There are more microorganisms in a spoonful of fertile soil that human beings on the planet. The rest are minerals, organic matter, water and air: yet depending on these simple and basic elements is much of life on Earth. But to talk of the soil is not enough: being too dry, too wet, too sandy, gravelly, steep or windy, the percentage of arable land is only 12% of the earth's surface, but it depends on 90% of the world production of food. This invaluable resource is essential for feeding the 9 billion people that we will be here in 2050, most of whom will be born and will live in their own areas where the fertile soil is already scarce and rapidly diminishing.
Erosion, deserts, concrete: the missing ground under our feet
It takes 500 years to produce a layer of fertile soil that is 2.5 cm high, yet every year we consume more than we produce. In 1960 every inhabitant of the earth had access to about half a hectare; today it has just over a fifth. The main causes of the loss of good quality soil are erosion, cement and advancing desertification. Erosion alone eradicates 24 billion tons of fertile soil every year. Rwanda loses an amount that could feed 40 thousand people every year. The limited availability of water causes desertification in many poor countries of the tropics, particularly in India. In developed countries, the great destroyer of land is concrete: in Europe, from the fifties onwards the surface of urban areas increased by 78%, while the population grew by 33%. If, globally, the expansion of urban areas follows current trends, by 2030 we will have cemented an area of 1.2 million square kilometers, an area the size of the whole of South Africa.
Defending the soil
Once we understand that arable land is precious, the decision remains how not to waste it. Looking at the European context there would be little to be optimistic about, given that in May 2014 the European Union decided not to adopt a specific Framework Directive on soil protection. Fortunately other initiatives are growing a little everywhere. Britain has created "green belt" around its cities which since 2003 have saved 1.6 million hectares of arable land from overbuilding. In 2006, the German city of Stuttgart adopted a strategy of preserving terrain based on sustainable land management and the densification of the existing urban fabric, thanks to which from 2007 to 2010 it has lost almost no agricultural land despite intense urban planning and construction activity.
Leaving the land to lie fallow
Healthy soil is essential to stem climate change, because it retains 10 times more carbon than that stored by forests. Aware of this, since 2007, the Canadian state of Alberta has introduced a policy of incentives for farmers who pass to the system of "No-till Conservation Agriculture", a system of managing agricultural production which reduces tillage to minimum, preserving agronomic fertility, and chemical, physical, microbiological balance. An expert in this field is Michele Pisante, Professor of Agronomy at the University of Teramo and President of AIGACoS – the Italian Association for Agronomic Management and Soil Conservation. "Seeding is one of the three pillars of Conservation Agriculture - explains Pisante - The second is crop rotation. The third is permanent covering of the soil thanks to crop residues or specific cover crops, such as Facelia in northern Italy and Vetch in the South." To the no-till farming system is often attributed an excessive use of herbicides and fertilizers, but Pisante states: "Scientific evidence on a global scale and experimental trials by AIGACoS in Italy, after five or seven years of no-till agriculture show a gradual reduction in the use of herbicides and fertilizers compared with traditional agriculture and at the same time a more stable and efficient productivity." Speaking on Thursday, November 27 at the workshop "La sostenibilità nell’agricoltura intensiva e nell’industria alimentare” (Sustainability in intensive agriculture and in the food industry) Michele Pisante is an associate of Laboratorio Expo, the program of Expo Milano 2015 and Fondazione Giangiacomo Feltrinelli that promotes scientific research into the theme Feeding the Planet, Energy for Life.