Soil organic matter (SOM) plays a vital role not only in soil fertility and quality (by providing a number of physical, chemical, and biological benefits), but also in C cycling.
The decline of SOM represents one of the most serious threats facing many arable lands of the world. Crop residues and animal manures have long been used as soil organic amendments to preserve and enhance SOM pools. Nowadays, organic amendments originate from many kinds of organic wastes, which are being increasingly produced mainly by farms, food and energy industries, and municipalities. Besides serving as a source of organic matter and plant nutrients, these materials may contribute to fight plant diseases and reduce soil contamination, erosion, and desertification.
At the same time, a safe and useful application of organic amendments requires an in-depth scientific knowledge of their nature and impacts on the soil-plant system, as well as on the surrounding environment.
This session will focus on the current research and recent advances on the use of organic amendments in modern agriculture as well as for the restoration of degraded soils, covering physical, chemical, biological, biochemical, environmental and socio-economical aspects.

Convener: Claudio Zaccone | Co-conveners: Gabriel Gascó Guerrero, Ana María Méndez, Maurizio Ventura, Claudia Kammann, Jorge Paz-Ferreiro, César Plaza
| Attendance Tue, 05 May, 10:45–12:30 (CEST), Attendance Tue, 05 May, 14:00–15:45 (CEST)

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Chat time: Tuesday, 5 May 2020, 10:45–12:30

Chairperson: Claudio Zaccone
D2221 |
| Highlight
Maria Pimenta, Ruben Sakrabani, Wilfred Otten, Gabriel Gasco, and Ana Maria Mendez

Currently, phosphorus (P) mine reserves are monopolised by several countries and its market price variations represents a challenge for modern agriculture systems. Consequently relying on alternative renewable sources of P such as sewage sludge (SS) is timely as its supply is expected to increase with population worldwide. However, this has to be carefully managed to ensure potential pollutant transport when applied to soils.

However, alternative treatment options can reduce this risk and create greater value from SS as a P-fertiliser. By carbonizing the residues through Pyrolysis or Hydrothermal Carbonization (HTC), organic pollutants can be significantly decomposed, and its volume reduced, which ease enormously its management (R. Huang & Tang, 2015). Different characteristics will be obtained depending on the thermal process and the conditions to which the sample is subjected, differentiating the potential applications of the pyrochar/hydrochar obtained respectively. Nevertheless, the data gathered for yield crop responses from sewage sludge thermal derivatives is still very scarce and hence more information needs to be produced.

The aim of this research is to evaluate interactions in phosphorus availability of spring wheat from SS and its thermally treated derivatives, when added on its own and in combination with raw SS as soil amendment. Two pyrochars were produced at the Polytechnic University of Madrid though pyrolysis at 400⁰C-1h and 300⁰C-1h using pre-oven dried (105⁰C-48h) sewage sludge from Spain.  Two hydrochars were obtained through Hydrothermal Carbonization in another reactor at 180⁰C-4h and 240⁰C-4h using raw sludge adjusted to 15% d.m. All samples were analyzed for physical-chemical changes and applied to the soil in a glasshouse experiment.

Results confirmed different degrees of carbonization through the selected treatments, gaining similar characteristics to sub-bituminous coals after pyrolysis and midpoint after HTC. A germination test indicated that the phytotoxicity of the raw material was reduced after all thermal treatments, with the best effect being through pyrolysis. However, P availability was reduced in all derivatives, 65.6% in Pyrochars and 41.5% HTC from the original SS.

 A 136 pots study with amended soils at different rates showed that despite P availability on initial conditions, after 3 months P became more available, being at least twice the amount found in the original soil, higher if the treatments were combined with additional wet SS (1:1). It also revealed a reduction of pHinitial=[7-8] to pHfinal=[6-7] after harvesting and a slight increment on the Electrical Conductivity [0.15-6.7]µS/cm (max value 16.6µS/cm) probably due the different mineralization of the derivatives amendments and the washing of the materials through the soil profiles.

The data gathered with this research to date suggests that, the addition of the sewage sludge derivatives on their own indeed decreases the production of grain. However, with the combination of a commercialized sludge (SS2) at the highest rate, no negative effects have been reported after the first crop season. Derived pyrochar and hydrochar offer an alternative source of available phosphorus to mitigate the growing demand of mineral phosphorus reserves whilst providing at the same time a good base of organic matter for low fertile soils.

How to cite: Pimenta, M., Sakrabani, R., Otten, W., Gasco, G., and Mendez, A. M.: Evaluating phosphorus availability from sewage sludge derived pyrochar and hydrochar in European agriculture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22161, https://doi.org/10.5194/egusphere-egu2020-22161, 2020.

D2222 |
Irene Criscuoli, Maurizio Ventura, Katja Wiedner, Bruno Glaser, Pietro Panzacchi, Christian Ceccon, Marta Petrillo, Damiano Zanotelli, Carlo Andreotti, and Giustino Tonon

Biochar is a carbonaceous material produced through the pyro-gasification of biomass. In the last decade, biochar has been proposed as a soil amendment because it can improve soil physico-chemical properties and carbon stocks, contributing to climate change mitigation.

In the framework of the Wood-Up project (Optimization of WOOD gasification chain in South Tyrol to prodUce bioenergy and other high-value green Products to enhance soil fertility and mitigate climate change, FESR1028), we studied the impact of conifer wood biochar on the emissions of the main greenhouse gases (GHGs) from the soil: carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4), as well as on the soil carbon stock of agricultural fields in South Tyrol.

In May 2017, 25 and 50 t ha-1 of pure biochar and biochar mixed with compost (45 t ha-1), were applied to the soil of a vineyard near Merano (South-Tyrol, northern Italy) following a randomized block experimental design with four replicates per treatment.

Soil GHGs fluxes were monitored from June 2017 until December 2019. Fluxes were measured, in real time, with a high-resolution portable multi-gas analyzer based on cavity ring-down spectroscopy technology (Picarro inc., Santa Clara, CA, USA) connected to an automated dynamic chambers system (Eosense Inc., Dartmouth, NS, Canada). Gas emissions were measured monthly and were related to soil temperature and moisture to evaluate the impact of treatments on the sensitivity of GHGs fluxes to environmental parameters. The stability of conifer wood biochar in soil was assessed through the quantification of the Benzene PolyCarboxylic Acids (BPCA), specific biomarkers of black carbon, over time. The BPCA content in the soil was measured before the application of biochar and compost, three weeks after the application and two years later.

During the first year of experiment, in biochar-amended soils, we observed a reduction of the temperature sensitivity of all GHGs fluxes in comparison to treatments without biochar (control and compost alone). In the second and third year an opposite trend was observed, with an increase of temperature sensitivity of GHGs fluxes in biochar-treated soil. The change of biochar effect over time might be linked to biochar ageing in soil. However, a role of soil moisture cannot be excluded, as it was higher in the first year of experiment. The experimental results will be presented in the broader context of the Wood-Up project.

How to cite: Criscuoli, I., Ventura, M., Wiedner, K., Glaser, B., Panzacchi, P., Ceccon, C., Petrillo, M., Zanotelli, D., Andreotti, C., and Tonon, G.: Conifer wood biochar as an amendment for agricultural soils in South-Tyrol: impact on greenhouse gases emissions and soil carbon stocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6817, https://doi.org/10.5194/egusphere-egu2020-6817, 2020.

D2223 |
Paloma Campos Díaz de Mayorga, Ana Z. Miller, Heike Knicker, Águeda Sánchez-Martín, Elena Fernández-Boy, and José María De la Rosa

Biochar, the solid carbonaceous material produced by pyrolysis of biomass, is a promising alternative for restoring degraded soils [1]. Specifically, biochar has been reported to increase agronomic productivity of acidic soils. Nevertheless, the theoretical high stability and recalcitrance of biochar is being questioned by recent studies [2]. In addition, the alterations on biochar C after its application into low C soil is still under debate. Thus, this study intends to evaluate the changes in carbon stability when biochars from different feedstock are applied into trace element polluted soils.

For this purpose, biochars were produced from rice husk-RHB, olive pit-OPB and almond shell-ASB using a steel batch reactor (temperature of 500 ºC; reaction time of 2 h under N2 atmosphere with a heating rate of 20 ºC min-1). A certified wood biochar (CWB) was also studied for comparative purposes. Two soils with a moderate and a high concentration of trace elements (called MPS and HPS respectively) were sampled for this study. Mixtures of each soil and 10 % (w/w) of the biochars were prepared in triplicates. Each pot was inoculated with 1 ml of a standard microbial suspension, the moisture was adjusted to 50 % of the water holding capacity and incubated in the automatic respirometer Respicond (Nordgren Innovations, Sweden) at 25 ºC for 60 days similarly to the procedure described by De la Rosa et al (2018) [2]. The CO2 released was measured automatically every 6 h and the kinetics of the biological decomposition of the materials were fitted by a double exponential model. Results showed that the feedstock nature influenced the decomposition rates. Thus, the biochar stability of the tested materials followed the order ASB>RHB>OPB according to MTR2.

Soil respiration showed a different C decomposition rate in both soils, having greater mean residence time in HPS (MTR2=14.9 years) than in MPS (MTR2=5.7 years). Our findings suggest that biochar addition increased the MTR2 of the slow C pool in both soils.


[1] Lehmann, J., Joseph, S., 2015. Biochar for environmental management: science and technology. 2nd ed. London & New York: Earthscan from Routledge.

[2] De la Rosa, J.M., Rosado, M., Paneque, M., Miller, A.Z., Knicker, H., 2018. Effects of aging under field conditions on biochar structure and composition: Implications for biochar stability in soils. Science of the Total Environment 613-614, 969-976.


The former Spanish Ministry of Economy, Industry and Competitiveness (MINEICO) and AEI/FEDER are thanked for funding the projects CGL2016-76498-R and GL2015-64811-P. P. Campos thanks the “Fundación Tatiana Pérez de Guzmán el Bueno” for funding her PhD.

