The Leadville Mining District in central Colorado, USA began in 1860, extracting over $2 billion USD (current value) in precious metals over its 140 year history.  Unfortunately, mining operations and pyritic deposits contributed to metals contamination in surface/ground waters, ultimately decimating parts of the food chain.  Some sediments contained > 30,000 ppm available Zn; subsequently, sites were devoid of vegetation leading to enhanced erosional losses.  The location was deemed a US EPA Superfund site in 1983.  In 1998, a study was initiated to prove that alluvial mine tailings’ acid-generating potential can be reduced via lime application (224 Mg ha^-1), and the addition of biosolids (224 Mg ha^-1) in conjunction with native seed mixes could help reclaim these locations. 

In 2019, we revisited Leadville to access reclamation success on soil health, plant metal accumulation, and the potential positive or negative long-term environmental effects.  Four transects were located on-site, corresponding to past locations that contained varying heavy metal concentrations yet with ~ the same soil pH.  Five soil samples (to 15 cm) were collected along each transect; all plants were collected within a 1-m quadrant next to each soil sampling location.  Five additional soil samples were collected on-site in areas represented by seeps, where no plants were growing and soil surface metal salt precipitates were present.  We utilized the Soil Management Assessment Framework (SMAF) to ascertain changes in soil health between on-site locations, and overlaid this data with plant metal concentration data.  We found that soil organic C, aggregate stability, bulk density, microbial biomass C, pH, EC, and extractable P and K were indicative of soil reclamation success.  Unfortunately, SMAF does not ascertain differences in bioavailable heavy metals, which were still elevated at locations across the site, leading to excessive plant heavy metal accumulation even though plants did not show toxicity symptoms. However, the presence of plants has helped stabilize these alluvial mine tailings, protecting them from loss via water erosion, leading to improved ecosystem function and services. We anticipate this work leading towards a framework to ascertain soil-plant health on heavy metal contamination mine lands globally.

How to cite: Ippolito, J., Li, L., and Banet, T.: Can soil and plant health, and ecosystem services, be improved via reclamation efforts in heavy metal-contaminated alluvial mine tailings deposits?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1635, https://doi.org/10.5194/egusphere-egu23-1635, 2023.

The aim of this study is to understand better how potentially toxic elements (PTE) interact with biofuel crops when they are grown on contaminated land. Bioenergy has considerable sustainability challenges to overcome including the risk of diverting farmland for biofuel production to the detriment of food supply. The use of contaminated land to grow bioenergy crops would increase the sustainability of bioenergy resulting in an increase in land available for energy crops whilst enabling the remediation of degraded soils and providing ecosystem services. It is important to understand how the biofuel plant is interacting with the PTE as this will inform pre-treatment options. The approach taken involved field trials of 648 pre-grown Phalaris arundinacea plants which were begun in 2018 in soils at a historic Pb-Zn mine site in the North East of England. Soils from this mine site were found to have very low levels of nutrients and very high levels of PTE (Pb and Zn >13000 mg/kg). The way that high density PTE phases (such as Pb minerals) interacted with the biomass was assessed with an innovative approach involving imaging the biomass with x-ray computed tomography (XCT). The use of the XCT allowed for greater understanding of the location and nature of the Pb within the biomass and is a frequently used non-destructive 3D imaging and analysis technique where X-rays are used to create a radiographic image of the scanned component. Whilst the use of this technique for 3D imaging of plant root and soil systems and in plant structures is increasing its application remains rare, particularly in the context of this study.

Plants in their third year of growth were sampled in a random pattern from the field trial in Summer 2022 by cutting with scissors at a height of 10cm. The sample was then divided equally with one left unwashed and another washed with HCl in a 1 molar solution and the surfactant Tween80. The biomass was then dried and a sample of both the washed and unwashed was selected for imaging with the XCT. The innovative use of the XCT has allowed for several key discoveries. Firstly, there are considerable numbers of high density dust particles across the biomass and concentrated in particular areas in the unwashed biomass (Fig 1). The density of some of this dust ~6g/cm³ is similar to that of the expected Pb mineral forms (e.g. cerussite 6.58 g/cm³). In the images of washed biomass, the high density dust remains in the joints between the “node” and leaf “sheath” of the plant. This is an important finding as it suggests that in order to achieve “clean” biomass from contaminated land, plants could be ground and then washed allowing the high density dirt to sink and be removed. Resulting far simpler pre-treatment procedure than if the PTE were found to have been absorbed into the plant by biological processes.

