Browsing by Subject "Biochar"

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  • Baltrenaite, Edita; Baltrenas, Pranas; Bhatnagar, Amit; Vilppo, Teemu; Selenius, Mikko; Koistinen, Arto; Dahl, Mari; Penttinen, Olli-Pekka (2017)
    The environmental legislation and strict enforcement of environmental regulations are the tools effectively used for developing the market of materials for environmental protection technologies. Sustain ability criteria shift environmental engineering systems to more sustainable-material-based technologies. For carbon-based medium materials in biofiltration, this trend results in attempts to use biochar for biofiltration purposes. The paper presents the analysis of biochar properties based on the main criteria for biofiltration medium integrating the environmental quality properties of biochar, following the European Biochar Certificate guidelines. Three types of biochar produced from feedstock of highly popular and abundant types of waste are analysed. A multi component approach was applied to summarize the results. The lignocellulosic type of biochar was found to be more competitive for use as a biofiltration medium than the types of biochar with high ash or lignin content. (C) 2016 Elsevier Ltd. All rights reserved.
  • Sarvi, Minna; Hagner, Marleena; Velmala, Sannakajsa; Soinne, Helena; Uusitalo, Risto; Keskinen, Riikka; Ylivainio, Kari; Kaseva, Janne; Rasa, Kimmo (2021)
    Production of organic fertilizers from poultry manure may compromise availability of phosphorus (P) to plants. This study examined the effects of granulation, feather meal addition, and pyrolysis on bioavailability of P in broiler manure in a pot experiment with ryegrass and assessed whether P availability is enhanced by inoculating arbuscular mycorrhizal fungi (AMF) into soil. Granulated broiler manure gave similar plant yield and P uptake to superphosphate. Feather meal addition had a minor negative effect on P availability, whereas pyrolysis lowered the fertilization effect of broiler manure. The yield-based mineral-P equivalences were 120%, 85% and 75% during the first harvest, and 100%, 75% and 45% during one growing season for granulated unamended, granulated amended with feather meal and pyrolyzed broiler manure. Soil inoculation with AMF did not enhance P availability. Granulated poultry manure is suitable as a P fertilizer for annual crops with comparable bioavailability to mineral fertilizer P, whereas pyrolyzed poultry manure is suitable as a slow-release or storage P fertilizer in slightly acidic soils. Knowledge on P bioavailability in organic fertilizers produced with different technologies can be used for optimizing fertilization, minimizing build-up of soil P and its adverse environmental effects. (C) 2021 The Author(s). Published by Elsevier B.V.
  • Kinnunen, Niko; Laurén, Annamari (Ari); Pumpanen, Jukka; Nieminen, Tiina M.; Palviainen, Marjo (2021)
    A 96-h laboratory experiment was conducted to assess the potential of biochar as a water protection tool for acid sulfate soil runoff. Acid sulfate soils pose a risk to water bodies due to acid, metal-rich runoff, especially in drained peatland forests. New water protection methods, such as adsorption with biochar, are needed. We investigated the capability of spruce and birch biochar to adsorb metals and reduce acidity in the water. Water from an acid sulfate site was stirred with biochar, biochar with lime, and biochar with ash. We determined water Al, S, Fe, Cu, Co, Cd, Ni, and Zn concentrations periodically, as well as pH and total organic carbon at the beginning and the end of the experiment. The studied substances are considered the most abundant and environmentally harmful elements in the acid sulfate soils in Finland. Biochar surface characteristics were analyzed with FTIR spectroscopy. Concentration changes were used to parametrize adsorption kinetics models. Biochar adsorbed metals and increased pH, but lime and ash additives did not always improve the adsorption. Spruce biochar and ash addition had generally higher adsorption than birch biochar and lime addition. The adsorption was dominated by Al and Fe at lower pH, while increasing pH improved the adsorption of Cd and Zn. The results show that biochar can increase the water pH, as well as adsorb Al, Fe, Co, Cd, Ni, and Zn. Further work could include an actual-scale biochar reactor in a laboratory and field conditions.