How to cite: Campos Díaz de Mayorga, P., Miller, A. Z., Knicker, H., Sánchez-Martín, Á., Fernández-Boy, E., and De la Rosa, J. M.: Effect of biochar application at a trace-elements polluted area on soil carbon stability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-856, https://doi.org/10.5194/egusphere-egu2020-856, 2020.

D2224 |
David Lefebvre, Jeroen Meersmans, Guy Kirk, and Adrian Williams

Harvesting sugarcane (Saccharum officinarum) produces large quantities of biomass residues. We investigated the potential for converting these residues into biochar (recalcitrant carbon rich material) for soil carbon (C) sequestration. We modified a version of the RothC soil carbon model to follow changes in soil C stocks considering different amounts of fresh sugarcane residues and biochar (including recalcitrant and labile biochar fractions). We used Sao Paulo State (Brazil) as a case study due to its large sugarcane production and associated soil C sequestration potential.

Mechanical harvesting of sugarcane fields leaves behind > 10 t dry matter of trash (leaves) ha-1 year-1. Although trash blanketing increases soil fertility, an excessive amount is detrimental and reduces the subsequent crop yield. After the optimal trash blanketing amount, sugarcane cultivation still produces 5.9 t C ha-1 year-1 of excess trash and bagasse (processing residues) which are available for subsequent use.

The available residues could produce 2.5 t of slow-pyrolysis (550°C) biochar C ha-1 year-1. The model predicts this could increase sugarcane field soil C stock on average by 2.4 ± 0.4 t C ha‑1 year‑1, after accounting for the climate and soil type variability across the State. Comparing different scenarios, we found that applying fresh residues into the field results in a smaller increase in soil C stock compared to the biochar because the soil C approaches a new equilibrium. For instance, adding 1.2 t of biochar C ha‑1 year‑1 along with 3.2 t of fresh residue C ha‑1 year‑1 increased the soil C stock by 1.8 t C ha‑1 year‑1 after 10 years of repeated applications. In contrast, adding 0.62 t of biochar C ha‑1 year‑1 with 4.5 t of fresh sugarcane residues C ha‑1 year‑1 increased the soil carbon soil stock by 1.4 t C ha‑1 year‑1 after 10 years of application. These are reductions 25% and 40% of the potential soil C accumulation rates compared with applying available residues as biochar.   

We also tested the sensitivity of the model to biochar-induced positive priming (i.e. increased mineralization of soil organic C) using published values. This showed that the C sequestration balance remains positive over the long term, even considering an extremely high positive-priming factor. Upscaling our results to the total 5 Mha of sugarcane in Sao Paulo State, biochar application could sequester up to 50 Mt of CO2 equivalent per year, representing 31% of the emissions attributed to the State in 2016.

This study provides first insights into the sequestration potential of biochar application on sugarcane fields. Measurements of changes in soil C stocks in sugarcane field experiments are needed to further validate the model, and the emissions to implement the practice at large scale need to be taken into account. As the climate crisis grows, the need for greenhouse gas removal technologies becomes crucial. Assessing the net effectiveness of readily available technologies is essential to guide policy makers.  

How to cite: Lefebvre, D., Meersmans, J., Kirk, G., and Williams, A.: Biochar from sugarcane residues: An overview of its sequestration potential in Sao Paulo, Brazil , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2880, https://doi.org/10.5194/egusphere-egu2020-2880, 2020.

D2225 |
Kuppusamy Sathishkumar, Yi Li, and Rana Muhammad Adnan Ikram

Biochar is extensively used in environmental pollutant remediation because of its diverse property, however the effect of biochar on microbial nitrate reduction and electrochemical behavior of biochar remain unknown. Also electron transfer from the microbial cells to electron donor or acceptor have been transport across the extracellular polymeric substances (EPS), however it was unclear whether extracellular polymeric substances captured or enhance the electrons.  Hence, aim of the present study is to investigate the electrochemical behavior of biochar and its effects on microbial nitrate reduction and elucidate the role of extracellular polymeric substances in extracellular electron transfer (EET).  The biochar was prepared at different pyrolysis temperatures (400 °C, 500 °C and 600 °C) and their electrochemical behavior was characterized by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectrum, chronoamperometry). Results demonstrated that all the biochars could donate and accept the electrons, impact of biochar on microbial nitrate reduction was studied and the results showed that biochar prepared at 400 °C significantly enhances microbial nitrate reduction process. Phenol O-H and quinone C=O surface functional groups on the biochar contributes in the overall electron exchange which accelerated the nitrate reduction. The role of EPS in EET by electrochemical analysis results reveals that outer membrane c-type cytochrome and flavin protein from the biofilm was involved in electron transfer process, and EPS act as transient media for microbial EET. Overall, present study suggested that biochar could be used as eco-friendly material for the enhancement of microbial denitrification.

How to cite: Sathishkumar, K., Li, Y., and Ikram, R. M. A.: Wood derived biochar as electron donor and its influence on microbial denitrification: Role of extracellular polymeric substances in extracellular electron transfer , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3824, https://doi.org/10.5194/egusphere-egu2020-3824, 2020.

D2226 |
Silvia Baronti, Anita Maienza, Fabrizio Ungaro, Antonio,Antonello Montagnoli, Lorenzo Genesio, Alessandro, Girolamo Rombolà, Laura Giagnoni, and Francesco, Primo Vaccari

There are extensive reports and scientific articles in literature on the applicability of biochar as soil amendment in agriculture and on the benefits that this practice can bring in terms of soil improvement and optimization of water resources. The use of biochar as a soil amendment in agriculture is a suitable option that helps to mitigate the effects of climate change. Biochar has an approximate mean residence time in the soil over 1,000 years and this long-term stability is a fundamental prerequisite for considering biochar as a suitable method for carbon sequestration. Unfortunately, most literature provides results based on one-year trials. Not enough for a soil amendment to be able to claim effectiveness for many decades and not enough for a soil treatment to be considered irreversible. An effective option to fill this knowledge gap is represented by long-term field experiments. In this study, we investigated the effect of biochar application on plant water relations and soil properties during 10 years in a field experiment in Central Italy on Vitis vinifera. Biochar was applied at a rate of 22 t ha-1 in two consecutive growing seasons: 2009 and 2010. The results obtained during these years on biochar treatment compared to the control treatment are exciting: we demonstrated an increase in grape production, up to 66%, without a decrease of the grape quality, an increase in plant-soil water relations, no effects on the concentrations of soil PAHs, no eco-toxicity soil effect and a positive effect on soil chemical and biological parameters. Surprisingly, after 10 years the biochar effect continued to demonstrate significant differences among treatments, in particular: a significant increase of soil biological quality, decrease in soil bulk density coupled with a corresponding increase in saturated hydraulic conductivity, an enhance in soil available water content and a significant improvement of plant water status. The modification of plant water availability induced by biochar application increase the resilience of vineyards to droughts, as demonstrated by the lower leaf potential and higher stomatal conductance. This effect has a significant impact on quantity and quality of grape production after 10 years. Moreover, in the long-term perspective the biochar demonstrates to have an effect on soil biological communities that resulted sensitive to biochar with positive increase of abundance of species related to soil moisture content and enhance of biodiversity index. According to these results, the viticulture is now in the position to provide an effective contribution to mitigate climate change and we expect that this will be an example for other Mediterranean countries.

How to cite: Baronti, S., Maienza, A., Ungaro, F., Montagnoli, A., Genesio, L., Rombolà, A. G., Giagnoni, L., and Vaccari, F. P.: The Biochar challenge in Mediterranean viticulture: results from 10 years of field experiment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20731, https://doi.org/10.5194/egusphere-egu2020-20731, 2020.

D2227 |
Viktoriia Hetmanenko, Ievgen Skrylnyk, and Anzhela Kutova

Soil organic carbon management is a key element in solving such urgent global-scale challenges as overcoming degradation of soils and mitigating climate change. Organic fertilizers application has a significant potential for sequestering C in soils, but their efficiency depends on decomposition characteristics. Firstly, it noted the dependence of resynthesis of humic compounds in a soil on a quality of organic inputs, secondly - a need for zonal approach to fertilizers production based on amphiphile properties of macromolecules.

The present study was conducted in long-term field experiment on black soil in Forrest-Steppe zone of Ukraine. The technology of production of organo-mineral fertilizers (OMFs) was based on the regulated processing of livestock waste with mineral components to stabilize it with hydrophobic bonds. OMFs in amorphous and granular form were compared in case of broadcast and band method of incorporation. The dose of OMF input was equivalent 350 C kg ha-1 and 80 N, 80 P, 80 K kg ha-1. Organic carbon content in soil was determined by Turin method. Different organic matter fractions were isolated: humic acids (HA), fulvic acids (FA), and humin.

The soil C accumulation rates in OMF treatment was by 15 % higher than in manure treatment and up to 70 % higher than in chemical fertilizer treatment, respectively. The soil C accumulation was strongly influenced by the form of OMF and method of their application. The highest TOC level was found over band application of amorphous OMF, accumulating 6.2 t C ha–1 yr–1 in 0-20 cm soil layer. Lower efficiency of broadcast incorporation OMFs could be explained by more intensive mineralization due to higher aeration. Taking into account the effect of OMFs on C stock an advantage of amorphous form versus granulated OMF with similar composition was proven. Black soil on control plot (without fertilization) had almost equal ratio between HA, FA and humin in humus composition. The content of humic compound increased in all treatments. Applying OMF significantly increased HA content in black soil compared to applying mineral fertilizer. OMFs application promoted the increase of the degree of condensation of organic matter. The highest HA/FA was found under the effect of broadcast incorporation OMF. That means that low molecular weight compounds were rapidly degraded while more resistant to mineralization HA were formed in soil. There was no significant difference in humus composition between amorphous and granulated OMF.

How to cite: Hetmanenko, V., Skrylnyk, I., and Kutova, A.: Soil Organic Carbon Accumulation under Different Forms of Organo-Mineral Fertilizers and Methods of Their Application on Ukrainian Black Soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3282, https://doi.org/10.5194/egusphere-egu2020-3282, 2020.