Figure 1 XCT image of unwashed Phalaris arundinacea  

How to cite: Nunn, B., Lord, R., Davidson, C., Minto, J., and Manzoor, N.: Contaminated or just dusty? Understanding the nature of contaminants found in biomass grown on historic mine sites to inform pre-treatment options, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1006, https://doi.org/10.5194/egusphere-egu23-1006, 2023.

Phosphorus (P) is an essential element for biomass growth and is a major component of fertilizers applied to crops. Excessive application of P to agricultural soils may lead to P-leaching and increasing concentrations of this element in aqueous system. This may cause the degradation of water quality through eutrophication processes. Arsenic on the other hand is a very toxic element that may be present at high concentrations in soil and aqueous environments due to weathering processes or to anthropogenic sources as mining and agricultural activities.

To design adequate remediation techniques for the mitigation of phosphorus (P) and arsenic (As) pollution it is key to understand the geochemical processes and the environmental drivers controlling their availability. In soil systems, the mobility of P and As is controlled by their interaction with soil minerals. Among these minerals, iron and aluminum oxyhydroxides are known to form especially strong surface complexes with both components, limiting its availability to the environment. On the other hand, the presence of soil organic matter may compete with these pollutants for the mineral surface sites, increasing the contamination risk in the soil system.

In the present work, we have studied at laboratory scale the As and P adsorption process on iron mineral surfaces under variable conditions. This includes changes of pH, redox conditions, presence of major ions (i.e. calcium, sulfate) or other trace elements (i.e. chromate, copper), and the presence of natural organic matter (i.e. humic substances or simple organic acids). Also, surface complexation models were applied in order to simulate and predict the behavior of such systems. The obtained results reveal that the presence of organic matter or other anionic species are important factors capable of increasing the mobility of P and As contaminants, whereas changing the redox potential or the carbon content in the organo-mineral aggregates has little effect.

The information obtained, allowed to design remediation solutions that could be applied at field scale. The soil characteristics and the biogeochemical processes can be improved by the application of amendments based on circular economy aspects, i.e. compost, biochar, Technosols. We have studied the effectiveness of the superficial application of these materials to immobilize both P and As, varying the main environmental drivers affecting to the sorption or desorption processes.

How to cite: Antelo, J., Fiol, S., Otero-Fariña, A., Amini, M., Rahnemaie, R., Otero, X. L., and Macías, F.: Mitigation of phosphorus and arsenic pollution in soils: from the laboratory to the field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15857, https://doi.org/10.5194/egusphere-egu23-15857, 2023.

The traditional use of agrochemicals causes environmental pollution and global public health problems. The fact that plants use only a part of the agrochemicals added to the soil makes them ineffective. The frequent application of excessive doses of fertilizers to soils can lead to risks of environmental contamination, mainly of aquifers and surface waters. This opens up new technological challenges that can be applied to agriculture and food production to meet the needs of the population. The use of nanoagrochemicals (NAC) is recent and there are insufficient studies to provide information on their potential impact on the environment. In this study, NACs were synthesized by simple, rapid, economical, and sustainable methods to evaluate their potential impact on the soil-water system and in the cabbage (Brassica oleracea var. capitata L.)  crop. The main objective of this study is to synthesize urea-hydroxyapatite and potassium sulfate NACs for application in soils as nanofertilizers, in order to reduce agricultural inputs, to achieve more environmentally friendly agrochemicals and to evaluate from an economic point of view the cost-effectiveness of the use of these nanomaterials in agriculture versus the traditional use of agrochemicals. For this purpose, the aforementioned nanoparticles were synthesized and characterized. Subsequently, a field assay was carried out in experimental plots of 4 m² in which four different treatments with NAC and traditional fertilizers were applied (in quadruplicate): (i) urea-hydroxyapatite NAC; (ii) potassium sulfate NAC; (iii) urea-hydroxyapatite NAC and potassium sulfate NAC; and (iv) non-nanoparticulate traditional fertilizer treatments; and two doses: (i) an optimum dose according to the usual fertilizer contents (NPK) used for this crop.; and (ii) half the optimum dose.  Soils were sampled at the beginning and end of the assay for characterization. The crop was closely monitored throughout the growing period and at the end of the crop cycle, the cabbages were harvested for size, weight, yield, and nutrient content determination. An economic-financial analysis was also carried out comparing the yield of the use of NAC versus the use of traditional fertilizers. The main results showed that the treatment with NAC at half the dose showed similar yield (number of cabbage harvested: 93), size (diameter) (35.3 ± 2.1 cm), and weight (0.38 ± 0.08 kg) values as the cabbages treated with traditional fertilizers (yield: 91; size: 34.8 ± 1.5 cm; weight: 0.41 ± 0.10 kg). Thus, NAC applied at half dose was efficient for the production of this crop. The analysis of cost-effectiveness proved that the treatment cost with NAC at half dose was lower than the treatment with optimal doses of traditional fertilizers, which indicates that the use of these NAC can be profitable and minimizes the input of fertilizers to the soil.

