Solid digestate as a soil conditioner: benefits over compost and bokashi

Re-publication of an article by Mario A. Rosé on Agronotizie.

There is no doubt that the drought that is tormenting our country is one of the many consequences of climate change. It is not easy to obtain firm evidence on press complaints, but on the other hand, it is also not difficult to believe that bad territorial management involves more than the 30% of losses in water networks.

Unfortunately, we are now used to bad governance. On the other hand, the consumption of water for irrigation it can be drastically reduced with adequate soil management, and if we don't, or if we do it wrong, the fault is ours alone. The water retention capacity, or field capacity, depends on the type of soil (Table 1). Obviously, a farmer cannot change the soil type of his land, but it can improve their field capacity, thus reducing the need for irrigation and, indirectly, also of fertilizers.

Table: Field capacity of soils

Table 1: Field capacity of soils

(Photo Source: University of California, translation and conversion of the units by the author)

(Click on the image to enlarge)

The surplus of water that can store organic matter in any soil depends on many factors, such as the type of tillage, the slope, the depth of the organic layer, etc. One studio critic on sixty publications (1) concludes that, on average, to the values ​​shown in the Table 1 we must add 1,16 millimeters of H2Or for each percentage point of organic carbon each 100 millimeters of organic layer. The relationship between organic matter and organic C is known in the scientific literature as a van Bemmelen factor equal to 1,724, that is, the organic matter of the soil contains the 58% the C. For our calculations we assume 56% (value defined in the Regulations (EC) No 2019/1009, text in Italian).

To example, an arid soil to which a soil improver is added so that i 300 millimeters of surface layer contain the 5% of organic matter, will increase the available water capacity of:

D = 1,16 x 300 mm/100 mm x 5 x 0,56 = 9,74 mm = 9,74 l/m2

It means 1 hectare of this corrected land will be able to retain 97,4 m3 more water available to plants than soil without organic matter. It may seem little, but if we see it on a territorial scale, the potential improvement in water management is significant.

By way of example, the Photo 1 shows the consistency of organic C in Italian soils. It is observed that many areas are now devoid of organic coverage (light grey) and only the soils of the mountain and foothills, together with leopard spots on the plains, have an organic C content > 75 tons / hectare (or > 2%). This implies that the majority of our crops need more irrigation water than would be needed if the soils were richer in organic matter..

C content in Italian soils

Photo 1: C content in Italian soils

(Photo Source: Ispra)

(Click on the image to enlarge)

What has been said so far does not mean that any source of organic C is good for improving soil texture. We have already covered in another item the institutional ravings on the concept of “digestate equated to fertilizers”, concept that, in addition to not being defined in the Decree (it refers to a future decree that perhaps will never arrive), adds confusion to an already complex issue such as the balance of C and nutrients in soils. Recall that the European legislation (Regulation (EC) No 2019/1009, text in Italian) defines seven “functional categories of products” for European fertilizers.


In the context of this article, the organic matter can be classified into three broad categories, but they intersect to a certain extent:

  • Organic soil improvers: contain more C in a stable form (humus), smaller amounts of nutrients (N, P, K…) and live microorganisms in populations varying in quantity and composition.
  • Organic fertilizers: they contain C in reduced and easily oxidizable quantities, consistent amounts of nutrients (N, P, K…) and live microorganisms in populations varying in quantity and composition.
  • Microbial biostimulants: they contain more C in the form of live or latent microbial biomass (mushrooms, protozoa, bacteria and their spores), but they can also contain small proportions of stable C and nutrients.

