Microorganisms are critical in mediating carbon (C) and nitrogen (N) cycling processes in soils. Yet, it has long been debated whether the processes underlying biogeochemical cycles are affected by ...the composition and diversity of the soil microbial community or not. The composition and diversity of soil microbial communities can be influenced by various environmental factors, which in turn are known to impact biogeochemical processes. The objectives of this study were to test effects of multiple edaphic drivers individually and represented as the multivariate soil environment interacting with microbial community composition and diversity, and concomitantly on multiple soil functions (i.e. soil enzyme activities, soil C and N processes). We employed high-throughput sequencing (Illumina MiSeq) to analyze bacterial/archaeal and fungal community composition by targeting the 16S rRNA gene and the ITS1 region of soils collected from three land uses (cropland, grassland and forest) deriving from two bedrock forms (silicate and limestone). Based on this data set we explored single and combined effects of edaphic variables on soil microbial community structure and diversity, as well as on soil enzyme activities and several soil C and N processes. We found that both bacterial/archaeal and fungal communities were shaped by the same edaphic factors, with most single edaphic variables and the combined soil environment representation exerting stronger effects on bacterial/archaeal communities than on fungal communities, as demonstrated by (partial) Mantel tests. We also found similar edaphic controls on the bacterial/archaeal/fungal richness and diversity. Soil C processes were only directly affected by the soil environment but not affected by microbial community composition. In contrast, soil N processes were significantly related to bacterial/archaeal community composition and bacterial/archaeal/fungal richness/diversity but not directly affected by the soil environment. This indicates direct control of the soil environment on soil C processes and indirect control of the soil environment on soil N processes by structuring the microbial communities. The study further highlights the importance of edaphic drivers and microbial communities (i.e. composition and diversity) on important soil C and N processes.
•Same edaphic factors shaped both bacterial/archaeal and fungal communities.•Soil environment directly affected soil C processes.•Bacterial/archaeal communities affected soil N processes.•Both bacterial/archaeal and fungal diversity were linked to soil N processes.
Soil plays a crucial role in ecosystem functioning. In the 1990s ecosystem services (ES) research focused on developing the concept and framework and only a few studies linked soil properties to ...ecosystem services. This study reviews the literature on the relationship between soils and ecosystem services and aims to contribute to the scientific understanding on soil and ecosystem services and their interrelations. Most studies have focused on provisioning and regulating ES relating to soil physico-chemical properties. Cultural services had only a few studies, and supporting services were mostly related to soil physico-chemical and biological properties. The number of ES papers increased rapidly after 2000 and in the past 5years, regulating services such as carbon sequestration, climate and gas regulations, were commonly studied. Once the concept was established in the 1990s, studies focusing on the assessment, valuation, and payments of services became more prominent. Most soil-ES research is published in Geoderma. Soil scientists seems to be hesitant to use the term ‘ecosystem services’ even if their research is devoted to linking soils to ecosystem services. We suggest that future ES research should focus on exploring soil functional diversity of soil biota and the spatial aspects of soil properties to lower level ecosystem services (e.g., water purification, gene pool, and climate regulation). Soil scientists should engage professionals from other disciplines to further promote the contribution of soils to ecosystem services delivery and human well-being. ES soil studies could be used in local and national policy development and program on natural resource use and management.
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•Contributes to the understanding of soils in relation to ecosystem services (ES)•Temporal and geographical distribution of soil ES studies has been analyzed.•Highlights use of soil information on the spatial aspects of soil ES studies•Recommends the future soil ES research focus
Capturing the complexity of soil life for soil quality assessments is one of the most challenging paradoxes of contemporary soil science. Soil biota perform a plethora of processes that are ...fundamental to soil quality. As the concept of soil quality developed, so have the attempts to integrate soil biological measurements into monitoring schemes from field to regional scale. To date, however, soil science has not yet succeeded to provide flexible yet objective biological indicator methods to assess soil multifunctionality, customised to the user's context.