Acknowledgements

This research was supported by the grants to research groups in the Campus of Ourense (InOu 2022). Daniel Arenas-Lago thanks for the postdoc grant Juan de la Cierva Incorporación 2019 (IJC2019-042235-I).

How to cite: Arenas Lago, D., Villanueva Villar, M., González Feijoo, R., Vaquero García, A., Fernández Calviño, D., Rivo López, E., and Arias Estévez, M.: Environmental, agricultural and economic implications of the use of nano-agrochemicals for a sustainable food production of Brassica oleracea var. capitata L., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11837, https://doi.org/10.5194/egusphere-egu23-11837, 2023.

Water, being the most important resource in the world, has become a cause of concern in the present time. About one-fifth of the population on earth lack access to safe drinking water. Access to safe drinking water has been a grave problem for India, especially in rural areas where the lack of usable water has resulted in decades-old sanitation and health problems. The main access to potable water is generally surface water and groundwater. However, with the increasing population and emerging demands, there is a possibility of a threat to groundwater in terms of both contamination and depletion. The potential sources of groundwater contamination include storage tanks, septic systems, uncontrolled hazardous waste, landfills, chemicals and road salts, and atmospheric contaminants. Among the contaminants, heavy metals contamination in water is a major concern worldwide- wide and it adversely affects human health. The major problem with heavy metals is their non-biodegradable nature, because of which their persistence is likely to be for a longer time. Toxic heavy metals like Cr, Pb, Cd, Hg, Ni, Cu, and Zn pose a threat to the ecology even at their lowest concentrations.

            This study takes into account the contamination problem of Northeast India. Among the toxic heavy metals, contamination by iron (Fe), arsenic (As) and fluoride (F^-) is found to create much of problems for the people of the region due to their toxicity to many life forms. According to the groundwater yearbook 2020-2021, the amount of arsenic and iron in groundwater is noted to be 71.29µg/l and 12.93mg/l. Most of the treatment processes like, electrocoagulation, adsorption, membrane processes, ion exchange, precipitation, and chemical oxidation processes are employed for the removal of heavy metals from water, the majority of which are either challenging or need high maintenance costs. This paper focuses on developing a low-cost and efficient adsorbent that can remediate the toxic heavy metals from groundwater. In this study, wood biochar is used as the low-cost adsorbent for remediation. The study takes into account the effect of physicochemical parameters like pH, dosage, and initial concentration along with a thorough study of the characteristics of biochar to examine the removal efficiency and the optimum was found to be 99.5% in the case of both iron (Fe) and arsenic (As) respectively.

How to cite: Boraah, N., Chakma, S., and Kaushal, P.: Remediation of toxic contaminants from groundwater using low-cost adsorbent, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-559, https://doi.org/10.5194/egusphere-egu23-559, 2023.

Community gardens and allotments are being trialled as a nature-based solution to mitigate multiple health and social, economic, and environmental/climate issues in Belfast. However, working in close proximity to urban lead-contaminated soils and ingestion of site-grown produce may pose significant health risks to community members unless remediating action is undertaken. Current research indicates that organic soil amendments adsorb common urban metal contaminants, particularly lead, and thus may limit plant/crop uptake and consequent human health risks after ingestion. This research seeks to investigate health risks associated with ingesting soils and vegetables grown in lead-contaminated and biochar-remediated soils in Lower Botanic Gardens, Belfast, using controlled pot experiments and concurrent field plots. Pots and plots will comprise combinations of high and low lead concentrations in soil, high and low lead concentrations in soil amended with 5%w/w biochar, and seeded with leaf (lettuce), bulb (garlic), and root (carrot) vegetables. Following a standard growth period, the pre- and post-growth soils, and vegetables will be tested using the Unified BARGE Method in vitro bioaccessibility methodology to determine the bioaccessible fraction for lead derived from soils and vegetables with and without biochar remediation. This will then give an indication of ingestion risk associated with biochar-amended and non-amended lead-contaminated soils, and different soil-grown vegetables. It is anticipated that there may be a mild-moderate risk of lead absorption in the gut after ingestion of non-amended contaminated soils; followed by a reduced risk posed by ingestion of site-grown vegetables with a risk hierarchy of carrot > garlic > lettuce; and a further reduced risk from produce grown in biochar-amended soils. These results would support the use of soil amendments to improve the scope of greening nature-based solutions on typically unfeasible contaminated sites, with the ultimate goal of enhancing health and social, economic, and environmental/climate conditions in urban areas.