D2228 |
Ronley Canatoy, Seung Tak Jeong, and Pil Joo Kim

Biochar is a carbon-rich black stable solid substance that when utilized as soil amendment can effectively mitigate greenhouse gas (GHG) emission. However, during the pyrolysis process of organic feedstock (i.e. manure) greenhouse gases are released as the feedstock undergo thermochemical degradation. Many studies were reported with regards to the effectiveness of biochar to mitigate greenhouse gas emission and to maintain soil quality via carbon sequestration. However, no clear investigation was done regarding biochar utilization on reducing GHG emission in an integrated perspective that starts from pyrolysis (production) to field application (utilization). To evaluate the integrated influence of biochar utilization on the overall Global Warming Potential (GWP) and (Greenhouse Gas Intensity) GHGI at different temperature, the fluxes of GHGs during feedstock pyrolysis to soil application were calculated. The key components include GHGs released during production processes and biogenic GHG emissions taking place in the soil via short-term incubation experiment in lowland and upland condition treated with biochar pyrolyzed at different temperature. Highest pyrolysis temperature of 700oC emitted 6.92 Mg CO2-eq ton-1 biochar, wherein 8.7% and 91.2% was contributed by Carbon dioxide (CO2) and Methane (CH4) effluxes, respectively, during pyrolysis. This GHG emission during pyrolysis at 700oC was 5.6, 2.2, and 1.5 times higher than at 400oC, 500oC and 600oC, respectively. Meanwhile, biochar produced at lowest temperature (Biochar400) when utilized as soil amendment emitted 43.4 and 38.2 Mg CO2-eq ha-1 in lowland and upland condition, respectively. In addition, this emission value under lowland (and upland) condition was 1.38 (1.36), 1.51 (1.56) and 1.86 (1.91) times higher than Biochar500, Biochar600 and Biochar700, respectively. Combining the GWP during the production and the utilization processes in lowland and upland condition reveal that at 400oC emanates the lowest overall GWP of 93.3 and 88.1 Mg CO2-eq ha-1, respectively.  Moreover, under lowland (and upland) condition, overall GWP at 400oC was noted to be 65.7% (71.7%), 131.6% (140.4%) and 221.9% (237.1%), lower than at 500oC, 600oC and 700oC, respectively. In conclusion, the use of lower temperature during biomass pyrolysis and utilization of its derived biochar could be a practical approach to mitigate GHG emissions.


Keywords: Biochar, Pyrolysis, Greenhouse gas, Methane, Global warming potential, Greenhouse gas intensity

How to cite: Canatoy, R., Jeong, S. T., and Kim, P. J.: Biochar production under low pyrolysis temperature leads to lesser overall global warming potential and greenhouse gas intensity under lowland and upland short-term condition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6273, https://doi.org/10.5194/egusphere-egu2020-6273, 2020.

D2229 |
Aubertin Marie-Liesse, Girardin Cyril, Houot Sabine, Le Brech Yann, Bena Sarah, and Rumpel Cornelia

Application of biochar, a solid product produced from biomass pyrolysis under low oxygen conditions, has been suggested as a low emission technology capable of increasing soil C sequestration to mitigate climate change. Its combined application with compost may be a promising avenue to ameliorate soil quality while increasing C sequestration. We hypothesized that biochar addition to compost reduces the mineralization of the mixture compared to compost alone. The study aimed to compare the mineralization rate of six biochar-compost mixtures differentiated by biochar feedstocks. Biochars were produced at temperatures ranging from 450 to 650°C for 10 minutes. Our conceptual approach included incubation of fresh and artificially aged biochar-compost mixtures. Physical ageing of the mixtures was performed with successive cycles of humidification/drying and freezing/thawing. We evaluated elemental composition and biological stability of the fresh and aged mixtures after incubation with a soil inoculum for 1 year. We monitored components of biochar-compost mixtures decomposition when biochar were produced from C4 feedstock by determination of the 13C signature of emitted CO2.

Combination of compost with biochar induced synergistic effects in terms of the mixtures stability. Isotopic analyses showed that carbon mineralization from compost was greatly reduced, while biochar mineralization was increased. Physical ageing induced a strong leaching of water-soluble compounds of both substrates. Carbon mineralization of aged material was however not reduced as much as expected when comparing with mineralization rates of single compounds of the mixture. Furthermore, isotopic signatures showed that compost, when amended with biochar, mineralized better after ageing. We thus suggest that the water-soluble fraction of biochar may induce an inhibitive effect on the mineralization of compost. The intensity of this effect seems to be dependent upon the feedstock of the biochar in the mixture.

We conclude that biochar addition to compost may reduce the mineralization of the mixture depending on biochar feedstock and that this effect may be alleviated after ageing.

How to cite: Marie-Liesse, A., Cyril, G., Sabine, H., Yann, L. B., Sarah, B., and Cornelia, R.: Effect of biochar addition to compost on biological stability of the mixture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9632, https://doi.org/10.5194/egusphere-egu2020-9632, 2020.

D2230 |
Henrik Thers, Sylvestre Njakou Djomo, Lars Elsgaard, and Marie Trydeman Knudsen

Biochar is related to multiple greenhouse gas (GHG) mitigation potentials, namely nitrous oxide (N2O) mitigation, carbon (C) sequestration and the possible green electricity produced in the pyrolysis process. Whereas the mechanisms behind potential N2O mitigation effects of biochar are still unclear, the mechanisms behind C sequestration is agreed to be caused by C compound conversion towards aromatic structures in the biochar C as a consequence of the heating treatment in the pyrolysis process. The specific recalcitrance of the biochar is, however, difficult to estimate. The possible electricity production from the syn-gas and bio-oil pyrolysis products depends on the feedstock and process temperature, and can contribute considerably to total system GHG mitigation. However, the multiple effects on GHG balances of biochar and pyrolysis represent a complexity, which may best be analysed by a life cycle assessment (LCA) approach. In this study, the average Danish oilseed rape cultivation was set as the reference scenario in an LCA of cultivation related GHG emissions. The reference was compared with two scenarios with theoretical inclusion of pyrolysis and biochar, meaning that the oilseed straw residue was transported to a pyrolysis plant and the biochar was returned to the field in a corresponding amount (ca. 1 Mg ha-1). Transportation, additional field operations, N2O mitigation, electricity production and C sequestration was included, and the latter was calculated by using the concept of avoided atmospheric CO2 load. The latter approach resulted in larger mitigation effects than derived from calculations of just the remaining C in soil. In total, GHG emissions were reduced by 73 to 83% in the two biochar scenarios as compared with the reference scenario, mainly due to increased C sequestration. The study suggests that even low application rates and rather conservative biochar C recalcitrance estimates lead to considerably reductions in GHG emissions from oilseed rape and expectedly other crops.

How to cite: Thers, H., Njakou Djomo, S., Elsgaard, L., and Trydeman Knudsen, M.: Biochar reduces total greenhouse gas emissions from oilseed rape cultivation, mainly due to C sequestration quantified by the concept of avoided atmospheric CO2 load – a theoretical life cycle assessment study., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20412, https://doi.org/10.5194/egusphere-egu2020-20412, 2020.

D2231 |
Jessica Graca, Brian Kelleher, and Brian Murphy

It is estimated that up to 138 million tonnes of bio-waste are produced in Europe annually, with only 25% being recycled into high-quality compost and digestate. Currently, residual organic waste is generated as by-product of municipal solid waste treatment. Its reuse options vary across EU countries, due to the lack of clear guidance at European level. In some countries, compost derived from municipal solid waste (MSW – compost) is restricted to being used as landfill cover or in land reclamation, under the premises of meeting national legal criteria. Other countries, have regulated its used as marketable compost if it meets defined compost standards. However, for many countries the value-added use of MSW derived compost is uncertain.

The restricted use of MSW - compost is linked to the organic and inorganic contamination associated with such a heterogeneous material. Despite this, under the European view of the Circular Economy, MSW-compost has great potential to be reused and recycled for the benefit of all. Controlled use on land would off-set carbon emissions by diverting the material from a waste that is largely incinerated or added to landfill to a carbon positive soil additive that increases soil quality particularly in restoration sites. 

Our study aims to risk-assess the use of MSW-compost as a soil amendment by monitoring resulting water run-off for metal and nutrient content. Leaching trials, conducted over 6 months were performed in a forest soil (20 cm depth) with a history of Sitka Spruce plantation (c.a 20 years). Adapted water storage tanks were set-up to conduct the trials. Leachate was collected weekly in the first two months, and monthly thereafter. Four treatments 1) control, 2) sewage sludge chemically stabilized (10 t/ha), 3) MSW-compost (10 t/ha) and 4) MSW-compost (25 t/ha) were established in duplicate. Sewage sludge was used as a comparison material, due to its current legal status allowing for controlled land spreading. Leachate samples were analysed for nitrate, ammonium and the metals aluminium, cadmium, copper, total chromium, mercury, nickel, zinc and lead. 

Preliminary results from the first 6 weeks show that metals concentrations in the leachate from all trials were below threshold criteria in surface water quality regulations. Levels of ammonium above detection limits were only detected at week one and surpassed 0.2 mg/L. Nitrate concentration in the leachates was found to be below 50 mg/L and it peaked in the sewage sludge and MSW-compost (25 t/ha) at week 2.

Results gathered so far show that the use MSW-compost in land compares to sewage sludge application in relation to their potential for water pollution. MSW-compost could be used as a soil improver under a regulatory alignment similar to the sewage sludge regulations, aligned with the current European Circular Economy goals.

How to cite: Graca, J., Kelleher, B., and Murphy, B.: The use of MSW-compost on land, a study of metal and nutrient leaching , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17771, https://doi.org/10.5194/egusphere-egu2020-17771, 2020.

D2232 |
Nicolas Greggio, Carlotta Carlini, Francesco Vaccari, Silvia Baronti, Andrea Contin, and Diego Marazza

In the recent years many papers explored the potentiality of biochar as soil improver as for water retention capacity and chemical and biological fertility. Many of these studies are 1-2 years lab-scale to study the biochar short term effects.

