| 1. |
- Jarvis, Nicholas, et al.
(författare)
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Improved descriptions of soil hydrology in crop models: The elephant in the room?
- 2022
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Ingår i: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- Soil-crop simulation models are widely used to assess the impacts of soil management and climate change on soil water balance, solute transport and crop production. In this context, it is important that hydrological processes in the soil-crop system are accurately modelled. We suggest here that empirical treatments of soil water flow, water uptake by plant mots and transpiration limit the applicability of crop models and increase prediction errors. We further argue that this empiricism is to a large extent unnecessary, as parsimonious physics-based descriptions of these water flow processes in the soil-crop system are now available. Recent reviews and opinion articles, whilst strongly advocating the need for improvements to crop models, fail to mention the significant role played by accurate treatments of soil hydrology. It seems to us that empirical models of soil water flow have become the elephant in the room.
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| 2. |
- Jarvis, Nicholas, et al.
(författare)
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Interactions between soil structure dynamics, hydrological processes, and organic matter cycling: A new soil-crop model
- 2024
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Ingår i: European Journal of Soil Science. - 1351-0754 .- 1365-2389. ; 75
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Tidskriftsartikel (refereegranskat)abstract
- The structure of soil is critical for the ecosystem services it provides since it regulates many key soil processes, including water, air and solute movement, root growth and the activity of soil biota. Soil structure is dynamic, driven by external factors such as land management and climate and mediated by a wide range of biological agents and physical processes operating at strongly contrasting time-scales, from seconds (e.g., tillage) to many decades (e.g., faunal activity and soil aggregation). In this respect, positive feedbacks in the soil-plant system may lead in the longer term to soil physical degradation or to the recovery of structurally poor soils. As far as we are aware, no existing soil-crop model can account for such processes. In this paper, we describe a new soil-crop model (USSF, Uppsala model of Soil Structure and Function) that accounts for the effects of soil structure dynamics on water and organic matter cycling at the soil profile scale. Soil structure dynamics are expressed as time-varying physical (bulk density, porosity) and hydraulic properties (water retention, hydraulic conductivity) responding to the activity of biological agents (i.e., earthworms, plant roots) and physical processes (i.e., tillage, soil swell-shrink) at seasonal to decadal time-scales. In this first application of the model, we present the results of 30-year scenario simulations that illustrate the potential role and importance of soil structure dynamics for the soil water balance, carbon storage in soil, root growth, and winter wheat yields on two soils (loam and clay) in the climate of central Sweden. A sensitivity analysis was also performed for these two scenarios using the Morris method of elementary effects, which revealed that the most sensitive parameters controlling soil structure dynamics in the USSF model are those determining aggregation induced by organic matter turnover and swell/shrink. We suggest that the USSF model is a promising new tool to investigate a wide range of processes and phenomena triggered by land use and climate change. Results from this study show that feedback in the soil-crop system mediated by the dynamics of soil physical and hydraulic properties are potentially of central importance for long-term predictions of soil water balance, crop production, and carbon sequestration under global change.
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| 3. |
- Lewan, Mats
(författare)
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The future of the nation-state how the nation-state can find a way through digitalization
- 2019
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Ingår i: Digital Transformation and Public Services. - London : Taylor and Francis. - 9781000690644 - 9780367333430 ; , s. 293-317
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter is an analysis of the future role of the nation-state in a digitalized world. Building on a framework called the innovation loop, developed by the author, this study considers societal evolution largely to be a continuous adaptation to changed conditions brought by innovations. The analysis traces the development of the modern nation-state in the perspective of major human inventions. It addresses the topic of globalization and the changing role of the nation-state, with less autonomy on one hand but with a new position in an increasingly interconnected world on the other. Based on the fundamental aspects of digitalization as a driving force for change, three fields where the nation-state needs to adapt are identified – efficiency of services, alternative providers of services, and the structure of the democratic process. The threat from supra-states, localism, and cosmopolitanism is also discussed, and the study concludes that the nation-state still has a future as an important component of an international governance system, if it keeps changing. However, the rule of law, the monopoly of coercive power, and the control over a physical territory ultimately give the nation-state a significant power, which can provide extended time for implementing the necessary change.
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| 4. |
- Meurer, Katharina, et al.
(författare)
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A framework for modelling soil structure dynamics induced by biological activity
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26, s. 5382-5403
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Tidskriftsartikel (refereegranskat)abstract
- Soil degradation is a worsening global phenomenon driven by socio-economic pressures, poor land management practices and climate change. A deterioration of soil structure at timescales ranging from seconds to centuries is implicated in most forms of soil degradation including the depletion of nutrients and organic matter, erosion and compaction. New soil-crop models that could account for soil structure dynamics at decadal to centennial timescales would provide insights into the relative importance of the various underlying physical (e.g. tillage, traffic compaction, swell/shrink and freeze/thaw) and biological (e.g. plant root growth, soil microbial and faunal activity) mechanisms, their impacts on soil hydrological processes and plant growth, as well as the relevant timescales of soil degradation and recovery. However, the development of such a model remains a challenge due to the enormous complexity of the interactions in the soil-plant system. In this paper, we focus on the impacts of biological processes on soil structure dynamics, especially the growth of plant roots and the activity of soil fauna and microorganisms. We first define what we mean by soil structure and then review current understanding of how these biological agents impact soil structure. We then develop a new framework for modelling soil structure dynamics, which is designed to be compatible with soil-crop models that operate at the soil profile scale and for long temporal scales (i.e. decades, centuries). We illustrate the modelling concept with a case study on the role of root growth and earthworm bioturbation in restoring the structure of a severely compacted soil.
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| 5. |
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| 6. |
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| 7. |
- Steffens, Karin Anna, et al.
(författare)
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Modelling pesticide leaching under climate change: parameter vs. climate input uncertainty
- 2014
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 18, s. 479-491
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Tidskriftsartikel (refereegranskat)abstract
- Assessing climate change impacts on pesticide leaching requires careful consideration of different sources of uncertainty. We investigated the uncertainty related to climate scenario input and its importance relative to parameter uncertainty of the pesticide leaching model. The pesticide fate model MACRO was calibrated against a comprehensive one-year field data set for a well-structured clay soil in southwestern Sweden. We obtained an ensemble of 56 acceptable parameter sets that represented the parameter uncertainty. Nine different climate model projections of the regional climate model RCA3 were available as driven by different combinations of global climate models (GCM), greenhouse gas emission scenarios and initial states of the GCM. The future time series of weather data used to drive the MACRO model were generated by scaling a reference climate data set (1970-1999) for an important agricultural production area in south-western Sweden based on monthly change factors for 2070-2099. 30 yr simulations were performed for different combinations of pesticide properties and application seasons. Our analysis showed that both the magnitude and the direction of predicted change in pesticide leaching from present to future depended strongly on the particular climate scenario. The effect of parameter uncertainty was of major importance for simulating absolute pesticide losses, whereas the climate uncertainty was relatively more important for predictions of changes of pesticide losses from present to future. The climate uncertainty should be accounted for by applying an ensemble of different climate scenarios. The aggregated ensemble prediction based on both acceptable parameterizations and different climate scenarios has the potential to provide robust probabilistic estimates of future pesticide losses.
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