Exploring the relationship between soil structure and soil functions via pore-scale imaging

Geoderma ◽  
2020 ◽  
Vol 370 ◽  
pp. 114370 ◽  
Author(s):  
Steffen Schlüter ◽  
Stephane Sammartino ◽  
John Koestel
Keyword(s):  
Soil Structure ◽  
Pore Scale ◽  
Soil Functions ◽  
The Relationship

USING SILICATE MINERALS AS MICROMODELS TO ACCESS THE RELATIONSHIP BETWEEN TRANSPORT AND REACTION AT THE PORE SCALE

2016 ◽  
Author(s):  
Heewon Jung ◽  
◽  
Alexis K. Navarre-Sitchler ◽  
Nathan Worts ◽  
Erica Block ◽  
...  
Keyword(s):  
Pore Scale ◽  
Silicate Minerals ◽  
The Relationship

Systemic soil modelling and the evaluation of functions

2021 ◽  
Author(s):  
Ulrich Weller ◽  
Sara König ◽  
Bibiana Betancur-Corredor ◽  
Birgit Lang ◽  
Mareike Ließ ◽  
...  
Keyword(s):  
Travel Time ◽  
Soil Structure ◽  
Field Experiments ◽  
Current Knowledge ◽  
Agricultural Management ◽  
Water Dynamics ◽  
Plant Production ◽  
Soil Processes ◽  
State Variables ◽  
Soil Functions

<p><span>We developed an integrated model of soil processes – the Bodium – that enables us to predict possible changes in soil functions under varying agricultural management and climatic change.</span></p><p><span>The model combines current knowledge on soil processes by integrating state-of-the-art modules on plant growth, root development, soil carbon and matter turnover with new concepts with respect to soil hydrology and soil structure dynamics. The model domain is at profile scale, with 1D nodes of variable thickness and weight. It is tested with long-term field experiments to ensure a consistent output of the combined modules. The model is site-specific and works with different soil types and climates (weather scenarios).</span></p><p><span>The output can be interpreted towards a broad spectrum of soil functions. Plant production and nutrient balances can be determined directly. The same is possible for water dynamics, with potential surface runoff (as infiltration surplus), storage and percolation together with travel time and groundwater recharge. In addition, nitrate losses are calculated, and the travel time distribution can help with the evaluation of pesticide percolation risk. To evaluate the habitat for biological activity, the activity is calculated in terms of carbon turnover, and the state variables carbon availability, water, air and temperature for the are accessible. Also, for macrofauna the earthworm activity is included. The comparison of scenario runs can be evaluated quantitatively in terms of potential developments of soil functions.</span></p><p><span>The model is work in progress. Further modules that will be implemented are pH dynamics, more explicit microbial activity, and a more complete set of effects of agricultural management on soil structure are integrated.</span></p>

Systemic modelling of soil functions under the impact of agricultural management

2020 ◽  
Author(s):  
Sara König ◽  
Ulrich Weller ◽  
Birgit Lang ◽  
Mareike Ließ ◽  
Stefanie Mayer ◽  
...  
Keyword(s):  
Soil Structure ◽  
Water Distribution ◽  
Management Strategies ◽  
Simulation Models ◽  
Crop Growth ◽  
Soil Productivity ◽  
Soil Functions ◽  
Management Options ◽  
Soil Organic Matter Turnover ◽  
The Impact

<p>The increasing demand for food and bio-energy gives need to optimize soil productivity, while securing other soil functions such as nutrient cycling and buffer capacity, carbon storage, biological activity, and water filter and storage. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soil with those functions, as well as the feedbacks between these functions.</p><p>We developed a systemic soil model to simulate the impact of different management options and changing climate on the named soil functions by integrating them within a simplified system. The model operates on a 1d soil profile consisting of dynamic nodes, which may represent the different soil horizons, and integrates different processes including dynamic water distribution, soil organic matter turnover, crop growth, nitrogen cycling, and root growth.</p><p>We present the main features of our model by simulating crop growth under various climatic scenarios on different soil types including management strategies affecting the soil structure. We show the relevance of soil structure for the main soil functions and discuss different model outcome variables as possible measures for these functions.</p><p>Further, we discuss ongoing model extensions, especially regarding the integration of biological processes, and possible applications.</p>

Non-living soil organic matter: what do we know about it?