How to cite: Doherty, R., Cox, S., and Newell, J.: Investigating ingestion risks from soils and vegetables grown in urban lead-contaminated soil, and mitigation by soil amendments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17177, https://doi.org/10.5194/egusphere-egu23-17177, 2023.

Biochar produced via pyrolysis is increasingly used in agriculture, either applied pure in larger amounts or as part of fertilizer applications. Biochar production temperatures above 500 °C result in highly persistent aromatic carbon that sequesters C with mean residence times of centuries to millennia [1]. Research over the last decade has shown that its agricultural use has mainly positive effects [2] although these are not guaranteed. Biochar is discussed as one of the few available ready-to-go negative CO₂ emission technologies with agricultural benefits; its production and use can already be certified and traded as a carbon sink [3]. However, with regard to agricultural applications, the initial research approach to use large amounts of biochar per hectare (>10 t ha^-1) is usually not sufficiently incentivised by corresponding yield increases covering the expenses for biochar [1]. Hence, recent research focuses on biochar use as a mixing component of organic or mineral fertilizers. Here, we report the results of repeated smaller amount applications (2.5 t ha^-1 per crop cycle) of biochar to the root-zone with each cropping, i.e. to the same plots over four consecutive vegetable crop production sets during 2021 to 2023. The experimental set-up was a two-factorial randomized block design field study with five blocks (plot replications). Factor 1 was the use of mineral versus organic fertilizer, factor 2 was no biochar application (control) or two differently produced biochars from woody waste materials (i.e. 6 treatments overall). Fertilizers or biochar-fertilizer mixtures were applied to the root zone at seedling planting; for the mineral fertilization, part of the total fertilizer sum was added manually as fertigation irrigation during crop growth. In 2021, spring and summer 2022, celery root, salad and broccoli were grown, while in autumn-winter 2022/2023, spinach was grown. Greenhouse gas fluxes were measured weekly for the last crop cycle to investigate long-term (partly-aged) biochar effects with the closed-chamber method and will be reported. The biochar-organic fertilizer blends never increased yields significantly for either of the crop species. However, in the beginning, organically fertilized vegetable yields were generally lower than those with mineral fertilization which reversed over the third and fourth crop cycles (broccoli and spinach) for the controls. When combined with mineral fertilizer, biochar significantly increased the yield of celery (up to 20%), of broccoli (up to 70%) and spinach (up to 54%) while the biomass of salad was slightly reduced with biochar application. Soil mineral N concentrations before or after crop plantings / harvests and plant N uptake indicated an improved N use efficiency with biochar use. Our results demonstrate that lower amounts of biochar plus repeated applications with each crop cycle may be a way forward for agriculture in particular when combined with mineral fertilization.

• Lehmann, J., et al., Biochar in climate change mitigation. Nature Geoscience, 2021. 14(12): p. 883-892.
• Schmidt, H.P., et al., Biochar in agriculture - A systematic review of 26 global meta-analyses. Global Change Biology Bioenergy, 2021. 13(11): p. 1708-1730.
• EBC Certification of the carbon sink potential of biochar. (http://European-biochar.org). Version 2.1E of 1st February 2021, 2020. 35.

How to cite: Kammann, C., Funk, C., Spiller, A., Koppel, M., Zinkernagel, J., and Geilfus, C.-M.: Effects of repeated root-zone application of biochar-fertilizer mixtures in the field on vegetable crop yields, plant N use and N2O emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14303, https://doi.org/10.5194/egusphere-egu23-14303, 2023.