Although is well known that the behavior of biochar in soil changes with the progress of time, few are the open-field 5 years longer experiments which we propose to consider as Long Term Experiments (LTE). Furthermore the few current LTE experiments repeat the same experimental design, changing every time biochar (feedstocks and pyrolysis parameters), soil type and crop.

In this context, there is an evident need for a common platform where assembling information e where new experiments can be designed to progress and demonstrate biochar effectiveness.

The ICHAR (the Italian Biochar Association) and the University of Bologna - CIRSA Department are launching a Long-Term Experiment Platform (LTEP) aiming to be the house for all the Italian LTE for agronomic applications of the biochar. The LTEP is currently based on data from more than 15 experiments in Italy, looking for include also other European trials and it is preparing an identity card with a) a description of the project and its objectives, b) site description, c) tested biochar and substrates, d) published results, e) a working group description.

As an example of application and identity card, we present the experiment started in Tebano during 2019. Differently from the other operating LTEs, it brought biochar in a new vineyard field, amending soil before the shoot transplanting and just in proximity of the rows, exactly at root depth. The applied biochar has been produced by local the vineyard pruning residues with the purpose to establish a closed circular pattern in grape cultivation. Biochar was applied to soil as such and blended with a fertilizing sludge-based compost, produced by a company owned by a winery cooperative.  The compost, labelled as ACFa in accordance to the Italian legislation, is obtained mixing ligno-cellulosic biomass and centrifuged-sludge from digestate from anaerobic digestion plants, in a ratio 6:4, respectively. Biochar as such and 3 blends were distributed, four replica each one, in a randomized design experiment. Each of the 20 treated parcels includes 15 grape plants. Soil characterization, before the amending and yearly at the end of the growing season is planned. Plant biomass, leaf nutrient content, quantity and quality of the production of grape and wine will be monitored. Weathering of the amending matrices, especially biochar will be investigated every year. From last summer, 4 stations for continuous monitoring of water content, electrical conductivity and temperature are operating for all the matrices.

The working group involved in the project is multidisciplinary including environmental scientist, chemists, soil experts, agronomic experts, grape and winery expert, as well as personnel of a regional research center for agronomic studies and personnel from the industry and winery cooperative of compost suppliers.

How to cite: Greggio, N., Carlini, C., Vaccari, F., Baronti, S., Contin, A., and Marazza, D.: Long Term Experiment Platform (LTEP) to establish the effectiveness of biochar applications: a case study in vineyards at Tebano, Ravenna, Italy., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11376, https://doi.org/10.5194/egusphere-egu2020-11376, 2020.

D2233 |
Kenneth Peltokangas, Jimi Havisalmi, Jussi Heinonsalo, Kristiina Karhu, Liisa Kulmala, Jari Liski, and Mari Pihlatie

In agriculture, organic soil amendments are envisioned to mitigate climate change through carbon sequestration. However, the full impact of the organic amendments on soil physico-chemical dynamics is still poorly understood. We conducted a laboratory incubation to assess the net climate effect of four ligneous organic amendments: two biochars (willow and spruce) and two fiber byproducts of paper and pulp industry. Soil samples were collected from a soil-amendment field experiment at Qvidja farm, South-West of Finland. Soil samples were sieved, air-dried and adjusted to 30%, 50%, 80% and 110% of water holding capacity (WHC), and incubated for 32 days in standard laboratory conditions. Greenhouse gas (GHG) emissions were measured after 1, 5, 12, 20 and 33 days. 

The carbon dioxide (CO2) emissions were highest at 80% WHC, and lowest at severely water stressed conditions at 30% WHC. The organic amendments did not have an observable effect on CO2 dynamics. The CO2 emissions correlated linearly with soil moisture and microbial biomass nitrogen. Nitrous oxide (N2O) emissions were systematically lower in the amended soils compared to the control soil, and independent of soil nitrate concentrations. Without organic amendments, N2O emissions increased exponentially with soil moisture content. Methane (CH4) emissions fluctuated throughout the incubation, exhibiting mostly negative values. Consequently, CH4 emissions played only a minor role in the GHG budget.

CO2, N2O and CH4 emissions, calculated as CO2 equivalent, exhibited a linear correlation with the moisture gradient. CO2 dominated the GHG budget up to a moisture of 80% WHC, but was superseded by N2O emissions at 110% WHC. The results indicate that soil moisture content is critically affecting the GHG emissions and that while organic soil amendments may have persisting effects on GHG exchange, they primarily occur through N2O dynamics.

How to cite: Peltokangas, K., Havisalmi, J., Heinonsalo, J., Karhu, K., Kulmala, L., Liski, J., and Pihlatie, M.: Persisting effects of ligneous organic soil amendments on CO2, N2O and CH4 emissions in relation to moisture content in northern agricultural clay soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7464, https://doi.org/10.5194/egusphere-egu2020-7464, 2020.

D2234 |
Zulin Zhang, Yongfei Ma, Siyu Chen, Tingmei Lu, Lie Yang, and Li Wu

In addition to the advantage for resource utilization of municipal sludge which is an important solution to reduce the secondary pollution (e.g. landfill and incineration) to the environment, biochar derived from municipal sludge displayed a potential adsorption capacity for emerging contaminants, particularly with appropriate modification. This study synthesized a green adsorbent (Graphene oxide modified magnetic sludge biochar, GO/CoFe2O4-SBC), which showed the superiority of low cost, effective adsorption and separation for the environmental concentration level of pesticide (Imidacloprid, IMI) removal from water. The results suggested that higher dose and temperature would facilitate the contaminant removal. The optimum removal rate of IMI obtained at pH=6 was due to the weakest electrostatic repulsion. Pseudo-second kinetic, Freundlich and Temkin isotherm models fitted the experimental data, which indicated that both physisorption and chemisorption were involved in the adsorption process. The maximum adsorption capacity of sludge biochar (SBC), magnetic sludge biochar (CoFe2O4-SBC) and GO/CoFe2O4-SBC were 3.11×103, 5.99×103 and 8.92×103 μg g-1, respectively. Physicochemical characteristics, kinetics, isotherms and thermodynamics analysis suggested that the better adsorption performance for GO/CoFe2O4-SBC was attributed to pore filling, π-π electron donor-acceptor and oxygen-containing functional groups (e.g. C=O, C-O, -OH, Fe-O and Co-O) interaction. IMI adsorption was a spontaneous endothermic process and GO/CoFe2O4-SBC exhibited the greater spontaneous. Ethanol extraction increased the regeneration of adsorbents and maintained more than 90% of adsorption capacity in the recycles (1-5 cycles) of the fresh. The leaching concentrations of Fe and Co of adsorbent (GO/CoFe2O4-SBC) were below drinking water standard (0.5 mg L-1) in the range of pH 3 to 12. In conclusion, this work not only provided a promising biochar (e.g. GO/CoFe2O4-SBC) with superior removal capacity for pesticides in water at low concentrations, but also offered a sustainable and cost-effective way for the resource utilization of municipal sludge.

How to cite: Zhang, Z., Ma, Y., Chen, S., Lu, T., Yang, L., and Wu, L.: Graphene oxide modified magnetic sludge biochar as a green adsorbent for environmental concentration level of pesticide removal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21932, https://doi.org/10.5194/egusphere-egu2020-21932, 2020.

D2235 |
Evan Diamadopoulos, Paraskevi Velli, and Ioanna Manolikaki

The present study refers to biochar production, its application to soil with or without combining it with compost, as well as its effect on tomato (Solanum Lycopersicum L.) cultivation. The feedstock selected for biochar production was a mixture of primary and secondary sewage sludge, which had previously been anaerobically digested and thermally dehydrated. Sewage sludge pyrolysis was conducted at 300 °C. The produced biochar was initially characterized and subsequently applied to soil, in order to study its effect on Solanum Lycopersicum L. cultivation. Pot trials which included four treatments, each comprising of three replicates, were carried out during a period of three months, using pots with a 10 kg capacity. More specifically, the following treatments were studied: i) Control (soil without biochar addition), ii) soil with biochar at a rate of 2% w/w (BC-SS), iii) soil with compost at a rate of 2% w/w (Compost), and iv) soil with a mixture of biochar and compost at a total rate of 2% w/w (BC-SS+Compost). The aim of the study was to examine whether sewage sludge biochar with or without compost affects: a) the dry weight and morphological characteristics of the plant, b) the concentrations of macronutrients, micronutrients and heavy metals in aboveground and belowground plant tissues, c) soil properties, including nutrients and heavy metals.

With biochar application a number of soil properties exhibited substantial improvement. Specifically, significant increases were noticed for TOC (67% - 85% increase), NO3–N (55% increase) and ΝΗ4–Ν (145% increase). Moreover, biochar with or without compost, substantially improved plant growth (25% – 34% increase in the first 40 days), and led to a significant increase of the dry weight of aboveground and belowground plant tissues. Heavy metal concentrations in plant tissues were quite low. Specifically, traces of Cr, Ni and Co were found only in plant roots, while Si was present in plant roots and stems. As, Mo and Pb were present in all plant tissues, albeit without exceeding the permissible levels established for vegetables. Finally, no traces of Hg, Se and Cd were found in any of the tissues.

Generally, sewage sludge biochar addition to soil, with or without compost, improved soil characteristics and increased plant yield. Moreover, heavy metal concentrations within permissible levels do not raise any concerns regarding safe consumption of tomato fruits.


How to cite: Diamadopoulos, E., Velli, P., and Manolikaki, I.: Effect of sewage sludge biochar on tomato plant (Solanum lycopersicum L.) cultivation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6953, https://doi.org/10.5194/egusphere-egu2020-6953, 2020.

