132 133 «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 project4 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 noncrop 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 4 online @ www.slowfood.com/saving-permanent-meadows
RkJQdWJsaXNoZXIy NDUzNDc=