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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    An in vitro – in vivo integrated approach for hazard and risk assessment of silver nanoparticles for soil organisms
    Makama, S.I. - \ 2016
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Nico van den Brink. - Wageningen : Wageningen University - ISBN 9789462578432 - 190
    particles - nanotechnology - toxicity - earthworms - gene expression - soil - coatings - deeltjes - nanotechnologie - toxiciteit - aardwormen - genexpressie - bodem - afdeklagen

    Owing to their small sizes, nanoparticles (NPs) exhibit completely different and novel characteristics compared to their bulk counterparts of the same chemical composition. These novel properties include increased reactivity due to large specific surface area, fluorescence and colour changes, increased biological barrier crossings and increased material strengthening combined with light-weight. Virtually all fields of human endeavours are exploiting nanotechnology to combat different challenges. This has led to an increase in the production and potential release of NPs into the environment. The novel properties of these NPs however, mean an enhanced potential for interactions with biological systems that are different from the interactions of known conventional chemicals, thus raising environmental and public health/safety concerns. Available literature has reported NP uptake in different organisms along with associated hazards. Therefore, to safeguard human and environmental health and safety, regulatory measures are necessary. Such measures must be based on sound scientific evidence and be risk-based rather than hazard-based. As such, the need to understand the fate of NPs after environmental release and their potential to pose hazards and risks to the environment is critical for a proper risk assessment and further development of policy strategies on the future regulation of the use of NPs.

    Some studies have demonstrated different and sometimes conflicting effects of NP properties on their uptake in different organisms. Given that exposure determines whether hazards will turn into risks, there is a critical need for further systematic evaluation of the physico-chemical properties of engineered or manufactured NPs that influence uptake in terrestrial organisms, and also of how soil properties may affect these processes. The objective of this project was to determine the influence of size and surface coating (charge), two important physico-chemical properties of NPs, on their bioavailability, uptake and toxicity. The red earthworm Lumbricus rubellus, common in most parts of Europe, was used as a model soil organism. Silver nanoparticles (AgNPs) have been identified as one of the most commonly used NPs in many products, and their production is expected to continue to increase. Therefore, we selected AgNPs as our model NPs. For our investigations, we applied an integrated in vitro - in vivo approach, utilising high throughput in vitro methods as well as well-established in vivo toxicity end-points in the earthworm. A systematic experimental approach was developed for which AgNPs were synthesized in three sizes: 20, 35 and 50 nm. Surface-coating with bovine serum albumin (AgNP_BSA), chitosan (AgNP_Chit), or polyvinylpyrrolidone (AgNP_PVP) resulted in negative, positive and neutral particles respectively.

    Firstly, macrophage cells (RAW 264.7) were exposed to AgNPs at 0 – 200 µg/mL (nominal concentrations) and uptake dynamics, cell viability, as well as induction of tumour necrosis factor (TNF)-α and reactive oxygen species (ROS) were assessed (Chapter 2). Generally, the adverse effects of exposure to the tested AgNPs resulted in reduced overall viability of the cells, which was similar for all AgNPs tested. On adenosine triphosphate (ATP) production and specific mechanisms of toxicity (TNF-α and ROS production) however, we observed that the AgNPs differed significantly, with the negatively charged AgNP_BSA being the most toxic. Significant ROS induction was only observed after exposure to the 20 nm positively charged AgNP_Chit. Effect of size was less prominent than that of surface coating, showing mostly limited differences that were not statistically significant under our experimental conditions. Live confocal imaging of exposed cells allowed the monitoring of the uptake dynamics and subcellular cytoplasmic accumulation of AgNPs. We observed fast uptake of AgNPs within 2.5 hours which is essential in case of exposure durations of 6 and 24 hours, as applied in our experiments. However, similar uptake did not always result in similar effects.