  • Bada, Bolajoko (Helsingin yliopisto, 2017)
    This research was conducted to examine the effect of biochar on drought tolerance and growth of a grain crop. Biochar is a multipurpose charcoal that heals the soil and promotes crop yield. The experiment was part of University of Helsinki biochar research during the summer and autumn of 2011. The effect of biochar was studied in a greenhouse experiment to determine how well it can improve sorghum (Sorghum bicolor Moench) yield. The experimental factors were amount of water given at low, intermediate and full watering levels, and the absence or presence of Acacia-biochar at level of 10 t/ha in the pots of soil used. The number of leaves per plant, leaf surface area, number of panicles, number of grains per panicle, plant and panicle height, root biomass, and whole plant (above ground) biomass was obtained. The plants were grown in a high greenhouse temperature to mimic the Sudanese extreme weather temperature according to the Khartoum Sudan weather forecast at the time of the experiment. The plants got same amount of water from cultivation until the emergence of 5 leaves. Early drought was proposed to determine its effect as the plant move from vegetative to reproductive stage and the effect of biochar on the soil water holding capacity (WHC). The drought stress started at 5 leaf stage of the plant life cycle. The data were analyzed using 2-way analysis of variance (Anova) statistical tools in SPSS (version 20.0, SPSS Inc., Chicago, IL, USA) software. Drought stress affected panicle development, grain yield, plant height, leaf surface area and overall biomass yield. Grain yield and whole plant biomass weight was higher in non-stressed plants. The results indicated no relief to drought stress by biochar addition. In this experiment, the addition of low biochar might be responsible for it inefficiency.
  • Li, Quan; Song, Xinzhang; Yrjälä, Kim; Lv, Jianhua; Li, Yongfu; Wu, Jiasheng; Qin, Hua (2020)
    Increased reactive N deposition has widespread effects on terrestrial ecosystems, such as biodiversity loss, soil acidification, as well as stimulated plant growth. Empirical studies show that biochar often affects soil quality, crop productivity, soil microbial community composition and enzyme activities. However, the effect of biochar addition on forest soil bacterial community along with enzyme activities under nitrogen (N) deposition and its related mechanisms have not been well studied yet. Therefore, a 2-year field study was conducted to investigate the effects of biochar amendment (0, 20, 40 kg biochar ha−1 yr−1) on soil nutrients, enzyme activities, and bacterial community in a Torreya grandis orchard under different levels of N deposition (0, 30, 60 kg N ha−1 yr−1). N deposition significantly increased soil nutrients availability, such as N, phosphorus (P) and potassium (K), while biochar amendment led to significant increase in soil pH, organic carbon (SOC), total N (TN), total P (TP), available P (AP) and available K (AK). Both N deposition and biochar amendment significantly decreased the soil microbial biomass carbon (MBC), altered soil microbial community and enzyme activities significantly. Biochar addition increased the relative abundance of phylum Proteobacteria under different levels of N deposition, but had variable effect on Acidobacteria groups. Non-metric multidimensional scaling (NMDS) indicated that biochar amendment can mitigate the effect of N deposition on soil bacterial community composition and enzyme activities. Soil pH and SOC played an important role in shaping soil bacterial community composition, while available AP and AK contents significantly related to the variation of soil enzyme activities. Structure equation modeling (SEM) revealed that N deposition had negative effect on soil enzyme activities while biochar amendment can mitigate this negative effect through increasing AP content. Our result suggests that biochar amendment can mitigate the alteration of soil bacterial community and enzyme activities induced by N deposition, and this mitigation effect was linked to the alteration of soil physicochemical properties, especially the increased AP content. Thus, biochar amendment could be a promising way to develop sustainable forest management under increasing N deposition.