D2236 |
Vilim Filipović, Lana Filipović, Yusong Wang, Michael V. Braunack, Raju Adhikari, George Freischmidt, Priscilla Johnston, Phil S. Casey, and Keith L. Bristow

Agricultural management techniques like plastic mulch films are widely used to enhance crop production by conserving soil water and increasing temperature with the ability to suppress weeds. However, the use of plastic represents large environmental concern since the recovery of plastics from soils and its persistence in the environment is causing global problems. The EU in leading in policy with ban on single use plastics and it is a matter of time when conventional plastic mulch films will be banned as well. To solve the problem, researchers have turned their attention to biodegradable products while lately sprayable biodegradable polymer membrane (SBPM) technology was introduced. Here, we present first results of glasshouse study and in-field experiments with SBPM technology in Australia where with the use of subsurface drip irrigation we could improve water use efficiency of crops with reducing evaporation. First results indicate that SBPM technology could limit soil evaporation, reduce irrigation needs and prevent weed emergence while at the same time providing environmentally sustainable agricultural practice through its biodegradability, nontoxicity and sprayability nature. This innovative technology shows large potential even at this early development stage with the need for further improvement of SBPM formulation, management and properties.

How to cite: Filipović, V., Filipović, L., Wang, Y., Braunack, M. V., Adhikari, R., Freischmidt, G., Johnston, P., Casey, P. S., and Bristow, K. L.: Environmental and Hydrological Implications of Innovative Sprayable Biodegradable Polymer Membrane: First Results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7268, https://doi.org/10.5194/egusphere-egu2020-7268, 2020.

D2237 |
Vince Chukwu, Jo Smith, Norval Strachan, Lisa Avery, and Smart Obiekezie

Organic wastes, such as cattle manure, are widely used as organic amendments but may constitute a potential risk to human and animal health if they are not properly treated before application to agricultural soil. This study investigated the impact of different common household treatment methods on the reduction of pathogens in organic wastes and the spread of pathogens to food crops. Fresh cattle manure was subjected to three different treatments available to households; anaerobic digestion, burning and composting. Sub-samples were screened for E. coli contents using standard plating and IDEXX Colilert Quanti-Tray 2000 system. The numbers of organisms were used to assess the effectiveness of the treatment methods in the reduction of pathogens in the organic wastes. The E. coli count of the cattle manure was 391.42 CFU/g before treatment. After treatment, there was significant reduction in the E. coli in all treatments. Burning was most effective at reducing pathogens in the cattle manure (95%) followed by anaerobic digestion (50%) and composting (40%). Ash, bioslurry, compost and untreated manure were all significantly different in the ratio of pathogens to nitrogen. Bioslurry contained more nitrogen than ash, compost and untreated manure. Application of the recommended nitrogen dose of 120 kg/ha as bioslurry resulted in significantly lower contamination of soil (4.19 most probable number (MPN) per g) than ash (9.73 MPN/g), compost (6.89 MPN/g) or untreated manure (13.77 MPN/g). The E. coli content of lettuce grown on soil amended with ash, bioslurry or compost at recommended rates was significantly lower than lettuce crop grown on soil amended with untreated cattle manure. The results from this study provide information on the transmission of the pathogens remaining in the treated and untreated wastes when applied as organic fertilizer to food crops. This information will help to reduce the potential risks associated with the use of organic manures in growing food crops, as well as determining the optimum rate of application of organic waste after treatment.

How to cite: Chukwu, V., Smith, J., Strachan, N., Avery, L., and Obiekezie, S.: Impacts of different treatment methods on spread of pathogens from organic wastes to vegetable crops in Nigeria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1114, https://doi.org/10.5194/egusphere-egu2020-1114, 2020.

D2238 |
Chihhao Fan, Pei-Wen Chang, and Ya-Zhen Huang

The present study aimed to investigate the effect of the waste lemon extract on the flushing treatment of the copper-contaminated soil collected from contaminated farmland, in which the copper concentration was measured as high as 2487 mg/kg. The soil flushing solution was prepared using the extract from collected waste lemons. The soil flushing treatment using the solution containing commercial citric acids was also conducted for comparison. Additionally, the waste lemon was used for soil rehabilitation after composting treatment.

The soil copper concentration treated with the solution containing waste lemon extract decreased more than that treated by the commercial citric acid solution at the comparable citric acid concentration. This is because the waste lemon extract solution contains additional co-dissolved organic substances other than citric acid and the flushing treatment had a higher retention time. For the treatment with lemon extract, the soil pH values were 4.56, 5.70 and 6.29 before, after lemon extract flushing and after compost treatment. The copper plant availability dropped from 677 mg/kg for the soil before flushing to 156 mg/kg after stabilization with composted waste lemon. Therefore, the citric acid flushing combined with stabilization was found effective for heavy metal removal in the soil environment.

How to cite: Fan, C., Chang, P.-W., and Huang, Y.-Z.: Application of waste lemon extract to rehabilitate the copper-contaminated farmland through gravitational soil flushing and stabilization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2681, https://doi.org/10.5194/egusphere-egu2020-2681, 2020.

Chat time: Tuesday, 5 May 2020, 14:00–15:45

D2239 |
Magdalena Wołowiec, Małgorzata Komorowska-Kaufman, Alina Pruss, Grzegorz Rzepa, and Tomasz Bajda

The ever-increasing water pollution caused by an increase in industrial activity in developing countries is a major worldwide problem. Heavy metal contamination is particularly dangerous because of their toxic and carcinogenic nature as well as harmful effects on human and animal health. Over the past decades, considerable efforts have been made to develop effective technologies for removing heavy metals from water. Adsorption seems to be the most promising out of the many methods. Conventional adsorbents used to remove heavy metals include activated carbon or clay minerals. However, due to the need for waste management, waste products have recently become very popular, especially industrial wastes containing iron and/or aluminum oxides. One of the possible sorbent are water treatment residuals (WTRs) which are generated during drinking water treatment process. The aim of this work was to examine the possibility of using residuals from deironing of underground water (G-WTRs) as effective sorbents of Cd (II), Pb(II), Zn(II), Cu(II), Cr(III), Cr(VI) P(V), and As(V) as a function of initial concentration, pH, temperature and time.

The G-WTRs were poorly crystalline and composed predominantly of ferrihydrite with minor calcite and quartz admixture. The main chemical components were iron (32%) and calcium (17%). Specific surface area was 144 m2/g with a total pore volume of 0.181 cm3/g. The proportion of micropores was 29%, mesopores occupied the greatest volume – 54%, while micropores the lowest volume – 17%.

Cation sorption efficiecy was almost 100%, in the case of anions it ranges between 50 – 100%. Sorption capacity increased with an increase in the initial pollutant concentration. Adsorption of the metal cations was higher with and increasing pH of the solution and the best results were obtained for pH 6.0 to 7.0. While anions were preferably sorbed in lower pH. Sorption was the efficient in the temperature range of 20-40 ℃. The greatest differences in the sorption efficiency were observed within the first 2 – 4 h. The possible sorption mechanism was chemisorption.

The results showed that G-WTRs can be effective and cheap sorbents of heavy metals and metalloids. However, further research including desorption process as well as the long-term stability of formed metal-G-WTRs complexes.

Acknowledgments: This work was financed by the National Science Centre, Poland Grant No. 2017/27/N/ST10/00713.

How to cite: Wołowiec, M., Komorowska-Kaufman, M., Pruss, A., Rzepa, G., and Bajda, T.: Iron-based water treatment residuals as sorbent of heavy metals and metalloids, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2762, https://doi.org/10.5194/egusphere-egu2020-2762, 2020.

D2240 |
Donguk Seo

Reclaimed land in Korea is increasingly being used for horticulture, grains, livestock, etc. However, soil reclaimed land located in coastal lowland have so high salinity, poor fertility, high possibility of pollution that farming is difficult. Therefore, it is needed to reduce environmental burden and to promote fertility of soil through natural circulation farming. Therefore, we presented sustainable eco-friendly natural circulation model of agricultural resources in reclaimed land. It promotes desalination and fertility of soil through eco-friendly circular farming by integrating horticulture and livestock. To demonstrate the model, the test complex is planned to apply energy and resources circulation between horticulture and livestock focusing on Hanwoo, Korean-bred cattle. Basically high-technical plastic greenhouse-type horticultural complexes and livestock complexes including fuel facility using manure pellet are planned. Additionally, agricultural product processing, sales and distribution centers, themed landscape agricultural complexes, ecological parks, agricultural tourism facilities, and observation facilities were arranged.

How to cite: Seo, D.: A Study on Development of Test Complex for Natural Circulation Agriculture in Reclaimed Land, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8532, https://doi.org/10.5194/egusphere-egu2020-8532, 2020.

D2241 |
Friederike Klos, Magdalena Sut-Lohmann, Thomas Raab, and Florian Hirsch

Natural and anthropogenic activities can result in soil contamination and thus disturb their important functions for the abiotic and biotic environment, e.g. filtering, buffering or plant growth. Specific remediation measures are already taken for such environmental issues including phytoremediation using plants that are able to reduce heavy metal concentrations in the pedosphere and accumulate these heavy metals in their biomass. A fast monitoring system for a large-scale and area-wide mapping of metal contents in plants is still missing. However, such a monitoring system would be a very helpful tool to the recycling of heavy metals and supports the development of environmentally friendly processes for metal recovery. We present the concept of the innovative HyPhy project, which studies the possibility of monitoring heavy metal accumulation in hyperaccumulators with drone-based hyperspectral sensors. The phytoscreening considered here can be used to profitably mine raw materials such as nickel, zinc and copper using hyperaccumulating plants. Method will be validated using green house and field measurements based on hyperspectral sensors supported by drones. Two sensors will be used, the VNIR hyperspectral sensor from Cubert GmbH (450-950nm) and the SWIR hyperspectral sensor HySpex from the Norwegian company NEO (1000-2500nm). The two optical sensors are validated with the point spectrometer PSR+ from Spectral Evolution (350-2500nm). This presentation will show background, methods and first results of our project.


