied by feeding them with pure cane molasses and other elements according to recipes.

Diluted in water, TCO is sprayed on plants to increase their photosynthetic capacity, vigor, and resilience against bio-aggressors and various types of stress.

Benefits for Plant Health

Effects on Plant Nutrition

A TCO contains compost minerals (mostly macro-elements) & dead and living microorganisms. Both can be sources of nutrition for the plant.
TCO is not sufficient alone to fulfill the nutrition of plants: it must be used in addition to practices that improve the soil organic matter content and can be a food source for microorganisms.
TCO significantly increases the effectiveness of foliar applications with trace elements.

Effect on Pathogen Reduction

Direct effect by competition with plant pathogens: inoculating a diversity of beneficial microorganisms occupying ecological niches can make the environment less favorable for pathogenic microorganisms.
Indirect effect by inducing the specific response of the plant immune system and by strengthening plant health.
To favor the fungal effect, prioritize large volumes (300 L/ha per pass) at low pressure.
The goal is to create a mist to apply on and under the leaves.
It is also possible to add "anti-pathogen" fungi such as trichodermas which have interesting preventive effects on pathogen reduction. Alternatively, a fungicide can be applied to "clean" the existing crop, then trichodermas can be applied to colonize the environment and limit pathogenic fungal attacks.
It is possible to multiply trichodermas on a substrate such as vermicompost and infuse them into TCO: fungal strains with fungicidal effect (generalist trichodermas can also attack beneficial fungi like mycorrhizae).

Equipment

Setup

A professional mixing tank OR a plastic or stainless steel conical tank (⚠️ for stainless steel tanks: if there are rough spots or scratches, they can harbor pathogenic microorganisms and deteriorate TCO quality; cleaning is a major point of vigilance);
An air compressor connected to the bottom of the tank;
A 400-micron nylon bag;‍
Various PVC plumbing fittings, depending on the setup.

Components

Quality compost rich in beneficial microorganisms (e.g., Vermicompost);
Good quality water: rainwater is ideal (otherwise, let the water rest for 12h then aerate and actively stir for 2h);
Food for microorganism development (molasses, humic acids, protein meals, fish hydrolysate).
Oxygen content must be monitored: the more bacteria multiply, the more oxygen they consume, until anoxia occurs (= time to stop the TCO). In a 1000 L tank, avoid putting more than 800 L of water to prevent overflow risk.

Recipe 1: Dr. Ingrid Hörner’s Basic Recipe

Ingredients for 200 liters of compost tea

According to Dr. Ingrid Hörner’s basic recipe

200 liters of good quality water (rainwater or well water). If chlorinated water is used, run the machine for 4 to 6 hours. To avoid this problem and ensure quality water, reverse osmosis water can also be used.
30 g BioAktiv Plants (energy component) or Guérande salt
100 g basalt powder (mineral component (trace elements) - e.g., Eifelgold)
300 g sugarcane molasses (component to feed microorganisms; do not use vinasse)
200 g Maltaflor with mycorrhizae (fertilizer based on malted barley)
1 liter of good quality compost (source of bacteria, fungi and humic substances - preferably use old wood compost - do not use young compost or vermicompost unless very mature and passes the watercress test)
0.5 liter of good forest soil
Depending on crop needs, mineral supplements, humic acids, etc. are added when filling the sprayer.

Preparation of the compost tea

Fill the machine with water and start it. If necessary, pre-treat the water for 4 to 6 hours to eliminate chlorine and neutralize lime effects.
Set the temperature to 25°C (+/- 3°C) and maintain for 24h. At 20°C up to 48h. At 30°C only 12-15h (control by foam formation - the compost tea is ready to use when the foam cap begins to fall).
Add ingredients in the order listed above : always start with BioAktiv followed by basalt. Molasses is first dissolved in 5 liters of warm water and Maltaflor soaked and diluted for a quarter of an hour in one liter of water. Once homogenized, slowly pour them into the machine.
Important : to avoid contamination and thus losing subsequent batches, clean the machine immediately; once dried, residues are difficult to remove and, due to lack of oxygen, aerobic microorganisms risk suffocating and decomposing anaerobically. The process then turns to putrefaction, producing pathogens and bad odors.

Emeric Saboureau presents in this video his way of making TCO as well as his recipe :

Note : According to Emeric Saboureau, infusion duration affects TCO composition.

With water between 18 and 22°C, if compost is infused for :

12h : the TCO will be mostly bacterial,
18h : the bacteria/fungi ratio will be roughly equal but tending towards fungal TCO,
Between 18 and 24h : the TCO will be mostly fungal,
Beyond : nematodes and protozoa are favored.