  • Pousi, Matti August Oskari (Helsingin yliopisto, 2021)
    The ecological crisis is ravaging the planet. Governments and businesses have set carbon neutrality targets as part of a necessary green transformation. One promising negative emission technology is based on biochar, which has created excitement in the voluntary carbon markets. However, the voluntary carbon markets and carbon sequestration with biochar both stand at a crossroads. There is currently no regulation that would govern the markets. Only voluntary standardizations and the sellers and buyers’ conscience provide directions for the quality of offsets and real carbon cuts achieved. In addition, the production of high-quality biochar remains at a low level. This thesis contributes to the research on green transformations by examining critically the expectations and promises related to biochar and voluntary carbon markets. The focus of this study is on the framings and discourses related to the role of biochar and the voluntary carbon markets in low-carbon pathways. The main research question is: What are the different narratives and perspectives on the role of biochar and voluntary carbon markets in sustainable low-carbon pathways? To answer this, I have identified and interviewed the main actors and stakeholders in the supply chain of biochar-based offsets as well as analyzed key policy and research documents that take part in the biochar offset related discourses. The research approach draws from two theoretical frameworks: the sustainable pathways approach developed by Melissa Leach, Ian Scoones, and Andy Stirling and Maarten Hajer’s critical discourse analysis on environmental policy. These frameworks are used to analyze the informant interviews and policy and research documents. It is found out that there are five discursive patterns shaping the discourses related to biochar and the voluntary carbon markets: biochar as a magic bullet, market-led low-carbon pathway, techno-managerialism, traces of more transformative greening, and climate-centrism. Techno-managerialism is the most distinctive feature of the biochar and voluntary carbon market discourse. Together, the five patterns shape the way in which biochar and the voluntary carbon markets are perceived, how policy problems related to them are defined and framed, and finally, what type of policy solutions are formulated.
  • Zrim, Jure (Helsingfors universitet, 2016)
    Soil carbon sequestration is one of the most promising solutions to mitigate climate change. Biochar, a carbon rich solid obtained via pyrolysis and intended to be used as a soil amendment material, is currently the most efficient tool available for carbon sequestration. Further, some biochars can also improve soil properties and increase crop yield. Before the concept of using biochar as soil amendment can be implemented in a bigger scale, it is necessary to know how biochar affects soil fauna in long term. Earthworms present one of the largest animal biomass in soil. They feed on decomposed organic matter and also biochar and transfer it to pedosphere. Effect of biochars and fertilizers on earthworm abundance, biomass and community structure was studied in two field experiments, one on fertile Stagnosol and other on nutrient deficient Umbrisol. In both study sites, split-plot experiments with four replicates were arranged. The earthworms were sampled more than four and five years after the biochar have been applied to the fields on Umbrisol and Stagnosol, respectively. No significant effect of biochar or fertilizer treatments or their interactions were found on earthworms communities, suggesting biochar to be a safe method for carbon sequestration in Southern Finland conditions. The composition of earthworm species was typical for Finnish agricultural land with A. caliginosa dominating in both soils. However further research on long-term experiments are needed, in order to fully understand mechanisms of biochar effects on earthworms.
  • Deng, Biar; Tammeorg, Priit; Luukkanen, Olavi; Helenius, Juha; Starr, Mike (2017)
    We studied the effects of Acacia seyal Del. intercropping and biochar soil amendment on soil physico-chemical properties and sorghum (Sorghum bicolor L.) yields in a two-year field experiment conducted on a silt loam site near Renk in South Sudan. A split-plot design with three replications was used. The main factor was tree-cropping system (dense acacia + sorghum, scattered acacia + sorghum, and sole sorghum) and biochar (0 and 10 Mg ha(-1)) was the subplot factor. The two acacia systems had lower soil pH, N and higher C/N ratios compared to the sole sorghum system. Biochar significantly increased soil C, exchangeable K+ contents, field capacity and available water content, but reduced soil exchangeable Ca2+ and effective CEC, and had no effect on soil pH. Acacia intercropping significantly reduced sorghum grain yields while biochar had no significant effect on sorghum yields. The land equivalent ratio (LER) for sorghum yield was 0.3 for both acacia systems in 2011, with or without biochar, but increased in 2012 to 0.6 for the scattered acacia system when combined with biochar. The reduction in sorghum yields by the A. seyal trees was probably due to a combination of competition for water and nutrients and shading. The lack of a yield response to biochar maybe due to insufficient time or too low a dosage. Further research is needed to test for the effects of tree intercropping and biochar and their interactions on soil properties and crop yields in drylands.
