EtymNologically the wordbody really knows what "humus" meanis ground, dirt; the meaning of "homo" o. Even if the same word "human" is near to earthlingt or being of the earth, earth here referring to the ground, or dirt (https://sites.psu.edu/josephvadella/2017/09/08/origins-of-human/). Essentially the words humus and human mean "connected to the earth", earth understood as dust, soil, dirt. The best wa origin of "human". In this short entry we try to express such a concept comes from an ancient religious Latin sentence: "pulvis est et pulvis reverteris", solemnly pronounced by priests as they deposited a pinch of ash on the believers' heads. Consider that earth has also become the name of the whole planet Earth, and that the Lovelock's Gaia hypothesis assigns the planet the functioning of a quasi-organism (https://en.wikipedia.org/wiki/Gaia_hypothesislain the reason for this coincidence (Part one: What's life?). The notion of humus contains and makes explicit the very concept of all existing matter. What is matter (living or not), if always, at a given cyclical moment, matter is forced to disappear by a principle which founds the future of this same matter? Understanding even partially this principle is useful for every single individual and for the whole of the co-evolving societyn we will explain what humus systems (chapter 2) and humus forms are (part 3).
TEssentially, with the word "Humus" we intend the meeting point of two opposing processes of: degradation and construction of organic molecules/bodies (organic = built around a skeleton of carbon atoms) occur in the organic and organo-miner. Referring to the dominant biological parts of the soil. Referring to these rather biological se processes, soil scientists and biologist it is prefer able to use the more rigorous e terms of mineralisation (return to mineral components) anbiodegradation and humification (genesis of new organic molecules). The more organic and richer in organisms, respectively. Naturally you find humus in the top part of the soila soil. This part is called Humipedon is the point where the phenomena of life and death meet. Any dead structure body or body part naturally falls to the ground and is here decomposed there. It is not even that easy to define when a structure is dead. Yellow leaves on a tree, for example, are they still dead? Wtell when a body is dead. A falling leaf, for example, can we say that it is more dead on the ground than when it was already yellow on the tree? If we leave aside these "border areas", we can probably say that when a leaf reaches the ground it is on the waydead and is on to become something else. The future of a leafbody under degradation is parted in two: mineralisation and humification, both necessary to build new living structures. To stay anew life. To live, a living complexyou must loose part of its components, which must die to produce new input first die (Figure 1). Or vice versa, as in the question: "Was the chicken or the egg born first?"
Figure 1. TTo stay alive, people must die. In a single person's stay alive, complex structure must partially dietime, an individual is born, grows and dies. Even in the time of the generation of a population. However, But something almost miraculous happens: the newxt generation never starts from the same point ofas the previous generation; it starts from a re-elaborated baseone, but from something different. It is this new basesomething different that evolves linearly over time, regardless of the ilife of the individuals' life or the population. In this long-term process, the humus characterise the period of time that separates dying and nascent generations. For thishumus is found between one generation and another, between the death of the first and the life of the second. For this reason it is intriguing as a concept. There are scientists who claim that humus does not exist, that thereason the are molecules that change, but never humus concept is an intriguing matte. But if we think in this way, then we human beings don't even exist, because we ar e just molecules that chattractednge over time too. Not even Erwin Schrödinger's spiri was able to answer t.
Ifhe wque consider that listion, and no one else did better than him. The feinal begins with a first "living cell", timpression is that to be able to live well is not necessary to know what life is.
The early Earth was devoid of life if we consider that life begins with a first "living cell". A name has also been found for this hypothetic primordial "living cell"it: LUCA (Last universal common ancestor: https://www.imperial.ac.uk/news/120606/who-what-luca/ ). Problem: to make a cell is made of you need complex components that themselves mightcould be considered "alive". On one side, a living structure should be able of auto-ready alive". It is objected that in order to be alive it is necessary to reproduction; on the other sidee. Unfortunately, even an atom is so complex, if studied in its elementary components, even a physical atom is so complex and moving, wthat we have not yet understood what it is made of, except by activating our imagination. We don't know whether it is composed of micro-creaturesif an atom is "alive". At the larger molecular level, thinking that a DNA molecule might be is somewhat "alive" is not considered completely absurd. Although not everyone agrees that viruses are living beingsalive (https://www.scientificamerican.com/article/are-viruses-alive-2004/ ). There are scientific reasons to think that the molecules that make up the genes of each DNA command natural evolution. Are those selfish genes alive?