Biochar amendments to fertilized soils are an important step towards more resource-efficient practices in agriculture by limiting the amounts of nutrients being leached to water bodies or transformed to the potent greenhouse gas (GHG) nitrous oxide (N₂O). Biochar was often amended to the soil separately to the fertilizer application. Alternatively, biochar and nutrient bearing salts or minerals can be blended and aggregated, e.g., granulated prior to soil application. However, the impact of this practice on biochar effects on nutrient availability, leachability and soil-borne N₂O emissions is so far largely unexplored. Here, we present data on the effects of a granulated, biochar-blended mineral NPK fertilizer applied to a sandy soil in two different greenhouse pot trials on white cabbage and spinach, respectively. In the white cabbage (Brassica oleracea convar. Capitata var. Alba) experiment, the biochar blended NPK fertilizer reduced nitrogen leaching by 30 to 45% compared to the pure NPK fertilized control following two simulated heavy precipitation events. Results in a similar range were obtained when pure, milled biochar was homogeneously mixed with pure NPK fertilizer in the soil as a further control. The reduced nutrient loss in biochar-amended pots may have contributed to increases in cabbage head biomass of 14% for the granulated biochar NPK fertilizer and 34% for the loose mix of milled biochar with pure NPK fertilizer, when compared to the NPK fertilizer control without biochar. In the spinach (Spinacia oleracea, no precipitation events) experiment, the biochar-blended granulated fertilizer increased the marketable fresh spinach yields by 5% while the mixture of milled biochar and pure NPK fertilizer in the soil increased yields by 13% compared to the control without biochar, respectively. The analyses of GHG emissions that were measured during this experiment allows to comprehend whether these yield increases were also caused by a lower volatilization of fertilized nitrogen as N₂O-N. With these two experiments, we provide insights on how biochar-blended fertilizers interact with plants and the soil system and how biochar could be used in agricultural practices to increase nutrient use efficiencies, i.e., the environmental costs per unit of yield produced, by reducing the undesired loss of nutrients from soil in combination with yield increase.

How to cite: Grafmüller, J., Kray, D., Kammann, C., Mühe, M. E., Schmidt, H.-P., and Hagemann, N.: Granulated biochar-based NPK fertilizer and its impact on nutrient leaching, plant growth and soil-borne N2O emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9066, https://doi.org/10.5194/egusphere-egu23-9066, 2023.

The use of peat in traditional agricultural systems and nursery enterprises is an environmental concern. Since the high CO₂ and greenhouse gas emission due to peat excavation contributes considerably to climate change and global warming it is key to find new valuable resources in the field of carbon based materials production and application. This approach not only contributes to the concept of circular economy and the reduction of contaminants and waste, such as excessive nitrogen (N) fertilizers, but is also beneficial with respect to nutrient recovery and use efficiency. In this work we partially replaced peat with different amounts of biochar obtained from vineyard pruning as plant growing substrates while implementing N fertirrigation. We studied the effect on the growth, different content of N forms and other nutrient dynamics impact of lettuce plants grown under greenhouse and semi-hydroponics conditions. Substrate mixtures contained 30% of vermiculite and 70% of different biochar:peat treatments as follows: 0:70 (B0), 15:55 (B15), 30:40 (B30), 50:20 (B50), and 70:0 (B70). Higher biochar treatments increased pH and electrical conductivity of the substrate, negatively affecting plant growth and germination (especially in B70). The substitution of 30% peat by biochar (B30) delayed seed germination but improved plant growth and N use efficiency. This is related with a higher nitrate (NO₃^‒) retention capacity in the substrate, leading to higher contents of organic N and NO₃^‒ in the plant shoot. The treatment B30 also increased the water holding capacity of the substrate, which may enhance soil moisture characteristics and pore size distribution, maximizing water availability to plants. Our study demonstrates that the use of biochar can reduce the consumption of peat and excessive N fertilizers, while promoting a more sustainable farming with positive impact on both the plant growth and the environment.

Acknowledgement: This research was funded by European Union’s Horizon 2020 research and innovation programme un-der the Marie Skłodowska-Curie grant agreement No 895613 and EIT Food program (Black to the Future Project, EIT-21217). This EIT Food activity has received funding from the European Institute of Innovation and Technology (EIT), a body of the European Union, under Horizon Europe, the EU Framework Programme for Research and Innovation. A.F. Garcia-Rodriguez acknowledges the Spanish National Research Council for providing JAE Intro-ICU grant.

How to cite: Garcia Rodriguez, A. F., Moreno-Racero, F. J., García de Castro Barragán, J. M., Colmenero-Flores, J. M., Greggio, N., Rosales, M. A., and Knicker, H.: Partial peat replacement by biochar as a potential strategy to increase plant growth, nutrient sink and circular economy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-238, https://doi.org/10.5194/egusphere-egu23-238, 2023.