  • Mishra, Anup (Helsingin yliopisto, 2018)
    Tiivistelmä * * Abstract Biochar is a porous carbonaceous solid material produced by pyrolysis, the thermochemical conversion of biomass in anoxic conditions. Various studies suggest that biochar amendment has a postitive effect on soil pH, soil respiration, carbon/ nitrogen ratio, nitrogen mineralization, ammonifcation and nitrification. These measurements have been studied in agricultural systems but are poorly understood in boreal forests. The study was done to investigate the effects of different wood biochar application rates: 0 t ha-1, 5 t ha-1, 10 t ha-1 on soil pH, respiration and nitrogen mineralization. Replicated studies were conducted at field sites located in Juupajoki (61⁰ 48´ N, 24⁰ 18´ E), southern Finland in young pine forest stands. The measurements were taken one year after the addition of biochar. The soil respiration ( CO2 effluxes ) were measured in June and july with different biochar ( pyrolysis temperatures 500⁰ C and 650⁰ C) while N mineralization was measured in November with biochar produced at 650 C. Biochar amendment increased soil pH in plots having biochar 10 t ha-1. Nitrogen mineralization rate in the organic layer increased with the increasing amount of biochar addition but the increase was not statistically significant. The pyrolysis temperature had no significant impact on soil CO2 effluxes. The biochar also did not have any significant impact on soil CO2 effluxes. However, in June, the plots treated with 10 t ha-1 biochar produced at 650⁰ C had significantly higher CO2 effluxes than control plots. The soil respiration data showed that biochar did not have any negative effect on native soil C stocks. We conclude that biochar exhibits important charactertics that will help carbon sequestration and N cycling in boreal forests.
  • Kalu, Subin; Simojoki, Asko; Karhu, Kristiina; Tammeorg, Priit (2021)
    Biochars (BC) have tremendous potential in mitigating climate change, and offer various agricultural and environmental benefits. However, there is limited information about the long-term effects of added biochars particularly from boreal regions. We studied the effects of a single application of softwood biochars on two contrasting boreal agricultural soils (nutrient-poor, coarse textured Umbrisol and fertile, fine-textured Stagnosol), both with high initial soil organic carbon contents, over eight years following the application. We focused on plant nutrient contents and nutrient uptake dynamics of different field crops over these years, as well as on soil physical properties and greenhouse gas emissions during seven to nine growing seasons. We found that, added biochars had minor long-term effects on the crop biomass yield, plant nutrient contents and plant nutrient uptake in both soil types. In terms of crop biomass yields, significant biochar × fertilization interactions were observed in barley (in 2013) and peas (in 2016), three and six years after the application of biochar in Stagnosol, respectively. In both cases, the biochar combined with the normal fertilization rate (100% of the recommended value) significantly increased crop biomass yield compared to corresponding fertilization treatment without biochar. However, the biochar had no effect at a lower fertilization rate (30% of the recommended value). Similar significant biochar × fertilization interactions were observed for several plant nutrient contents for peas in 2016, and for uptake for both barley in 2013 and peas in 2016. Thus, the ability of biochar to enhance the supply of nutrients to plants and hence to improve the crop biomass yield exists in boreal conditions, although these effects were minimal and not consistent over the years. Biochar notably increased plant K content, and also increased K:Mg ratio in plant biomass, suggesting a possible antagonistic effect of K on Mg in Umbrisol. Similar K antagonism on Na was observed in Stagnosol. The applied biochar also reduced the plant content and uptake of Al and Na in several years in Stagnosol. Furthermore, we found that, increased plant Mn content with biochar in the initial years subsequently declined over the following years in Umbrisol. On the other hand, the relative plant contents of Cd and Ni in Umbrisol, and P, K, Mg, S, Al, Cu, Fe and Ni in Stagnosol increased over the years. Despite these increased plant contents, no significant improvement was observed in crop biomass yield by added biochar over the years. The enhanced plant available water and reduced bulk density previously reported during the initial years were faded in long-term, likely due to dilution of biochar concentration in topsoil. However, the potential of biochar to affect N2O emission persisted, even seven years after the application.