How they behave therefore the different organic materials when they come into contact with the soil? More or less, the transformation of organic C it undergoes two stages:

  • Mineralization. The microorganisms present in the soil – and possibly also in the same organic matter applied to it – they oxidize organic C by emitting CO2. The percentage of C lost in this way (mineralized) in one year it is known in the literature as the Coefficient of Mineralization (MC o k2 depending on the authors). He k2 depends on the type of soil: the more porous (sandy soils with skeleton) or the more intense and frequent the processing, the greater the circulation of air and therefore the higher will be k2. On the contrary, in clayey soils or with minimal tillage, organic matter is less dispersed.
  • Humification. A part of the organic C (typically lignocellulosic compounds and more concretely lignin) it is refractory to microbial activity and transforms into complex substances, generically called humic substances. A fraction of these (humic acids) it is slowly oxidized and dispersed as CO2. The most refractory and stable fraction constitutes humus. The percentage of organic C that remains in the soil after one year is called the Humification Coefficient (HC or k1 depending on the authors). The absolute amount of humus that remains in the soil after one year is known as Effective Organic Matter (EOM = Effective Organic Matter) and it is the one that we have to replenish every year because in any case the soil microorganisms degrade it to CO2, albeit at a slower pace.

Calculations of the amount of organic matter to add to a depleted soil to restore its fertility, or the one to be added annually to maintain it, require some tables with coefficients k1 e k2, some additional information on the type of soil and soil conditioner and a little’ of patience (see for example the manual of the Campania Region (2)).

For the convenience of our readers we propose a simple online organic soil improver calculator to be applied according to the type of soil, initial organic matter content and desired fertility goal.


Calculate the organic soil improver

Digestate, compost is bokashi: let's be clear

There is a lot of misinformation about’use of digestate in agriculture. On many blogs of political activists and in social networks, digestate is accused – sometimes with partially founded arguments, but of a manipulative or ideological nature – to be harmful to the soil (see for example: I “committees of the no” and the biogas and biomass handbook, What future for bioenergy in the next legislature, No more glycerol in biogas plants – First part e Second part).

The benefits of the bokashi – a particular type of fermented compost originating in Japan – they are many and undeniable, but they are often exaggerated by ideology “bio at any cost” e “anti-system”.

Read also

Efficient Microorganisms: the biorefinery at home?

So let's try to do a little’ of light on the subject, starting with the most controversial fertilizer: the digestate.

The digestate is never used as it comes out of the digester. All plants have a separator, typically screw type, from which two come out “digested” with very different characteristics: solid and liquid. The first tends to be a soil improver: brings to the soil C, P (typically as struvite or hydroxyapatite crystals), and a little’ of live bacteria. The second is more like a liquid fertilizer, it mainly supplies N in ammonia form, K and soluble salts and very little organic C, especially in the form of live bacteria. Paradoxically, the high bioavailability of ammoniacal nitrogen for bacteria means that the reckless application of liquid digestate to the soil suddenly lowers the C ratio:N, making the humification coefficient null or even negative. This fact, told in an exaggerated and incomplete way, is the typical argument of “no biogas” against the agronomic use of digestate – without specifying which fraction – and livestock sewage. The problem is therefore not the use of liquid digestate per se, but the lack of solid digestate (o compost, or straw, or any other source of organic C) in sufficient quantity to maintain a C ratio in the soil:N adequate.

Recall that an organic fertilizer with C:N = 25 it is conducive to the synthesis of stable humic acids, a C:N < 10 facilitates mineralization, a C:N > 30 immobilizes nitrogen, which is consumed by bacteria to break down humic substances, making it unavailable to the roots.

As for the solid fraction of the digestate, its mineralization and humification coefficients depend on the power supply of the digester. A solid digestate from plants fed mainly with vegetable biomass (a sword, agri-food residues, Maybe) it will contain a large fraction of lignin, very refractory substance and direct precursor of humus. A solid digestate from plant fed with sludge or with slaughter residues will have a zero or even negative humification coefficient, therefore it will be more like a fertilizer than a soil improver. The humification coefficient of the solid digestate also depends on the type of separator used (auger or centrifuge) and any post treatments: it is maximum in the case of the solid separated from dried Forsu a 60°C until you have less than 50% humidity (3).

