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Division 2 - Soil Properties and Processes - Paper Submission
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Symposia for each of the Divisions, Commissions and Working Groups available
within Division 2.
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Biogeochemical processes in wetland soils and their role in global change.
Large areas of the world are covered by natural wetlands or soils which
are regularly flooded by irrigation. These soils play an important role
in food production, biodiversity and ecology, water resources, carbon
sequestration, and climate change. This symposium will discuss the
current state of knowledge on the biogeochemical cycling of elements in
wetland soils. Topics may include the formation and emission of
climate-relevant trace gases, carbon sequestration, nitrogen fixation,
denitrification, chemical weathering and formation of secondary
minerals under anoxic conditions, and the biogeochemistry of trace
elements in wetland soils (e.g., Hg, As).
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How do we manage our landscapes to provide economic, social and environmental services for the future?
The long term ability of our landscape of producing more food with less
water, in a socially and environmentally sustainable manner are
challenges that must be addressed through research that integrates
across disciplines and scales. Furthermore climate change and energy
(depletion of fossil fuels) now command greater attention. Many of the
contemporary environmental problems are being approached by
stakeholders on the geographic basis of catchments or river basins,
where the underlying physical, biological, and chemical science is
complex. This session will focus on defining the fundamental
disciplinary knowledge needed to explore the interactions among
hydrology, biology, geochemistry, and water productivity to better
manage our landscapes in a sustainable manner.
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Optimizing the use of limited water: how soil physics research and models can help
There is a global thirst for knowledge
on how to overcome the threats by posed by depleting freshwater reserves. Soil
physics can play a major role in finding ways to conserve and make the most
efficient use of water for crop production to support our growing population,
maintain its quality, preserve natural ecosystems and address projected effects
of climate change on water. This session will focus on recent advances in
understanding and modelling: 1) the infiltration and retention of water in soil
and the management practices that enhance these; 2) the old questions of when
to apply irrigation water and how much to apply for optimal crop performance;
3) associated optimal applications of N and other nutrients; and 3) more
efficient cropping and management scenarios for current and future climate
change conditions. Specific interest will be placed on novel solutions to
harness and preserve water in soil, the potential impacts of drought resistant
crop varieties and new plants with better water use efficiency, and predictions
of the threats posed by water scarcity in the future. Recent advances in
modelling of evapo-transpiration and solutes from the pore to larger scales,
and their implications to water scarcity, are also major topics of this
session.
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The physics of soil pore structure dynamics
One of the greatest challenges in
describing soil physical processes is the continuously changing pore structure
that regulates flow and transport. Shrinking and swelling through cycles of
wetting and drying, instabilities like slumping and slaking and external
stresses from vehicles and overburden can all alter pore structure considerably
over time. Coupled hydrological and mechanical models have been developed to
account for the deformation of the pore matrix. This work is complemented by
fundamental studies on the underlying physical processes that drive changes in
pore structure at multiple scales. Some of this work even tackles the
thermodynamics of pore structure evolution. This session focuses on the
physical processes that drive pore structure dynamics and the impacts on flow
and transport properties.
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Biogeochemical interfaces in soils – molecular process govern functions
Soil is intimately involved in the absorption, storage, transfer and
release of heat, water, gases and chemical constituents and has a
distinct influence on the environments of all living organisms. Changes
in land use, soil management and environmental parameters have distinct
impact on these processes. The main locations where these processes and
interactions occur are the interfaces between solid, liquid and gaseous
phases in soil. The major challenge is to link processes on the
atomistic and molecular level to mechanisms observed in the micro and
plot scale. In the field of soil chemistry, we have observed a rapid
development of emerging characterization and probing techniques adopted
from the fields of analytical and computational chemistry, as well as
more physically oriented methods from material and nano-sciences. Novel
spectroscopic, microsocopic and tomographic techniques in combination
with advanced approaches in computational chemistry allow the
exploration of the architecture of biogeochemical interfaces and reveal
direct information on their structure and dynamics. This session will
focus especially on the recent developments of these techniques and on
their application on contaminant - soil interactions including
biological surfaces. The major focus of the symposium will be on the
atomistic, molecular up to the microscale level.
