Rainer Horn - Academia.edu (original) (raw)

Papers by Rainer Horn

Geosciences, Oct 10, 2018

International Agrophysics, Oct 1, 2016

Journal of Hydrology and Hydromechanics, Feb 4, 2023

Vadose Zone Journal, 2016

The remarkable complexity of soil and its importance to a wide range of ecosystem services presen... more The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling c...

Environmental Earth Sciences, Sep 1, 2022

Soil systems, Sep 25, 2019

Biochar impacts soil-water related processes such as infiltration and contributes to the hydrolog... more Biochar impacts soil-water related processes such as infiltration and contributes to the hydrological response of catchments. The aim of this work is to determine the impact of wetting and drying conditions on the infiltration behavior of two biochar amendments and to validate the performance of three infiltration models: Kostiakov, Horton, and Philips. Two materials, sand and a sandy loam, were mixed with 0%, 2.5%, and 5% (by dry wt.) mango wood biochar produced at a highest heating rate of 600 • C and with a particle size of <63 µm. A sequence of four wetting and drying cycles were simulated. In each cycle, infiltration was measured. We found that biochar addition decreased infiltration because the formation of narrower pores reduced infiltration capacity. The higher the biochar dosage, the more resilient the treatment became concerning the changes on the water infiltrated. Repetitive wetting and drying cycles resulted in a reconfiguration of structural pores affecting the transport of water and air. The infiltration models of Kostiakov and Horton could predict the infiltration dynamics in the amended materials, although they show some instabilities along the WD cycles.

Geosciences, Sep 20, 2018

The effects of compaction on soil shrinkage behavior need to be considered for engineering long-t... more The effects of compaction on soil shrinkage behavior need to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a new three-dimensional laser scanning device was coupled with a mathematical-empirical model to simultaneously determine the shrinkage behavior of a boulder marl (bm) and a marsh clay (mc). Therefore, both materials were precompacted in 200 soil cores (100 cm 3) on the basis of the Proctor test results with five different degrees of compaction (bm1-bm5; mc1-mc5). Thus, the shrinkage behavior, intensity, and tendency were determined during a standardized drying experiment. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and was classified as high to very high (11.3-17.7%) for the marsh clay and medium (5.3-9.2%) for the boulder marl. Additionally, only the boulder marl (bm2), compacted up to 88% of Proctor density, could be installed as landfill bottom liner in drier locations if the local matric potentials did not exceed the previously highest observed drying range (i.e. values below −300 hPa), to avoid crack formation and generation.

Die Festschrift zeichnet die Entwicklung der Agrar- und Ernährungswissenschaftlichen Fakultät der... more Die Festschrift zeichnet die Entwicklung der Agrar- und Ernährungswissenschaftlichen Fakultät der Christian-Albrechts-Universität zu Kiel von ihrer Vorgeschichte bis zur Gegenwart nach. Gezeigt wird der Wandel der Instituts- und Forschungsstruktur ebenso wie der Weg vom einstigen Landwirtschafts- zum heutigen Bachelor- und Masterstudium der Agrar- und Ernährungswissenschaften. Von der Phase der Ernährungssicherung nach dem Zweiten Weltkrieg bis zu den aktuellen vernetzten Forschungsgebieten haben sich Agrarökonomie, Ernährungs-, Nutzpflanzen-, Nutztier- und Umweltwissenschaften in den vergangenen 75 Jahren stark verändert. Damals wie heute sind sie gleichwohl gesellschaftlich hochrelevante Leuchttürme der Forschung im hohen Norden.

Journal of Soil Science and Plant Nutrition, 2022

Soil and Tillage Research, 2021

Abstract Effective stress is an important strength indicator for understanding and fundamentally ... more Abstract Effective stress is an important strength indicator for understanding and fundamentally predicting soil behaviour due to mechanical disturbance. This study investigated the influence of `soil properties on effective stress in relation to matric potential, and soil sampling direction (vertical/horizontal). Undisturbed soil samples representing 3 different locations were collected at 4 depths and in 2 sampling directions, to determine which soil properties mostly affect the effective stress in response to the magnitude of the stress applied. The soil properties included texture, organic carbon content, dry bulk density, void ratio, pre-compression stress and prevailing matric potential. The results showed that both the effective stress and the concomitant changes in pore water pressure largely depend on the prevailing matric potential in the soil. In addition, changes in soil structure caused by subsurface soil compaction as a result of tillage, organic carbon and clay content influenced the magnitude of the effective stress and pore water pressure in soils during loading. The porewater pressure measured under static loading is sampling direction dependent due to differences in hydraulic conductivity and pore continuity. Porewater pressure increases (become less negative) with increases in the fraction of fine pores in the soil while it may either remain constant or decrease, when the medium and coarse pore fractions in the soil increases. This implies that the smaller the pore connectivity and continuity, the less negative the changes in pore water pressure become. Also, the higher the pre-compression stress (sometimes due to higher organic carbon content), the more consistent the applied stress induced an increase in the calculated effective stress.