    With the insights obtained from the in vitro assessments, we investigated the effects of size and surface coating (charge) of AgNPs on the bioaccumulation in, and toxicity (survival, growth, cocoon production) to the earthworm L. rubellus. Currently, metal engineered NPs in tissues are generally quantified based on total metal concentrations after acid destruction of samples. Such destructive methods are limited in providing information on the speciation and the forms of NPs which is essential for characterising the fate of NPs. In the present thesis, we developed a method using a combination of enzymatic tissue processing and single particle inductively coupled plasma–mass spectrometry (sp-ICP-MS) to characterise and quantify AgNPs in tissues of earthworms (Chapter 3). Subcellular fractionation of tissues was also applied to investigate potential association of AgNPs with the cellular metallothionein (MT) containing fraction of the earthworm tissues. This study provided, to the best of our knowledge, the first estimates of tissue Ag concentrations in both particulate and ionic forms in earthworms exposed in vivo to AgNPs via soil. The results obtained showed fairly low uptake of AgNPs, with earthworms exposed to a commercially obtained PVP-coated AgNP showing approximately 34% of their total Ag tissue burden being in particulate form. This indicates that although AgNPs accumulated in tissues of earthworms in their primary form, the dissolution of Ag in the soil, organism, or both played an important role in determining the ultimate fate of the AgNPs. Although the biological uptake of AgNPs was generally low, the method described in Chapter 3 was still capable of extracting NPs in quantities sufficient for identification, quantification and characterisation. It should be noted however, that the lower size detection threshold for the ICP-MS instrument used for these analyses is approximately 30 nm. Consequently, information on NPs smaller than 30 nm was not available. With the increasing optimisation of analytical systems that combine sp-ICP-MS, or other detection methods with, for example, asymmetric flow field-flow fractionation (AF4) which pre-sort different particle sizes, the potential for application of methods described in this thesis will be even greater.

    Having developed a method for extracting Ag from tissues, we exposed earthworms to all nine synthesized AgNPs as well as to AgNO3 at two concentrations below known EC50s to control for ionic effects of Ag in a 28-day sub-chronic reproduction toxicity test in soil in Chapter 4. Uptake was observed to be generally highest for the negatively charged AgNP_BSA especially at the lower exposure concentration ranges. Total Ag concentrations in earthworm tissues reached a plateau level of about 80 mg Ag/kg dry weight (DW) for exposure concentrations between 15 – 100 mg Ag/kg soil DW. Reproduction was impaired at high nominal soil concentrations of all AgNPs tested, with AgNP_BSA particles being the most toxic. Size had an influence on uptake of the AgNP_PVP, showing both uptake and effect on reproduction of the 20 nm sized group to be significantly more than those of the 35 and 50 nm AgNP_PVP. This size effect however, did not hold for AgNP_BSA nor AgNP_Chit. Higher uptake from the soil may consequently lead to a higher potential for toxicity in organisms. Interestingly, internal total Ag tissue concentrations measured after 72 hour exposure were better at predicting the effect on reproduction than tissue concentrations after 28 days exposure. It is likely therefore, that reproduction was affected already in the 72 hour exposure window.

    In order to further elucidate the likely mechanisms by which these AgNPs were exerting their effects, we conducted a toxicogenomic study in Chapter 5. Although AgNPs have been increasingly investigated, information regarding their effect on the gene expression profile of especially soil organisms is yet inadequate. Using RNAseq, we investigated the transcriptome and gene expression profiles of the earthworm L. rubellus, following exposure to the nine AgNPs. Overall, exposure to medium sized AgNPs at a concentration close to the EC50 for effects on cocoon production caused most pronounced responses at the transcriptional level. There was a correlation however, between the numbers of differentially expressed genes (DEGs) and internal Ag concentrations in the earthworms. Within the medium size AgNPs, AgNP_BSA caused extensive transcriptional responses, with 684 genes affected. In contrast ionic silver (AgNO3) did not affect gene expression at low as well as higher exposure levels. Only one gene was regulated by all AgNP and Ag+ treatments, indicating that there was hardly any functional overlap between the responses of the organisms to AgNPs with different coatings. Remarkably, this gene was metallothionein, a cysteine-rich peptide known to strongly bind free metal ions for chelation and detoxification, which was strongly up-regulated. Gene ontology enrichment analysis for 35 nm AgNP_BSA exposures revealed a total of 33 significantly enriched gene ontology terms related to biological processes. These included responses to pH, proton transport, cell differentiation, microtubule organisation, and and MT induction. Surface coating (BSA) was important in triggering the AgNP-induced differential gene expression profiles in earthworms. The importance of physicochemical properties of NPs in influencing their fate and toxicity is thus elucidated in the current study.

    The studies reported in the current thesis showed that within the range of 20 to 50 nm, effects of the size of AgNPs on toxicokinetics and toxicodynamics are limited. However, effects of surface coating were consistent over the different levels of biological integration. Generally, the negatively charged AgNP_BSA accumulated to a higher extent in the earthworms, especially at lower concentrations. The in vitro uptake was fast for all NPs, but also showed the highest uptake of AgNP_BSA. The negatively charged AgNPs were also the most toxic, likely related to their increased uptake. This was evident at all levels: gene expression, cellular, and individual (population dynamic parameters) levels. At the in vitro level, this applied mostly to effects on specific modes of action (TNF-α induction, ROS production). For more general cytotoxic effects, the effects of surface coatings were less evident. Except in cells exposed to AgNP_Chit 20 nm, where there was a slight increase in ROS production, this set of AgNPs under the experimental conditions applied, did not appear to induce the production of ROS. This was supported by the lack of expression of any ROS-related gene in the gene expression profile analyses.