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Dynamics and fate of natural and waste organic material in soils
Tremendous amounts of by-product organic materials are produced each
year from agriculture, domestic and municipal systems, agro-food
industries and enterprises, pulp and paper mills, and others. Some of
these organic materials are deliberately produced to manage and amend
soil properties (eg. crop stubble residues left in-situ), while those
from other sources have the potential to be used to amend soils.
Together with the combustion of fossil fuels, they can strongly
contribute to the carbon emissions into the atmosphere if not properly
managed, therefore affecting the fundamental biogeochemical cycling of
elements, favouring the exploitation of natural resources and
contributing to the overall climatic changes.
Application of organic wastes to natural and agricultural soils may
significantly contribute to the reduction of gas emissions, favor the
restoration and reclamation of marginal lands, improve the amount and
quality of stable organic matter and fight against progressive
desertification processes. This session will discuss the latest result
of long- and short-term experiments of treated and untreated organic
waste application to soils. It will describe the chemical and
biochemical transformation of residual materials, and provide novel
insights on the potential mobility and (bio)availability of inorganic
and organic contaminants (pathogens, hormones, metals, etc.) applied
with wastes widely occurring in soil amendments.
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The soil-root interface: microbial community dynamics and microbe-plant communications (Joint with 2.5)
Soil in the vicinity of the root (the rhizosphere) presents a higher
microbial biomass and microbial activity than the bulk soil due to
rhizo-deposition: the release of low and high molecular weight
compounds by the root. The large variety of chemicals in the
rhizosphere influences many processes that control plant growth,
microbial infections and nutrient uptake. Beneficial (e.g. bio-control,
mycorrhizal and rhizobial symbioses, nutrient transformation and
uptake) and harmful (e.g. phytopathogens, inorganic and organic
phytoxicity, nutrient immobilization, climate change induced stress)
interactions and their manipulation are of great topical interest.
Model systems are available to study processes and changes in microbial
communities in the rhizosphere soil. In recent years we have seen a
rapid development of innovative techniques to: quantify
rhizodeposition, assess microbial diversity and gene expression (mRNA
characterization and proteomics), monitor the flow of root exudates to
microbial communities, and characterise the many and often-specific
signals involved in root-root and root-microbe communications. This
symposium will focus on the recent development of these techniques and
their application to the study microbial diversity and gene expression
in the rhizosphere and a better understanding of microbe-plant
interactions.
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Gene expression and proteomics in soil
Molecular techniques have mainly applied in soil to characterise DNA so
as to assess microbial diversity whereas few studies have been carried
out to monitor gene expression by extraction and characterization of
mRNA and proteins. Novel techniques are available to extract mRNA from
soil with successive characterisation. Functional metagenomics based on
cloning of large genomic inserts containing operons and promoters can
allow screening for specific functions and novel bioproducts. Soil
proteomics can give useful information on cell-environment processes,
by analysing proteins acting as biosensors, extracellualr enzyme
activities, stress proteins and metabolic proteins, and on homologous
and heterologous cell-to cell interactions with analysis of proteins or
peptides involved in quorum sensing and genetic exchange activities, or
defining competition, predation, commensalims and symbiosis. We will
encourage presentations which emphasise metagenomic and proteomic
studies aimed to better characterise soil functionality.
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The role of soil minerals in forming and maintaining associations in soils to ensure their future sustainability
Soils are primarily composed of associations of minerals with organic
compounds, microbes and solutes. The formation of these associations
constitutes a basic feature of the genesis of soils and governs their
capacity to sequester and store carbon and plant nutrients. These
associations also provide habitats for microbes to perform their vital
role as decomposers of plant and animal debris and even minerals. This
session will focus on the inorganic component in soil associations. It
will include examination of the mechanisms whereby different minerals
contribute to the formation and stabilisation of complexes involving
biochemical compounds including carbohydrates, proteins, and humic
substances. It should also discuss the consequences of these mechanisms
for devising management systems to enhance the sustainability of soils
and of their environmental and agronomic functions.
