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Talking about vermiculture is almost talking about a part of the history of the human being in his relationship with nature, when it comes to obtaining resources from it. What today looks like a new culture responsible and respectful of the environment was already known and practiced by the ancient Chinese and Egyptian cultures, so that it has been incorporated into the history of art, the British Museum in its section dedicated to ancient Egypt houses two tombs with engravings of men mowing the earth and collecting earthworms. Homer also talks about the cultivation of the worm in his magnum opus "The Iliad" and there are Arabic references, in the twelfth century, to the same subject.

These are some of the historical references found by biologist Manuel Blasco, scientific advisor to the Spanish Association of Vermiculture (ASESLOM) and a member of it since its foundation. He likes "a lot the History and dig in it for detecting the presence of the species that I investigate." M. Blasco, PhD in Biology from the University of Granada, is Professor of Animal Biology at the Faculty of Sciences of the University of Extremadura. He has served as Zoology Department Director of the universities of Malaga and Extremadura, between 1972 and 2002, in addition to having published more than eighty scientific works and being the author of 12 books.

As a scientist and a member of ASESLOM, he considers the cultivation of the worm in agriculture positive because "what it does is producing on an industrial scale, but in a natural way, the adequate substrate so that the plants can also develop naturally. Given the current needs of the agriculture substrate, the vermicompost produced at macroscale satisfies the needs of the agricultural activity, balancing the soil-plant system".

What is vermiculture?

Vermiculture is an activity mainly aimed at obtaining natural fertilizers, through the partial mineralization of organic matter and with the help of annelid worms. The main product is called earthworm humus or worm casting, a semi-solid material similar to the casting resulting from the natural decomposition of organic matter in a forest or wild shrub. Thus, the earthworm casting returns the nutrients to the environment without adding contaminants that delay the assimilation of these nutrients. However, the idea that this product is achieved thanks to the exclusive activity of earthworms is not entirely appropriate because other organisms also contribute to prepare the susceptible substrate to be transformed by the earthworms. A definition must be exact, brief, complete and exclusive. And for worm humus, the concept is complicated by the fact that the product is a complex resulting from the activity of many organisms that coexist in a special ecosystem, the residual organic matter. An adequate approximation to a definition that meets the above requirements would be the following: "The earthworm humus product is the result from the oxidative metabolism of organic matter made by the combined activity of microorganisms and earthworms of the oligochaete class".

How important is vermiculture (or worm casting) in agricultural activity?

The vermiculture is not a defect of earthworm humus but is a consubstantial part of it. Earthworm humus is a consequence of the metabolism of earthworms and their excrements are plant nutrients for millions of years. These metabolic products are absolutely necessary for the microorganisms that live in the soil (mainly fungi -mycorrhizae and bacteria -rhizobacteria), attached to the roots that help the plants absorb their nutrients, in the same way as our digestive enzymes metabolize food to prepare its nutrients in the appropriate way so that our organs can assimilate them and transform them into their own material. It is therefore a natural cycle, by which an ecosystem remains balanced. So, what the vermiculture does is to produce on an industrial scale (but in a natural way), the appropriate substrate so that the plants can also develop naturally, but given the current needs of the fertilized for agriculture. The vermicompost produced on a macro scale satisfies the needs of agricultural activity, balancing the soil-plant system.

Why adding worm casting instead of another fertilizer?

A fertilizer is a product that, as you can understand, contributes to a certain system: something that is needed for its development. Fertilization is inherent to life, without which, it would not exist. Bacteria, fungi, protists, plants and animals need fertilizing components for their development, whether they are sex hormones, gaseous, liquid, solid chemical emissions or excretory materials from other organisms, in synergy, symbiosis or commensalism. As it is logical, each system needs its fertilizer, its nutrient, which should be as natural as possible, which is what the system recognizes. The lombrihumus is what the soil, in perfect balance between its components, recognizes more easily and, therefore, it is not an additive to the soil but the natural material that is added when the nutrients of that have been exhausted or you want to enrich. Hence, the contribution of earthworm humus does not have excess threshold, since the soil assimilates what it needs. The rest is being maintained as reserve materials, without danger to nature and without any danger of pathogens. On the contrary, in case of providing an excess of nutrients, the micro and mesoorganisms of the soil are nourished by them, facilitating the evolutionary sequencing of the soil. The great difference of using earthworm humus instead of other fertilizers is that using other fertilizers can cause imbalances in the soil and, in case of exaggerating the contribution, you have the danger of poisoning, so the use of chemical fertilizers have to be carefully dosed. And the use of one or the other has nothing to do with the price, but with the needs.