  • Yli-Halla, Markku Juhani; Rimhanen, Karoliina; Muurinen, Johanna; Kaseva, Janne; Kahiluoto, Helena (2018)
    Soil carbon (C) represents the largest terrestrial carbon stock and is key for soil productivity. Major fractions of soil C consist of organic C, carbonates and black C. The turnover rate of black C is lower than that of organic C, and black C abundance decreases the vulnerablility of soil C stock to decomposition under climate change. The aim of this study was to determine the distribution of soil C in different pools and impact of agricultural management on the abundance of different species. Soil C fractions were quantified in the topsoils (0-15 cm) of 23 sites in the tropical highlands of Ethiopia. The sites in central Ethiopia represented paired plots of agroforestry and adjacent control plots where cereal crops were traditionally grown in clayey soils. In the sandy loam and loam soils of northern Ethiopia, the pairs represented restrained grazing with adjacent control plots with free grazing, and terracing with cereal-based cropping with adjacent control plots without terracing. Soil C contained in carbonates, organic matter and black C along with total C was determined. The total C median was 1.5% (range 0.33.6%). The median proportion of organic C was 85% (range 53-94%). 6% (0-41%) for carbonate C and 6% (421%) for black C. An increase was observed in the organic C and black C fractions attributable to agroforestry and restrained grazing. The very low concentration of the relatively stable black C fraction and the dominance of organic C in these Ethiopian soils suggest vulnerability to degradation and the necessity for cultivation practices maintaining the C stock. (C) 2018 Elsevier B.V. All rights reserved.
  • Karhu, Kristiina; Kalu, Subin; Seppänen, Aino; Kitzler, Barbara; Virtanen, Eetu (2021)
    Addition of biochar to soil has been shown to reduce nitrogen (N) leaching in pot experiments, but direct field measurements are scarce, and data is lacking especially from colder, boreal conditions. We studied the effect of soil organic amendments on nitrate (NO3-) and ammonium (NH4+) leaching using the resin bag method, by placing the bags containing ion-exchange resins under the plough layer. We compared N leaching under five different treatments at the Päästösäästö project site (Soilfood Oy) in Parainen, south-western Finland: non-fertilized control, fertilized control, and three different organic amendments: spruce biochar, willow biochar and nutrient fiber. During the 2017 growing season, resin bags were changed monthly between the end of May and beginning of September, extracted with 1 M NaCl, and analyzed for inorganic N. The daily leaching rate of NO3- was greatest at the beginning of the growing season, right after fertilization. Ammonium leaching was generally lower, and independent of the time since fertilization. The spruce biochar reduced cumulative NO3- leaching by 68% compared to the fertilized control. The NH4+leaching in the organic amendment treatments did not statistically significantly differ from the fertilized control in pairwise comparisons. In October 2017, after harvesting, the resin bags were placed under soil columns again, and left in the soil over winter to accumulate N leached during the plant-free period. Cumulative NO3- leaching during winter was consistent with the corresponding summer results, and average leaching decreased in the order: willow biochar >fertilized control >nutrient fiber >non-fertilized control >spruce biochar. Thus, we show here, for the first time in a field study from boreal conditions that spruce biochar soil application decreased nitrate leaching, while increasing its retention in the surface layer of the biochar-amended soil.
  • Rasa, Kimmo; Vihera-Aarnio, Anneli; Rytkonen, Peetu; Hyvaluoma, Jari; Kaseva, Janne; Suhonen, Heikki; Jyske, Tuula (2021)
    Novel bioeconomic approaches call for increasingly faster production of lignocellulosic biomass and its bettertailored use for higher added value. The high-yield capacity and structural properties of willows (Salix spp.) suggest their excellent potential for the production of designed biochar for use in agronomic, electronic and technical applications. All these applications rely on the internal pore structure of biochar. However, we lack an in-depth quantitative understanding of the interlinkages between the feedstock properties and the physical quality of the biochar produced. We studied quantitatively how the clonal and within-plant properties of five different willow clones (hybrids of Salix schwerinii E.L. Wolf) affected the micrometre-scale pore properties of the produced biochars (pyrolyzed at + 462 ?C). The porosity and pore size distribution were analysed before and after slow pyrolysis by X-ray microtomography and image analysis. We also studied the potential of conventional low-cost fibre analysis techniques to be used to predict biochar pore properties directly from fresh feedstock. The total porosity (0.55?0.62) and the pore size distribution of willow wood and derived biochars varied between clones. Approximately two-thirds of the biochar total porosity was associated with pores formed by wood fibres. Pyrolysis levelled off the structural variation detected between and within the clones. Pyrolysis-induced shrinkage reduced the pore sizes and narrowed the pore size distribution. The results suggest that conventional fibre analysis techniques could be utilized to predict biochar homogeneity. Short rotation coppice willows are suitable feedstock to produce homogenous biochar precursor for production of bio-based carbon materials to be used in high value-added technical applications. The structural homogeneity of the feedstock and produced biochar can be enhanced by selecting proper harvesting strategy and clones used in plantations. From the industrial perspective, comprehensive understanding of feedstock properties helps to control quality of the produced biochar.