Encouragement will be given to the definition of those properties of
minerals, e.g. measures of surface area, charge and micro-porosity,
which influence their abilities to associate with other entities, and
the use of these properties to explain and predict the useful functions
of soils. The interaction of minerals with microbes deserves attention
in this session because it affects the minerals through their
alteration, as well as influencing their associations with the other
entities in soils. Contributions on advances in instrumental techniques
such as electron microscopy and atomic force microscopy which can be
used to examine the microenvironment interactions will be welcome.
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Soil minerals for the uptake and control of contaminants (Joint with 2.2)
Soils often come into contact with contaminants, which may be heavy
metals, metalloids, excess nutrients, e.g. N, P and dissolved organic
C, biochemical wastes, or xenobiotic organic compounds. Soils are
sometimes used as filters of contaminants, or for their containment. As
the most reactive inorganic materials in soils, minerals, and
particularly those of clay-size are able to adsorb, immobilise and even
transform the various contaminants to varying extents. While there have
been many studies of the adsorption of each of the various contaminants
by clay minerals, these latter have most often been well-crystallised
examples obtained from pure geological deposits or by laboratory
synthesis. Few studies have considered interaction of contaminants in
multi-component solutions with the imperfectly and poorly crystallised
minerals commonly found in soils. These latter include poorly ordered
nano-particulate materials (PONM). In this session, contributions will
be welcomed on:
1. The particular characteristics of minerals, e.g. their surface
chemistry and microstructure, that affect the adsorption of each
contaminant type
2. Methods for the modification of soil minerals to enhance contaminant uptake, and
3. The effect of competing species, including organic compounds.
Encouragement will be given to studies employing modern instrumental
techniques, such as synchrotron-based X-ray absorption spectroscopy, as
well as electron and atomic force microscopy, electron spectroscopy and
NMR.
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Extracellular proteins and nucleic acids
in soil and consequences for microbes, plants and environmental quality
(Joint with 2.3)
Surface-reactive inorganic and organic soil particles concentrate
biologically-important molecules in their near vicinity. These
interfaces may have an extensive three dimensional structure as a
result of biofilm formation. Organic molecules include carbon and
energy sources, DNA, antibiotics, xenobiotics, quorum sensing
chemicals, amino acids, proteins and enzymes. The movement and
reactivity of these sorbed and sometimes more loosely associated
structures are of great current interest as is the manipulation of
these properties. For example, clay-associated extracellular DNA
(arising from both natural and transgenic sources) may survive long
enough to be transported by water through the soil profile or even
taken up and incorporated into the genome of bacterial cells.
Extracellular enzymes may retain their catalytic activity following
adsorption to clays and humates: a property and a location that may
have a significant impact on the degradation of organic macromolecules
and the nutrient and energy dynamics of soil microroganisms.
Associations of prions with clays can affect their migration and
infectivity. We invite the submission of papers and posters that focus
on the release of these diverse bio-chemicals by bacteria, fungi and
plant roots and their extra-cellular locations and multiple functions
in soil biology in relation to biodegradation processes, pathogenicity,
gene transfer, plant nutrition, and the fate and behaviour of
pollutants.
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Bioavailability of metals and organics and their impact on soil and water quality
The bioavailability of potentially harmful organics and metals and
their subsequent impact on microbes, plants, animals and humans as well
as water quality is much researched. Measurements, definitions and the
interpretation of bioavailability are controversial and often confusing
but new research and ideas are moving us towards a resolution. The
length of time which the xenobiotic is exposed to the soil (i.e.
ageing) influences its chemical and physical state as well as its
biological impact. Methods to assess the dynamics of sorption,
desorption and other accumulation processes and to visualise the
spatial relationship of the adsorbents and adsorbates to the soil
biological components, have advanced in recent years. This symposium
will emphasise new ideas concerning the processes and consequences of
bioavailability and present ways in which surface associations can be
manipulated in order to reduce undesirable impacts and to stimulate
degradation and detoxification.
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