How to cite: Klos, F., Sut-Lohmann, M., Raab, T., and Hirsch, F.: Innovative Drone-based Hyperspectral Detection of Heavy Metals (Ni, Zn, and Cu) in Plants cultivated for Phytomining, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9370, https://doi.org/10.5194/egusphere-egu2020-9370, 2020.

D2242 |
Javier Rodrigo-Ilarri and María-Elena Rodrigo-Clavero

Municipal solid waste landfills are one of the most relevant soil and groundwater pollution sources. Monitoring networks should be designed on the preliminary phases to guarantee that groundwater quality control is performed periodically over both the operation and post-closure phase of the landfill.

This work shows the results of a groundwater quality detailed monitoring campaign developed on a municipal solid waste landfill in Valencia Region (Spain). The sampling campaign included the continuous analysis over 11 boreholes of the following parameters: mineral oil, As, B, Ba, Cd, Chlorine, electric conductivity, TOC, total Cr, Cr VI, Cu, COD, phenols, fluorine, total P, Hg, hydrocarbons, Mo, total N, Ni, Pb, pH, Sb, Se, suspended solids, sulphates and Zn. Besides, the piezometric levels around the landfill were also controlled.

Despite there is no clear Spanish legislation concerning groundwater quality, results show that the evolution of groundwater quality over time is satisfactory, fulfilling the requirements of the American (USEPA) and European (Dutch) legislation standards.

How to cite: Rodrigo-Ilarri, J. and Rodrigo-Clavero, M.-E.: Detailed monitoring of groundwater quality near municipal solid waste landfills. Case study in Valencia region (Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9436, https://doi.org/10.5194/egusphere-egu2020-9436, 2020.

D2243 |
María-Luisa Carnero-Pousa, Javier Rodrigo-Ilarri, and María-Elena Rodrigo-Clavero

Municipal Solid Waste (MSW) management activities are an important tasks of both national and municipal governments as they can induce significant impacts on the environment, the economy and the living quality of the population involved.

The optimal design of a MSW management plan depends greatly on the waste production values and its distribution over the territory. This production depends mainly on the socioeconomic level of its inhabitants. On the scientific literature several studies have already been carried out, concluding that there exist a direct relationship between the waste production of a certain country or region and its Gross Domestic Product (GDP). Therefore, if GDP increases, so will the rate of waste production, although not necessarily at the same rate.

The objective of the work was to carry out an evaluation of the future production of (MSW) within the V5 production area inside Valencia Region (Spain) in the 2012-2034 time horizon. The year 2011 was used as the starting point for the simulation as this was the last year in which the population census was taken. The correlation between the evolution of the economic growth indicators and the waste production indicators was analyzed. Results showed a linear correlation between all the variables studied so that variations in one of them are reflected in the same direction in the others.

How to cite: Carnero-Pousa, M.-L., Rodrigo-Ilarri, J., and Rodrigo-Clavero, M.-E.: Evaluation of future municipal solid waste production. Case study in Valencia region (Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9437, https://doi.org/10.5194/egusphere-egu2020-9437, 2020.

D2244 |
Frantseska-Maria Pellera, Panagiotis Regkouzas, Ioanna Manolikaki, and Evan Diamadopoulos

In the last years, global focus has been directing towards the circular economy model. In this framework materials that had so far been regarded as waste, are now considered as valuable resources for both energy and added-value materials recovery. In this context, more and more valorization methods and technologies are being developed for waste valorization, with biomass materials of municipal and agroindustrial origin constituting ideal options, due to both composition and availability.

Biochar generation from waste biomass is a method with high potential for effectively valorizing such residual resources, by providing not only a waste management option, but also multiple agronomic and environmental benefits. In fact, biochar materials are characterized by high versatility as far as their applications are concerned. Due to their wide variety of properties, biochars can be used in various applications, such the use as an adsorbent for contaminant removal from water or wastewater, or the use as an amendment for improving soil characteristics and remediating contaminated sites.

In the present study, six different waste biomass feedstocks, specifically three of municipal origin, namely two types of sewage sludge and the organic fraction of municipal solid waste, and three of agroindustrial origin, namely grape pomace, rice husks and exhausted olive pomace, were used to generate biochar through pyrolysis at two different temperatures, i.e. 400 and 600 °C. The resulting carbonaceous materials were then characterized through a series of analyses. Based on both physical and chemical biochar properties, it was able to evaluate their potential use in different applications, for agronomic or environmental purposes.

How to cite: Pellera, F.-M., Regkouzas, P., Manolikaki, I., and Diamadopoulos, E.: Biochar production from waste biomass: Characterization and evaluation for potential applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9694, https://doi.org/10.5194/egusphere-egu2020-9694, 2020.

D2245 |
Gianluca Bianchini, Ristovski Igor, Milcov Igor, Zupanc Alojz, Natali Claudio, Salani Gian Marco, Marchina Chiara, and Valentina Brombin

Construction and Demolition (C&D) waste is the solid debris resulting from construction and demolition activities. Recycling of this solid waste may result in substantial economic and environmental benefits. Unfortunately, is some Balkan countries such as Macedonia C&D recycling awareness is not developed yet. In this country, C&D are often dumped without control. According to the Macedonian landfill operator "Drisla" the estimated amounts of C&D waste generated per year in the Skopje surroundings approach 150.000 tons, but nothing is known on their composition. On this basis, a know-how exchange programme (KEP) called SAMCODE was financed by the Central European Initiative (CEI) and specifically dedicated to the characterization of C&D waste in Macedonia. GAYA operators sampled C&D landfills in the surroundings of Skopje, verified the absence of radioactivity, and then crushed the C&D down to the grain size of two millimetres. Crushed C&D chips were sent to the Department of Physics and Earth Sciences of the University of Ferrara, where the materials were powdered and analysed by X-ray fluorescence (XRF). Moreover, to characterize elemental mobility leaching tests on the C&D powders were carried out according to the following protocol: 1g of C&D powder has been soaked with 10 ml of deionized water, for 24 h. Subsequently the solutions have been centrifuged, filtered (at 45 mm) and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). XRF analyses showed that – although variable - silica, calcium and aluminium are always the dominant components (SiO2 between 32 and 60 wt%, CaO between 7 and 30 wt%, Al2O3 between 7 and 16%) suggesting possible recycling in the ceramic/cement industrial processes. However, the real re-use of these materials in industrial processes is hampered by the lack of homogeneity, a feature required by the industries. The analysis of trace elements emphasized another critical aspect: Macedonian C&Ds often contain anomalously high concentrations of elements potentially hazardous, especially chromium (Cr), nickel (Ni), lead (Pb) and zinc (Zn). Note that the high concentrations of Cr, Ni, Zn and Pb do not necessarily recall the presence of contaminants, as these elements can be present in natural raw materials used in the country. Noteworthy, in Macedonia there are rocks included in the ophiolite sequences such as peridotites, serpentinites, pyroxenites and chromitites that can contain thousand(s) ppm of chromium and nickel, and also mining areas where there are sulphides of lead (galena) and zinc (sphalerite). If similar rocks are used as raw materials in the building activity, it is not strange to have C&D anomalously enriched in Cr, Ni, Pb, Zn. This hypothesis is confirmed by soil studies retrieved in the literature that highlighted that Macedonian soils can contain anomalous content of these elements. ICP-MS analyses of leachates show negligible concentrations of Ni, Pb and Zn, but significant concentrations of Cr. The results indicate that to foresee effective recycling Macedonian C&D have to be preliminarily screened to eliminate Cr-bearing components, crushed and sorted to obtain a better homogenization.

How to cite: Bianchini, G., Igor, R., Igor, M., Alojz, Z., Claudio, N., Gian Marco, S., Chiara, M., and Brombin, V.: Construction and demolition waste in Macedonia, a study financed by the know-how exchange program SAMCODE promoted by the Central European Initiative, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10568, https://doi.org/10.5194/egusphere-egu2020-10568, 2020.

D2246 |
Enrico Destefanis, Caterina Caviglia, Davide Bernasconi, Costanza Bonadiman, Giorgia Confalonieri, Linda Pastero, Renzo Tassinari, and Alessandro Pavese

The management of waste and its sustainable reuse is one of the most important concern in our society in recent years, together with the increasing need to find primary materials without resorting to new extraction of resources. In this context, the thermovalorization of municipal solid waste (MSW) is currently the method that is spreading and replacing landfill disposal; the thermal treatment allows to reduce the volumes significantly, producing energy and returning bottom ashes (BA) and fly ashes (FA) in the measure of 20% and 5% of the total waste respectively.
The MSW incineration BA are classified as non-hazardous waste and can be reused as a raw material after some physical-chemical treatments.
The FA, on the contrary, are classified as hazardous waste and according to current legislation, they are usually subjected to vitrification treatments and stored in dedicated landfills. The hazard is due to the high content of soluble salts (chlorides and sulfates) and heavy metals (mainly Zn and Pb). Therefore, for their possible reuse as construction materials (e.g. ceramic, cement, concrete aggregates) or base roads, a preliminary stabilization step is required which often requires the use of significant quantities of energy.
In the present work, low energy cost methods are considered to reduce the dangerousness of FA and consequently make them more easily treatable for their reintegration into the production cycles.
Among the methods, washing of FA with water is examined, to find the lowest L / S ratio in the reduction of salts and heavy metals, analyzing the dissolution kinetics and the mineralogical content of fly ash before and after each washing treatment.
For a better definition of the kinetics, the FA are previously submitted to particle size separation to understand in which fractions the most dangerous substances are concentrated.
Washing treatments can be useful to remove or reduce soluble salts, in particular chlorides, by using a different liquid / solid (L / S) ratio, in order to obtain a more suitable material for the solidification / stabilization treatments carried out by geopolymerization or in cement.
The eluates of washing are also taken into consideration to evaluate the recovery of elemental species of interest and the purification of the liquid phase with biochar.

How to cite: Destefanis, E., Caviglia, C., Bernasconi, D., Bonadiman, C., Confalonieri, G., Pastero, L., Tassinari, R., and Pavese, A.: Study of pre-treatments of fly ashes aimed to the reuse as construction materials: chemical and mineralogical characterization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16760, https://doi.org/10.5194/egusphere-egu2020-16760, 2020.