The hydrothermal carbonization (HTC) of organic feedstocks results in hydrochar, a product free of pathogens with the potential to be used as soil amendment as an efficient tool to recycle nutrients from organic waste and improve soil quality. However, presently the knowledge about the mechanisms of controlling hydrochar biogeochemical effects in planted soils is still scarce. Likewise, there is not much understanding about the effects under deficit irrigation conditions. In the present work, a hydrochar (250 ºC, 0.5 h) from chicken manure was used to evaluate the impact of this amendment on nutrient status and dynamics, the microbial activity and the quantity and quality of the organic matter of sunflower-planted soils during a 77 days greenhouse experiment. The main objective of this study was to obtain a better understanding of the interrelationship between soil organic matter (SOM), soil nutrients, microbial activity and irrigation management of soils.

The hydrochar was applied to a Cambisol with doses of 3.25 and 6.5 t ha^-1. For comparison, mineral fertilizer treatments with the same contribution of total nitrogen (N) as the amendment were included in the study. Sunflower plants (Helianthuus annus L.) were grown in pot cultures under two irrigations conditions (60 and 30% of the soil water retention capacity).

Total macro- and micronutrients, along with soluble nutrients among the soils were monitored after 30 and 77 days. The SOM composition of these soils was characterized by solid-state NMR spectroscopy. For the microbiological studies, the microbial biomass carbon (MBC) and N (MBN) were analysed by the fumigation-extraction technique. Dissolved organic carbon (DOC) and N (DON) were also analysed. Determination of β-glucosidase, acid phosphomonoesterase and dehydrogenase activities were assayed to study the microbial metabolism of soil. We test the hypothesis that hydrochar has an impact on composition and dynamics of nutrients, SOM quality and soil microbial activities, resulting in a beneficial effect on the soil-plant system in both irrigation conditions.

How to cite: Moreno Racero, F. J., Velasco Molina, M., López Núñez, R., Martínez Force, E., Rosales Villegas, M. Á., and Knicker, H.: Impact of hydrochar on the soil organic matter, nutrients status and microbial activity in sunflower-planted soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-519, https://doi.org/10.5194/egusphere-egu23-519, 2023.

Nutrient density in manure and fermentation residues is too low to economically justify transporting them to regions with phosphorus (P) and nitrogen (N) demands. However, they present a valuable feedstock for the production of commercial P fertilizers via pyrolysis. Phosphorus availability in the resulting chars for plant uptake can be further improved by adding potassium (K) salts to the feedstock prior to pyrolysis, while vinasse can be added for N enrichment. Such recycling-derived N-P(-K doped) fertilizers are expected to release nutrients slowly to the plants and to have positive environmental effects like nitrate retention, reduction of nitrous oxide (N₂O) emissions and carbon (C) sequestration. We conducted a greenhouse pot experiment with celery and spinach cultures to investigate the P fertilization performance and environmental effects of newly developed recycling-derived N-P(-K) char fertilizers. Four novel pyrolysis products were tested: three different N-enriched (vinasse) dry flowable products (pyrolyzed material: dried pelletized chicken manure, digestate, and the dried solid fraction of pig slurry, respectively), and a char from dried pig manure, which had been enriched with potassium acetate prior to pyrolysis. The pot experiment demonstrated that P-char fertilizers, combined with a liquid organic N fertilizer commonly used in organic farming (vinasse), can provide the same P-fertilization as triple super phosphate (TSP), with yields similar to or higher than those obtained with mineral N fertilizers. Furthermore, the char fertilizers, and in particular the K-doped char, reduced nitrate leaching significantly compared to treatments with TSP + calcium ammonium nitrate (CAN) or TSP + vinasse. Liquid vinasse application drastically enhanced N₂O emissions compared to pots where less or no liquid vinasse was applied without char. P-char fertilizers may thus provide a promising building block for a circular economy-based P supply chain while simultaneously reducing environmental costs in the form of less nitrate leaching and lower N₂O emissions and contributing to soil C sequestration in the plough layer.

The project was funded by the Federal Ministry of Food and Agriculture (BMEL) on the basis of a resolution of the German Bundestag. The project was carried out by the Federal Agency for Agriculture and Food (BLE) within the framework of the Innovation Promotion Program. Title of the research project: "Carbon-based fertilizers from phosphorus-rich slurry, manure and fermentation residues by carbonization with nitrogen recovery", grant numbers 2818105215, 2818105015 and 2818107115.

How to cite: Görres, C.-M., Kammann, C., and Appel, T.: Potential of novel organic NP(K)-char fertilizers as part of a circular economy-based phosphorus supply chain – results from a pot experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13312, https://doi.org/10.5194/egusphere-egu23-13312, 2023.

