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Agroecology and mitigation of hydrogeological risk

Agroecology and mitigation of hydrogeological risk

To understand where and when hydrogeological instability arises and, therefore, how to mitigate it, we must address the issue in agroecological terms, to broaden the concept and therefore the causes that determine hydrogeological risk.
To carry out this in-depth analysis we need to start from what happens at a more microscopic level at soil level.
By analyzing their particles, their structure, their interconnections and their functioning, clarifying, once and for all, that soil is a living and not inert matter and, as such, must be assisted and treated.
According to the definition adopted by the Italian Society of Pedology, soil is the most superficial layer of the Earth and is defined as a natural entity composed of solids (50%), water (25%) and air (25%). The solid component is made up of minerals (45%) and organic matter (5%). The stability, cohesion and functionality of soils are largely at stake in the 5% of organic substance.
The figure schematizes the mechanism of cohesion and water retention in the soil, where:
S: particella non colloidale;Particelle colloidali del terreno
A: mineral colloid;
H: organic colloid;
I: imbibition water;
C: capillary water;
m: macropore.
This mechanism is fully operational only if:
– the presence of organic substance (SO), microorganisms (which partly make up SO), the quantity and quality of salts and other factors is normal.
Let’s now go into the numerical details and analyze the data for Sicily. According to the latest ISTAT data, the total agricultural area (SAT) registered amounts to 1,504,240 hectares, a decrease of approximately 400,000 hectares compared to 1990 (-21.4%), while the regional utilized agricultural area (UAA) stands at 1,281. 655 hectares and also presents a significant reduction (-19.8%).
If we divide 400,000 hectares by the number of inhabitants (last census) which are 4,785,711, there will be a loss of 0.0836 Ha per capita; a value achieved in just 30 years.
The missing 400,000 hectares are surfaces removed from agricultural land use, which have been urbanized, concreted and therefore, almost always, “waterproofed”.
The 1,281,655 cultivated hectares are largely the subject of intensive agriculture which makes extensive (and often excessive) use of herbicides, pesticides, synthetic fertilizers, etc.; all substances that compromise the functioning of colloidal particles and the very structure of soils.
The use of herbicides, pesticides and synthetic fertilizers causes a decrease in soil biodiversity, organic matter, salinization and sodification and, therefore, a destructuring of the soil.
There is therefore a direct relationship between soil degradation, agricultural practices and soil-relevant policies.
To this we must add that this degradation of functionality causes a lower vitality of the topsoil, which contributes less to its covering systems, to the connection between root systems (with their exudates) and the microbiology of the soil and, ultimately, to an overall loss of functionality of the soil/topsoil system.
In these conditions there is a loss of soil, fertility, contamination of the same and a decreased storage capacity of atmospheric carbon.
In summary there is a loss of the ecological functionality of the soil which leads to various phenomena including:
– loss of soil;
– shallow landslides;
– loss of fertility;
– desertification, etc.
There is therefore a relationship between Land Cover and Land Use as defined by Directive 2007/2/EC.
Irrational use of land causes an acceleration of land consumption.
In Italy, land consumption is monitored by the National System for Environmental Protection (Law 28 June 2016, n. 132) which every year produces the national report “Land consumption, territorial dynamics and ecosystem services”.
The data reported by ISPRA in this regard, as can be seen from the following table, leave no doubt; we are witnessing unprecedented land consumption.
Perdita di suolo ISPRA
A factor that, unfortunately, unites the entire planet. In fact, 33% of the world’s soil is degraded. The percentage in Europe rises to 60%, where, in just 10 years, 177 thousand square kilometers of land have undergone progressive desertification (an area more than half the size of Italian territory).
Degradazione dei suoliTo this, as highlighted previously, we must add the loss of biodiversity (with its functions) which has led to a decreased interaction in the soil/topsoil system, with consequent degradation , loss of fertility and soil structure.
This is why despite the recommendations and indications contained in Agenda 2030, in the European Green Deal and above all in the two Farm to Fork and Biodiversity 2030 strategies, we must accelerate the transition towards zero land consumption (due to anthropic activities, such as urbanization , etc.) and sustainable use of the same.
In this sense, ISPRA, in 2021, with the “White Paper on sustainable soil management” recommends and urges the adoption of an Agroecological System.
Obviously the transition from conventional to agroecological land use must address two major issues:
• The first is linked to the insufficient scientific research on the subject (which still suffers from a systemic methodological gap) that can propose consolidated and reliable agroecological methods (not only productive but also distributional);
• The second is that the Ecosystem is not a linear function which, like all complex systems, cannot be changed immediately so the introduction of new management and production models (and their results) requires medium-long times .
In Sicily, to start the “Agroecological transition” process, the Regional Law was approved. 21 of 07.29.2021 concerning “Provisions regarding agroecology, protection of biodiversity and Sicilian agricultural products and technological innovation in agriculture”.
The law in question promotes:
a) the protection of human health, the natural environment, biodiversity, ecosystems and agricultural activities;
b) the fight against desertification, hydrogeological risk and fires;
c) the protection of Sicilian agricultural products and all related production sectors;
d) an agro-forestry-pastoral model compliant with agroecology criteria;
e) an efficient control and verification service in the agri-food sector.
To understand the practical implications of this law on the soil/topsoil system, some simulation studies were carried out, also published in specialized journals at national level.
For example, with the implementation of art. 3 of the law, if only 10% of agricultural companies transitioned to the agroecological system, over 5,500,000 trees of native Sicilian species would be planted, with a clear advantage not only at the level of the root systems but also in terms of lower incidence of the effects meteoric, for greater coverage of the foliage on the soil.
Furthermore, according to the calculations carried out, this would compensate, due to the greater absorption of CO2, the emissions caused by the activities of 166,000 inhabitants of the island, to which the better storage of CO2 by the soil should be added.
Other calculations tell us that with the transition towards the agroecological system (again only for 10% of companies) there would be an increase in the surfaces of flora useful for pollinators and other insects which, as is known, contribute to a better primary productivity of the topsoil and therefore to a better efficiency of the usual soil/topsoil balance.
Ultimately, the issue of hydrogeological disruption must be addressed with a systemic scientific vision, abandoning the old technological scheme in favor of a more integrated and interrelated one. We also have the rules and laws but we need much greater political will and social sensitivity.

Guido Bissanti

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