One comparative study (4) on the transformations of carbon in three processes – anaerobic digestion, lactic fermentation and composting – highlighted that the European classification of organic fertilizers is reductive because functional products are not always a mixture of fertilizer, soil conditioner and biostimulator, in variable percentages. The aforementioned study shows that the amount of residual C in the solid digestate is less than that of bokashi or compost, taken for granted because the purpose of anaerobic digestion is precisely to convert most of the biomass into methane. But, the contribution of easily oxidizable organic matter, N and P of the anaerobic amendments of solid digestate and bokashi are practically equivalent. Both also bring their own bacterial flora, favoring the microbial activity of the soil much more than compost. Anaerobic treatments are therefore overall better than composting, which effectively retains a greater fraction of the initial C of the composted material, but it loses more nutrients and does not favor the bacterial activity of the soil so markedly.


Organic fertilization cannot be done on the basis of tables or recipes “flat rate”, in the same way ours online calculator it does not replace the inspection and analysis of a professional. The calculator allows you to make a quick preliminary assessment, after the development of a strategy for restoring the fertility of tired or otherwise impoverished soils and conservation of the same through the annual contribution of organic matter. Such organic matter cannot be of any kind: solid digestate and compost guarantee a C ratio:N more balanced which allows to store more carbon in the soil than organic matter “fresh” (green manure, paglia, stalks) or to materials with zero or negative humification coefficient (sewage, slaughter residues, solid digestate from sludge). The solid digestate from agricultural residues, rich in lignin, it can be considered a soil improver equivalent to compost, but it provides more N and P than the latter and also provides a greater biostimulating effect of the bacterial flora of the soil.

Of course, making solid digestate or commercial compost represents a cost for the farm, that our online calculator makes it easy to estimate. That cost But leads a series of earnings, often not considered in the evaluations of farmers: saving of fertilizers (greater efficiency in the absorption of plants and less washout), saving of water and the corresponding energy for pumping. Ma, mostly, a good organic matter content in the soil reduces the risk of losing the crop due to water stress in the event of drought or torrential rain.


(1) Minasny, B. and McBratney, A.B. (2018), Limited effect of organic matter on soil available water capacity. Eur J Soil Sci, 69: 39-47.

(2) Mauro Mori, Ida Di Mola, et al.; Guide to fertilization – Methods, procedures and tools for a consultancy service; Campania Region – Agriculture Department – Experimentation Sector, Information, Agricultural Research and Consultancy (SESIRCA), 2012. ISBN 978-88-95230-14-6.

(3) Own, C.E., Safeguard, I., control link, I.C. et al. Solid fraction of separated digestate as soil improver: implications for soil fertility and carbon sequestration. J Soils Sediments 21, 678–688 (2021).

(4) Vania Scarlet Chavez-Rico, Paul L.E.. Bodelier, Miriam van Eekert, Valentina Sechi, Adrie Veeken, Cees Buisman, Producing organic amendments: Physicochemical changes in biowaste used in anaerobic digestion, composting, and fermentation, Waste Management, Volume 149, 2022, Pages 177-185, ISSN 0956-053X.


An English village becomes self-sufficient thanks to biogas

Re-publication of an article by Mario A. Rosé on Agronotizie

Bureaucracy and Nimby at Italian levels, but perhaps with clearer regulations.

The political debate of the last month has focused on the consequences for the Italian economy of the international embargo on Russian gas. Despite the Guidelines contained in the communication of the Ce REPowerEU and the Spanish example of a quick and pragmatic reaction to the supply problem, the only answer that Italian politics was able to find was simply to replace dependence on Russia with dependence on other countries. Inter alia, not all democratic or politically stable.

Read also

Biogas and independence from Russian gas: Spain will beat Italy on time?

According to the president of the Italian Biogas Consortium (Cib), Piero Gattoni, to increase by 20% the production of existing biogas plants would be enough only to reduce the bureaucratic burden. Moreover, says Gattoni, the delay in issuing clearer rules on the injection of biomethane into the network has slowed the construction of new plants, which today would be able to replace the 30% of natural gas imports. A delay what time the Government tries to compensate by desperately seeking alternatives abroad.