    Based on the results of the current research, it can be concluded that the physico-chemical properties of NPs do influence their environmental fate and toxicity. It should be noted however that general predictions on the outcome of exposure to NPs are difficult to make, and NPs should be evaluated on a case by case basis. Our research supports the use of in vitro models to limit and prioritize further in vivo studies. Studies investigating the fate and effects of NPs for soil organisms are vital for a holistic approach towards a comprehensive and adequate environmental risk assessment (ERA). The studies described in this thesis contribute to this knowledge, thereby improving our understanding of the hazards and risks due to exposure to AgNPs, thus enabling their adequate and comprehensive ERA.

    Aandacht voor de regenworm
    Pulleman, M.M. ; Frazao, J.F.T.A. ; Faber, J.H. ; Goede, R.G.M. de; Groot, J.C.J. ; Brussaard, L. - \ 2016
    Landschap : tijdschrift voor landschapsecologie en milieukunde 33 (2016)1. - ISSN 0169-6300 - p. 23 - 26.
    akkerbouw - aardwormen - akkerranden - bodemstructuur - bodembeheer - landinrichting - landschapsbeheer - zuidhollandse eilanden - arable farming - earthworms - field margins - soil structure - soil management - land development - landscape management - zuidhollandse eilanden
    Regenwormen leveren een belangrijke bijdrage aan de omzetting van bodemorganische stof en nutriënten en zorgen voor een goede bodemstructuur, maar ze zijn gevoelig voor verstoringen die de moderne landbouw met zich meebrengt (onder meer Pelosi et al., 2014). Naar aanleiding van strengere regelgeving rond het gebruik van meststoffen en toenemende bodemverdichting staat een beter begrip van de effecten van bodembeheer en landinrichting op regenwormengemeenschappen momenteel volop in de belangstelling.
    Monitoring van ecologische risico’s bij actief bodembeheer van slootdempingen in de Krimpenerwaard : afrondende rapportage T1-monitoring Ecologie
    Lange, H.J. de; Hout, A. van der; Faber, J.H. - \ 2016
    Alterra, Wageningen-UR (Alterra-rapport 2703) - 61
    bodemverontreiniging - zware metalen - polychloorbifenylen - bodemsanering - ecologische risicoschatting - risico - aardwormen - talpidae - krimpenerwaard - zuid-holland - soil pollution - heavy metals - polychlorinated biphenyls - soil remediation - ecological risk assessment - risk - earthworms - talpidae - krimpenerwaard - zuid-holland
    In de Krimpenerwaard liggen circa 6500 slootdempingen en vuilstorten. Het dempingsmateriaal bevat
    regelmatig verontreinigingen, zodat voor de hele regio sprake is van een geval van ernstige
    bodemverontreiniging. Het gebiedsgericht bodembeheerplan voorziet in het afdekken van de
    verontreinigde slootdempingen met gebiedseigen schone grond. De effectiviteit van de sanering wordt
    geëvalueerd op basis van monitoring van ecologische risico’s. Dit rapport beschrijft de resultaten van
    de T1-monitoring, waarin in een relatief korte tijd na afdekken (twee tot vier jaar) de effectiviteit van
    de maatregel wordt beoordeeld. De saneringsmaatregel blijkt de meeste nadelige effecten van de
    slootdemping op soortensamenstelling en aantallen regenwormen te hebben weggenomen. De
    gehalten zware metalen in twee onderzochte regenwormsoorten zijn na sanering over het algemeen
    lager dan de gebiedseigen referentie in de T0-monitoring. De saneringsmaatregel is dus op de korte
    termijn effectief om de risico’s voor doorvergiftiging van zware metalen terug te brengen tot
    gebiedseigen niveau. De PCB-gehalten in de twee soorten regenwormen vertonen veel variatie tussen
    de jaren. De tendens is dat de gehalten in dempingmonsters lager zijn dan in referentiemonsters.
    Vanwege de grote variatie en het beperkt aantal onderzochte locaties zijn deze conclusies alleen met
    voorzichtigheid te trekken. Het PCB-gehalte in mollen bleek ook sterk variabel, in ruimte en in tijd.
    Mollen die in de T1-monitoring gevangen zijn op afgedekte Shredder en Huishoudelijk afval
    dempingen hebben significant hogere PCB-gehalten dan de dieren op de referentiepercelen. Het
    afdekken van de demping heeft voor deze dempingcategorieën de ecologische risico’s onvoldoende
    weggenomen. De effectiviteit op langere termijn met betrekking tot het al dan niet optreden van
    herverontreiniging als gevolg van bioturbatie en capillaire opstijging werd niet onderzocht
    Ecological functions of earthworms in soil
    Andriuzzi, W.S. - \ 2015
    Wageningen University. Promotor(en): Lijbert Brussaard; T. Bolger, co-promotor(en): O. Schmidt. - Wageningen : Wageningen University - ISBN 9789462574175 - 154
    aardwormen - oligochaeta - bodemfauna - bodembiologie - bodemecologie - ecosystemen - bodemstructuur - earthworms - oligochaeta - soil fauna - soil biology - soil ecology - ecosystems - soil structure

