The role of bioenergy in soil protection

republication of an article by Mario A. Rosé on Agronotizie

In data 24 February 2021 it was held, in webinar format, the conference “Caring for soil is caring for life”, as part of the European Mission for Soil and Food Health.
The event was organized by the Ministry for University and Research, Opens, Agency for the Promotion of European Research, Resoil foundation e Santa Chiara Lab (University of Siena). The Minister for University and Research has opened the meeting, Cristina Messa, and Dr. Antonio Parenti, head of the European Commission Representation in Italy.
The video recording was made available to the public on the Open YouTube channel. The presentations of the various speakers can be downloaded from this page.

Environmental problems, social and economic degradation of agricultural soils, overbuilding and other phenomena induced by human activity, they are extremely complex and go beyond the main topic of this column. We offer our readers a report to Professor Giuseppe Corti, president of Sipe, Italian Society of Pedology, who kindly gave us a deepening of his presentation, focused on the potential of agro-energy for soil recovery.

Why is the health of European soils a concern??
“The concern is great and has been denounced for several years by the scientific societies that deal with soil. My company (Sipe), eg, in 2013 has presented a bill to uniquely define the soil and safeguard it; the proposal received a number (the 1181) after some years, but it was never scheduled. After a few more years, during a meeting, a government official told us (verbatim): 'Your proposal will never find acceptance for adverse crystallized interests!’. Then, evidently, we are not compatible with the general interests of the country. And we instead thought we were working for the good of the country, because the soil is the basis of a healthy and lively economic and social policy without which we can hardly hope for a brighter future than the past.

In any case, the most urgent threats facing soil across Europe are ten:

Reduction of organic matter. The problem of problems. In fifty-seventy years of intensive agriculture not harmonized with the pedoclimatic conditions, it has also produced 3% (absolute) of organic matter from agricultural soils. We have soils with less than 1% of organic matter, whose management becomes more and more difficult. (1)
Erosion. Unsustainable! In many areas of the country, erosion also takes away 1 centimeter of soil per year, in some cases even 2. Consider that 1 centimeter of soil per hectare per year means 100 tons of land per hectare removed every year, that sooner or later will end up in the sea, creating eutrophication problems. Then, double damage: the most fertile part of soil leaves and becomes a pollutant of the seas. (2)
Pollution. Italy is among the countries with the largest amount of areas polluted by organic pollutants (Petroleum, oil…) and minerals (especially heavy metals). If we start right away, we may be able to successfully recover the less polluted soils in a few decades, for others it will take centuries. And all this time, those soils will prevent the production of food and will not help purify the water. (3)
Soil consumption and sealing. Even in the midst of the economic crisis following the collapse of the so-called construction bubble, in Italy we continued to consume land at a rate of 10 thousand hectares per year (Ispra data). To do what? To sell to whom? We have tens of thousands of empty buildings, skeletal, abandoned, unsold that fall on themselves. Useless to the economy and the country, where, however, it is no longer possible to produce anything. We have areas covered with useless concrete or asphalt, where we could have grown chickpeas, tomatoes, eggplant .... Nothing, we'll never do anything about it again. (4)
Salinization. Problem on the rise throughout Italy. The soils are becoming rich in salt, of marine origin in the vast majority of cases. We also blame climate change, but we begin to check the concessions of the wells and swoop down the illegal ones. Then we also talk about climate. (5)
Loss of biodiversity. The reduction of organic matter and erosion have already caused a great loss of biodiversity at the level of higher organisms (snakes, amphibians, insects, spiders, …), but also in soil microorganisms. And to think that in many cases, at least the cleansing of organic pollutants could be easily canceled by the soil's trophic chain. (6)
Vertisolization. Soils with a significant amount of clay (greater than 30%), if in a climate that foresees a strong alternation between the rainy season and the dry season they tend to become dizzy, that is, to form fractures that deepen even further 1 metro. The cause of the transformation is partly to be found in the extreme rainy events, but it is largely caused by erosion, which prevents more and more water from penetrating the soil. Once the process has begun, difficult to go back, with the impossibility of continuing to produce tree and shrub crops. (7)
Entisolizzione. With erosion accelerated at a rate of 1-2 centimeters per year, soils become Entisols. This is how soil scientists define soils that have now become not very fertile terrigenous mattresses, without an optimal differentiation in horizons, reduced production capacity. Commonly defined as “soil-not-soil”, they represent the step before the disappearance of the soil itself. (8)
Acidification. This is a problem that does not interest Italy too much but, Rather, the countries of Northern Europe, dell’Africa, of South America and China. As acidification proceeds, the ability to retain nutrients is reduced and food production drops inexorably.
Fires. Another huge problem affecting forest and natural soils. It must be said that, absolutely, fire is also an evolutionary agent of vegetation, but if it is repeated with excessive frequencies (due to mismanagement or vandalism) then it involves a degradation of vegetation and soil”.

