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Soil aggregation and soil organic matter in conventionally and organically farmed Austrian Chernozems
Sandén, Taru ; Lair, Georg J. ; Leeuwen, Jeroen P. Van; Gísladóttir, Guorún ; Bloem, Jaap ; Ragnarsdóttir, Kristín Vala ; Steffens, Markus ; Blum, Winfried E.H. - \ 2017
Bodenkultur 68 (2017)1. - ISSN 0006-5471 - p. 41 - 55.
Aggregate hierarchy - Aggregate stability - Organic matter dynamics - Particulate organic matter (POM) - Solid-state 13C NMR spectroscopy
In order to study the soil aggregate distributions and soil organic matter (SOM), we sampled top- and subsoils in four intensively farmed croplands (two organic (Org-OB and Org-LA), and two conventional (Con-OB and Con-LA)) on Haplic Chernozems located in Marchfeld in the east of Vienna (Austria). Soil structure and SOM quantity, quality and distribution between free and occluded particulate organic matter and aggregate size fractions (<20 μm, 20-250 μm, 250-5000 μm) were studied by following a density fractionation procedure with low-energy ultrasound treatment. Te relation of the soil physicochemical (e.g., particle size distribution, pH, organic carbon, total nitrogen) and biological properties (e.g., fungal biomass, active fungi) with stable soil aggregate size fractions and SOM was studied. Te mean weight diameter (MWD) showed no significant difference between all studied sites and was between 3.8 mm and 10.0 mm in topsoils and between 6.7 mm and 11.9 mm in subsoils. In topsoils, the contents of calcium-acetate-lactate (CAL)-extractable P, active fungal biomass, dithionite-extractable Fe and sand were significantly positively correlated with the amount of the macroaggregates and with the MWD. We observed that most soil organic carbon, depending on soil texture, was stored in the microaggregate size classes <20 μm and 20-250 μm.
Soil Functions in Earth's Critical Zone : Key Results and Conclusions
Banwart, S.A. ; Bernasconi, S.M. ; Blum, W.E.H. ; Souza, D.M. de; Chabaux, F. ; Duffy, C. ; Kercheva, M. ; Krám, P. ; Lair, G.J. ; Lundin, L. ; Menon, M. ; Nikolaidis, N. ; Novak, M. ; Panagos, P. ; Ragnarsdottir, K.V. ; Robinson, D.A. ; Rousseva, S. ; Ruiter, P. de; Gaans, P. van; Weng, L. ; White, T. ; Zhang, B. - \ 2017
Advances in Agronomy 142 (2017). - ISSN 0065-2113 - p. 1 - 27.
Critical zone - Ecosystem services - Soil - Soil functions - Water
This chapter summarizes the methods, results, and conclusions of a 5-year research project (SoilTrEC: Soil Transformations in European Catchments) on experimentation, process modeling, and computational simulation of soil functions and soil threats across a network of European, Chinese, and United States Critical Zone Observatories (CZOs). The study focused on the soil functions of biomass production, carbon storage, water storage and transmission, water filtration, transformation of nutrients, and maintaining habitat and genetic diversity.The principal results demonstrate that soil functions can be quantified as biophysical flows and transformations of material and energy. The functions can be simulated with mathematical models of soil processes within the soil profile and at the critical zone interfaces with vegetation and atmosphere, surface waters and the below-ground vadose zone and groundwater. A new dynamic model for soil structure development, together with data sets from the CZOs, demonstrate both seasonal fluctuations in soil structure dynamics related to vegetation dynamics and soil carbon inputs, and long-term trends (decadal) in soil carbon storage and soil structure development.Cross-site comparison for 20 soil profiles at seven field sites with variation in soil type, lithology, land cover, land use, and climate demonstrate that sites can be classified, using model parameter values for soil aggregation processes together with climatic conditions and soil physical properties, along a trajectory of soil structure development from incipient soil formation through productive land use to overly intensive land use with soil degradation.A new modeling code, the Integrated Critical Zone model, was applied with parameter sets developed from the CZO site data to simulate the biophysical flows and transformations that quantify multiple soil functions. Process simulations coupled the new model for soil structure dynamics with existing modeling approaches for soil carbon dynamics, nutrient transformations, vegetation dynamics, hydrological flow and transport, and geochemical equilibria and mineral weathering reactions. Successful calibration, testing, and application of the model with data sets from horticulture plot manipulation experiments demonstrate the potential to apply modeling and simulation to the scoping and design of new practices and policy options to enhance soil functions and reduce soil threats worldwide.