    Ecological functions of earthworms in soil

    Walter S. Andriuzzi

    Abstract

    Earthworms are known to play an important role in soil structure and fertility, but there are still big knowledge gaps on the functional ecology of distinct earthworm species, on their own and in interaction with other species. This thesis investigated how earthworms affect soil biochemical and biophysical functioning, and other organisms such as plants and smaller soil organisms.

    Two field experiments with stable isotope tracers were performed to investigate how anecic earthworms (which feed on organic matter at the soil surface and dig deep burrows) transfer carbon and nitrogen from fresh plant litter into soil, and how this in turn affects soil organic matter composition, protists and nematodes. Another field experiment tested whether the anecic earthworm Lumbricus terrestris can counteract negative effects of intense rainfall on soil and plants (ryegrass). A greenhouse experiment was carried out to study how co-occurring earthworm species – two anecic and one endogeic (smaller, soil-feeding) – affect transfer of nitrogen from dung to soil and plants, nitrogen retention in soil, and plant growth. For the latter experiment, a method to produce herbivore (rabbit) dung triple-labelled with carbon, nitrogen and sulphur stable isotopes was developed.

    Overall, the findings highlight important functions of earthworms in carbon and nitrogen cycling, soil biophysical structure maintenance due to burrow formation, and resulting biotic interactions. A novel finding was that the sphere of influence of anecic earthworms in soil (the ‘drilosphere’) is a much larger biochemical and biological hotspot than hitherto assumed. Rapid movement of carbon and nitrogen from surface to soil thanks to anecic earthworm activity resulted in spatial heterogeneity in soil carbon content, organic matter composition, and density of smaller eukaryotes (e.g. bacterial-feeding protists). Evidence was found that distinct earthworm anecic species may have dissimilar effects on soil biochemistry and plant growth, and that both anecic and endogeic earthworms may feed on surface organic matter (dung). This shows that the validity of earthworm ecological groups depends on the function under study, and suggests that, for some research questions, species identity should not be neglected; other approaches to quantify ecological differences between species (e.g. functional traits) are appraised. Finally, L. terrestris was found to ameliorate the disturbance of intense rain on plants, giving evidence to the idea that some components of soil biodiversity may contribute to ecosystem stability in the face of disturbance.

    Tot de bodem uitzoeken : micro-organismen beïnvloeden plantengroei
    Beintema, N. ; Groenigen, J.W. van - \ 2015
    WageningenWorld (2015)2. - ISSN 2210-7908 - p. 10 - 15.
    bodembiologie - bodembeheer - organische stof - aardwormen - bodemkwaliteit - organisch bodemmateriaal - koolstof - micro-organismen - bodemvruchtbaarheid - gewasbescherming - plantenontwikkeling - soil biology - soil management - organic matter - earthworms - soil quality - soil organic matter - carbon - microorganisms - soil fertility - plant protection - plant development
    Per vierkante meter bodem leven honderden wormen en insecten samen met kilometers aan schimmeldraden, vele miljoenen aaltjes en miljarden bacteriën. Onderzoek maakt steeds meer duidelijk van het precaire evenwicht ondergronds, en de grote invloed daarvan op het leven bovengronds. Het levert nieuwe strategieën op voor gewasbescherming.
    Earthworms and the soil greenhouse gas balance
    Lubbers, I.M. - \ 2014
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Jan-Willem van Groenigen. - Wageningen : Wageningen University - ISBN 9789461739315 - 222
    aardwormen - oligochaeta - broeikasgassen - bodem - koolstofvastlegging in de bodem - koolstofvastlegging - emissie - bodembiologie - earthworms - oligochaeta - greenhouse gases - soil - soil carbon sequestration - carbon sequestration - emission - soil biology

