The importance of laying down the GROUNDwork – Part 2.
Soil formation
Where should I begin the story… Maybe it’s best to start at the very beginning: billions of years ago, when Earth’s surface was still defined by rocks and turbulent water surfaces. Let’s see what these two substances actually are. For the sake of simplicity, let’s regard water as a liquid substance. Water, i.e. H2O, is a compound of hydrogen and oxygen, which is a colourless, odourless, tasteless liquid chemical substance. In nature, however, we very rarely encounter its colourless, odourless and tasteless form. Since water is a very good solvent, it contains some kind of dissolved substance (e.g. iron, magnesium) most of the time, smaller floating particles (e.g. grains of sand, clay) and under normal conditions (mainly surface) waters are teeming with microscopic organisms as well. All of these things affect the properties of water. Rocks are a mixture of solid materials consisting of various minerals. How do we distinguish soil from rock? The difference lies in their fertility. What makes soil fertile? Well, from life itself!
The first organisms that filled the water with life (at first only those) were bacteria. In the beginning, the bacteria consumed substances dissolved in water, then suddenly blue-green algae appeared that were able to photosynthesize (blue-green algae are actually bacteria). This is an important point in our story. On bare soil surface, the primary organisms, the photosynthesizing blue and green algae, create the basis for soil organisms (Soil fungi and vital vitamins in a healthy soil-plant system).1
The emergence of photosynthesis as a biological process made it possible first for the carbon in the atmosphere to enter the plants and then the soil with the help of solar energy. Fallen leaves, dead plant remains, or various sugars (carbohydrates) selected through the root system of living plants are all carbon-rich substances, which are further developed into humus with the help of life in soil. The more living and dead plant organic matter there is in the soil, the more carbon and humus will form in it. The more humus there is, the more biomass will develop in that area. The more green plant parts, the more carbon will be sequestered by photosynthesis. This process progresses and will reach its peak as long as the properties of the given soil allow it (each type of soil has its own maximum humus capacity).
Now that we understand why the appearance of the first organisms capable of photosynthesis is important, let’s move on to the first plants “climbing” onto land. It is highly likely that the blue-green algae and kelp living in the seas got to dry areas from time to time due to changes in water level, so they began to adapt to life on land as well. A powerful selection began here. Individuals that could not tolerate terrestrial conditions died, while individuals that evolved and surrounded themselves with protective shells or developed resistant spores. This is how the first amphibian plants appeared. After that, there was only one step missing for life to form on land. Long story short, this is the way plants started to grow on land. As vegetation conquered larger and larger areas, the fertility of the soil in the areas they inhabited has also changed. The rock dust and the sediment from crushed rocks mixed with the dead plant parts, consequently the structure, humus content and quality of soils gradually improved. This is how the infertile rock dust became nourishing soil.
Stromatolites, the oldest fossils known, are fossils of the first photosynthetic organisms. Their age is estimated to be 3.5-2.8 billion years. These fossilized communities were created by bacteria (mostly the above-mentioned blue-green algae/cyanobacteria). These microscopic organisms formed large slime-like communities in shallow waters.2 The first photosynthetic organisms started the process on our planet that made it possible for oxygen to accumulate in our atmosphere. It was an extremely long and intricate process of events triggering one another, until we got from these tiny “plants” to the appearance of complex organisms formed to inhale and utilize oxygen.
As they unfolded, more and more dry subareas popped up that had plants on them. These plants probably took root in soils that had some level of fertility.
The best way to describe soil and plants’ progression is taking a look at the level of soil health as well as succession.
For a clear explanation of soil maturity, I refer to G. Adolf Manninger’s book “Shallow Cultivation of Soil”. Manninger (1880-1954) was an agriculturist ahead of his time. He saw how important it is to pay attention to and deal with soil life. Matured soil has a durable, crumbly structure formed by sufficient, intensive work of microorganisms. In mature soil that absorbs, drains and distributes vadose water without any kind of problem, air, water and soil particles are present in the most ideal ratio. Succession is the gradual, unidirectional development of plant communities, which happens simultaneously with the development of soils. To provide a simple example, think of the evolution of the vegetation of a disturbed area (e.g. abandoned arable land, abandoned construction site) or an area left bare after deforestation. The species composition of the vegetation that surfaces there are bound to change from year to year.3
The essence of succession is that the plant communities (groups of plants with a defined species composition) alternate in accordance with the optimization of the habitat conditions. On destroyed or newly formed soil surface (e.g. when the river Danube deposits a large amount of sediment during a flood thus destroying the plant community that had been established there), the so-called pioneer species are going to appear first (e.g. weeds people dislike so much, so it is not a coincidence these pop up in fields or kitchen gardens either…). After the pioneer species have improved the organic state and biological activity of the soil and provided shade to the surface, grasses come out. Annual dicotyledonous weeds gradually give way to turf. Over time, leguminous plants develop among the grasses, which live in symbiosis with nitrogen-fixing bacteria and indicate the further development of the quality of the soil. At the end of this process, woody plants surface, forests are formed. The level of development of the plant cover in the given area goes hand in hand with the development of the soils. Without vegetation there is no development.
Let’s sum up where we are. We started this train of thought with the lifeless environment (rock, water), then went on writing about the first organisms capable of photosynthesis, to fertile soils. Plant communities appeared on fertile soils, which enabled the formation of various soil types (I must state that plant cover is not the only factor playing a part in this process, we also shouldn’t forget about the five soil-forming factors, however one of those is the biological factor in which vegetation has a crucial role).
The above-mentioned processes resulted in the emergence of different soil types, which lead to 23 distinguished main soil types in Europe, each of which can be divided into additional types and subtypes.4 Isn’t it amazing to think about these interconnected events that had to take place for us to have a blade of grass or a couple of hundred years old oak? It all started with bacteria and now all of these…
„Hazel-nut grows from seed, / proud, titanic oak grows from acorn, what you would consider of / no weight later becomes a tree.” (Heinrich David Wilckens)
Translated by Zsófia Horváth.
Notes:
- Bíró B. 2024 Talajgombák és életvitaminok az egészséges talaj-növény rendszerben. TalajPlusz+ magazin – 2024 / 2., 14-20. ↩︎
- Čeman R. 2007 Élő természet – Növényvilág. Bratislava, Slovart ↩︎
- Manninger G.A. 1957 A talaj sekély művelése. Budapest, Mezőgazdasági Kiadó ↩︎
- Soil Atlas of Europe, European Soil Bureau Network European Commission, 2005, 128 pp Office for Official Publications of the European Communities, L-2995 Luxembourg ↩︎
About the author: Erik Paxian, wildlife management engineer, soil science engineer, golden wheat ear farmer. He specialised in permaculture, garden and agro-environmental systems, sustainability, water management, medicinal herb cultivation.
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