Are there specific studies on this activity? What lines of trials are being carried out and what are the conclusions?

Vermiculture is as old as history. Already Egyptians and Chinese spoke of earthworms as favoring soil fertilization. Aristotle echoed these observations and Columella in the time of Claudius and Nero, rated earthworms as agricultural fertilizers. From then until today, farmers know that earthworms are good for their crops, although there have been those who believed that the worms devoured the roots. But it is in the mid-twentieth century when the controlled cultivation of earthworms is used in agriculture, choosing an European species as a standard of study, the Californian earthworm (Eisenia fetida), even though is an European species and not American. The name comes from the fact that it was in California that studies were started on the cultivation of the species and its massification for agricultural uses. Naturally, research has multiplied throughout the world, aimed both at promoting scientific knowledge of this species and other nearby forms, and the application of research results for an agriculture that is both more natural and intense. Currently, research focuses on genetic studies, molecular biology, immunocytochemistry, tissue regeneration, apoptosis (programmed cell death), hybridizations and search for new species that can provide different nutrients or resistance to predators. Globalization has also led to the development of studies on the introduction of exotic species that can become invasive and compete with native species. As it is logical, each of these lines of work has its own conclusions and, in general, it is corroborated again and again what is already known from old: the great importance that worm casting has for the soil and its metabolic components.

What benefits does this activity bring to organic farming?

This question has already been largely answered above. Organic farming is based on the application of knowledge about the way nature produces its materials in a natural way, without extraneous additives. We have already seen that earthworm casting is a natural fertilizer, manufactured in the same way as the decomposition of organic matter that occurs in the biosphere, taking advantage of the nutrients that come from this decomposition, mainly microorganisms and microfauna (nematodes, crustaceans, insects, worms), and even more conspicuous animals such as amphibians, reptiles, birds and micromammals. Therefore, vermiculture not only favors the development of organic farming but is an unavoidable necessity for it. But there is more: the main action the vermiculture is the decomposition of organic matter in synergy with microorganisms. Therefore, it provides an extra service of great importance: the elimination of waste, both from agriculture and livestock, as long as it does not carry toxic additives. Thus, manures of varied origin, agricultural waste, fruits and non-commercial vegetables, are recycled and disappear thanks to the intervention of this activity. Otherwise, they would accumulate dangerously, with the risk of pathogens development, soil poisoning and of the phreatic layer, increase of harmful insects (with their possible bacterial and viral load), bad smells and increase of the social costs by decontamination.

Is the trend of switching the chemical fertilizers by organic agriculture really happening?

Chemical fertilizers fulfill a mission that should not be neglected, although it is true that their use has been exaggerated, with the consequent accumulation of waste that is often not recyclable. For instance, the problem of phosphogypsum ponds near the city of Huelva or those that caused identical complications in the old Spanish Sahara, all motivated by the exaggerated demand for fertilizers needed by intensive agriculture, and forgetting the services that nature itself could contribute in. In our opinion, rather than reversing a trend, what is likely to happen is the increasing demand for biological fertilizers (of which earthworm humus is the most representative) by proportional increase in organic farming and exponential demand for food without potentially dangerous additives. But it does not mean an increase in prices, simply a mental reorganization of the needs in accordance with the current moment, cheered by an increasingly developed culture based on the immense services offered by nature. Therefore, the tendency we see is that chemical fertilizers must comply with a certain function and biological fertilizers must comply with theirs: each one having to satisfy the citizenship.

We already know the benefits of earthworm casting (vermicompost). But do earthworms have some other applications?

As in almost all biological phenomena that occur naturally, there are always contingency benefits. one of the obligations of scientific research is precisely to discover those contingency applications that give so many added values to nature. Worms are not an exception, especially when, like good invertebrates they are, they reproduce exponentially, which also results in the exponentially contingent benefits. It is common knowledge that earthworms are magnificent continental fishing baits, not only sport but also industrial, serving as live feed in aquaculture. Also, they are food for cage animals, even in ecological farms. On the other hand, given their habits, earthworms are used as cleaning agents in those areas where organic waste can accumulate. They are even used as human food, either fresh (as eels) or dehydrated and ground, giving rise to a worm flour good to make tortas, which are in high demand in South American and Asian countries. For cultural reasons, the intake of earthworm tortas has not yet reached Europe, but given the migratory current, custom will soon be imposed, for which it is necessary to be prepared both in supply and in the different culinary preparations. And surely in the future, earthworms will discover new products and applications, from the sequentially beneficial food chain to the pharmaceutical industry. Biological science and engineering work together, having the worms as patterns of action on which humanity relies to advance its development.