1998 ◽  
Vol 38 (7) ◽  
pp. 667 ◽  
Author(s):  
J. O. Skjemstad ◽  
L. J. Janik ◽  
J. A. Taylor
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Structure ◽  
Chemical Structure ◽  
Review Paper ◽  
Critical Component ◽  
Biological Functions ◽  
Soil Functions ◽  
Mineral Associations ◽  
Considerable Work

Summary. Non-living soil organic matter is a small but critical component of soils contributing to soil structure, fertility and a range of other chemical, physical and biological functions. Although considerable work has contributed to our knowledge of its distribution, chemical structure, mineral associations and turnover, there is still little information on which fractions or pools of non-living soil organic matter are implicated in various soil functions and to what extent. This review paper summarises some of what is known about the distribution, chemistry, mineral associations and soil structure, turnover and the measurement of non-living soil organic matter, with particular emphasis on Australia. It also discusses some of the difficulties in using current methods for describing the function of this material in soil.

scholarly journals Land use impact on carbon mineralization is mainly caused by variation of particulate organic matter content rather than of soil structure

2021 ◽  
Author(s):  
Steffen Schlüter ◽  
Tim Roussety ◽  
Lena Rohe ◽  
Vusal Guliyev ◽  
Evgenia Blagodatskaya ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Particulate Organic Matter ◽  
Soil Structure ◽  
Predictive Power ◽  
Carbon Mineralization ◽  
Basal Respiration ◽  
Microstructural Properties ◽  
Soil Functions ◽  
Microbial Hotspots

Abstract. Land use is known to exert a dominant impact on a range of essential soil functions like water retention, carbon sequestration, matter cycling and plant growth. At the same time, land use management is known to have a strong influence on soil structure, e.g. through bioturbation, tillage and compaction. However, it is often unclear whether differences in soil structure are the actual cause for differences in soil functions or just co-occurring. This impact of land use (conventional and organic farming, intensive and extensive meadow, extensive pasture) on the relationship between soil structure and short-term carbon mineralization was investigated at the Global Change Exploratory Facility, in Bad Lauchstädt, Germany. Intact topsoil cores (n = 75) were sampled from each land use type at the early growing season. Soil structure and microbial activity were measured using X-ray computed tomography and respirometry, respectively. Grasslands had a greater microbial activity than croplands, both in terms of basal respiration and rate of carbon mineralization during growth. This was caused by a larger amount of particulate organic matter (POM) in the topsoil of grasslands. The frequently postulated dependency of basal respiration on soil moisture was absent even though some cores were apparently water limited. This finding was related to microenvironments shaping microbial hotspots where the decomposition of plant residues was obviously decoupled from water limitation in bulk soil. Differences in microstructural properties between land uses were surprisingly small, mainly due huge variability induced by patterns of compacted clods and loose areas caused by tillage in cropland soils. The most striking difference was larger macropore diameters in grasslands soil due to the presence of large biopores that are periodically destroyed in croplands. Variability of basal respiration among all soil cores amounted to more than one order of magnitude (0.08–1.42 µg CO2-C h−1 g−1 soil) and was best described by POM mass (R2 = 0.53, p < 0.001). Predictive power was hardly improved by considering all bulk, microstructure and microbial properties jointly. The predictive power of image-derived microstructural properties was low, because aeration was not limiting carbon mineralization and was sustained by pores smaller than the image resolution limit (< 30 µm). The rate of glucose mineralization during growth was explained well by substrate-induced respiration (R2 = 0.84) prior to growth, which was in turn correlated with total microbial biomass, basal respiration and POM mass and again not affected by pore metrics. These findings stress that soil structure had little relevance in predicting carbon mineralization in well-aerated soil, as this predominantly took place in microbial hotspots around degrading POM that was detached from the pore structure and moisture of the bulk soil. Land use therefore affects carbon mineralization in well-aerated soil mainly by the amount and quality of labile carbon.

Development of soil structure in some turbic cryosols in the Canadian low Arctic

1991 ◽  
Vol 71 (1) ◽  
pp. 11-29 ◽  
Author(s):  
C. A. S. Smith ◽  
C. A. Fox ◽  
A. E. Hargrave
Keyword(s):  
Soil Structure ◽  
Granular Structure ◽  
Soil Horizons ◽  
Structural Units ◽  
The Core ◽  
Prismatic Structure ◽  
Permafrost Table ◽  
Low Arctic ◽  
The Relationship ◽  
Surface Vegetation

This study was undertaken to examine the relationship between periglacial processes and the development of soil structure in some Turbic Cryosols. Three active nonsorted pattern ground features (mud hummocks) were examined for field macrostructure and micromorphological characteristics. The surface of unvegetated mud hummocks exhibited granic fabric expressed as strong granular structure. Cryoturbic movement caused surface materials to be cycled downward toward the permafrost table and upward into the hummock core. Resultant compression caused coalescence of discrete structural units resulting in matrigranodic fabric and subangular blocky structure. Porphyroskelic fabric associated with massive and occasionally prismatic structure was observed in the core of the hummocks although some remnant granularity was evident in thin section. Cycled fragments of surface vegetation 10–1000 μm in length were observed dispersed through all soil horizons. All horizons within the active layer contained more than 2% organic carbon. Key words: Turbic Cryosol, micromorphology, soil structure, cryoturbation

