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- ItemHydrothermal Carbonization and Pyrolysis of Sewage Sludge: Effects on Lolium perenne Germination and Growth(Basel : MDPI, 2019) Paneque, Marina; Knicker, Heike; Kern, Jürgen; De la Rosa, José MaríaThe pyrolysis and hydrothermal carbonization (HTC) of sewage sludge (SS) resulted in products free of pathogens, with the potential for being used as soil amendment. With this work, we evaluated the impact of dry pyrolysis-treated (600 °C, 1 h) and HTC-treated (200 °C, 260 °C; 0.5 h, 3 h) SS on the germination, survival, and growth of Lolium perenne during an 80 day greenhouse experiment. Therefore, the hydrochars and pyrochars were amended to a Calcic Cambisol at doses of 5 and 25 t ha−1. The addition of sludge pyrochars to the Cambisol did not affect Lolium germination, survival rates or plant yields. However, the use 25 t ha−1 of wood biochar reduced germination and survival rates, which may be related to the low N availability of this sample. In comparison to the control, higher or equal plant biomass was produced in the hydrochar-amended pots, even though some hydrochars decreased plant germination and survival rates. Among all the evaluated char properties, only the organic and inorganic N contents of the chars, along with their organic C values, positively correlated with total and shoot biomass production. Our work demonstrates the N fertilization potential of the hydrochar produced at low temperature, whereas the hydrochar produced at 260 °C and the pyrochars were less efficient with respect to plant yields.
- ItemBiochars in soils: towards the required level of scientific understanding(Vilnius : VGTU Press, 2016) Tammeorg, Priit; Bastos, Ana Catarina; Jeffery, Simon; Rees, Frédéric; Kern, Jürgen; Graber, Ellen R.; Ventura, Maurizio; Kibblewhite, Mark; Amaro, António; Budai, Alice; Cordovil, Cláudia M.d.S.; Domene, Xavier; Gardi, Ciro; Gascó, Gabriel; Horák, Ján; Kammann, Claudia; Kondrlova, Elena; Laird, David; Loureiro, Susana; Martins, Martinho A.S.; Panzacchi, Pietro; Prasad, Munoo; Prodana, Marija; Puga, Aline Peregrina; Ruysschaert, Greet; Sas-Paszt, Lidia; Silva, Flávio C.; Teixeira, Wenceslau Geraldes; Tonon, Giustino; Delle Vedove, Gemini; Zavalloni, Costanza; Glaser, Bruno; Verheijen, Frank G.A.Key priorities in biochar research for future guidance of sustainable policy development have been identified by expert assessment within the COST Action TD1107. The current level of scientific understanding (LOSU) regarding the consequences of biochar application to soil were explored. Five broad thematic areas of biochar research were addressed: soil biodiversity and ecotoxicology, soil organic matter and greenhouse gas (GHG) emissions, soil physical properties, nutrient cycles and crop production, and soil remediation. The highest future research priorities regarding biochar’s effects in soils were: functional redundancy within soil microbial communities, bioavailability of biochar’s contaminants to soil biota, soil organic matter stability, GHG emissions, soil formation, soil hydrology, nutrient cycling due to microbial priming as well as altered rhizosphere ecology, and soil pH buffering capacity. Methodological and other constraints to achieve the required LOSU are discussed and options for efficient progress of biochar research and sustainable application to soil are presented.
- ItemDirect nitrous oxide emissions from oilseed rape cropping – a meta-analysis(Milton Park : Taylor & Francis, 2014) Walter, Katja; Don, Axel; Fuß, Roland; Kern, Jürgen; Drewer, Julia; Flessa, HeinzOilseed rape is one of the leading feedstocks for biofuel production in Europe. The climate change mitigation effect of rape methyl ester (RME) is particularly challenged by the greenhouse gas (GHG) emissions during crop production, mainly as nitrous oxide (N2O) from soils. Oilseed rape requires high nitrogen fertilization and crop residues are rich in nitrogen, both potentially causing enhanced N2O emissions. However, GHG emissions of oilseed rape production are often estimated using emission factors that account for crop-type specifics only with respect to crop residues. This meta-analysis therefore aimed to assess annual N2O emissions from winter oilseed rape, to compare them to those of cereals and to explore the underlying reasons for differences. For the identification of the most important factors, linear mixed effects models were fitted with 43 N2O emission data points deriving from 12 different field sites. N2O emissions increased exponentially with N-fertilization rates, but interyear and site-specific variability were high and climate variables or soil parameters did not improve the prediction model. Annual N2O emissions from winter oilseed rape were 22% higher than those from winter cereals fertilized at the same rate. At a common fertilization rate of 200 kg N ha−1 yr−1, the mean fraction of fertilizer N that was lost as N2O-N was 1.27% for oilseed rape compared to 1.04% for cereals. The risk of high yield-scaled N2O emissions increased after a critical N surplus of about 80 kg N ha−1 yr−1. The difference in N2O emissions between oilseed rape and cereal cultivation was especially high after harvest due to the high N contents in oilseed rape's crop residues. However, annual N2O emissions of winter oilseed rape were still lower than predicted by the Stehfest and Bouwman model. Hence, the assignment of oilseed rape to the crop-type classes of cereals or other crops should be reconsidered.
- ItemImpact of chars and readily available carbon on soil microbial respiration and microbial community composition in a dynamic incubation experiment(Amsterdam : Elsevier, 2016) Lanza, Giacomo; Rebensburg, Philip; Kern, Jürgen; Lentzsch, Peter; Wirth, StephanThe carbonisation of biomass and organic residues is discussed as an opportunity to store stabilised carbon compounds in soil and to reduce mineralisation and the emission of CO2. In this study, pyrolysis char (600 °C, 30 min) and hydrothermal carbonisation char (HTC char; 210 °C, 23 bar, 8 h), both derived from maize silage, were investigated in a short-term incubation experiment of soil mixtures with or without readily available carbon (glucose) in order to reveal impacts on soil microbial respiration and community composition. In contrast to pyrolysis char, the addition of HTC char increased respiration and enhanced the growth of fungi. The addition of glucose to soil-char mixtures containing either pyrolysis or HTC char induced an additional increase of respiration, but was 35% and 39% lower compared to soil-glucose mixtures, respectively, providing evidence for a negative priming effect. No significant difference was observed comparing the soil mixtures containing pyrolysis char + glucose and HTC char + glucose. The addition of glucose stimulated the growth of most microbial taxa under study, especially of Actinobacteria at the expense of fungi. Adding pyrolysis or HTC char to soil induced a decline of all microbial taxa but did not modify the microbial community structure significantly. Addition of pyrolysis or HTC char in combination with glucose however, increased the abundance of Actinobacteria and reduced the relative abundance of Acidobacteria and Betaproteobacteria while fungi were further increased in case of HTC char. We conclude that both chars hold the potential to bring about specific impacts on soil microbial activities and microbial community structure, and that they may compensate the variations induced by the addition of readily available carbon.
- ItemEinfluss der mineralischen Stickstoff-Düngung auf den Biomasseertrag von Pappel und Weide sowie Ermittlung relevanter Umweltwirkungen : Abschlussbericht ; Projektlaufzeit: 01.09.2008 bis 31.12.2012(Hannover : Technische Informationsbibliothek, 2013) Kern, Jürgen; Balasus, Antje; Forstreuter, Manfred; Kaupenjohann, Martin[no abstract available]