Initial and subsequent effects of hydrochar amendment on germination and nitrogen uptake of spring barley |
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| Authors: | Inge Bargmann Matthias C Rillig Andrea Kruse Jörg‐Michael Greef Martin Kücke |
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| Institution: | 1. Freie Universit?t Berlin, Institute of Biology, Plant Ecology, Altensteinstra?e 6, 14195 Berlin, Germany;2. Karlsruhe Institute of Technology (KIT), Institute for Catalysis Research and Technology, Hermann‐von‐Helmholtz‐Platz 1, 76344 3. Eggenstein‐Leopoldshafen, Germany;4. University Hohenheim, Institute of Agricultural Engineering, Conversion Technology and Life Cycle Assessment of Renewable Resources, Garbenstra?e 9, 70599 Stuttgart, Germany;5. Julius Kühn‐Institut, Institute of Crop and Soil Science, Bundesallee 50, 38116 Braunschweig, Germany |
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| Abstract: | The application of hydrochars as soil amendments could be an option to ameliorate soil quality by enhancing nutrient and water‐holding capacity of sandy soils. But when hydrochar application is directly followed by sowing, it can decrease the soil mineral‐N concentration and the germination rate of crops. We currently lack evidence, whether these effects are persistent or transient and thus can be avoided by adjusting the application strategy, e.g., by prolonging the period between application and sowing. A set of pot trials with spring barley (Hordeum vulgare L.) was performed to study the initial and subsequent effects of different hydrochar amendments on germination, biomass production, and plant N availability. To this end, two subsequent cultivations of barley were grown on hydrochar‐amended soil–peat substrates. The first barley cultivation was sown directly after hydrochar application. After the harvest, the same substrates were cultivated with barley again. Germination, biomass production, and N concentration in the biomass were reduced when sowing directly followed the application of hydrochars. Differences in germination rate and biomass production between hydrochar treatments depended on the hydrochar feedstock. A recultivation of the hydrochar‐amended substrates 9 weeks after hydrochar application showed no significant effects on germination and biomass production. The N concentration in plants was still lower in the hydrochar treatments despite additional fertilization. The N immobilized during the first cultivation period was not released in the following weeks. We conclude that the germination‐inhibiting substances in hydrochars were removed in the weeks after soil incorporation. This is probably due to microbial degradation of hydrochar components and a consecutive immobilization of mineral N. Hydrochar amendment had only short‐term effects on germination and biomass production of barley that can be avoided by applying hydrochar at least 4 weeks prior to sowing. The N concentration in plants was persistently low even 4 months after hydrochar application which can only be redeemed by adjusting the fertilization strategy. |
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| Keywords: | hydrothermal carbonization germination inhibition nitrogen immobilization nitrogen availability |
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