It depends on what you want to spray in the fields and what you want to achieve. In any case, never spray TCO with a putrefaction odor as it indicates it is loaded with human pathogens.

Recipe 2: Simple Recipe

Put water in the tank;
Put compost in the nylon bag (25-35kg for 1000 L);
Dilute molasses in a little water first;
Add molasses (1-2 L per 1000 L of water);
Option: fulvic humic acids (1-2 L per 1000 L);
Stir for 12 to 24h;
Use within 24h.

Recipe 3: More Complex Recipes by Elaine Ingham

Elaine Ingham is an American microbiologist and soil biology researcher. Multiple recipes exist with preparation costs ranging from €7 to €15/ha depending on TCO complexity and volume applied.

Quality Criteria

It is recommended (for those not wishing to start on a large scale immediately) to try first on a small area.

There is a typical odor and the formation of a foam cap. When it begins to fall, compost tea is ready to use.
Absence of foam and/or a putrefaction odor indicates a problem. Do not use it.

The Watercress Test

The watercress test checks compost quality: watercress is a plant that grows in good quality streams and is very sensitive to diseases. Applying TCO shows effects quickly on watercress. If it weakens, the TCO is not of good quality.

Put 150 ml of compost in two 1500 ml glass jars.
Moisten the compost well with a sprayer, place about twenty watercress seeds, and hermetically seal one of the jars.
If the compost is good quality, watercress in both jars should germinate and grow without problems.

Spraying

At the end of the process, compost tea must be spread within a few hours.
If partial quantities are taken, remove the remaining compost, compensate the volume taken with water, and keep the machine running. This ensures the remaining quantity continues to be well oxygenated.
Dosages :
- 20 to 100 liters/ha for plant vitalization.
- 100 to 500 l/ha to stimulate soil life and for a pseudo-fertilization effect.
Dilute the correct amount of compost tea with the amount of water that, depending on the sprayer’s technical characteristics, allows good application conditions.
Minimum dilution 1:3, maximum 1:10.
General rule :
- low dosage = fast but short-lived effect (ideal for the first pass).
- higher dosage = slower but longer-lasting effect (subsequent passes).
To increase the effectiveness of compost tea sprays, various mineral and biological components can be added when filling the sprayer tank (ferments, humic acids, enzymes, algae extracts, etc.)
A refractometer and Horiba testers (pH, EC, Ca, K, NO3-) are effective instruments to test foliar spray efficiency at field end.
To aid cereal maturation, spray a water extract of good quality hay after the last compost tea application. It is a good source of organic silica, also useful in other situations.
Spraying times are chosen based on crop development stages and stress factors (heat, cold, lack of nutrients and water, physical stress (compaction, hail, etc.)

Application Timing

Foliar spraying to vitalize a plant can help dissipate abiotic stress and improve the plant’s symbiosis with rhizosphere microbiology, thus increasing nutrient uptake and consequently crop health and productivity.

Avoid applications in dry summer and cold winter;
Applications to prevent stress:
- Application at end of winter before stress (frost) or to accompany plant regrowth;
- Application a few days after pesticide application to rebalance microbial life;
- Prefer night application with temperatures between 10 and 20°C;
- Avoid direct sunlight rays (TCO is UV sensitive during application).

Cereals

After emergence, mid-tillering.
At heading.
Always during stress.

Corn

After emergence.
At 3 to 4 leaf stage.
At stem elongation, as late as possible while still able to spray.

Rapeseed

After emergence.
Before the end of the vegetative period in autumn.
At the start of vegetative growth in spring.
At the start of stem elongation, especially in conventional due to significant nitrogen fertilization.
Just before flowering.

Forage

1 to 2 weeks before mowing and again just before mowing for more sugar.

Spring Foliar Sprays

Vitalization of our crops already in place should be a priority in spring, as THIS IS THE TIME to help plants build a solid base for the rest of the season. This makes them more resistant to stresses they may face later, especially under difficult weather conditions.

Winter cereals need sufficient boron, silicon, and calcium supply from the start of the vegetative period. This supply is not always ensured in case of excess/deficiency and low microbial activity linked to too low soil temperatures. Microbial activity really starts only above 6°C soil temperature for a prolonged period.

The same problem exists for rapeseed, but it is worsened by cold soil reducing mobilization of key trace elements such as manganese. If at the same time there is a considerable excess of nitrogen in the soil, deficiencies may worsen.

Winter Cereals

Vitalizing spray based on compost tea or water-soluble humic acids.