In Italian soils we have lost the 2-3% of organic matter in the last fifty-seventy years. It is not enough to add compost and / or digestate? Because in Italy it is “virtually prohibited” use the sludge deriving from sewage treatment? If they are dangerous, as i claim “local committees”, environmental groups and some politicians, why in countries like Sweden they are even used in organic farming?
“For the first question, unfortunately it may not be enough to add organic substance to the soil to see it increase. It can happen in cold environments, we say from us above at least one thousand-1,200 meters of altitude, but not elsewhere. And the reason is the activation of the microflora, the more active the more easily degradable is the organic substance. For the second question I answer that unfortunately in this country things are banned because we do not trust who could go to manage them., perhaps because we imagine that others behave as I would behave in their place ...”.

What can you tell us about biochar? Better to apply it alone, or mixed with compost, or to digestate?
“We must get rid of the fact that biochar is the panacea for all evil. For biochar to have an effect on crops, a soil thickness of at least 20 centimeters contains at least 1% of biochar. If we plan to improve the conditions of degraded soils by adding biochar, the forests of two planets like the Earth would not be enough! Biochar is an excellent solution for small surfaces, where it does its best to increase and improve production (also reducing the availability of heavy metals) when combined with other fertilizers”. (9, 10)

Since the area more “biodiverse” of the soil are i 30 superficial centimeters: we must deduce that it is better to use herbaceous energy crops to decontaminate soils? There is a criterion for choosing between herbaceous and woody?
“The greatest biodiversity of the soil is in the former 30 centimeters because that is the thickness of the soil richest in organic matter (which is the substrate on which microorganisms live) and oxygen. This does not mean that there are important microorganisms even at greater depths. To decontaminate soils, probably the best solution is to use both types of plants, arboreal and herbaceous, so as to affect a wider thickness of soil from which to extract (in the case of heavy metals) or in which to degrade (in the case of organic materials) pollutants. But we must be aware that, In many cases, it will take decades or centuries to bring the pollutant values ​​back to the current legal parameters, also using varieties of plants with high absorbing or degrading power of pollutants”.

What an energy crop it is, in his opinion, the most suitable for containing erosion? Why do you say there is still a need for field research rather than desk research?
“There is probably no crop more suitable for reducing erosion, rather a productive system (choice of crop / crops, type of processing, development of hydraulic arrangements) that aims to reduce runoff formation, that is, the surface flowing water.
It takes field research why, also guilty of ridiculous funding to cope with field and long-term research, more and more research is being done based on pedofunctions and models, sometimes without even trying again in the field the veracity of the model developed, but based on values ​​published by other authors on soils similar to those considered in the desk research. If we want to acquire seriousness and authority in this field of study, in a country that badly needs it, research needs to be funded in the field, where you go to test the validity of a production system for years. The variability of weather events is such that based on one year's data we could conclude that there is no erosion, except the year after they found themselves with hundreds of tons of soil removed. We need targeted research, functional in order to reduce erosion, multi-year e, then, adequate funding”.

