Soil biological activity
Having good microbial activity is essential for maintaining soil fertility and structure. Here are four key points to consider to stimulate the biological activity of your soils.
The soil must maintain a balanced ratio between stable organic matter and soluble elements. It is important to consider the strategy as a whole and to think about which type of microorganism to favor: bacteria, fungi or both.
Mow cover crops before flowering
The younger the cover crop, the more it is concentrated in soluble elements: sugars from photosynthesis, amino acids, mineral elements, etc.
Conversely, the more advanced the cover crop stage, the higher its lignin content.
- Mowing a cover crop before flowering therefore returns labile organic matter to the soil: elements with a low C/N ratio and a rapid degradation time (from a few days to a few months). Labile carbon is the fuel of the soil; it serves as energy for microorganisms. This labile carbon offers very good efficiency in conversion to stable humus through enhanced soil biological activity.
- Humus, on the other hand, has a very slow degradation time. It plays a more stabilizing role for soils through chemical and physical protections. Stable organic matter alone is not enough to structure the soil. It must be accompanied by intense biological activity, made possible by good levels of labile carbon.
Use C4 plants
Plants with a C4 mechanism (e.g., corn or sorghum) differ from C3 plants (e.g., wheat or beet) by their mode of carbon dioxide fixation during photosynthesis. This allows these plants to assimilate all the internal atmospheric CO2 of the plant and achieve a higher photosynthetic yield than C3 plants.
These plants capture more carbon and produce more root exudates than their C3 counterparts. Root exudates are soluble carbon-rich molecules such as simple sugars, amino acids, organic acids, or enzymes released by roots into the rhizosphere.
They are rapidly assimilated by soil microorganisms and constitute an energy source for the humification process. According to Sébastien Fontaine, research director at Inrae Clermont-Ferrand, “these exudates would be responsible for more than 80% of this stimulation.”
Incorporate EM to inoculate the plot
Effective Microorganisms (EM) ("effective micro-organisms") are mixtures of common microorganisms predominantly anaerobic in a liquid carbohydrate-rich substrate (a combination of about 80 microorganisms: lactic acid bacteria, photosynthetic bacteria, yeasts, actinomycetes).
They are capable of positively influencing the decomposition of organic matter to stimulate soil biological activity.
They can be multiplied with 15 minutes of work; the rest of the process happens automatically and lasts 1 to 2 weeks. Here is the recipe to multiply them:
- Equipment: a 1000 L tank with heating elements for water (e.g., 300 W aquarium heater for 500 L).
- Ingredients:
- 1 L of EM inoculant;
- 30 L of preferably sugarcane molasses (microorganism food);
- 970 L of non-chlorinated water;
- 3 kg of Guérande salt.
- Process::
- Heat the water in a 1000 L tank to 30-34°C (maintain this temperature during the manufacturing process);
- Add the EM, molasses, and salt to the tank;
- Seal the tank airtight and install an air evacuation mechanism;
- Let ferment for 7 to 10 days: fermentation is complete when the pH reaches 3.5.
- Storage: 6 to 12 months at room temperature and protected from sunlight.
Use fermented alfalfa extract
Fermented extracts or plant macerates are natural products derived from a fermentation process. Their main objectives: stimulate soil life and provide an alternative for protection against fungal diseases. Their advantage over chemicals: their low cost (when made artisanally).
Alfalfa has high conductivity and is rich in nitrogen and amino acids. Fermented alfalfa extract has the effect of restarting soil microbial life and accelerating the decomposition of crop residues.
For it to work on microbial life, it must be applied on soil with a temperature above 12°C. This product is particularly recommended for degraded soils (e.g., wheat-beet crop establishment) at a dose of 10 L/ha.
The sun’s energy to feed biological activity and boost natural crop nutrition processes
A soil yes, but a functioning soil
Alongside policies, there is a rise of increasingly well-trained and innovative farmers on the subject who have demonstrated that a functioning soil is a profitable soil and a source of savings and consistent yields.
A functioning soil is a soil that favors the establishment and activity of living organisms: from microbes to earthworms to soil fungi and a whole range of other organisms.[1] This is why the expression "living" soil is often used in professional media to indicate that a soil is healthy.
In a living soil, there are enough organisms to carry out all the essential soil processes: from organic matter degradation to maintaining a favorable soil structure to providing natural and sustainable fertility.
Promote a living soil: transform the sun’s energy into living organisms
To benefit from the services of soil fauna, a threshold must be reached. The difficulty is then to know this threshold. Just as applying 10 kg of ammonium nitrate will not significantly change yield, increasing the population of earthworms by 2% will not change soil functioning; neither in its humification or mineralization functions, nor in its ability to maintain better natural porosity.
It is therefore necessary to have a significant effect, a leverage effect on populations of living organisms to observe beneficial effects on the soil and thus on crops. For example, doubling or tripling the earthworm population will have a considerable effect on the chemical and mechanical fertility of the soil.[1] This can be clearly observed in soils transitioning to conservation agriculture, where earthworms gradually play an essential role in maintaining permanent macroporosity, favoring drainage and rooting.
To improve the presence of living organisms in soil, you must provide them with shelter and food so they can multiply. The base of the soil food chain is decomposer organisms (earthworms, springtails, fungi…) whose role is to decompose organic matter (composed of carbon) derived from plants. These are the almost exclusive energy source for soil fauna and microfauna. Moreover, plants are among the few organisms able to fix carbon in their biomass thanks to the sun’s energy. This process is called photosynthesis.
Thus, all vital processes consist of capturing the sun’s energy and fixing it as carbon in organic matter and living beings.
To improve your soil, you must therefore take care to feed it with quality carbon resources derived from plants but also minimize mechanical disturbances which greatly reduce biological activity and notably organisms living in soil porosity: some earthworms and various arthropods.
Appendices
Sources
Four keys to stimulate soil biological activity, AgroLeague
- ↑ 1.0 1.1 LE SOL AU SERVICE DE LA PERFORMANCE DE L’EXPLOITATION AGRICOLE https://www.agri-lyonnaise.top/le-sol-au-service-de-la-performance-de-l-exploitation-agricole
