That spoon that ensures life (and heals the soil)

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Thousands. Or rather millions, billions. These are the living beings in our soils. And not in an area the size of a football pitch, or in a cubic metre, or inside a child’s bucket. It only takes a simple tablespoon: f ill it with soil and you will have, in there, more living organisms than all the human beings currently on the planet.

The image that agronomists and soil scientists use to impress school students and non-insiders is also a perfect example of how much life can exist beneath our feet. Often unknown. Certainly underestimated. But fundamental to our lives, our future, our health. Indeed, the healthiness of the soil depends on these micro-organisms and, with it, its ability to provide ecosystem services: that is, to meet the needs of food production, carbon storage and hence the reduction of CO2 in the atmosphere, ensuring agricultural yields and nutritious, healthy fruit.

The same spoon can also be useful to visually understand the difference between a healthy and a degraded soil. Just fill one with highly fertile soil and another with a soil depleted by years of aggressive and incorrect agronomic treatments. One glance at both, and you can easily see that the pale, sickly colour of the unhealthy soil is a silent cry for help. It’s up to us humans to hear it.

On the other hand, soil scientists agree that in the last seventy years – in which agriculture has given way to agro-industry, the world population has grown, and fertile soils have too often been sealed off by infrastructure and cement – we have forgotten management techniques that we thought were outdated and instead, for centuries, they have preserved the very health of soils, whose life (or death) of entire populations depended on.
There are countless publications highlighting how synthetic chemical compounds – starting from pesticides and phytosanitary products – that have been used for decades are becoming increasingly impactful. The Pesticide Action Network (www.pan-europe.info), which brings together NGOs from over sixty different countries, has underlined that the contamination of fruit and vegetables in Europe has increased by 53% in the last decade. The EU Regulation[1], which aims to reduce the risks associated with phytosanitary products by 50% by 2030, emphasises that at least 54 hazardous substances must be candidates for substitution due to their impact on health, soil and ecosystems.

Luckily for us, like a loving mother who forgives the mistakes of her children, nature is often benevolent and, despite the snubs it has received, it contains within itself the tools to allow us to fix the damage done so far. Once again, these allies of ours are tiny and live inside the soil. As long as we will listen to them. If we want to enshrine them in a single word that everyone can understand, we should speak of microbes. Even if that noun sounds with an often negative connotation to our ears, it literally encompasses a world within itself.

In fact, there is a close connection between soil fertility and the biodiversity of the micro-organisms that populate it: they act as a veritable bank of resources which the plant can selectively draw from, according to its needs, contributing to the decomposition of organic substances and the release of essential mineral nutrients. Components of a virtuous circle that allows plant and grasses to grow better and thus, in turn, to fulfil their functions, among which stands that of giving new life once dead, favouring the spread of micro-organisms that populate the subsoil, while avoiding many of the phenomena leading to soil degradation.

Secrets best known to farmers, true custodians both of soil and its future for hundreds of years. Today, all this has become a thriving field of study for researchers on every continent, committed to systematising the use of micro-organisms to heal soils, preserve their fertility and ensure adequate agricultural yields. Agronomists from the US Department of Agriculture and the Agriculture and Agri Food Canada agency are, for example, engaged in analysing the present microbial communities in order to assess soil health through them. The goal: to offer practical solutions as an alternative to the use of chemical inputs. Their research, which has been going on for about twenty years, has shown that some plants are more helpful than others in maintaining soil balance.

For example, fields cultivated with monocultures such as soya have the worst health status. The corn ones are in the middle.
On the other hand, those permanently covered with grass and rich in gorse, a plant widespread in North America, boast the greatest biodiversity of micro-organisms and a greater presence of fungi.

«Sustainable farming practices that limit soil disturbance reduce the application of chemical and preserve soil health», emphasises Lori Phillips, researcher at the Canadian government agency involved in the research.

A concept so important, that of the link between the biodiversity of plants present in the soil and the richness of soil micro-organisms, that it has become the focus of a Slow Food project[2] dedicated to permanent meadows, those soils covered with grasses and vegetation that do not undergo ploughing or tilling, but are left to vegetate spontaneously for a very long time – from a minimum of twelve months to tens, hundreds of years. Human being’s contribution exists, but it is limited to mowing and fertilisation. The rest is taken care by the farm animals, who obtain from the permanent meadows biodiverse nutrients, precious for improving the quality of the milk (and products derived from it), richer in aromatic compounds guaranteed by the ingested grasses, in antioxidant molecules and with an exceptional ratio between omega-3 and omega-6 acids.

All this biome, however, is getting lost, due to the depopulation of inland areas, the abandonment of extensive livestock farming in favour of industrial farming, and the spread of monoculture crops through which animals are fed. The result: 16% of permanent meadows are lost, an area the size of Bulgaria. In our Alps, the rate rises to 45%.