Meanwhile, the Parliament Italian perseveres in Byzantine discussions on the possibility of reintroducing nuclear power or install more solar panels on the roofs to solve the energy crisis, a small English village has reached the paradigm of’circular economy and l’energy self-sufficiency. South Molton is a rural village with 4.093 inhabitants located in Devon, about 300 miles west of London. L’Condate biogas plant (Opening photo of the article), placed at approx 1,5 kilometers from the town center, produces enough renewable electricity for 2.300 families, and gas for 4.600.

It is one of several plants belonging to the Ixora Energy Group. It is equipped with two cogenerators from 500 kW and an upgrading system with capacities up to 600 m3/h. It looks a lot like any of the over a thousand existing plants in Italy, except for two details: the design choice to install two cogenerators in parallel instead of the usual engine from 1 MW, and the simultaneous production of electricity and biomethane, still a rarity in our country due to unclear regulations.

Thanks to the general manager, Mr Darren Stockley, who kindly gave us his time to answer our questions, we offer our readers a summary on the general state of simultaneous electricity and biomethane production in the UK.

Years ago, in Italy it was allowed to feed the digesters with up to 100% of dedicated crops, and many old plants still operate on this diet. After the revision of the Red II, the limit for new plants has been set at 30% of the total weight in feed. Since the UK is no longer subject to the EU regulations, what are the percentages of dedicated crops and residues / by-products in your feed mixture?

“New plants in the UK must be powered with at least 50% of agricultural residues. Our plants are not subject to this rule, so we can operate with mixtures containing the 20-50% of agricultural residues. Condate works with the 20% of agricultural residues. We are constantly trying to identify new sources of agricultural residues to increase their percentage in the feed mix”.

In your web page it says that Ixora Energy pays local farmers for their manure and by-products. Calculate the price based on measurements of the Bmp of each lot? Or take the German approach, based on Bmp tables?

“We pay farmers based on the content of Ss, Dry substance, of their supplies. We have contracts for the entire life of the plant (15 years) and the price per ton of dry matter is updated every year by an independent expert who reviews their costs”.

Return the digestate to the farmers free of charge or make them pay for it as fertilizer?

“We give it to him for free backards, but we do not allow them to charge us with artificial fertilizer costs in the by-products we buy”.

How do you manage digestate?

“We separate the solid and liquid fractions. The solid is applied directly to the ground. The liquid fraction is currently used as a liquid fertilizer, but we are working with several British and European companies to extract and recycle water. This is an area for which we are very interested in finding a solution”.

Recover the residual heat from the cogenerator and / or the CO2 from the upgrading system for some use?

“The heat is recovered, but only to reduce the humidity of the digestate. We are evaluating several options to make the best use of heat for hydroponic and vertical farming. We are also modifying our plants to capture CO2 for its use in the food industry”.

You have designed the Condate plant from the beginning for the simultaneous production of electricity and biomethane? Or you started as an electrical system and then added biomethane production at a later time?

“It was designed from the outset for the production of electricity and gas. Gas production is limited only by the extent of the pipeline serving our community”.

What are the electrical and biomethane rated powers?

“The flow rate of biomethane to the pipeline is approx 500 m3/h, and the electric power is 1 MW (of which 400 kW represent the self-consumption of the system)”.

The production of electricity and gas are simultaneous, or the electric generator is switched off when biomethane is produced?

“Before, enough electricity is produced to power the plant, then gas production is maximized, then the electric one. Therefore, the production is simultaneous.

How much time did you waste for the bureaucratic procedures before getting permission to start construction and operation?

“They have passed 12-18 months to obtain the building and environmental permits needed to start construction. Lately this problem has gotten worse in the UK, despite the need to become energy self-sufficient”.

There were local protest committees, or spreading fake news on biogas in an attempt to block your project? How did you solve the problem?

“Condate was not a problem, but we have other plants that suffer from the protests of the neighbors. This situation has worsened with the use of social networks. To overcome this problem, we try to invite as many people as possible to visit the site and show them that the rumors about biogas plants are incorrect. We also try to dialogue with local politicians to show the benefits that the plant provides to the environment”.

