Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2024
Sammendrag
The evolution of soil structure in agricultural soils is driven by natural and anthropogenic factors including inherent soil properties, climate and soil management interventions, all acting at different spatial and temporal scales. Although the causal relationships between soil structure and these individual factors are increasingly understood, their relative importance and complex interactive effects on soil structure have so far not been investigated across a geo-climatic region. Here we present the first attempt to identify the relative importance of factors that drive the evolution of soil structure in agricultural soils as well as their direction of effect with a focus on the temperate-boreal zone. This was done using a random forest (RF) approach including soil, climate, time, and site factors as covariates. Relative entropy, as quantified by the Kullback-Leibler (KL) divergence, was used as a quantitative index of soil structure, which is derived from the particle-size distribution and soil water retention data, and integrates the effects of soil structure on pores from the micrometre-scale to large macropores. Our dataset includes 431 intact topsoil and subsoil samples from 89 agricultural sites across Sweden and Norway, which were sampled between 1953 and 2017. The relative importance of covariates for the evolution of soil structure was identified and their non-linear and non-monotonic effects on the KL divergence were investigated through partial dependence analysis. To reveal any differences between topsoils (0–30 cm; n = 174) and subsoils (30–100 cm; n = 257), the same analysis was repeated separately on these two subsets. The covariates were able to explain on average more than 50% of the variation in KL divergence for all soil samples and when only subsoil samples were included. However, the predictions were poorer for topsoil samples (≈ 35%), underlining the complex dynamics of soil structure in agricultural topsoils. Parent material was the most important predictor for the KL divergence, followed by clay content for all soil samples and sampling year for only subsoil samples. Mean annual air temperature ranked third and annual precipitation ranked fourth for subsoil samples. However, it remains unclear whether the effects of climate factors are direct (e.g., freezing and thawing, wetting and drying, rainfall impact) or indirectly expressed through interactions with soil management. The partial dependence analysis revealed a soil organic carbon threshold of around 3% below which soil structure starts to deteriorate. Besides this, our results suggest that subsoil structure in the agricultural land of Sweden deteriorated steadily during the 1950′s to 1970′s, which we attribute to traffic compaction as a consequence of agricultural intensification. We discuss our findings in the light of data bias, laboratory methods and multicollinearity and conclude that the approach followed here gave valuable insights into the drivers of soil structure evolution in agricultural soils of the temperate-boreal zone. Theses insights will be of use to inform soil management interventions that address soil structure or soil properties and functions related to it.
Sammendrag
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Forfattere
Hans Martin Hanslin Ellen Johanne Svalheim Tobias A. Fuchs Elin Blütecher Trond Olav Pettersen Ove Hetland Trygve S. AamlidSammendrag
Erfaring har vist det er krevende å etablere blomsterengarter fra frø både i eksisterende grasmark og ved såing på bar jord. Dette er utfordringer som må løses for en mer målrettet restaurering eller rehabilitering av natur. Tidligere prosjekter har pekt på egenskaper hos planteartene, kvaliteten på frøet, og metoder for etablering som viktige faktorer. I dette prosjektet undersøkte vi 1) om frøplanteegenskaper kan forklare ulike blomsterengarter sine evner til å etablere seg i felt og 2) om bruk av eBeetle frøhøstemaskin til sams høsting av lokalt frø i donorenger kan være et alternativ til frøblandinger basert på håndhøsta og oppformerte frø av enkeltarter. Vi dokumenterte stor variasjon i frøplanteegenskaper for i alt 41 blomsterengarter. Selv om disse egenskapene gav en god prediksjon av plantevekst, men klarte ikke å predikere responser på konkurranse i like stor grad. Vi fant likevel at egenskaper for effektiv ressursinnhenting forklarer etablering for noen av artene. Det er altså noen mekanismer eller faktorer i selve konkurransesituasjonen som ikke er tilstrekkelig undersøkt. Feltetablering av frø samlet med eBeetle ble sammenlignet med håndhøstet frø fra de samme donorengene ved såing i bar jord i tre mottakerenger i Grimstad, Kongsberg og Asker. For utvalgte semi-naturlige arter som ofte er av høy prioritet i restaurering, ga frøblandinger basert på håndhøsta frø vesentlig bedre tilslag enn frø høsta med eBeetle. Frøhøstemaskinen klarte ikke høste en tilstrekkelig mengde av disse utvalgte artene og frøene ble tynnet ut med store mengder frø av vanlige arter og uønska arter som rotugras og grove, kraftigvoksende grasarter. Det var betydelige forskjeller i resultater mellom mottakerengene og arter. eBeetle egner seg for høsting av vanlige arter i enger uten rotugras eller andre problemarter, men må suppleres eller erstattes av tradisjonelt oppformerte naturfrøblandinger for etablering av et større mangfold arter fra semi-naturlige enger.
Sammendrag
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Sammendrag
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Forfattere
Valentina Sierra-Jimenez Jonathan P. Mathews Pilsun Yoo Alice Budai Farid Chejne Anthony Dufour Manuel Garcia-PerezSammendrag
A well-defined methodology for constructing appropriate atomistic representations of biochar will aid in visualizing the structural features and elucidating biochar behavior with molecular dynamics (MD) simulations. Such knowledge will facilitate engineering biochars tailored to specific applications. To achieve this goal, we adapted modeling strategies applied in coal science by employing multi-cross-polarization 13C nuclear magnetic resonance, ultimate analysis, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy to identify functional groups. Helium density, surface area, and porosity were used to assess structural features. Biochar's aromatic cluster size distribution was proposed based on data from the benzene polycarboxylic acid method. The computational framework reduces bias by incorporating chemical information derived from density functional theory, reactive MD simulations, and advanced characterization data. The construction approach was successfully applied to cellulose biochars produced at four temperatures, obtaining independent representations with a relative error on the atomic contents of <10 % for oxygen and nitrogen and <5 % for carbon and hydrogen. The atomistic representations were validated using X-ray diffraction, electron spin resonance data, and laser desorption/ionization Fourier-transform ion cyclotron resonance-mass spectrometry. The code will assist others in overcoming structural creation barriers and enable the utilization of the generated structures for further simulations.
Forfattere
Sonja Keel Alice Budai Lars Elsgaard Brieuc Hardy Florent Levasseur Zhi Liang Claudio Mondini Cesar Plaza Jens LeifeldSammendrag
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.
Forfattere
Jens Leifeld Brieuc Hardy Alice Budai Lars Elsgaard Sonja Keel Florent Levavasseur zhi lang Claudio Mondini Cesar Plaza Leonor RodriguesSammendrag
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Forfattere
Jens Leifeld Brieuc Hardy Alice Budai Lars Elsgaard Sonja Keel Florent levavasseur Zhi Liang Claudio Mondini Cesar Plaza Leonor RodriguesSammendrag
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Sammendrag
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