D2247 |
Houda Oueriemmi, Petra S Kidd, Ángeles Prieto-Fernández, Beatriz Rodriguez-Garrido, Mohamed Moussa, and Carmen Trasar-Cepeda

Soils from arid and semi-arid ecosystems are generally very low in organic matter content, poor in nutrients and typically with sandy texture.  The application of different organic amendments has been proposed as an adequate approach to improve the quality of these soils for their use in agriculture. The use of organic wastes of different origins (agricultural, industrial, urban, etc.) as soil amendments has a dual goal: i) improving soil fertility and quality, ii) reducing the environmental problem that poses the disposal of these residues. However, despite of the beneficial effects of these residues, undesirable changes may also occur in agricultural soils after their addition. For example, the presence of various pollutants of anthropogenic origin in organic wastes may cause adverse effects on soil microbiota.  Generally, the arid and semi-arid soils of Tunisia are well characterised. However, the use of organic amendments to improve the quality of these soils has been scarcely investigated. Soil biochemical properties, and specifically soil enzyme activities, have been often used to investigate the impact of different amendments on soil quality, because they are highly sensitive to human or environmental perturbations.

In this work, the results of a field trial established for investigating the effectiveness of three organic residues (composted municipal solid waste, composted sewage sludge and farmyard manure) to improve the quality of one agricultural soil from Tunisia are reported. The soil had a sandy texture, alkaline pH (pH 8.3) and was very poor in organic matter (0.21 and 0.03% of total C and N, respectively). Each of the organic residues was applied in triplicate at three different doses in nine sub-plots randomly distributed; three untreated sub-plots were also established for comparison. One, 6 and 18 months after the soil amendments, surface (0-20 cm) soil samples were collected from all the treated and untreated subplots. The soil samples were analysed for the enzyme activities of four hydrolases involved in the C, N, P and S cycles and for an oxidoreductase (dehydrogenase) reflecting soil microbial activity. All the soil samples were also characterised for their main physicochemical properties.

Addition of the three organic amendments induced slight increases of the total organic carbon and nutrients content; however, the improvements observed were generally not related with the amount of applied residue. The activity of the enzymes increased after the application of the three residues, but these increments were not correlated with the dose of residue and did not consistently varied with the time elapsed after residue application. Generally, the highest increases in absolute values were observed for manure-amended soils, but when the activities were considered in relation to the total organic C of the soils, the sludge amended soils appeared to be the most favoured. The results are discussed with regards to their implications for improving very poor agricultural soils.

Acknowledgements: This research was financially supported by the Xunta de Galicia (IN607A 2017/6), UE Interreg-Sudoe program (SOE1/P5/E0189) and the Tunisian Ministry of Higher Education and Scientific Research. H. Oueriemmi thanks founding support of Erasmus plus program for her stay at the IIAG-CSIC.

How to cite: Oueriemmi, H., Kidd, P. S., Prieto-Fernández, Á., Rodriguez-Garrido, B., Moussa, M., and Trasar-Cepeda, C.: Do different organic amendments effectively improve the soil biochemical activity of very poor arid soils from Tunisia?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19514, https://doi.org/10.5194/egusphere-egu2020-19514, 2020.

D2248 |
Mesfin Gebremikael, Ramon Vandendaele, Marta Alarcon, Ruben Torregrosa, and Stefaan De Neve

There is a wide variety of agricultural waste co- and by-products that could potentially be valorised in high-value applications. One of such products is lignin, the second most abundant organic biopolymer after cellulose. Because of the large amounts of pruning wastes in the Mediterranean regions, lignin extraction can be one of the possibilities for valorisation and sustainable management of agricultural wastes. Research on the application of lignin, particularly lignosulfonates, is limited to its use as a biostimulant for root growth under controlled laboratory conditions and as a complexing agent in micronutrient foliar fertilizer formulations. Little is known about the impacts of lignin extracted from various feedstock on plant growth and soil quality.


We investigated the potential of lignin as plant biostimulator and soil conditioner in a pot experiment with fresh soil and lignin extracts obtained from three types of pruning wastes (urban trees, fruit and forest trees) using ryegrass as a test plant, under laboratory conditions. Two doses of lignin extracts (equivalent to 5 and 20 kg lignin-C ha-1) were applied to assess whether the effect on plant growth and soil quality depends on the rate of application. Soil and plant parameters were determined seven weeks after the grass was planted at 17 °C and 16 h photoperiod. 


Root biomass significantly increased (62-152%) in treatments with lignin addition, particularly lignin from urban and forest pruning wastes compared to the control. However, the increase in root biomass did not result in a simultaneous increase in shoot biomass or N uptake showing the need to apply additional plant nutrient. The microbial biomass C did not significantly respond to the application of lignin. A significantly higher dehydrogenase enzyme activity was recorded in samples with the high dose of lignin extracted from the urban wastes compared to the lower dose. Urban waste lignin extract contains 15-18 times more total N compared to the lignin extracts from forest and fruit trees, which could explain its significant effect on enzymatic activities and root biomass.


The findings show that differences in feedstock properties may influence the plant growth stimulating activity of the lignin. Further research is needed to improve the plant growth-stimulating effect of lignin, to investigate the simultaneous application of the major plant nutrients and the response of the microbial community to lignin application.   


How to cite: Gebremikael, M., Vandendaele, R., Alarcon, M., Torregrosa, R., and De Neve, S.: The effect of lignin application on plant growth and soil biological quality, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19535, https://doi.org/10.5194/egusphere-egu2020-19535, 2020.

D2249 |
Gabriel Gascó, Ignacio Sánchez, José Manuel Fidalgo, Antonio Saa, Jorge Paz-Ferreiro, and Ana Méndez

Metal´s demand and price are increasing due to the global trend towards urbanisation and industrialisation. Metals and raw materials are crucial to Europe’s society, economy and industry. However, some of them show a high-supply risk due to high dependence of imports, being necessary to find alternative materials or new sources for their recovery. Additionally, the overall global reserves of high-grade ores are close to depletion. In this context, low-grade, complex ores like sulphide minerals and old waste deposits related to past mining activities have received much more attention in recent years as new metal sources. The main objective of the present work is the recovery of metals from mining tailings, mainly post-flotation wastes, by eco-friendly hydrometallurgical processes. The presence of low-grade minerals hinders metal extraction by traditional pyrometallurgical processes. Spanish mining tailings show different compositions depending on their origin. However, complex ores like sulphide minerals (pyrite; sphalerite; chalcopyrite; arsenopyrite and other polymetallic sulphides) are generally present. It is known that metals in the form of complex sulphide precludes their chemical leaching.  For this reason, some carbon materials have been studied during last years as efficient catalysts for the leaching of metals from complex sulphides. The present work will be performed during the project RTI2018-096695-B-C31 (Ministerio de Economía y Competitividad). Different mining taillings will be selected from Spanish mining areas and mix with corresponding carbon catalysts. Leaching experiments will be performed during 96 hours at 60 and 90ºC under continuous agitation. The results obtained in the project will contribute to better understanding of the influence of catalysts in the leaching of metals from mineral sulphides. 
Authors wish to thank Spanish Ministerio de Economía y Competitividad for economic support (RTI2018-096695-B-C31)

How to cite: Gascó, G., Sánchez, I., Fidalgo, J. M., Saa, A., Paz-Ferreiro, J., and Méndez, A.: Recovery of metals from mining tailings by eco-friendly hydrometallurgical processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19906, https://doi.org/10.5194/egusphere-egu2020-19906, 2020.

D2250 |
Iria Benavente-Ferraces, Fátima Esteban, Denis Courtier-Murias, Ana Rey, Claudio Zaccone, Eduardo Moreno-Jiménez, Gabriel Gascó, Marco Panettieri, María del Mar Delgado, Juan C. García-Gil, and César Plaza

Biochar application is now considered to be one of the most promising agricultural practices to mitigate climate change. However, to fully assess the benefits of biochar, we still need to better understand its effects on soil properties, and particularly on native soil organic matter (SOM) dynamics.

In this work, we investigated soil respiration and changes in SOM pools (mineral-free, intra-aggregate, and mineral-associated SOM) as affected by the application of 20 t / ha per year of biochar alone or combined with mineral fertilizer, municipal solid waste compost, or sewage sludge. The experiment was run for 7 years in a semiarid agricultural soil. We found that biochar had no effect on soil respiration with respect to mineral fertilization and no amendment (control), and tended to decrease CO2 emissions from soils amended with municipal solid waste compost and sewage sludge. Biochar accumulated mainly in the mineral-free SOM fraction and its addition, especially in combination with municipal solid waste compost, promoted the amount of SOM occluded with aggregates and associated to mineral surfaces.

Acknowledgments: to the Spanish MICINN (MINECO, AEI, FEDER, EU) for supporting the research project AGL2016-75762-R.

How to cite: Benavente-Ferraces, I., Esteban, F., Courtier-Murias, D., Rey, A., Zaccone, C., Moreno-Jiménez, E., Gascó, G., Panettieri, M., Delgado, M. M., García-Gil, J. C., and Plaza, C.: Soil respiration and soil organic matter pools in soils amended for 7 years with biochar combined with mineral and organic fertilizers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21181, https://doi.org/10.5194/egusphere-egu2020-21181, 2020.