How the sale of electricity and gas is organized in England? Sell ​​gas and electricity directly to the municipality or to a distributor that owns a local network? Or inject them into the national grid?

“We directly inject gas and electricity into national networks. We sell the production to private energy companies such as BP / Total / EDF, which they resell to the final consumer”.

British regulations recognize a rewarded rate compared to market prices, or subsidize the construction of the plant, or recognize only a fixed proportional to the nominal power of the system?

“We receive a subsidized payment based on actual gas and electricity production. Payment is made monthly by the Government and we must demonstrate our environmental performance by providing detailed information. Everything is regularly checked”.

summing up: the situation in England does not seem so different from the Italian one. Over-regulation seems to be a recurring problem both inside and outside the EU.

England benefits from greater flexibility in the use of dedicated crops to feed the digesters and slightly shorter administrative times, though 12-18 months is not a very short time if we consider the urgency of global climate change. The anaerobic digestion technology of the Condate plant is Central European, as in the majority of Italian plants. The logic of state incentives on biomethane and electricity products, as well as the way these incentives are administered, they look similar in both countries.

Comparing the statistics of energy production from biogas on a national scale, we observe some interesting additional differences on the evolution of both markets (Photo 1).

Graphic: Energy production

Photo 1: Official data on English production. Official data on Italian production. Conversion factors to be able to compare data from different sources: 1 TJ = 23,8846 TEP e 1 GWh = 85,9845 TEP

(Click on the image to enlarge)

On reason for which the biogas industry is growing faster in the UK than in Italy it seems to be legislation.

In Italy, the biogas boom began years earlier than in England, but Italian policies have remained static and at times alternately contradictory, therefore the Italian anaerobic digestion market is still strong globally, but stagnant. In the United Kingdom, the sector expanded between 2009 and the 2017 under the legislation known as Renewables Obligation (RO), main incentive mechanism for large renewable energy projects. In March 2017 RO is over and most of the significant growth in energy produced by anaerobic digestion is attributed to various mechanisms, specially designed to provide sufficient financial incentives to reduce the cost gap between conventional and renewable energy sources.

A example of these is the non-domestic Renewable Heat Incentive (Rhi, incentive for the production of heat for non-domestic use), which provides payments to encourage the production of renewable heat, both through direct production (combustion of biogas on site) and injection of biomethane into the network. In Italy, there is no direct combustion support policy for the production of heat from biogas. Incentives for heat recovery from cogenerators are not attractive to investors and plants capable of producing electricity and biomethane are just a handful.

Then, we deduce that the culprits of the stagnation of the biogas industry in Italy are bureaucracy and short-sighted policies. Elementary, Watson!

Biogas and independence from Russian gas: Spain will beat Italy on time?

advanced digester prototype

Re-publication of an article by Mario A. Rosé on Agronotizie.

The Spanish Council of Ministers approves the Guidelines to encourage biogas in record time.

Last 22 March the Spanish Council of Ministers approved the Guidelines on the Development of the Biogas Sector (full text in Spanish in This Page). A draft of the same had been submitted for public consultation in September 2021, receiving several suggestions from the Spanish trade associations which were included in the final document.

On conflict in Ukraine and the consequent price increase of fossil fuels pushed the European Commission to an official position with its Communication to European Parliament: REPowerEU: common European action for safer energy, more sustainable and at more affordable prices (Italian texts of the Communication and related annexes in This Page).

For several years the Spanish government has been trying to catch up on the development of renewable energies caused by previous governments. The war in Ukraine and the European thrusts have served to overcome the ideological discussions between the various parties at once, finding a agreement for the common good. This should be the norm in any democracy, but in a country that is culturally very similar to Italy, an agreement between parties based on scientific criteria is a rarity that constitutes news.

In a nutshell, the Guidelines just approved foresee:

  • Overcoming i 10,4 TWh, which means to multiply by 3,8 current biogas production by 2030 strengthening the circular economy and stopping the exodus of the rural population by creating new supply chains. It is expected to avoid the emission into the atmosphere of about 2,1 million tons of CO2 equivalent to the year.
  • Create a system of guarantees of origin for renewable gas, already in progress, with the possibility of setting objectives and entry quotas to develop the market.
  • Activate an aid line to implement biogas projects, for a value of 150 million euros, borne by the Recovery Plan, Transformation and Resilience (Prtr).