30 to 80 liters of compost tea
1 to 1.5 kg or liters of boron (e.g., boric acid as salt - most favorable variant; or corresponding liquid products), about 200 to 250 g of pure boron
3 kg finely ground zeolite (2 to 10 µm), a source of silicon (e.g., KlinoSpray)
3 kg finely ground calcium carbonate (2 to 10 µm), a source of Ca (sprayable lime from OmyaPro calcium)
OPTIONAL :
- 1.5 liters liquid humic acid (e.g., HF-Fulvic 25) if no compost tea is available. Covers most compost tea functions
- trace elements if deficiencies detected by sap analysis (NovaCropControl)

Total liquid volume should be at least 100 liters/ha, preferably 150 liters/ha.

Note : If other measures such as phytosanitary sprays, harrowing, or rolling are planned, a vitalizing spray should always be applied AFTER these measures, as vitalizing sprays help compensate stress caused by them.

In case of Ca deficiency in soil and a negative hydrochloric acid test (→ no bubbling!), a surface treatment with small amounts of highly reactive calcium carbonate (CaCO3) is effective. It opens the soil surface, improves respiration, ensures Ca availability, and improves nitrogen supply.

Application rate : 200 to 300 kg/ha finely ground and granulated CaCO3. Best effects are obtained with calcareous marine algae (e.g., Lithothamnium, Physiomax or Physiomag).

Rapeseed

Vitalizing spray based on compost tea or water-soluble humic acids.

30 to 80 liters of compost tea
1 to 1.5 kg or liters of boron (e.g., boric acid as salt - most favorable variant; or corresponding liquid products), about 200 to 250 g pure boron
3 kg finely ground zeolite (2 to 10 µm), a source of silicon (e.g., KlinoSpray)
3 kg finely ground calcium carbonate (2 to 10 µm), a source of Ca (e.g., OmyaPro calcium)
1.5 liters trace elements bound to humus (e.g., HF-Natrel with 5% Mn, 3% Zn, 2% Cu, 2% Fe, 0.03% Mo)
20 liters lactic ferment (e.g., Ferment Fischer, Bodenfit, EM-A, KE.....)
OPTIONAL :
- 1.5 liters liquid humic acid (e.g., HF-Fulvic 25) if no compost tea is available. Covers most compost tea functions.
- trace elements if deficiencies detected by sap analysis.

Total liquid volume should be at least 100 liters/ha, preferably 150 liters/ha.

In case of Ca deficiencies in soil and negative hydrochloric acid test, spreading small amounts of highly reactive calcium carbonate (CaCO3) is effective. It opens the soil surface, improves respiration, ensures Ca supply, and improves nitrogen assimilation.

Application rate : 200 to 300 kg/ha finely ground and granulated CaCO3.

Trial Results

Soil Analysis (by an AgroLeague member)

Émeric Saboureau, AgroLeague member based in Vienne (86), has been using oxygenated compost tea since 2018 on his crops.

Here is an overview of his results with AgroLeague soil analyses on 2 modalities in a plot: one without TCO and the rest of the plot with 3000 L/ha of TCO since the start (about 1000 L/ha per year).

An improvement in organic matter and soil life is observed for the TCO modality. Émeric also noted improvement in soil structure and rumex issues.

On Natural Pasture

This graph illustrates two years of trials on farms from the Agr'eau Adour-Garonne network aiming to measure the effects of TCO and/or soy hydrolysate on productivity of permanent irrigated pasture.

9 modalities were tested with 2 water-treated controls.
Application was done before rain.

It is observed that the modality with 200 L/ha compost tea is the only one showing a significant positive impact, with a +40% higher weight compared to controls (19.21 kg vs 13.63 kg).

On Corn

This table shows results of a Korean study on sweet corn comparing effects of applying mixtures of 3 different compost teas (oriental medicinal herb compost, rice straw compost, and TCO).

It is observed that applying TCO at 0.8% concentration has the best effect on plant biomass growth compared to other tested modalities.

Key points

Compost Oxygenated Teas (COT) can be used as seed coatings, foliar applications, or applied to the soil.

They are a means to improve germination, to revive microbial life, to enhance soil structure, and resilience against water stress.

COTs cannot be stored; they must be applied immediately after preparation. Therefore, they are not suitable for all production systems.

It is important to follow guidelines to avoid creating harmful bacteria.

COTs are an interesting lever in conservation agriculture. They help take care of soils and biological activity.

For further reading...

This article was written based on the document Compost tea and foliar fertilization to improve crop health and increase productivity authored by Ulrich Schreier.