But soil coverings with grasses and plants do not only improve the quality of the products supplied by cows, sheep and goats, nor do they only have a positive effect on mountain soils. The University of Cordoba investigated their impact on olive groves. «Soil cover not only reduces erosion and run-off, but also organic carbon losses», Francisco Márquez explains, scientist in the AGR 126 research group at the Spanish university.
The numbers are staggering, and should be well-kept in mind when we witness scenes of landslides, mudslides and floods that, on poorly managed and degraded soils, are unimpeded. «Land cover is responsible, on average, for a 36.7% reduction in runoff and 85.5% reduction in erosion, and this practice has furthermore reduced carbon loss by 76.4%». That’s not all: with respect to the effects of rainfall, cover crops provided 65.7% protection throughout the season – compared to 22.4% in conventionally tilled land.

What happens above, in short, helps the life and health of the world below, and vice versa. Here it is, again, that virtuous circle: forward-looking cultivation techniques, wide plant variety, soil fertility, microbial diversity. Which in turn extraordinarily support plant life. They are the primary beneficiaries of the action of soil micro-organisms, drawing from the soil as many as 18 of the 29 elements essential for their life. The microbiome of the rhizosphere – that is, the portion of soil surrounding the roots – also strengthens the metabolic repertoire of plants and facilitates a number of processes, including seed germination, plantlets settling, nutrition, water uptake, growth, pathogen suppression and stress tolerance.

Microbial diversity also shows us how synthetic chemical can be effectively and naturally replaced. Bacteria can indeed provide an alternative to pesticides. A team of researchers at Wageningen University & Research, a Dutch institute, is working on this line of study. Thanks to a public grant of five million euros, they are investigating the potential of these micro-organisms to combat plant pests without damaging the soil ecosystem. Bacteria are in fact able to produce particular substances – antimicrobial peptides – capable of killing pathogens without affecting the remaining microbiome of a plant. A selective fight that resembles the most modern medical or microsurgical techniques to eradicate a disease without damaging the entire body, but which has been guaranteed for thousands of years, spontaneously and free of charge. Pests go away, soil biodiversity stays intact.

And on healthy, well-managed soils, among the micro-organisms that act in an extraordinarily effective manner are fungi. It is no coincidence that a large presence of them is observed in herbaceous non crop areas, which have therefore had more time to build stronger microbial communities over the years. Any handful of healthy soil can contain a sequence of hyphae – the cell filaments that form the vegetative body of fungi – capable of extending over a hundred kilometres. But they are also able to interact with plant roots, providing nutrients and absorbing CO2. An ability that is not only poetic, but it also has interesting practical and economic implications: the University of Zurich studied the reactions of soil samples to the activities of five different combinations of fungi and bacteria. Soils with a greater presence of fungi released less CO2, thus retaining a greater amount of carbon.

Overseas, this peculiarity has not gone unnoticed: Funga (www.funga.earth), an environmental services company from Austin, Texas, has in fact decided to launch projects to remove carbon dioxide through the use of soil micro-organisms, and has in short time secured funding of around four million dollars from investment and venture capital funds.

In addition to their function of aiding soil carbon storage, fungi are also proving to have another capacity: restoring contaminated soils, disaggregating toxic substances and avoiding disposal problems. A peculiarity that is by no means marginal, if we think that in Italy alone – as calculates the ISPRA, Italian government agency for environmental protection and research – there are over twelve thousand contaminated sites. These are territorial areas at high risk, where the insistence of human activities has over time caused such an alteration of the environmental qualitative characteristics of the soil, subsoil and water as to pose a danger to human health. Experiments by several universities around the world are focusing on petroleum and heavy metal pollution. Fungi, grown on polluted soils, have been shown to be able to feed on the organic compounds, breaking down crude petroleum contaminants and eliminating their toxicity. In soils contaminated by heavy metals such as mercury, the fungi instead absorb the harmful substances: they become toxic, but the soil becomes clean again. At that point, in short, disposal only concerns fungi, thus saving landfill space.

«Fungi are the most powerful decomposers in nature», researchers from the British Royal Geographical Society pointed out a couple of years ago. «For millions of years they have evolved to exploit the residues of other species, recycling nutrients back into the ecosystem. The only organisms on earth capable of decomposing wood, they are also able to extend into the soil with their filamentous mycelia, excreting digestive enzymes that allow them to biodegrade complex materials».

In a word: mycorrhization. One of the many ways in which nature is turning to us its other cheek.

 

Re Soil Foundation is a private non-profit organisation. Its creation is linked to the need to promote scientific research, technology transfer, training and dissemination on one of the most important, but increasingly degraded, assets on the planet: soil.

Emanuele Isonio is responsible for journalistic content at the Re Soil Foundation. In 2012 he was awarded as best Young Journalist by the European Commission’s Agriculture Directorate.

www.resoilfoundation.org

[1] see Regulation (EC) No 1107/2009 of the European Parliament and of the Council of 21 October 2009 concerning the placing of plant protection products on the market and repealing Council Directives 79/117/EEC and 91/414/EEC – online @ eur-lex. europa.eu/eli/reg/2009/1107

[2] online @ www.slowfood.com/saving-permanent-meadows