D2251 |
Naeema Al Nofeli and Fred Worrall

The date palm tree has been mainly used as a source of food in the MENA (Middle East North Africa) region. Specifically, in the United Arab Emirates produces over 44 million date palm trees yearly, each tree generates approximately 20 Kilograms of palm frond waste per year and this waste is currently sent to landfills. In this study, we proposed that in the arid soil conditions found in the UAE, this date palm waste could be converted to biochar and used to improve the water holding capacity of UAE soils. Therefore, the aim of this study was to test whether amendments of date palm frond (DPF) and its biochar could improve the water holding capacity of soils. A mesocosm design and a plant growth experiment were used to assess the treatments at summer temperature conditions. For the mesocosm, there were 6 different biochar and DPF treatments (1%, 3%, 6%, 12%, 15% and 18% biochar or DPF in soil) along with the controls (sharp sand, DPF biochar and DPF). The experiment was divided into 3 cycles (wet, dry, and dry with a water bowl (waw)). The impact of the experimental treatments was assessed using ANOVA. Both Biochar and DPF had no significant effect during the first two cycles (wet and dry) but during the third cycle, the DPF appeared to have better water holding capacity than Biochar. A plant growth experiment was conducted with 6 different treatment (controls - sand, DPF and Biochar; and Biochar at 1%, 6%,15% and 18%). Cat grass was used for measuring its temperature, height, moisture and pH. Water was irrigated during the first 3 weeks then the soil treatments left to dry. The results of the greatest growth for 1% Biochar. Further investigations are being processed using thermal gravimetric analysis (TGA), Carbon, Nitrogen, Hydrogen & Oxygen (CHNO), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) & Computerized tomography (CT) scan. This is to assess water binding capacity and physiochemical properties of the Biochar, DPF and soil.  

How to cite: Al Nofeli, N. and Worrall, F.: The Potential for Biochar to Mitigate the Impact of Climate Change, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21238, https://doi.org/10.5194/egusphere-egu2020-21238, 2020.

D2252 |
Jorge Medina, Marcela Calabi-Floody, Marco Panettieri, Pablo Cornejo, Fernando Borie, and Heike Knicker

The utilization of additives is a strategy commonly used in composting operations to enhance the physicochemical properties and optimize the process. However, little is known about the impact of nanominerals, biochar and their combination during composting. The objective of this research was to evaluate the effects of iron oxide/halloysite nanominerals and oat hull-biochar as additives in the physicochemical properties of an aerobic composting process, the emission of greenhouse gases (GHG) and the composition of end-products. In order to analyze the biodegradability of composting end-products in grassland soils, an incubation experiment was also carried out. Wheat straw, lupine and beef manure were mixed (C/N: ~25) with iron oxide (Fe) or halloysite (Ha) nanoparticles (2% w/w), oat hull-biochar (B) (7% w/w) and their combination (BFe, BHa). pH, EC, C/N ratio, NH4-NO3 contents and the emission of CO2 and CH4 were analyzed. After 128 days of aerobic composting process, the end-products and their NaOH soluble fraction were characterized by using spectroscopic analysis that included E4/E6 ratio and solid state nuclear magnetic resonance (13CNMR). To analyze the biodegradability of produced compost in grassland soils, a respiration experiment (60 days) using Respicond Apparatus IV, combined with δ13C isotopic analysis was conducted. A decrease of final C/N ratio was observed in all treatments that was lower in B treated compost. Nitrate concentration increased as composting progressed, and compost supplied with Ha showed the higher final content of NO3 (5800 mg kg-1) and NH4 (220 mg kg-1). The addition of B significantly decreased the mean emission of both CO2 (~400 g CO2 m2 d-1) and CH4 (~4.5 g CH4 m2 d-1). Nanominerals significantly decreased the final E4/E6 ratio (<6) and the addition of B increased the aromaticity (twice), the alkyl-C/O alkyl-C ratio and the hydrophobicity which are parameters associated to stabilized end-products. In soil, the incorporation of additives reduced the loss of C (<5% after 60 days of incubation). Treatments supplied with B and Ha showed a higher mean residence time (8 and 5 years respectively) than compost without additives. These results suggest that the addition of halloysite and biochar to composting operations have significant effects on C stabilization and biodegradability of compost in grassland soils, that is relevant in the production of C sequestrant amendments. Acknowledgments to FONDECYT N° 3170677.

How to cite: Medina, J., Calabi-Floody, M., Panettieri, M., Cornejo, P., Borie, F., and Knicker, H.: Nanominerals and biochar as additives in the composting of agricultural waste: effects on GHG emissions, composition and biodegradability of end-products on grassland soils., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21430, https://doi.org/10.5194/egusphere-egu2020-21430, 2020.

D2253 |
Frank Repmann, Nils Dietrich, Florian Hirsch, and Thomas Raab

An ever growing quantity of digestates produced from agricultural biogas facilities puts alternative use options, other than spreading those residues on agricultural land, into focus, particularly to protect the ground water from nitrogen leaching in intensively used regions. Within the framework of the FNR funded project Skarabäus, Brandenburg University of Technology (BTU) together with partners from the Institute of Agricultural and Urban Ecological Projects affiliated to Humboldt University Berlin (IASP) and the Humboldt University Berlin (HU) investigate whether biogas digestates could be converted to fertilizer products of defined composition to be used outside agricultural production particularly for gardening and landscaping. The project rationale is to agglomerate the separated digestates to produce a fertilizer which is flexible in the design of properties, easy to handle for application and  effective to plant’s growth. Basically the tumble agglomeration was considered as the main process. The properties of the fertilizer product, particularly the nutrient content with respect to nitrogen, phosphorus and potassium, was thought to be adjusted by adding nutrient rich secondary materials like meat and bone meal, replaced powders from fire extinguishers and recycled material originating from waste water treatment during the agglomeration process.

Experiments revealed that separated digestates could hardly be agglomerated due to the high amount of relatively large and inflexible fiber contained. The addition of binding agents like clay minerals strongly improved the agglomeration process. However, so far best results were achieved when separated digestates were composted prior to the agglomeration process. In this way no binding agents were necessary. Agglomerates produced from composted digestates showed a reasonable particle size distribution and nutrient- and organic matter content generally suitable for application in horticulture, given that future greenhouse and field experiments could also demonstrate the beneficial application.

How to cite: Repmann, F., Dietrich, N., Hirsch, F., and Raab, T.: Design and experimental production of organic fertilizers from biogas digestates and secondary materials for horticultural purposes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21625, https://doi.org/10.5194/egusphere-egu2020-21625, 2020.

D2254 |
Xudan Zhu

The use of biochar as a soil amendment has been proposed to increase the carbon (C) sequestration in soils. However, a more rapid soil organic matter turnover after biochar application might reduce the effectiveness of biochar applications for C sequestration. Data on the effects of biochar on soil C turnover is particularly important in boreal forests where large quantities of forest harvest residues would be available as feedstock for biochar production. To better understand the effects of biochar on boreal forest soil, we established a split-plot experiment where two spruce biochar produced with different temperatures (500°C and 650°C) were applied at a rate of 1.0 kg m-2 and 0.5 kg m-2 in a young xeric Scots pine forest in southern Finland. Measurement of soil CO2 effluxes and microbial biomass were used to investigate changes in soil C dynamics. Biochar application increased the rate of soil CO2 efflux by 10.6% across all biochar treatments and significantly (P<0.05) in 1.0 kg m-2 treatments. Soil microbial biomass remained unchanged. Soil temperature was 0.1 to 0.5°C higher in the biochar-amended treatments. Further analysis revealed that when soil CO2 efflux was corrected for the changes in soil temperature and soil moisture, there were no significant differences between treatments. We conclude that increase in soil CO2 efflux was attributed to warmer soils at the initial stage after biochar application to the soil surface; changes in soil chemical properties did not have any detectable effect on soil respiration.

How to cite: Zhu, X.: Short-term effects of biochar on soil CO2 efflux in boreal Scots pine forests, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21914, https://doi.org/10.5194/egusphere-egu2020-21914, 2020.

D2255 |
Susanne Eich-Greatorex, Annbjørg Øverli Kristoffersen, Jan Stabbetorp, Svein Jarle Horn, Trond Børresen, and Trine Aulstad Sogn

Anaerobic digestion of organic household waste as a means of energy production leaves considerable amounts of organic residues. These biogas digestates may represent a valuable source of nutrients and organic material, especially in areas with little application of animal manure to arable land. However, due to a typically high amount of available nitrogen and a low dry matter content, only small amounts of organic material are added with untreated digestates, also compared to other liquid organic fertilisers such as cattle slurry. The main objective of the study was to determine how the quality of liquid organic fertilisers affects soil properties. In soil samples from three field experiments in south-eastern Norway, aggregate stability, water retention characteristics, and selected chemical properties were determined. After three to seven years of application, the organic fertiliser treatments showed a positive effect on aggregate stability and pH compared to inorganic or no fertiliser, as well as a trend to higher carbon concentrations especially in soils with relatively low organic matter content. Effects on water retention characteristics depended on the quality of the organic fertilisers: Cattle slurry addition increased the number of medium-sized pores and thus plant-available water, whereas digestate addition instead increased the number of small pores in the soil.

How to cite: Eich-Greatorex, S., Kristoffersen, A. Ø., Stabbetorp, J., Horn, S. J., Børresen, T., and Sogn, T. A.: Effects of liquid organic fertilisers on selected soil quality indicators, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21730, https://doi.org/10.5194/egusphere-egu2020-21730, 2020.

D2256 |
Shu-Yuan Pan, Chao-Yu Wei, Anwar Jamaal Wade, and Po-Chih Tseng

Agricultural wastewater including anaerobic digestate is annually generated in a huge quantity in Taiwan. The management of agricultural wastewater should be emphasized on the recovery and production of value-added resources, such as macronutrients (nitrogen, phosphorus, and potassium), for realizing the circular bioeconomy. In this paper, we will illustrate the development of energy-efficient electrokinetic processes for nutrient recovery from agricultural wastewater. First, we evaluate the performance of electrokinetic separations processes for recovery of macronutrients. We also discuss major challenges in managing nutrient reuse by the developed electrokinetic methods. Then, we elucidate the process chemistry and reaction kinetics by the processes. Lastly, we consider the interconnectivity among water, energy and the produced macronutrients in the context of large-scale deployment.

How to cite: Pan, S.-Y., Wei, C.-Y., Wade, A. J., and Tseng, P.-C.: Nutrient Recovery from Agricultural Wastewater by Integrated Electrokinetic Processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21013, https://doi.org/10.5194/egusphere-egu2020-21013, 2020.