Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Soil food web assembly and vegetation development in a glacial chronosequence in Iceland
Leeuwen, J.P. van; Lair, G.J. ; Gísladóttir, G. ; Sandén, T. ; Bloem, J. ; Hemerik, L. ; Ruiter, P.C. de - \ 2018
Pedobiologia 70 (2018). - ISSN 0031-4056 - p. 12 - 21.
Ecosystem functioning - Glacial succession - Iceland - Soil food web structure - Vegetation development

Worldwide human activities threaten soil quality in terms of the soil's ability to deliver ecosystem services. This ongoing process of land degradation asks for effective strategies of soil protection. In this context, it is important to understand processes that build up and regenerate soil. The present study investigated how the soil ecosystem, including soil organisms, vegetation and soil ecological processes, develops during the process of soil formation in a chronosequence in a glacier forefield in Iceland. We hypothesised that along successional age we see increases in nutrient content, vegetation cover, and plant species richness linked to increases in soil food webs biomass and complexity. In line with our expectations all measured pools of carbon and nitrogen, and vegetation cover increased with age in the glacial forefield, but plant species richness levelled off after 30 years. Soil organisms generally increased in biomass with successional age, although some of the groups of soil organisms peaked at an intermediate successional stage. In contrast to our expectations, some of the calculated food web complexity metrics such as the number of trophic groups and trophic chain length did not increase linearly, but showed an intermediate peak or even decreased with successional age. However, plant cover and pools of carbon and nitrogen still increased after 120 years. From these results we conclude that soil ecosystem development takes more than a century under Icelandic climatic conditions to fully develop in terms of vegetation succession, food web structure and biogeochemical cycling.

Soil food web assembly and vegetation development in a glacial chronosequence in Iceland
Leeuwen, J.P. van; Lair, G.J. ; Gisladottir, G. ; Sanden, T.M. ; Bloem, J. ; Hemerik, A. ; Ruiter, P.C. de - \ 2017
In: Book of Abstracts Wageningen Soil Conference 2017. - Wageningen : Wageningen University & Research - ISBN 9789463430616 - p. 124 - 124.
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.
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
Do aggregate stability and soil organic matter content increase following organic inputs?
Bloem, J. ; Lehtinen, T. ; Gisladottir, G. ; Leeuwen, J.P. van; Steffens, M. - \ 2014
Agriculture is facing several challenges such as loss of soil organic matter (SOM); thus, sustainable farming management practices are needed. Organic farming is growing as an alternative to conventional farming; in Iceland approximately 1% and in Austria 16% of utilized agricultural area is under organic farming practice. We analyzed the effect of different farming practices (organic, and conventional) on soil physicochemical and microbiological properties in grassland soils in Iceland and cropland soils in Austria. Organic farms differed from conventional farms by absence of chemical fertilizers and pesticide use. At these farms, we investigated soil physicochemical (e.g. soil texture, pH, CAL-extractable P and K) and microbiological properties (fungal and bacterial biomass and activity). The effects of farming practices on soil macroaggregate stability and SOM quantity, quality and distribution between different fractions were studied following a density fractionation. In Iceland, we sampled six grassland sites on Brown (BA) and Histic (HA) Andosols; two sites on extensively managed grasslands, two sites under organic and two sites under conventional farming practice. In Austria, we sampled four cropland sites on Haplic Chernozems; two sites under organic and two sites under conventional farming practice. We found significantly higher macroaggregate stability in the organic compared to the conventional grasslands in Iceland. In contrast, slightly higher macroaggregation in conventional compared to the organic farming practice was found in croplands in Austria, although the difference was not significant. Macroaggregates were positively correlated with fungal biomass in Iceland, and with Feo and fungal activity in Austria. In Austria, SOM content and nutrient status (except for lower CAL-extractable P at one site) were similar between organic and conventional farms. Our results show that the organic inputs may have enhanced macroaggregation in organic farming practice compared to conventional in the permanent grassland soils in Iceland but were only enough to maintain the SOM content and macroaggregation in the cropland soils in Austria.
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.
Randomized trial of weight-loss-diets for young adults varying in fish and fish oil content
Thorsdottir, I. ; Tomasson, H. ; Gunnarsdottir, I. ; Gisladottir, E. ; Kiely, M. ; Parra, M.D. ; Bandarra, N.M. ; Schaafsma, G. ; Martinez, J.A. - \ 2007
International Journal of Obesity 31 (2007)10. - ISSN 0307-0565 - p. 1560 - 1566.
polyunsaturated fatty-acids - alpha-linolenic acid - hypertensive subjects - beta-oxidation - serum-lipids - overweight - women - taurine - protein - adolescents
Objective: To investigate the effect of including seafood and fish oils, as part of an energy-restricted diet, on weight loss in young overweight adults. Design: Randomized controlled trial of energy-restricted diet varying in fish and fish oil content was followed for 8 weeks. Subjects were randomized to one of four groups: (1) control (sunflower oil capsules, no seafood); (2) lean fish (3 x 150 g portions of cod/week); (3) fatty fish (3 x 150 g portions of salmon/week); (4) fish oil (DHA/EPA capsules, no seafood). The macronutrient composition of the diets was similar between the groups and the capsule groups, were single-blinded. Subjects: A total of 324 men and women aged 20-40 years, BMI 27.5 -32.5 kg/m(2) from Iceland, Spain and Ireland. Measurements: Anthropometric data were collected at baseline, midpoint and endpoint. Confounding factors were accounted for, with linear models, for repeated measures with two-way interactions. The most important interactions for weight loss were (diet x energy intake), (gender x diet) and (gender x initial-weight). Results: An average man in the study (95 kg at baseline receiving 1600 kcal/day) was estimated to lose 3.55 kg (95% Cl, 3.14 -3.97) (1); 4.35 kg (95% Cl, 3.94 -4.75) (2); 4.50 kg (95% Cl, 4.13 -4.87) (3) and 4.96 kg (95% Cl, 4.53 -5.40) on diet (4) in 4 weeks, from baseline to midpoint. The weight-loss from midpoint to endpoint was 0.45 (0.41 -0.49) times the observed weight loss from baseline to midpoint. The diets did not differ in their effect on weight loss in women. Changes in measures of body composition were in line with changes in body weight. Conclusion: In young, overweight men, the inclusion of either lean or fatty fish, or fish oil as part of an energy-restricted diet resulted in similar to 1 kg more weight loss after 4 weeks, than did a similar diet without seafood or supplement of marine origin. The addition of seafood to a nutritionally balanced energy-restricted diet may boost weight loss.
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