We present an integrative framework and elucidate the who and how of soil multifunctionality. The framework encompasses the current scientific understanding of the role of soil biota in supporting the many soil processes that underly soil quality. We specified these relationships for four soil functions (Carbon and Climate Regulation, Water Regulation and Purification, Nutrient Cycling, and Disease and Pest Regulation). We identify challenges often encountered in soil quality assessment and monitoring schemes and discuss how the framework can be applied to provide a flexible selection tool. Soil quality assessments are conducted in different contexts. As assessment objectives range from mechanistic understanding, to functional land management and large spatial scale monitoring so will the practical and logistical constraints for method selection vary.
Biological assessments need to move beyond the quest for a one-size-fits-all minimum dataset, and adopt a more nuanced selection approach founded in soil biology. We stress that biological attributes should not be considered in isolation but alongside soil chemical and physical attributes, as well as management and environmental contextualisation. The presented framework offers a structure to further quantify, understand and communicate the who and how of soil biology in defining multifunctionality.
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•We propose a new framework for understanding the role of soil biota in soil functions.•This paper identifies the challenges encountered in soil quality assessments.•Soil quality assessments require a nuanced measurement approach.•Soil biology should be measured in conjunction with chemical and physical properties.
Over the last few years, the question of whether soil carbon sequestration could contribute significantly to climate change mitigation has been the object of numerous debates. All of these debates so ...far appear to have entirely overlooked a crucial aspect of the question. It concerns the short‐term mineralization kinetics of fresh organic matter added to soils, which is occasionally alluded to in the literature, but is almost always subsumed in a broader modelling context. In the present article, we first summarise what is currently known about the kinetics of mineralization of plant residues added to soils, and about its modelling in the long run. We then argue that in the short run, this microbially‐mediated process has important practical consequences that cannot be ignored. Specifically, since at least 90% of plant residues added to soils to increase their carbon content over the long term are mineralized relatively rapidly and are released as CO2 to the atmosphere, farmers would have to apply to their fields 10 times more organic carbon annually than what they would eventually expect to sequester. Over time, because of a well‐known sink saturation effect, the multiplier may even rise significantly above 10, up to a point when no net carbon sequestration takes place any longer. The requirement to add many times more carbon than what one aims to sequester makes it practically impossible to add sufficient amounts of crop residues to soils to have a lasting, non‐negligible effect on climate change. Nevertheless, there is no doubt that raising the organic matter content of soils is desirable for other reasons, in particular guaranteeing that soils will be able to keep fulfilling essential functions and services in spite of fast‐changing environmental conditions.
Highlights
Attempts to promote soil carbon sequestration to mitigate climate change have so far ignored the short‐term effects of the mineralization of plant residues added to soils.
Only about 10%, at most, of added plan residues remain in soils after mineralization by soil organisms.
To have a significant effect on climate change, farmers would need to add impractically large amounts of plant residues, requiring unrealistic nitrogen inputs.
Therefore, rather than as a mitigation strategy, farmers should aim to increase the carbon content of soils to make them resilient to climate change.
•Most urban soil research is on supporting and regulating ecosystem services.•Soil biological activity, nutrient cycling and carbon storage are commonly quantified.•Food provision, cultural and ...water-related services are underexplored.•Urban soil multifunctionality is recommended as a direction for future research.•Work is needed on global studies, community integration and potential future drivers.
The expansion of urban areas worldwide is increasing the anthropogenic impact upon soil and highlights the important role of urban areas in supporting a sustainable future. As such, urban soils are becoming more important in the delivery of a broad range of ecosystem services (ESs), including carbon storage and climate regulation, biomass provision for food and water flow regulation, and recreational benefits. In this review, we aim to support the development of this emerging research area and, subsequently, support the improved treatment and management of urban soil and ES delivery. We present a systematic review of which ESs have been studied and examine trends in research using a co-occurrence analysis of key terms. We then provide a summary review of current knowledge on ESs and identify the gaps in knowledge. Our review highlights that this is a young, but growing, field of research, with a marked increase in publications since 2014. We found that supporting processes and regulating services were most commonly studied, with 88% and 71% of the papers relating to quantitative studies addressing these, respectively. Cultural, provisioning and water-related ESs were relatively understudied, suggesting key gaps for future research. However, this may be attributable to a disconnection between academic communities rather than a lack of knowledge. Fewer than 20% of quantitative studies addressed more than two ESs simultaneously, leading us to suggest that urban soil multifunctionality is a key area for future research, and highlighting the need to integrate understanding of urban soil ESs across disciplines and professions. In addition to this overarching suggestion, we propose six research gaps and opportunities: further research into biomass provision for food, water-related ESs and cultural ESs; greater geographical representation; further interconnection between research and practitioner communities; and a focus on the future drivers of soil change in urban environments.