How should the different agro-energy chains be integrated with soil protection policies?
“In a very simple way: polluted soils must be cultivated to eliminate pollutants with the biomass produced (obviously no food or fibers can be produced). Which means moving the problem from soil to biomass, with which we would not know what to do. Furthermore, at high costs and continued for decades, at least! How is it possible that the community can absorb such expenses? One possibility is to create biomass processing chains that can be economically sustainable, so that there is convenience in cultivating those soils, moving towards a progressive de-pollution. One possibility is therefore to assess the level and type of pollution and proceed with one type of supply chain rather than another.

For example, in case of minor pollution, herbaceous crops can be grown from which to produce methane (via digestore), ethanol (via fermentation), automotive oil (via extraction) and with residues (and other organic matter) produce soil improvers by composting that could re-enter the soil as fertilizer. Or, in the case of major pollution, produce firewood, from whose ashes to extract metals by electrochemical way. Consider that the extraction of metals such as gold, silver, platinum, chromium and others is cost effective starting from the ashes. A metal extraction plant could therefore be fed with ash from biomass power plants produced in polluted sites, without producing air pollution, helping to reduce our dependence on fossil fuels and creating jobs. (10)
in conclusion, bad to say so as not to stimulate its increase, but we can transform a problem such as that of polluting soils into an economic opportunity that acts as a driving force for their de-pollution”.

Photo 1: Possible agro-energy production chains for soil decontamination. (Photo Source: presentation by Professor Giuseppe Corti during the conference “Caring for soil is caring for life”)


The health of European and Italian soils is threatened by many anthropogenic causes e, to a much lesser extent, from climate change. We must therefore stop using climate change as a mitigating factor for the impossibility of improving the condition of our soils. Research has shown, for years, that land management has much more responsibility than climate change in degradation. This means that we no longer have time available and that we can start work without waiting for the climate to normalize or return to the levels of the second half of the century.. XX. We have to channel all our energies, technical and economic, in the undertaking of recovering degraded soils, with the commitment not to detract from those who are not yet.
At the European and national level, the conservation and recovery or improvement of the health of agricultural soils is also a duty to debase the drive to occupy forest soils, problem that is occurring in many parts of the world. We owe it to our children and grandchildren more than to us either, If we want, to our consciences.

Bibliographical references

(1) Short G., Cocco S., Brecciaroli G., Agnelli A., Seddaiu G.. (2013). Italian soil management from Antiquity to Nowadays. Chapter 9, pp. 247-293. In: Costantini, E.A.C., and Dazzi, C. (Eds.) The soils of Italy. World soils book series. Springer Science+Business Media, Dordrecht.
(2) Short G., Horse E., Cocco S., Biddoccu M., Brecciaroli G., Lambs A. (2011). Evaluation of erosion intensity and some of its consequences in Vineyards from two Hilly Environments Under a Mediterranean Type of Climate, Italy. In: Godone D., Tired S. (Eds.) Soil erosion in agriculture. Chapter 6. InTech Open Access Publisher, Rijeka, Croatia. ISBN 978-953-307-435-1.
(3) Visit this page.
(4) Visit this page.
(5) Dazzi C., The Pope G., 2013. Soil threats. Chapter 6, pp. 205-245. In: Costantini, E.A.C., and Dazzi, C. (Eds.) The Soils of Italy. World soils book series. Springer Science+Business Media, Dordrecht.
(6) Visit this page.
(7) Visit this page.
(8) Dazzi C., Monteleone S. (2002) – Soil emergency and anthropization of the territory: an example of loss of pedodiversity due to entisolization. Proceedings of the conference of the Cinquantenaire Siss “The soil emergency” Boll. SISS vol. 51, n° 1-2, pp. 557-570.
(9) Visit this and this page.
(10) Visit this page.