Firma Mortl, Pottmes; heute: ZIEGLER GmbH Deutschland, Schrobenhausener Str. 74, D – 86554 Pottmes

For permanent sealin of the base liner of waste deposits, the mineral material should possess pro... more For permanent sealin of the base liner of waste deposits, the mineral material should possess properties as a high incompressibility, very low hydraulic conductivities, dominance of fine pores, a low capacity of swelling and shrinkage and a high physicochemical buffering capacity (Fig. 1).

Soil and Tillage Research, 2020

In structured soils, water and reactive solutes can move preferentially through larger inter-aggr... more In structured soils, water and reactive solutes can move preferentially through larger inter-aggregate macropores (biopores and cracks) and smaller intra-aggregate pores. Especially clay-organic coating material is of major importance for the exchange of water and solutes between macro-and micropores and the soil matrix by affecting the reactive transport in a yet largely unknown way. The objective of this study was to compare the adsorption and desorption behaviour of clay-organic coatings from samples of till-(T-Bt) and loess-(L-Bt) derived Bt horizons of Haplic Luvisols with those of the soil matrix and a hillslope loam-derived Bsh (HL-Bsh) horizon of a forest Cambisol-Podzol (CM-PZ) without coatings. These coatings are characterized by q m-values of up to 1100 μmol cm −3 for clay contents of up to 330 g kg-1. The values are significantly higher than those of mixed samples without coatings (q m of 180 μmol cm −3 for clay content of 115 g kg-1). The results indicate two different adsorption mechanisms, i) sorption on siloxane surfaces of the alumosilicates (clay minerals) and ii) adsorption controlled by hydrophobic interaction with soil organic material which is possibly attached to clay-organic complexes. The great difference in sorption properties between coatings and matrix suggests that mean values obtained from analyzing mixed samples cannot be used to describe the retardation of dissolved reactive substances on the surfaces of biopores and larger cracks during preferential flow events.

Geosciences, Oct 10, 2018

International Agrophysics, Oct 1, 2016

Journal of Hydrology and Hydromechanics, Feb 4, 2023

Vadose Zone Journal, 2016

The remarkable complexity of soil and its importance to a wide range of ecosystem services presen... more The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling c...

Environmental Earth Sciences, Sep 1, 2022

Soil systems, Sep 25, 2019

Biochar impacts soil-water related processes such as infiltration and contributes to the hydrolog... more Biochar impacts soil-water related processes such as infiltration and contributes to the hydrological response of catchments. The aim of this work is to determine the impact of wetting and drying conditions on the infiltration behavior of two biochar amendments and to validate the performance of three infiltration models: Kostiakov, Horton, and Philips. Two materials, sand and a sandy loam, were mixed with 0%, 2.5%, and 5% (by dry wt.) mango wood biochar produced at a highest heating rate of 600 • C and with a particle size of <63 µm. A sequence of four wetting and drying cycles were simulated. In each cycle, infiltration was measured. We found that biochar addition decreased infiltration because the formation of narrower pores reduced infiltration capacity. The higher the biochar dosage, the more resilient the treatment became concerning the changes on the water infiltrated. Repetitive wetting and drying cycles resulted in a reconfiguration of structural pores affecting the transport of water and air. The infiltration models of Kostiakov and Horton could predict the infiltration dynamics in the amended materials, although they show some instabilities along the WD cycles.

Geosciences, Sep 20, 2018

The effects of compaction on soil shrinkage behavior need to be considered for engineering long-t... more The effects of compaction on soil shrinkage behavior need to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a new three-dimensional laser scanning device was coupled with a mathematical-empirical model to simultaneously determine the shrinkage behavior of a boulder marl (bm) and a marsh clay (mc). Therefore, both materials were precompacted in 200 soil cores (100 cm 3) on the basis of the Proctor test results with five different degrees of compaction (bm1-bm5; mc1-mc5). Thus, the shrinkage behavior, intensity, and tendency were determined during a standardized drying experiment. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and was classified as high to very high (11.3-17.7%) for the marsh clay and medium (5.3-9.2%) for the boulder marl. Additionally, only the boulder marl (bm2), compacted up to 88% of Proctor density, could be installed as landfill bottom liner in drier locations if the local matric potentials did not exceed the previously highest observed drying range (i.e. values below −300 hPa), to avoid crack formation and generation.