  • Kiani, Mina; Raave, Henn; Simojoki, Asko; Tammeorg, Olga; Tammeorg, Priit (2021)
    Sediment removal from eutrophicated shallow lakes may not only be an effective method for lake restoration but also provides the potential for recycling nutrients from sediments to crop production. However, finding a suitable strategy for sustainably reusing the sediment remains a challenge. Therefore, current study focused on the best practices in applying the sediment from a shallow eutrophicated lake to the soil in terms of grass yield, nutrient uptake, and nutrient leaching. During a nine-month lysimeter experiment, 100-cm high columns were filled with six combinations of soil, sediment, and biochar, with or without meat bone meal organic fertilizer. Aboveground biomass, root mass distribution in soil, nutrient concentration, phosphorus (P) uptake of perennial ryegrass (Lolium perenne L.) along with easily soluble nutrients in the growing medium, and leached mineral nitrogen (N) and P levels were measured. Plant growth conditions were improved by sediment additions, as the yield and P uptake of ryegrass nearly doubled in treatments containing sediment compared to the control soil. While the sediment was richer in macro and micronutrients (e.g. P and N) compared to the soil, the leached N and P levels from both treatments were almost equivalent (N < 830 mg m−2 and P < 3 mg m−2). In addition, applying a 2-cm layer of biochar between the sediment and soil reduced P and N leaching by 50%. According to the results, applying a 75-cm thick layer of sediments on agricultural sandy loam soils surrounding the lake seems a promising practice for improving plant yield and soil nutrient status without increasing of P and N leaching from soil.
  • Anasonye, Festus; Tammeorg, Priit; Parshintsev, Evgeny; Riekkola, Marja-Liisa; Tuomela, Marja Tuulikki (2018)
    The use of biochar (BC) has been suggested for remediation of contaminated soils. This study aims to investigate the role of microorganisms in sorption of PAH to BC-amended soils. Fungi, especially the wood and litter-degrading fungi, have shown the ability for humification and to degrade recalcitrant molecules, and are thus suitable model organisms. Haplic Arenosol with high organic matter content was chosen to highlight the importance of soil organic matter (SOM) in PAH sorption, possibly to form non-extractable residue. Basidiomycetous fungi Agrocybe praecox and Phanerochaete velutina grown on pine bark were inoculated in organic matter (OM)-rich Haplic Arenosol and OM-poor sandy loam with either BC or chemically activated BC (ABC) and 14C-labelled pyrene for 60 days. Fungi did not mineralize pyrene, but increased sorption up to 47–56% in BC-amended Haplic Arenosol in comparison with controls (13–25%) without a fungus irrespective of the presence of an adsorbent. In OM-poor sandy loam, only 9–12% of pyrene was sorbed to amended soil in the presence of fungus and adsorbent. The results suggest that BC and fungal amendment increased sorption of pyrene, especially to Haplic Arenosol more than by either BC or fungi alone.