We love be thinking that a Miller-Urey's soup might correspond to a primordial soil, a was a soil at its origins, an archaic very liquid primordial humipedon. Certainly there is organic matter in the black space of the universe. It is very likely that organic molecules from space were also present on the surface of planet Earth when LUCA was generated. Before LUCA there wereas only a Miller-Urey soups, probably at different stages of evolution. Admitting this does not only mean that this is how life was born, but also that it may continue to generate like this at present time; that LUCA was born in an "embryo- of "soil"; that this soil embryo-soils still exists today and continues to generate new ecosystems. In their soup, Miller-Urey did not foundlife, even if conditions have changed. It is assumed that at the origin, every living beings but molecules remaining separate. We know that embryo is a tiny Miller-Urey soup. In Miller-Urey's soup continued to evolve and to change until the conditions of the soup allowed a functional construction called LUCA to generate. We know the following steps in larger and larger soup-ecosystems. Citing only the crossing stones: Margulisno living beings are born but ecosystems, ecosystems that contain parts of living beings or complete living beings that are not separate from with her symbiotic primordial entities; Darwin's ecological vision of the evolution as a consequence of adaptation of individual characters within changing natural populationseir environment of genesis. We know the story for the next steps. Citing only the nerve centers of history, Darwin's evolution of species, contained in ecosystems as defxplained by TansleyLovelock, explained for the chemical-physical aspects at the planet level by Land by Margulis for the biological ones at the levelock of living primordial entities, connected to the rest of the living as in the observations of Darwin. From the point of view of a soil scientist, the process of "genesis and evolution of ecosystems" is still active and should be seek in a sort of "humipedon", even at present day. Mitosis, first, and meiosis, later, might be the result of a controlled evolution of Miller-Urey soup. That all cells are Miller-Urey soups evolving into larger ecosystems. A pure biologist point of view can take abe similar way whenhen they investigatinge the boundariesy between life and death in cells. Usually the concept of apoptosis comes into play, andwhich on the one hand il allows to kill/erasekills and on the other to create/modify cells, organs or whole organism, in equilibrium at each respective scale and within evolving specific environments. Diseases and cancer can be placed in a context of evolution.
AUn humus system is an abstract category in which soil scientists set all humipedons that show a similar aspect and functioning. Imagine a humus lover who studied manyspecialist who has seen all the humipedons all aroundin the world and who want to inform a friend on this: "in submerged areas I saw thick, organic and dark humipedons; in less humid environments I saw humipedons inhabited by earthworms which incorporate toishes to tell others about them. Recall that the humiped is the superficial part of the soil, the first centimeters of soil, those that if you open a hole, you see that they are darker than the rest of the soil all fallen litter; in dry zones. If one asks this specialist to describe the hiumipedons were full of insects, mites, springtails and litter accumulates at the surface of the soil as it was a roof for their home; on mountain rocks exposed to sun wind and rein I found thin crusty microbialhe has encountered, he will have to classify them, put them in different boxes. Roughly he will say: "I saw humipedons very different from those grein the water and they are usually very thick and silty forming in at the bottom of rivers and lakes or seas .... "
Th, organic and dark; then I saw buckets: in some there were earthumipedons cover all planet Earth surface. Theyworms, in others insects, mites, springtails; others were first classified in humus typin unthinkable places, on the highes,t thenrocks in humus forms,the world andbut finally in humus forms grouped in humus systems. Talso in the depths of the oceans .... "On planet earth the following have been provisionally described: five 5 systems in not submerged environments, five in submerged areas, two at the sea-side, six in very specific efresh water, 2 in salt water, 5 in dry environments (pioneer or primordial ecosystems), and two conditioned or man-made. Cand 6 in" strange "environments and 2 anthropogenic. See photographs in Humipedons. See classification and distinctive characters in the Morpho-Functional Classification of the Planet's Humipedons.
HOnce you know how to recognize humipedons are all, you want to see if within the category there are different, even "forms of them", i.e. humipedons that within a the same humus system. The thickness of the litter layer can be very can be different from the other but not so different even within a same to end in another system. For example humipedons of the Mull system. Why? L that never have leaves may be more or less palatable,on the surface. You wonder "they too are made from earthworms have preferences and do not eat all species of , I see their droppings here and there ... why in this forest the earthworms eat all the leaves, the number of earthworms is connected to many soil variables (compaction, acidity, humidity ...) and influences the thicknes quickly, while in this other they don't? And it turned out that there are more palatable leaves than others, that some species of the litter on which these animals feed, rees seem to want their leaves to be undigested to earthworms, that leaves remain a long time on poisoned soils .... In short, it is interesting to be abdescribe and be able to individuate some2 to 4 different humus formforms of humus in each humus system. Eventually, tgoing into detail, the planet Earth is covered with humipedons cwhich can be classified into "humus systems", detailed in which in turn can be subdivided into "humus forms" . This is already quite complicated and you can stop for a while (Figure 2).
Figure 2. Humus systems and humus forms. The figure shows an open profile divided into horizons. Each humus system is characterized by specific diagnostic horizons. Depending on the thickness of these horizons, humus forms can be identified within each humus system. The subdivision of the Moder system into three forms of humus has been illustrated on the figure. Hemimoder, Eumoder and Dysmoder. Eumoder is the "central" humus forms, corresponding to a typical Moder. To know more: https://www.sciencedirect.com/journal/applied-soil-ecology/vol/122/part/P1 ; https://www.sciencedirect.com/journal/applied-soil-ecology/vol/122/part/P2. AnThere is Android and iOSalso an application (TerrHum) is available for free.to take to the field Ithat helps to recognize these diagnostic horizons and humus systems and forms in the field.