Die Festschrift zeichnet die Entwicklung der Agrar- und Ernährungswissenschaftlichen Fakultät der... more Die Festschrift zeichnet die Entwicklung der Agrar- und Ernährungswissenschaftlichen Fakultät der Christian-Albrechts-Universität zu Kiel von ihrer Vorgeschichte bis zur Gegenwart nach. Gezeigt wird der Wandel der Instituts- und Forschungsstruktur ebenso wie der Weg vom einstigen Landwirtschafts- zum heutigen Bachelor- und Masterstudium der Agrar- und Ernährungswissenschaften. Von der Phase der Ernährungssicherung nach dem Zweiten Weltkrieg bis zu den aktuellen vernetzten Forschungsgebieten haben sich Agrarökonomie, Ernährungs-, Nutzpflanzen-, Nutztier- und Umweltwissenschaften in den vergangenen 75 Jahren stark verändert. Damals wie heute sind sie gleichwohl gesellschaftlich hochrelevante Leuchttürme der Forschung im hohen Norden.

Journal of Soil Science and Plant Nutrition, 2022

Soil and Tillage Research, 2021

Abstract Effective stress is an important strength indicator for understanding and fundamentally ... more Abstract Effective stress is an important strength indicator for understanding and fundamentally predicting soil behaviour due to mechanical disturbance. This study investigated the influence of `soil properties on effective stress in relation to matric potential, and soil sampling direction (vertical/horizontal). Undisturbed soil samples representing 3 different locations were collected at 4 depths and in 2 sampling directions, to determine which soil properties mostly affect the effective stress in response to the magnitude of the stress applied. The soil properties included texture, organic carbon content, dry bulk density, void ratio, pre-compression stress and prevailing matric potential. The results showed that both the effective stress and the concomitant changes in pore water pressure largely depend on the prevailing matric potential in the soil. In addition, changes in soil structure caused by subsurface soil compaction as a result of tillage, organic carbon and clay content influenced the magnitude of the effective stress and pore water pressure in soils during loading. The porewater pressure measured under static loading is sampling direction dependent due to differences in hydraulic conductivity and pore continuity. Porewater pressure increases (become less negative) with increases in the fraction of fine pores in the soil while it may either remain constant or decrease, when the medium and coarse pore fractions in the soil increases. This implies that the smaller the pore connectivity and continuity, the less negative the changes in pore water pressure become. Also, the higher the pre-compression stress (sometimes due to higher organic carbon content), the more consistent the applied stress induced an increase in the calculated effective stress.

Firma Mortl, Pottmes; heute: ZIEGLER GmbH Deutschland, Schrobenhausener Str. 74, D – 86554 Pottmes

For permanent sealin of the base liner of waste deposits, the mineral material should possess pro... more For permanent sealin of the base liner of waste deposits, the mineral material should possess properties as a high incompressibility, very low hydraulic conductivities, dominance of fine pores, a low capacity of swelling and shrinkage and a high physicochemical buffering capacity (Fig. 1).

Soil and Tillage Research, 2020

In structured soils, water and reactive solutes can move preferentially through larger inter-aggr... more In structured soils, water and reactive solutes can move preferentially through larger inter-aggregate macropores (biopores and cracks) and smaller intra-aggregate pores. Especially clay-organic coating material is of major importance for the exchange of water and solutes between macro-and micropores and the soil matrix by affecting the reactive transport in a yet largely unknown way. The objective of this study was to compare the adsorption and desorption behaviour of clay-organic coatings from samples of till-(T-Bt) and loess-(L-Bt) derived Bt horizons of Haplic Luvisols with those of the soil matrix and a hillslope loam-derived Bsh (HL-Bsh) horizon of a forest Cambisol-Podzol (CM-PZ) without coatings. These coatings are characterized by q m-values of up to 1100 μmol cm −3 for clay contents of up to 330 g kg-1. The values are significantly higher than those of mixed samples without coatings (q m of 180 μmol cm −3 for clay content of 115 g kg-1). The results indicate two different adsorption mechanisms, i) sorption on siloxane surfaces of the alumosilicates (clay minerals) and ii) adsorption controlled by hydrophobic interaction with soil organic material which is possibly attached to clay-organic complexes. The great difference in sorption properties between coatings and matrix suggests that mean values obtained from analyzing mixed samples cannot be used to describe the retardation of dissolved reactive substances on the surfaces of biopores and larger cracks during preferential flow events.