  • Zhu, Xudan; Zhu, Tingting; Pumpanen, Jukka; Palviainen, Marjo; Zhou, Xuan; Kulmala, Liisa; Bruckman, Viktor; Köster, Egle; Köster, Kajar; Aaltonen, Heidi; Makita, Naoki; Wang, Yixiang; Berninger, Frank (2020)
    Key message During the first summer, wood biochar amendments increased soil temperature, pH, and soil CO(2)effluxes in a xeric boreal Scots pine forest. The increase of soil CO(2)efflux could be largely explained by increases in by soil temperature. Higher biochar application rates (1.0 vs 0.5 kg m(-2)) led to higher soil CO(2)efflux while the pyrolysis temperature of biochar (500 or 650 degrees C) had no effect on soil CO(2)efflux. Context Using biochar as a soil amendment has been proposed to increase the carbon sequestration in soils. However, a more rapid soil organic matter turnover after biochar application might reduce the effectiveness of biochar applications for carbon sequestration. By raising the pyrolysis temperature, biochar with lower contents of labile carbohydrates can be produced. Aims To better understand the effects of biochar on boreal forest soil, we applied two spruce biochar with different pyrolysis temperatures (500 degrees C and 650 degrees C) at amounts of 1.0 and 0.5 kg m(-2)in a young xeric Scots pine forest in southern Finland. Methods Soil CO2, microbial biomass, and physiochemical properties were measured to track changes after biochar application during the first summer. Results Soil CO(2)increased 14.3% in 1.0 kg m(-2)treatments and 4.6% in 0.5 kg m(-2). Soil temperature and pH were obviously higher in the 1.0 kg m(-2)treatments. Differences in soil CO(2)among treatments disappear after correcting by soil temperature and soil moisture. Conclusion Biochar increased soil CO(2)mainly by raising soil temperature in the short term. Higher biochar application rates led to higher soil CO(2)effluxes. The increase in soil CO(2)efflux may be transient. More studies are needed to get the optimum biochar amount for carbon sequestration in boreal forest.
  • Song, Chengfang; Shan, Shengdao; Yang, Chao; Zhang, Cheng; Zhou, Xiaoqing; Ma, Qi; Yrjälä, Kim; Zheng, Huabao; Cao, Yucheng (2020)
    Dissolved organic matter (DOM) has an important effect on soil fertility, activity of microorganisms and transport of contaminants. In this study, DOM released by the hydrochar and biochar prepared under various conditions from pig manure, was assessed using a combination of UV–Visible spectroscopy, fluorescence excitation-emission (EEM) spectrophotometry and 1H-nuclear magnetic resonance (1H NMR). The dissolved organic carbon (DOC) extracted from the hydrochar and biochar ranged from 3.34–11.96% and 0.38–0.48%, respectively, and the highest DOM was released by HCK0.5 (180 °C and 0.5% KOH). The aliphatic compounds were most common in DOM which mainly included three humic acid-like and one protein-like substance. The hydrochar-DOM had a larger molecular weight and lower aromaticity than biochar-DOM, but the effect of temperature on the DOM characteristics of hydrochar and biochar was opposite. The acidic treatment increased the content of functional groups containing oxygen and nitrogen in hydrochar-DOM, and alkaline treatment increased the content of aliphatic compounds. The results obtained are beneficial to select carbonation process and guide the rational application of hydrochar and biochar from pig manure in soil remediation field.
  • Kuoppamäki, Kirsi (2021)
    Vegetated roofs, i.e. green roofs, were continuously measured for runoff to quantify their capacity to manage stormwater in a field experiment in southern Finland, with distinct seasonality and varying weather conditions. Attention was paid to heavy storms to study the potential in mitigating urban flooding. In addition, the impact of biochar amendment (10% v/v) on rainfall retention was studied. Meadow vegetation was established on crushed brick based substrate either by introducing plants as seedlings and seeds or by using pre-grown readymade mats. Annual retention varied from 40% to 70%. The highest retention, ca. 80%, was found in summer even though it was the rainiest season. Wintertime retention was 30-40%. The coarse substrate enabled infiltration even when frozen and, thus, the roofs operated also in winter. Heavy storms occurred mainly in summer, the season with the highest hydrologic performance of the roofs, resulting in >80% peak attenuation and slow release of runoff. In individual rain events, runoff from meadow roofs was largely a function of rainfall depth. However, retention was weakly explained by the amount of rainfall or by other variables, such as rainfall intensity or antecedent dry period, indicating the difficulty in capturing the complex phenomena behind variable weather conditions. Biochar improved retention only slightly, at maximum by ca. 10%. The empirical evidence of this study highlights vegetated roofs as a feasible technology to be applied in urban runoff management even in cold climate.