The Spanish strategy does not leave out any potentially fermentable matrix or push for a concrete model: agricultural waste, Forsu and mud will be used to produce electricity, industrial heat or traction biomethane. It is important to note that the Spaniards included in the plan the production of heat directly from biogas to be used in the same digestion plant or in small district heating networks.. Thermal use is the most logical and economical for biogas, but it has never been taken into consideration by the production model imposed in Europe which sees electricity generation or upgrading to biomethane as the only valid options, much more expensive and complex.

The Spanish plan to incentivize biogas includes 45 measures divided into five lines of action:

  • Regulatory tools. A guarantee of origin system will be created so that consumers can distinguish whether they purchase energy from biogas or natural gas. The simplification of the authorization procedures and above all the homogenization of the interpretations made by local authorities is expected – due to delays in Spain as in Italy – in particular with regard to the sustainable management of digestate as fertilized. On this last point, the reading of the text gives a glimpse of a somewhat approach’ leopard: the Spanish laws are simply listed which contain more or less the same ideological vices as the infamous Effluents Decree and the concept of “end of waste” – end of the legal status of refusal – for it is not clear what the simplification will be. As in Italy, digestate from sewage sludge will continue to be excluded from agricultural use.

Read also

The point of the situation on the Effluents Decree

  • Sectoral instruments. The possibility of defining annual targets for sales volumes or biogas consumption is established, mandatory quotas, as is done for example with liquid biofuels. It is proposed to encourage the production of biogas with the aim that it is consumed in situ, for example as process heat in the agri-food industry or in the waste treatment process, or in vehicle fleets. In accordance with the ideology of Green Deal and the anti-biomethane ideology of the Spanish right is mentioned the possibility of injecting biomethane into the grid or converting biogas into hydrogen, provided that it proves economically viable.

Read also

Hydrogen from biomethane, biomethane from hydrogen

  • Economic tools. It is proposed to divert existing aid funds (national programs) to finance the innovation and technological development of biogas and also take advantage of the Recovery Plan, Transformation and Resilience (Prtr). Apparently, the latter already provided for aid actions to the biogas sector, therefore its inclusion in the new Guidelines would seem rather a reminder or a kind of harmonization of measures.
  • Cross tools. An effort will be made to prioritize biogas projects in disadvantaged areas, to introduce it in public procurement specifications. The study of anaerobic digestion technology will be included among the technical training subjects. Citizen awareness campaigns will be organized to improve the quality of separate waste collection. The creation of rural energy communities and working groups within agricultural cooperatives will be facilitated to facilitate its implementation. The participation and coordination of research projects financed by the’European Union.
  • Driving research and development. Promote research into techniques for reducing emissions of contaminating gases that are not greenhouse gases, promote demonstration projects on the thermal use of biogas in industry and agriculture or innovation on less mature digestion technologies. It is not clear what the relationship of biogas with i is “non-greenhouse gas contaminants”, what these gases are or why some of the resources that should be used to promote biogas should be diverted to this small research niche. Whereas about the 60% of biomass (vegetable) when fed to the digester it comes out without being digested, the priority of research should be to increase digestion efficiency at all costs.

Read also

Digestate re-digestion and thermophilic digestion

The provision of the Spanish government provides us some food for thought:

  • Although Spain is a country that is less methanized and less dependent on Russian gas than Italy, ideology “anti biogas” it weighs less among the Spanish parties. The fear of war made it possible to find an agreement relatively quickly despite the extreme fragmentation of political forces and regional parochialisms that characterize our Iberian cousins.
  • The institutional attitude towards methane is more pragmatic – to put it mildly – in Spain than in Italy. To example, the project of the regasification plant in the port of Mugardos (A Coruna) has been exempted from the Environmental Impact Assessment (Via). In Italy, instead, the opposition to regasification terminal in the port of Trieste it demonstrated the ideological myopia and parochialism that characterize the Italian political class: for the then regional president Debora Serracchiani “it is incompatible with the Town Plan”; for the then minister Carlo Calenda “it is not strategic”; for the regional councilor Sara Vito is “oversized for the needs of the region”; e for the deputy Aris Prodani the Via had to be revoked due to a series of bureaucratic quibbles. The conspiracy hypotheses around the project are those common to the “committees of the no” and al M5S. We report a item as an example whose author hides behind a nickname.
    In a civilized country, a work of the scale of a regasification plant should be evaluated in a logical and rational way, with a view to the long-term national interest. Nor with the parochial conspiracy attitude of Friuli Venezia Giulia, but not even with an uncritical acceptance as in the Galician project.
  • The Spanish plan acknowledges and aims to enhance the environmental benefits of anaerobic digestion. The goal of a partial self-sufficiency on methane is therefore not an end in itself, but included in a broader circular economy perspective. In Italy, instead, we find an opposite example in the Autonomous Province of Trento where it is planned to methanize 47 mountain municipalities that would be perfectly self-sufficient with a modern and rational management of forest biomass.
    As the president of the Italian Federation for Renewable Energy (fiber), Walter Righini, in a press release: “In our country, the energy-programmable agroforestry complex would be able, if oriented properly, to avoid the import of at least 13 billions of cubic meters of natural gas, all with a very important financial impact on the national economic system. It deals with, indeed, of a value equal to 35/40% of the import of gas from Russia recorded in 2021, which today translates to 27-40 billion euros / year”. Among the points highlighted by President Righini, in his speech, there was also the importance of encouraging the development of biomethane for transport.
  • As for the issue of greenhouse gases it is as obvious as the politicians (and not only those of Rome and Madrid) they bring up the argument to defend their positions, without, however, having any scientific evaluation criteria. We have already pointed out in other articles the conceptual errors in the European doctrine of clean hydrogen (Biomass hydrogen and Green Deal e The return of biohydrogen) and also those of the no biogas political groups (I “committees of the no” and the vademecum no biogas and biomass e What future for bioenergy in the next legislature?). The commonplace is the demonization of conventional agriculture and livestock farming, guilty of methane emissions. The irrefutable reality is quite different. According to the data collected by the European satellite Ghgsat, the most technologically advanced tool for identifying methane emissions into the atmosphere, the contribution of agriculture and livestock is irrelevant. The main emitters of methane are the fossil fuel mining industries (Petroleum, natural gas and coal), followed by waste dumps (Photo 1). The emissions of Europe count for very little in the global balance, the main emitter of methane is China, followed at a great distance by the USA and Russia (Photo 2).


Methane emissions into the atmosphere by product sector

Photo 1: Methane emissions into the atmosphere by product sector. Ghgsat surveys, Relationship 2021, texts in Italian by the author

(Click on the image to enlarge)


Atmospheric methane emissions related to the coal mining industry

Photo 2: Methane emissions into the atmosphere related to the coal mining industry. Ghgsat surveys, Relationship 2021. Four mines in China and one opencast in Kazakhstan emit about the same as all other coal mines in the rest of the world

(Click on the image to enlarge)

Personal reflections of the author

Autarchy was a valid political philosophical concept (perhaps) at the time of the Cyrene philosophers, but it is utopian for an industrialized and interconnected society like that of the twenty-first century. But, without falling into the illusions of the fascist era – even those without a logical or scientific basis – it is undeniable that a certain amount of self-sufficiency – based on circular economy criteria – and a policy of diversification of resources – based on common sense – are essential to ensure the energy resilience of a nation.
By overcoming party ideologies in a timely manner to respond to the energy crisis in one's country, Spanish politics has given us a little lesson in pragmatism. The Italian political class, in the meantime, continues to waste time debating the moral and ethical implications of supplying or not supplying arms to Ukraine, or whether to allocate the 2% of the Gross Domestic Product (Pil) military spending will anger the Pope or whether Senator A or Deputy B are “Putinians”. According to the Savoyard philosopher Joseph De Maistre (1753-1821), “Every nation has the government it deserves”. But what have we done to deserve a government of Crocian pseudo philosophers for whom emotional reactions matter more than logic or science??