Image-based model quantification of pore-scale nitrogen diffusion and potential microbial ‘dead zones’ induced by fertilization application

2020 ◽  
Author(s):  
Siul Ruiz ◽  
Daniel McKay Fletcher ◽  
Andrea Boghi ◽  
Katherine Williams ◽  
Simon Duncan ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Microbial Communities ◽  
Microbial Activity ◽  
Soil Solution ◽  
Soil Structure ◽  
Water Saturation ◽  
Soil Microbial Communities ◽  
Scale Model ◽  
Organic N ◽  
Pore Scale

&lt;div&gt; &lt;p&gt;Soil microbial communities contribute many ecosystem services including soil structure maintenance, crop synergy, and carbon sequestration. However, it is not fully understood how the health of microbial communities is effected by fertilization at the pore scale. This study investigates the nature of nitrogen (N) transport and reactions at the soil pore scale in order to better understand the influence of soil structure and moisture content on microbial community health. Using X-ray Computed Tomography (XRCT) scans, we reconstructed a microscale description of a dry soil-pore geometry as a computational mesh. Solving two-phase water/air models produced pore-scale water distributions at 15, 30 and 70% water-filled pore volume. The model considers ammonium (NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;), nitrate (NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;) and dissolved organic N (DON), and includes N immobilization, ammonification and nitrification processes, as well as diffusion in soil-solution. We simulated the dissolution of a fertilizer pellet and a pore scale N cycle at the three different water saturation conditions. To aid interpretation of the model results, microbial activity at a range of N concentrations was quantified experimentally using labelled C to infer microbial activity based on CO&lt;sub&gt;2&lt;/sub&gt; respiration measurements in bulk soil. The pore-scale model showed that the diffusion and concentration of N in water films is critically dependent upon soil moisture and N species. We predicted that the maximum NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; and NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; concentrations in soil solution around the pellet under low water saturation conditions (15%) are in the order of 1x10&lt;sup&gt;3&lt;/sup&gt; and 1x10&lt;sup&gt;4&lt;/sup&gt; mol m&lt;sup&gt;-3&lt;/sup&gt; respectively (1-10 M), and under higher water saturation conditions (70%) where on the order of 2x10&lt;sup&gt;2&lt;/sup&gt; and 1x10&lt;sup&gt;3&lt;/sup&gt; mol m&lt;sup&gt;-3&lt;/sup&gt;, respectively (0.1-1 M). Supporting experimental evidence regarding microbial respiration suggests that these concentrations at the pore-scale would be sufficient to reduce microbial activity in the zone immediately around the fertilizer pellet (ranging from 0.9 to 3.8 mm depending on soil moisture status), causing a major loss of soil biological activity by up to 90%. This model demonstrates the importance of pore-scale processes in regulating N movement in soil with special capability to predict the effects of fertilizers on rhizosphere-scale processes and the root microbiome.&lt;/p&gt; &lt;/div&gt;

scholarly journals Hydropedology

2012 ◽  
Vol 36 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Carlos Rogério de Mello ◽  
Nilton Curi
Keyword(s):  
Soil Structure ◽  
Morphological Analysis ◽  
Soil Formation ◽  
Water Dynamics ◽  
Soil Science ◽  
Formation Processes ◽  
Hydrological Models ◽  
Physically Based ◽  
The Relationship ◽  
Soil Climate

Pedology consists of a sub-area of Soil Science that studies the soil and its origin as well as its inter-relationship with the landscape. Hydrology is the science that studies the water in nature in its different mediums (atmosphere, soil and rock), using the watershed as a reference for analysis of the water dynamics and also its interaction with the landscape. The relationship between these two branches of knowledge has been the object of debate and analysis in recent years, contributing to the creation of a multidisciplinary science, which seeks to integrate the respective fields of research. As such, for Hydrology, Pedology has been fundamental for enabling a foundation for the processes associated to the generation of runoff and groundwater recharge, especially concerning the micro-morphological analysis of the soil and the horizons which may impede the water flow, and their relationships with the soil structure. For Pedology, Hydrology can be fundamental to the understanding of the soil formation processes in the different landscapes, in the context of materials deposition as well as the shaping of the relief, as consequence of the soil-climate-drainage interaction, and its importance for pedogenesis. Therefore, the understanding and the deepening of the pedologic analyses, on a microscale and in toposequence in a specific landscape, and its insertion in the theories of Hydrology will allow the development of more realistic, physically based hydrological models and less parameterization dependence, this now being one of the most important challenges for the hydrologist.

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