The soil is the place where the cycle of life begins, where seeds germinate to give rise to the fruits that will feed us, and it is also the place where dead matter decomposes to give way to new life.
An infertile, punished, depleted and polluted soil will not be able to develop life, so its conservation and regeneration are essential to stop the accelerated deterioration to which it has been exposed in the times in which we live.
That is why since 2014, every December 5, World Soil Day is celebrated, being its main objective to raise awareness about the importance of soil and its relationship with water, to ensure the maintenance of life and achieve sustainable and lasting agri-food systems.
But what is a healthy soil?
A healthy soil is one that has the capacity to operate as an essential living ecosystem, capable of maintaining its functions. It is a complex environment composed of organic matter, insects, microorganisms, plant root systems, air, water and minerals. A healthy soil is productive and sustainable, being able to provide essential nutrients, water, oxygen and the necessary support for the establishment of plants, as well as the protection of their roots.
Importance of soil for food production
Maintaining soil health should be an imperative since food production depends on its condition: according to the FAO, 95% of the food we consume is produced directly or indirectly in our soils, and 15 of the 18 basic chemical elements essential for plants come from it. In addition, although it cannot be considered a non-renewable resource, the truth is that it takes up to 1,000 years for one centimeter of soil to be formed, so its conservation is very necessary. If we want to be able to supply the food demand estimated for the year 2050, we will have to implement sustainable management to be able to increase agricultural production to the estimated levels (60% worldwide) while preserving soil conservation in the long term.
One of the premises of sustainable soil management is based on the efficiency of the inputs used, adding just what our crops need and making their use more efficient. In the same way, the implementation of sustainable agricultural practices such as minimum tillage, crop rotation, organic matter input and maintenance of vegetation cover contribute to improving soil health and preserving soil biodiversity.
The role of microorganisms in soil health
This is where the microorganisms that inhabit our soils really come into their own. It is estimated that each centimeter of soil harbors millions of microorganisms such as bacteria and fungi, and these are responsible for improving soil structure and increasing the availability of nutrients and water for the plant. They also play a protective role against pathogenic organisms present in the soil that cause multiple diseases.
PGPR bacteria
Examples are PGPR bacteria (Plant Growth Promoting Rizobacteria), such as Pseudomonas spp and Bacillus spp, which inhabit the rhizosphere of plants and provide benefits such as stimulating plant growth, protecting the plant’s root system from attack by potential pathogens, and also increasing the availability of nutrients to the plant through the decomposition of organic matter.
An example of this is Pseudomonas putida, a potent bioactivator and plant growth promoter, capable of increasing the availability of phosphorus and iron in the soil by solubilizing inorganic phosphorus and producing siderophores that increase iron assimilation; unblocking calcium to favor its absorption by the plant, thus solving physiopathologies caused by its deficiency; and protecting the root from possible attacks by soil pathogens, through the secretion of EPS exopolysaccharides for the creation of biofilm.
Beneficial mushrooms
Among the different beneficial fungi present in the soil and interacting with the root of the plants are those belonging to the genus Trichoderma spp. which adapt to a wide variety of environmental conditions and obtain their energy from decomposing organic matter. They also have a fast growth, can proliferate in a multitude of soils, are tolerant to extreme environmental conditions and also have a great antagonistic potential against various phytopathogenic fungi that generate severe losses in agriculture.
The genus Trichoderma is considered as one of the best biocontrol agents due to its multiple mechanisms of action, which range from enzymatic to chemical tools. Its defensive activity can be based on direct mechanisms such as parasitization of other phytopathogenic fungi, or indirect mechanisms such as antagonism or competition for space and nutrients, antibiosis or secretion of compounds with microbial activity, and induced resistance, or stimulation of plant defense mechanisms.
Relationship between soil and climate change
In addition to ensuring food and nutritional security, soils rich in nutrients and microorganisms help mitigate the effects of climate change. Their relationship is so close that extreme weather events such as torrential rains, heat waves or a generalized increase in average temperatures, to name a few, directly affect soil health. Not only that, but it also affects its ability to absorb CO2 from the atmosphere, thereby increasing greenhouse gas emissions.
The adoption of agricultural practices that integrate the use of beneficial microorganisms must be a maxim in the future plan for sustainable agriculture, since without soil, there is no life. In addition, it is imperative to promote policies that foster education and awareness of the importance of soil health. Only through a global commitment can we ensure that future generations will have access to sufficient and healthy food resources. Soil health is not only a fundamental pillar for agricultural production, but also for climate change mitigation and the preservation of terrestrial ecosystems. It is therefore crucial that governments, scientists, farmers and society at large work together to protect and regenerate our soils, thus ensuring a prosperous and sustainable future for all.