Aggregation and organic matter in subarctic Andosols under different grassland management
Lehtinen, T. ; Gisladottir, G. ; Lair, G.J. ; Leeuwen, J.P. van; Blum, W.E.H. ; Bloem, J. ; Steffens, M. ; Ragnarsdottir, K.V. - \ 2015
Acta Agriculturae Scandinavica Section B-Soil and Plant Science 65 (2015)3. - ISSN 0906-4710 - p. 246 - 263.
c-13 nmr-spectroscopy - soil microbial biomass - mediterranean conditions - structural stability - cultivated soils - farming systems - volcanic soils - carbon stocks - land-use - tillage
Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.
An ecosystem approach to assess soil quality in organically and conventionally managed farms in Iceland and Austria
Leeuwen, J.P. van; Lehtinen, T. ; Lair, G.J. ; Bloem, J. ; Hemerik, L. ; Ragnarsdóttir, K.V. ; Gísladóttir, G. ; Newton, J.S. ; Ruiter, P.C. de - \ 2015
SOIL 1 (2015). - ISSN 2199-3971 - p. 83 - 101.
Intensive agricultural production can be an important driver for the loss of long-term soil quality. For this reason, the European Critical Zone Observatory (CZO) network adopted four pairs of agricultural CZO sites that differ in their management: conventional or organic. The CZO sites include two pairs of grassland farms in Iceland and two pairs of arable farms in Austria. Conventional fields differed from the organic fields in the use of artificial fertilisers and pesticides. Soils of these eight farms were analysed in terms of their physical, chemical, and biological properties, including soil aggregate size distribution, soil organic matter contents, abundance of soil microbes and soil fauna, and taxonomic diversity of soil microarthropods. In Icelandic grasslands, organically farmed soils had larger mean weight diameters of soil aggregates than the conventional farms, while there were no differences on the Austrian farms. Organic farming did not systematically influence organic matter contents or composition, nor soil carbon and nitrogen contents. Also, soil food web structures, in terms of presence of trophic groups of soil organisms, were highly similar among all farms, indicating a low sensitivity of trophic structure to land use or climate. However, soil organism biomass, especially of bacteria and nematodes, was consistently higher on organic farms than on conventional farms. Within the microarthropods, taxonomic diversity was systematically higher in the organic farms compared to the conventional farms. This difference was found across countries and farm, crop, and soil types. The results do not show systematic differences in physical and chemical properties between organic and conventional farms, but confirm that organic farming can enhance soil biomass and that microarthropod diversity is a sensitive and consistent indicator for land management.
|soil ecosystem development in a glacial chronosequence in iceland
Bloem, J. ; Leeuwen, J.P. van; Lehtinen, T. ; Gisladottir, G. ; Ragnarsdottir, K.V. - \ 2014
SoilTrEC: a global initiative on critical zone research and integration
Menon, M. ; Rousseva, S. ; Nikolaidis, N.P. ; Gaans, P. van; Panagos, P. ; Maia de Souza, D. ; Ragnarsdottir, K.V. ; Lair, G.J. ; Weng, L.P. ; Bloem, J. ; Kram, P. ; Novak, M. ; Davidsdottir, B. ; Gisladottir, G. ; Robinson, D.A. ; Reynolds, B. ; White, T. ; Lundin, L. ; Zhang, B. ; Duffy, C. ; Bernasconi, S.M. ; Ruiter, P.C. de; Banwart, S.A. - \ 2014
Environmental Science and Pollution Research 21 (2014). - ISSN 0944-1344 - p. 3191 - 3195.