Soil functions, including climate regulation and the cycling of water and nutrients, are of central importance for a number of environmental issues of great societal concern. To understand and manage ...these functions, it is crucial to be able to quantify the structure of soils, now increasingly referred to as their “architecture,” as it constraints the physical, chemical and biological processes in soils. This quantification was traditionally approached from two different angles, one focused on aggregates of the solid phase, and the other on the pore space. The recent development of sophisticated, non‐disturbing imaging techniques has led to significant progress in the description of soil architecture, in terms of both the pore space and the spatial configuration of mineral and organic materials. We now have direct access to virtually all aspects of soil architecture. In the present article, we review how this affects the perception of soil architecture specifically when trying to describe the functions of soils. A key conclusion of our analysis is that soil architecture, in that context, imperatively needs to be explored in its natural state, with as little disturbance as possible. The same requirement applies to the key processes taking place in the hierarchical soil pore network, including those contributing to the emergence of a heterogeneous organo‐mineral soil matrix by various mixing processes, such as bioturbation, diffusion, microbial metabolism and organo‐mineral interactions. Artificially isolated aggregates are fundamentally inappropriate for deriving conclusions about the functioning of an intact soil. To fully account for soil functions, we argue that a holistic approach that centres on the pore space is mandatory while the dismantlement of soils into chunks may still be carried out to study the binding of soil solid components. In the future, significant progress is expected along this holistic direction, as new, advanced technologies become available.
Highlights
We highlight the crucial importance of the temporal dynamics of soil architecture for biological activity and carbon turnover.
We reconcile controversial concepts relative to how soil architecture is formed and reshaped with time.
Soil is demonstrated to be a heterogeneous porous matrix and not an assembly of aggregates.
Biological and physical mixing processes are key for the formation and dynamics of soil architecture.
Participatory techniques are widely recognized as essential in addressing the challenges of agri-environmental policy and decision-making. Furthermore, it is well known that stakeholder analysis and ...social network analysis are useful methods in the identification of actors that are involved in a system and the connections between them. To identify key stakeholders and improve the transfer of information from national-to farm-level, we compared a stakeholder analysis with farmer-centric networks for primary productivity, carbon regulation and biodiversity through the case study of Latvia. Farmer-centric networks show a higher number of stakeholders communicating on the topic of primary productivity network comparing to other topics. We found three pathways for improving knowledge transfer in agri-environmental governance: horizontal strengthening of farming community, horizontal strengthening of policy departments, and vertical strengthening between policy departments and farmers. The first step is to ensure that policy-makers have a common understanding of the results that should be achieved. The second step is the transfer of know-how between farmers to develop new solutions. The third step is the training of advisers in the land multifunctionality and the strengthening of communication and knowledge transfer between policy departments and farmers in order to jointly achieve the desired direction at that national level. Long-term cooperation between many stakeholders, including knowledge transfer, the development and implementation of solutions, and monitoring are essential in order to adequately address global societal challenges. The application of our mixed methods approach to elucidate pathways for improved governance of knowledge and information is of direct relevance to other jurisdictions seeking to transition towards multifunctional and sustainable land management.
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•Common understanding of desired directions between different stakeholders and levels can help in achieving socio-economic and environmental objectives.•Farmers receive information overload and they need to distill it into practical actions and management plans by themselves.•Advisers are in a unique position to influence on-farm decisions and to help achieve national and international objectives on sustainability.
Soils play a key role for the functioning of terrestrial ecosystems. Thus, soils are essential for human society not only because they form the basis for the production of food. This has been ...recognized since long and during the last three decades the need to establish methods to evaluate the ability of soils to provide soil functions has moved towards the top of the agenda in soil science. Quantitative evaluation schemes are indispensable to adequately include soils into strategies to reach sustainable development targets. In this paper we build upon existing approaches and propose a concept to evaluate individual soil functions with respect to the soil’s natural potential in contrast to its actual state. This leads to a separation of indicator variables and allows for conclusions on the structure of appropriate models that are required to predict the dynamics of soil functions in response to external perturbation. This concept is demonstrated for the production function, carbon storage and water storage which are evaluated exemplarily for different plots of a long-term field experiment. It is discussed for nutrient cycling and the habitat function where evaluation schemes are still less obvious.