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.

Manure biomethane is more sustainable than hydrogen

Re-release of a article by Mario A. Rosato on Agronotizie

On Jrc (Joint research centre, Joint Research Center) is the institution that coordinates the European scientific community and elaborates the technical-scientific reports on which the European Parliament should then define its development policies. The last one studio on energy efficiency ed CO emissions2 in the transport sector was released in late September 2020. It is a colossal analytical work, which includes beyond 1.500 combinations of energy carriers and production and conversion technologies.

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From clean hydrogen to green ammonia. The ideological contradictions of the Green deal.

Re-publication of an article by Mario A. Rosé on Agronotizie

The trade association Hydrogen Europe is presented as a partnership between the European industries promoting technologies related to the use of hydrogen and the European Commission. This is a lobby, in the Anglo-Saxon sense of the term, or: "Group of people trying to influence lawmakers on a particular topic" (definition from the Oxford Dictionary ). We will not go into the merits if the interest of the association is that declared on the institutional web page - decarbonising the European economy- or the economic one of a group of multinational industries and spin-offs, or even worse, if it only serves to mask the hegemonic forces of the countries to which these companies belong under a "technical" appearance. In this article we will analyze what the consequences could be for our farms if the Italian government were to unconditionally follow the doctrine of "clean hydrogen" promoted by the Green Deal.

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The selection of the inoculum for the biogas plant – III Part

Easy Methane Lab

For each by-product its digestate!

Re-publication of an article by Mario A. Rosé on Agronotizie

In Part I of this article we have explained how an anaerobic digestion system works by comparing it with a “breeding of bacteria”. For the proper functioning of a biogas plant, its manager must know how to choose the inoculum according to the by-products with which the digester will be fed, just as a breeder chooses the breed to breed according to the business purpose, for example dairy or beef cattle. On the sidelines of the verification of methanogenic activity (SMA) – explained in Part II of this article – it is important to verify the ability of the inoculum to degrade complex organic matrices, such as cellulose, proteins and fats.

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How to select the inoculum for the biogas plant – Part II

BRS bioprocess control

The specific methanogenic activity (High school): realization and interpretation of the test results.

Re-publication of an article by Mario A. Rosé on Agronotizie

In Part I of this article we have illustrated how the biological activity of an inoculum is measured by introducing a certain amount of reference substrate into a test reactor and verifying that for each gram of COD (Chemical oxygen demand) are produced at least 350 Ncm3 of methane.

Let's analyze in this Part II of article le peculiarities of the test of Specific Methanogenic Activity (High school).

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How to select the inoculum for the biogas plant – Part I


The specific methanogenic activity (High school): a very useful test but still to be normalized. Re-publication of an article by Mario A. Rosé on Agronotizie

“I often say that when you canto measure what you are talking about, and express it in numbers, thensai something of it; but if you can'tmeasure it, if you can't express it in numbers, your knowledge is meager and unsatisfactory; it can be the beginning of knowledge, but he will not have allowed you, in your mind, to advance in the progress ofscience, whatever the discipline”.
  William Thomson, The Barons of Kelvin (Lesson on “Electrical units of measurement”, 3 May 1883)

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The biological self-management of the biogas plant


Re-publication of an article by Mario A. Rosé on Agronotizie

Optimally manage a biogas plant it means becoming a "breeder of bacteria".
Like farm animals, i battery they do their best if they are kept in conditions that are optimal for them, it is therefore essential to monitor the various aspects that affect the functioning of the entire anaerobic system. It is known to all that the different manufacturers and some independent workshops, offer biological care service.
Typically all of these services have a weakness: the results are not provided in real time. Moreover, the analyzes provided, generally they only concern the dynamics of the anaerobic degradation process, but not the verification of the biomass quality – silage or by-products that are – with which the system is powered.

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