Today's agriculture faces the challenge of guarantee food supply of a growing population while human activity has already degraded nearly 40 % of the world's soils [1], which lose productive capacity and increase dependence on mineral fertilizers. In this context, the valorization and recycling of mineral and agricultural waste for use as substrates or soil amendments promotes the local and sustainable economy as well as the implementation of activities based on closing the soil nutrients’ cycle. Moreover, pyroclastic rocks and volcanic ashes formed by volcanic eruptions are usually rich in Si, Ca, Mg, Al, Fe, K, P and S [2], so they can be used in agriculture as inorganic mulch. Looking for an effective solution to the great waste generation and the current challenges of sustainable agriculture [3], this study addresses the agronomic effects of the application of contrasting inorganic and organic materials including green compost, wood biochar, rice husk ash and volcanic ash released in the recent eruption of the Tajogaite volcano (La Palma Island, Spain) as amendments of an alkaline soil typical of the Mediterranean basin. For this purpose, barley seeds were planted and grown under controlled conditions in a greenhouse for 60 days on a Luvisol amended with the above-mentioned materials.

The organic amendments improved soil physical properties, such as the reduction of bulk density and of the soil resistance to penetration, and increased the organic carbon content. Biochar increased the amount of refractory organic matter of the Luvisol. The application of rice husk ash, volcanic ash, and to a lesser extent the green compost, increased the nutrient content of the soil. Nevertheless, no significant differences were observed on germination rates, productivity and abiotic markers of stress of the barley plants.

Acknowledgements: Authors thank the financial support from the Spanish Ministry of Science and Innovation (MCIN) under the projects RES2SOIL (PID2021-126349OB-C22) and TUBOLAN (PID2019-108672RJ-I00) supported by MCIN and AEI. The European Joint programme EJP SOIL funded from the EU Horizon 2020 research and innovation programme (Grant agreement Nº 862695) is also thanked for funding the subproject EOM4SOIL.

References:

[1] Gibbs, H.K., Salmon, J.M., 2015. Appl. Geogr. 57: 12-21.

[2] Ramos, C.G., Querol, X., Dalmora, A.C., Pires, K.C.J., Schneider, A.H., Oliveira, L.F.S., Kautzmann, R.M., 2017. J. Clean. Prod., 142: 2700-2706.

[3] De la Rosa, J.M., Campos, P., Diaz-Espejo, A., 2022. Agronomy, 12: 2321. https://doi.org/10.3390/agronomy12102321

How to cite: De la Rosa, J. M., Pérez-Dalí, S., Miller, A. Z., Campos, P., Sánchez-Martín, Á., Cubero, B., Jiménez-Morillo, N. T., Merino, A., and González-Pérez, J. A.: Assessment of the agronomic impact of rice husk ash, volcanic ash, green compost and wood biochar as soil amendments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2301, https://doi.org/10.5194/egusphere-egu23-2301, 2023.

Abstract

Biochar amendments are gaining globally for improving soil health and carbon storage.  This study investigated the physicochemical properties and impact on soil microbes of biochar amendments derived from two feedstock sources: date palm leaves (D), and mesquite plants (M); pyrolyzed at 450, 600 and 750 ℃. SEM images revealed that the pore size increased with increasing pyrolysis temperature. According to the Fourier transform infrared spectroscopy results, the increase in pyrolysis temperatures reduced the O-H and C-O bonds while increasing the proportion of C-C bonds. The dynamic thermal gravimetric analysis evidence that the thermostability was greatest at a pyrolysis temperature of 750 °C, and was also significantly different for the two feedstock materials used. The M feedstock produced biochar with the highest surface area (600 m² g^-1) and carbon content based on loss on ignition (95%); moreover, this biochar reduced soil microbial enumeration and respiration, and this effect was more pronounced for biochar pyrolysed at 750 °C. As a result, M biochar feedstocks are not recommended for improving soil health, but they may be useful as microbial inhibitors when soil-borne plant pathogens are present. Based on the physicochemical properties and the biochar impact on soil properties, D at 600 °C was chosen as the best-performing biochar in our study for improving soil health in arid lands and was selected for further research as a soil amendment. The large differences in biochar physicochemical properties and their observed effect on soil properties confirmed that the feedstock type and pyrolysis temperatures must be considered during biochar production for soil health applications in arid-land agroecosystems.