•Soil physical properties and soil functions were assessed in the MATOPIBA region.•No improvements on soil structure indicators were observed after LUC.•Agricultural expansion in the MATOPIBA region ...reduced the SPQI.•Water flux and air diffusion functions were the most affected by LUC.
In the so-called MATOPIBA region in northeastern Brazil, large areas of the Brazilian savannah (Cerrado biome) were converted to agricultural areas (e.g., soybean and cotton production) in recent years. However, little is known about the long-term impacts of this land-use change on soil physical properties and related soil functions. We carried out a field experiment in three consolidated agricultural areas (~23 years old) across a 1000-km transect within the MATOPIBA region to quantify land-use change effects from native vegetation (NV) to agricultural areas under no-tillage (NT) on soil physical properties and associated functions; and compare the obtained results with critical values from literature considered as thresholds for soil degradation. Soil samples were collected from paired plots (NV and NT) in each location at 0–5, 5–10, 10–20, and 20–30 cm soil depth to determine key soil physical properties related to soil texture, compaction, porosity, water storage, and structural stability. Additionally, a set of soil physical indicators was added into a soil physical quality index (SPQI) as an integrated and quantitative approach for evaluating changes in soil functions. Our results indicated that conversion from NV to agriculture under NT increased the compaction process and reduced total soil porosity, unbalancing the proportion between soil water and air storage to critical levels. Besides, water infiltration within the soil profile was strongly decreased. The land-use conversion further induced changes on soil aggregate stability, decreasing large macroaggregates (>2000 µm) and increasing small macroaggregates (250–2000 µm) and the silt/clay-sized fraction (<53 µm). The SPQI was reduced by ~33% in NT, indicating detrimental effects of agriculture expansion on soil functionality. Based on the SPQI, water availability and air diffusion were the soil functions most affected by land-use change. Our results provide a quantitative assessment of soil physical properties and soil function changes as a consequence of agricultural expansion in the MATOPIBA region, indicating the need to improve NT practices towards alleviating soil compaction and improving soil structure. Best management practices are fundamental to restore soil functionality, ensuring crop yields and other ecosystem services.
Soils host the vast majority of life on Earth including microorganisms and animals, and supporting all terrestrial vegetation. While soil organisms are pivotal for ecosystem functioning, the ...assemblages of different biota from a taxonomic and functional perspective, as well as how these different organisms interact, remains poorly known. We provide a brief overview of the taxonomic and functional diversity of all major groups of soil biota across different scales and organism sizes, ranging from viruses to prokaryotes and eukaryotes. This reveals knowledge gaps in relation to all soil biodiversity groups, which are especially evident for viruses, protists, micro- and meso-fauna. We review currently-available methods to study the taxonomic and functional diversity of soil organisms by grouping all commonly-used methods into morphological, biochemical and molecular approaches. We list potentials and limitations of the methods to reveal that there is, as yet, no single method to fully characterize the biodiversity even of a single group of soil biota. Yet, we stress that we now have the methods available to enable scientists to disentangle the taxonomic and functional diversity of virtually all soil organisms. We provide a user-friendly guide to help researchers address a wider variety of soil biodiversity in their studies by discussing and critically analysing the various potentials and limitations of diverse methods to study distinct groups of soil life. We highlight that integrative methodological approaches, ideally in collaborative interactions, are key to advancing our understanding of soil biodiversity, such as the combination of morphological and molecular approaches to overcome method-specific limitations. Together, integrative efforts can provide information on the abundance, biomass, diversity and function of several groups of soil biota simultaneously. This newly-obtained integrative information on soil biodiversity will help to define the importance of soil biodiversity in ecosystem processes, functions, and services, and serve to refine food-web and earth system models.
•Soil biodiversity is increasingly studied, yet knowledge remains limited.•New methods allow filling key missing knowledge gaps.•We provide an overview and guide to the main methods to study soil biodiversity.•Integrative method approaches are needed to increase our system-level understanding.•Collaborative efforts will uncover soil biodiversity and its functional importance.
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