Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2024
Authors
Sonja Keel Alice Budai Lars Elsgaard Brieuc Hardy Florent Levasseur Zhi Liang Claudio Mondini Cesar Plaza Jens LeifeldAbstract
To increase soil organic carbon (SOC) storage, we need to improve our understanding on how to make best use of available plant biomass. Is it better to leave harvest residues on the field, or can we achieve higher SOC storage after processing biomass through, for instance, composting or pyrolysis to produce biochar? In the present study, we developed new parameters for different types of exogenous organic materials (EOMs), which allowed us to estimate the long-term effect of EOM addition on SOC storage using the soil carbon model RothC. For this purpose, we used a model version that included two additional EOM pools. First, we simulated the SOC evolution after addition of equal amounts of C in plant material and different EOMs (manure, compost, digestate, biochar) for a 38-year cropland trial in Switzerland. As expected, biochar showed the greatest increase in SOC due to its high stability. Next, we estimated how much C would remain after subjecting equivalent amounts of plant material and other EOMs to different processes. Loss rates of C for different processes were obtained from the literature. Due to different decomposition rates, the amounts of C remaining in the EOMs ranged from 7 % for anaerobic digestion of animal excreta to 100 % for plant material added directly to soil. These amounts of C were then added to the soil in the model experiments. Although the largest amount of C is lost during processing to biochar, biochar would clearly lead to highest long-term SOC stocks. Based on these first results we conclude that the trade-off between off-site stabilization and in-soil mineralization does not compromise the use of biochar for soil C storage. This means that despite the high C losses of about 50 % during biochar production, higher amounts of C remain in the soil because biochar has very low decomposition rates. In terms of C sequestration efficiency, biochar thus clearly outperforms the other biomass processing pathways. However, for practical recommendations, additional factors should be considered, such as nutrient availability of EOMs and environmental effects during processing, storage and soil application like nutrient leaching or gaseous emissions. Furthermore, we suggest a full life cycle assessment that considers e.g. energy costs for transport of biomass and energy savings from fossil fuel substitution by natural gas.
Abstract
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Authors
Jihong Liu ClarkeAbstract
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Abstract
Since the 1950s, the use of plastics in agriculture has helped solving many challenges related to food production, while its persistence and mismanagement has led to the plastic pollution we face today. Soils are no exception and concentrations of polyethylene mulch debris up to 380 kg/ha have been reported in Chinese agricultural soils. A variety of biodegradable plastic products have thus been developed and marketed, with the aim to solve plastic pollution through complete degradation after use. But the environmental conditions for rapid and complete degradation are not always fulfilled, and the risk that biodegradable plastics could also contribute to plastic pollution must be evaluated. In this presentation, we want to share the knowledge gained through research projects on biodegradable plastics in agricultural soil, where we both studied the degradation of biodegradable mulch under Nordic soil conditions, and the fate of other biodegradable plastics in soil amendments such as compost and biogas digestate. A two-year field experiment with biodegradable mulch (PBAT-starch and PBAT-PLA) buried in soil in mesh bags showed that also under colder climatic conditions does degradation occur, involving fragmentation already after 2 months, but that complete degradation may take 3 to 9 years, depending on soil temperature and soil organic matter content (both correlate positively with degradation rate). Accumulation is therefore likely to happen when biodegradable mulch is repeatedly used every year. A full-scale experiment with compostable plastic cups (PLA) at an industrial composting plant, where we followed their fate and conducted metagenomic analysis over 13 weeks, demonstrated the major role played by fungi for a successful degradation of PLA. However, the successful management of biodegradable plastic products largely depends on existing waste management infrastructure. Most biodegradable plastic bags, labelled as compostable and used for food waste collection do not end up in industrial composting plants in Norway, but in biogas production plants. Here, we showed that these plastic bags (Mater-Bi®) are only marginally degraded (maximum 21-33 % mass loss) during biogas production, and likely to end up in biogas digestate and then in agricultural soils, unless digestate is treated to remove plastic residues.
Abstract
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Authors
Cornelya Klutsch Junbin Zhao Mikhail Mastepanov Hanna Marika Silvennoinen Juho Vuolteenaho Erling Fjelldal David Kniha Runar Kjær Snorre HagenAbstract
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Authors
Aline Roma Tomaz Ademir de Oliveira Ferreira Rattan Lal Telmo Jorge Carneiro Amado Belchior Oliveira Trigueiro da Silva William Ramos da Silva Felipe José Cury Fracetto Thiago Inagaki Maria Betânia Galvão Santos Freire Elves Obede dos Santos NunesAbstract
Land-use change has driven soil carbon stock losses in ecosystems worldwide. Implementing agricultural crops and exploiting forest resources trigger the breakdown of soil aggregates, thus exposing organic matter to microbial decomposition and enhancing carbon dioxide emissions, especially in biomes more susceptible to climate extremes as in the tropical semiarid regions. This study was based on the hypothesis that the undisturbed soil from the dry forest (Caatinga biome under natural revegetation in Brazilian semiarid) would have an improvement in the mass of macroaggregates and recover more than 50% of the soil C stock within 10 years. Thus, a field experiment was conducted to investigate soils from the Caatinga biome under native vegetation, “cowpea cropping” for over 30 years, and soil under natural revegetation for over 10 years, after conventional soil cultivation of maize and cowpea, to determine soil and soil-aggregates carbon stocks and to estimate the recovery rate of these stocks. The proportional mass of aggregates of different sizes and the total stock of particulate organic carbon (POC) were also quantified. The results showed that soil under preserved native vegetation of dry forest Caatinga biome had higher total soil C stock (50.9 Mg ha−1) than that under cowpea cropping (23.2 Mg ha−1) and natural revegetation (45.1 Mg ha−1). The proportional mass of large macroaggregates was higher in soil under native vegetation for all depths. However, soil under cowpea cropping had lower C stocks in macroaggregates, and recovered roughly 63% of the original C stocks, while revegetation recovered 78% of the stock in 10 years. Although the conventional management system for cowpea monoculture aggravated losses in soil carbon stock by more than 50% of the original C stocks, dry forest under natural revegetation recovered 79% of this stock and almost 100% of POC stock in 10 years (~12 Mg ha−1). Furthermore, soil under undisturbed Caatinga dry forest achieved C stock levels equivalent to that of the global average range for semiarid tropical environments. The high recovery rate of C stock in forest soil under natural revegetation indicates the resilience potential of organisms responsible for structural protection of aggregates and the encapsulated soil organic matter content.
Authors
Arne Verstraeten Aldo Marchetto Andreas Schmitz Nicholas Clarke Anne Thimonier Catherine Hilgers Anne-Katrin Prescher Till Kirchner Karin Hansen Tamara Jakovljevic Carmen Iacoban Wim de Vries Bernd Ahrends Peter WaldnerAbstract
No abstract has been registered
2023
Abstract
No abstract has been registered
Abstract
No abstract has been registered