Soil is a complex natural resource that is considered non-renewable in policy frameworks, and it plays a key role in maintaining a variety of ecosystem services (ES) and life-sustaining material cycles within the Earth's Critical Zone (CZ). However, currently, the ability of soil to deliver these services is being drastically reduced in many locations, and global loss of soil ecosystem services is estimated to increase each year as a result of many different threats, such as erosion and soil carbon loss. The European Union Thematic Strategy for Soil Protection alerts policy makers of the need to protect soil and proposes measures to mitigate soil degradation. In this context, the European Commission-funded research project on Soil Transformations in European Catchments (SoilTrEC) aims to quantify the processes that deliver soil ecosystem services in the Earth's Critical Zone and to quantify the impacts of environmental change on key soil functions. This is achieved by integrating the research results into decision-support tools and applying methods of economic valuation to soil ecosystem services. In this paper, we provide an overview of the SoilTrEC project, its organization, partnerships and implementation.
|Farming effects on soil organic matter and aggregate stability of Icelandic Brown and Histic Andosols
Lehtinen, T. ; Gisladottir, G. ; Lair, G.J. ; Leeuwen, J. van; Blum, W.E.H. ; Bloem, J. ; Ragnarsdottir, K.V. - \ 2013
In: Proceedings of the Soil Carbon Sequestration for climate, food security and ecosystem services, May 26-29, 2013, Reykjavik, Iceland. - Reykjavik : Soil Conservation Service of Iceland & Agricultural University of Iceland - p. 32 - 32.
Response of soil properties to different farming practices - case studies in Iceland and Austria
Lehtinen, T. ; Lair, G.J. ; Gisladottir, G. ; Bloem, J. ; Leeuwen, J. van; Ragnarsdottir, K.V. ; Blum, W. - \ 2012
In: Proceedings of the 4th International Congress EUROSOIL, July 2-6, 2012, Bari, Italy. - European Confederation of Soil Science Societies - p. 2661 - 2661.
Arable land covers approximately one fourth of the global land area, but only half of it can be used efficiently for cultivation to feed the growing population. Modern agriculture has developed highly productive food and biomass-producing systems based on industrial principles, which has lead to a considerable environmental burden. Organic agriculture has expanded as a movement towards more sustainable food production, which aims to maintain the key functions and ecosystems services of soils. At present, approximately 0.7% of global and 4% of European agricultural lands are managed organically (Willer and Youssefi, 2007). Soil organic matter (SOM) and its turnover play a pivotal role in the biogeochemical cycling of nutrients and in the response of terrestrial carbon to future climate scenarios. Its fate and dynamics are mainly governed and understood by its properties and physiology of the soil organisms (von Lützow and Kögel-Knabler, 2009). A key to understand and define a sustainable agricultural soil system is to quantify the impact of different land use on soil structure and biogeochemistry, with emphasis on nutrient turnover. The goal of our future research is to evaluate SOM pools in different soil aggregate sizes under different farming systems (organic vs. conventional) and link them to soil biodiversity. Soils were selected along cultivation age gradients under subarctic (Iceland, Andosols) and continental climate (Austria, Chernozems). The further outcome of this research is to identify quantifiable natural indicators for farm sustainability assessments. Gained data will also be linked to energy balance and food productivity in order to get more insights in benefits of different farming practices.
Assessing the impact of soil degradation on food production
Bindraban, P.S. ; Velde, M. van der; Ye, L. ; Berg, M. van den; Materechera, S. ; Kiba, D.I. ; Tamene, L. ; Ragnarsdottir, K.V. ; Jongschaap, R.E.E. ; Hoogmoed, M. ; Hoogmoed, W.B. ; Beek, C.L. ; Lynden, G.W.J. van - \ 2012
Current Opinion in Environmental Sustainability 4 (2012)5. - ISSN 1877-3435 - p. 478 - 488.
conservation agriculture - carbon sequestration - land degradation - africa - erosion - yield - management - security - climate - trends
Continuing soil degradation remains a serious threat to future food security. Yet, global soil degradation assessments are based on qualitative expert judgments or remotely sensed quantitative proxy values that suffice to raise awareness but are too coarse to identify appropriate sustainable land management interventions. Studies in China and Sub Saharan Africa illustrate the considerable impact of degradation on crop production but also point to the need for solutions dependent on location specific agro-ecological conditions and farming systems.The development of a comprehensive approach should be feasible to better assess both extent and impact of soil degradation interlinking various scales, based on production ecological approaches and remote sensing to allow disentangling natural and human induced causes of degradation. A shared common knowledge base cataloguing hard-won location-specific interventions is needed for successfully preventing or mitigating degradation