How to cite: Al Rabaiai, A., Menezes-Blackburn, D., Al-Ismaily, S., Janke, R., Pracejus, B., Al-Alawi, A., Al-Kindi, M., and Bol, R.: Feedstock type and pyrolysis temperatures regulate the impact of biochar on soil health in arid land agroecosystems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7819, https://doi.org/10.5194/egusphere-egu23-7819, 2023.

The aim of this study was to investigate the transport behavior of two selected organophosphorus pesticides (chlorpyrifos-CP and chlorpyrifos-methyl-CPM) through Danube alluvial sediment in the absence and in the presence of microbially inoculated chars originated from sugar beet shreds (biochar produced at 400°C and three hydrochars produced at 180, 200, and 220°C). Bacillus megaterium strain was used for microbial inoculation of investigated carbon-based adsorbents. Column experiments were used to simulate sorption in non-equilibrium conditions. Obtained results were modeled using the advective-dispersive equation (ADE). For column experiments only with alluvial sediment retardation coefficient (R_d) was in the range (R_d=15.5-16) and higher biodegradation was observed for CPM (λ=4.15) than for CP (λ=1.80). The retardation coefficient (R_d) for investigated compounds in column experiments with the addition of inoculated carbon-based materials ranged from (R_d=20-275). The addition of inoculated carbon based materials in a column filled with alluvial sediment significantly increases the retardation coefficient (R_d). This may be a consequence of simultaneous adsorption on the organic matter of the alluvial sediment, on carbon-based materials and results of biosorption. The biodegradation (λ) of the investigated compounds in a column filled with the addition of inoculated adsorbents was in range (λ=0.4-4.5) and was lower compared to the column without the addition of chars. A higher retardation coefficient (R_d) in column experiments with the addition of inoculated chars was observed for biochar than for hydrochars, which is directly correlated with the higher specific surface area (SSA) of the investigated biochar. Generally, the addition of inoculated carbon-based materials to contaminated sediments has the potential as a remediation technique to inhibit the leaching of pollutants to groundwaters and affect their immobilization.

Keywords: transport, biochar, hydrochar, chlorpyrifos, chlorpyrifos-methyl, sugar beet shreds

Acknowledgment

Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 101059546

How to cite: Jevrosimov, I., Kragulj Isakovski, M., Apostolović, T., Rončević, S., Tamindžija, D., and Maletić, S.: Transport of selected organophosphorus pesticides through alluvial sediment with the addition of microbially inoculated chars, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9431, https://doi.org/10.5194/egusphere-egu23-9431, 2023.

How to cite: Kourtaki, K., Martin, P., Buchner, D., and Haderlein, S.: Application of carbon compound-specific isotope analysis (carbon-CSIA) to investigate microbial transformation of glyphosate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8289, https://doi.org/10.5194/egusphere-egu23-8289, 2023.

Wastewater and drainage waters that discharge in the water bodies contain phosphates that increase eutrophication. In order to remove phosphates ions different type of sorbent materials have been examined such as biochar (BC). The aim of our study was to investigate the effectiveness of biochar produced from easily available food processing waste materials, the effect of pyrolysis temperature, and the modification of biochar for the removal of phosphates from water. Eggshells (EGS), rice husk (RH) and Coffee materials were pyrolyzed at 400 and 800^oC. The sorption efficiency of each raw material (eggshells, spent coffee grounds and rice husks) was also examined after modification with MgCl₂⋅6H₂O.

Generally, biochars pyrolyzed at 800^oC had higher sorption capacity compared to biochars pyrolyzed at 400^oC. Kinetic experiments demonstrated that magnesium modified EGS pyrolyzed at 800^oC were superior for the removal of phosphates (27.5 mg P/g). The EGS and RH biochars and the corresponding magnesium modified biochars pyrolyzed in 800^oC were further examined in isotherm studies. The highest sorption capacity (q_max) was observed with EGS pyrolyzed at 800^oC and was 11.4 mg PO₄^3--P/g. Modified EGS biochars pyrolyzed at 800^oC had almost the half sorption capacity compared to unmodified materials. Modification of RH biochar pyrolyzed at 800^oC resulted in higher sorption capacity by 34% for phosphates, compared to the RH biochar. The specific surface area values of the biochars examined is not a decisive factor for nutrient sorption. Reaction between magnesium and calcium (for the eggshell samples) ions with phosphates is responsible for the higher sorption efficiency.

How to cite: Biliani, S., Vakros, J., and Manariotis, I.: Phosphates removal from water by raw and modified biochar from food processing wastes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5791, https://doi.org/10.5194/egusphere-egu23-5791, 2023.