    Earthworms play an essential part in determining the greenhouse gas (GHG) balance of soils worldwide. Their activity affects both biotic and abiotic soil properties, which in turn influence soil GHG emissions, carbon (C) sequestration and plant growth. Yet, the balance of earthworms stimulating C sequestration on the one hand and increasing GHG emissions on the other has not been investigated. Indeed, much is still unclear about how earthworms interact with agricultural land use and soil management practices, making predictions on their effects in agro-ecosystems difficult. In this thesis, I aimed to determine to what extent GHG mitigation by soil C sequestration as affected by earthworms is offset by earthworm-induced GHG emissions from agro-ecosystems under different types of management. To reach this aim, I combined mesocosm and field studies, as well as meta-analytic methods to quantitatively synthesize the literature.

    Using meta-analysis, I showed that, on average, earthworm activity leads to a 24% increase in aboveground biomass, a 33% increase in carbon dioxide (CO2) emissions and a 42% increase in nitrous oxide (N2O) emissions. The magnitude of these effects depends on soil factors (e.g., soil organic matter content), experimental factors (e.g., crop residue addition or fertilizer type and rate) and earthworm factors (e.g., earthworm ecological category and -density).

    Conducting both a mesocosm and a field study, I showed that earthworm activity results in increased N2O emissions from fertilized grasslands. Under field conditions I found an increase in earthworm-induced N2O emissions in autumn but not in spring, suggesting that earthworm effects in the field depend on soil physicochemical parameters influenced by meteorological and seasonal dynamics.

    In a unique two-year experiment with a simulated no-tillage (NT) system and a simulated conventional tillage (CT) system, I found that earthworm presence increases GHG emissions in an NT system to the same level as in a CT system. This suggests that the GHG mitigation potential of NT agro-ecosystems is limited. When considering the C budget in the simulated NT system, I demonstrated that over the course of the experiment earthworms increase cumulative CO2 emissions by at least 25%, indicating a higher C loss compared to the situation without earthworms. Yet, in the presence of earthworms the incorporation of residue-derived C into all measured soil aggregate fractions also increased, indicating that earthworm activity can simultaneously enhance CO2 emissions and C incorporation into aggregate fractions.

    In conclusion, the revealed dominance of GHG emissions over C sequestration as affected by earthworms implies that their presence in agro-ecosystems results in a negative impact on the soil greenhouse gas balance.

    Regenwormen op het melkveebedrijf : handreiking voor herkennen, benutten en managen
    Eekeren, N.J.M. van; Bokhorst, J. ; Deru, J. ; Wit, J. de - \ 2014
    Driebergen : Louis Bolk Instituut (Rapport / Louis Bolk Instituut 2014-004 LbD) - 37 p.
    aardwormen - bodemkwaliteit - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - melkveehouderij - bodembiologie - graslanden - bouwland - graslandbeheer - earthworms - soil quality - soil fertility - soil fertility management - dairy farming - soil biology - grasslands - arable land - grassland management
    In deze brochure worden handreikingen gegeven voor de praktijk, waarbij zowel strooiselbewonende, bodembewonende en pendelende regenwormen aan bod komen.
    Koester de regenworm
    Eekeren, N.J.M. van; Deru, J.G.C. ; Poot, N. - \ 2014
    V-focus 11 (2014)2. - ISSN 1574-1575 - p. 40 - 41.
    melkveehouderij - aardwormen - grondbewerking - voedingsbehoeften - nadelige gevolgen - strooisel - bodemstructuur - bodemfauna - dairy farming - earthworms - tillage - feed requirements - adverse effects - litter (plant) - soil structure - soil fauna
    Regenwormen zijn belangrijk op een melkveebedrijf voor de afbraak van organische stof, het beschikbaar maken van nutriënten, behoud van bodemstructuur, waterinfiltratie, beworteling en uiteindelijk gewasopbrengst. Vooral pendelende wormen hebben unieke functies, maar zijn heel gevoelig voor een intensieve en/of kerende grondbewerking door hun levenswijze, in permanente gangen, en hun behoefte aan strooisel als voedsel. Als de melkveehouderij beter gebruikt wil maken van de pendelaars is de vraag wat het belangrijkste knelpunt is: grondbewerking of een gebrek aan voedsel en bescherming. Resultaten van een proef naar het effect op regenwormen wordt besproken.
    Herkenningskaart Regenwormen
    Zanen, M. ; Alebeek, F.A.N. van; Hanegraaf, M. - \ 2013
    bodembiologie - aardwormen - akkerbouw - graslanden - inventarisaties - soil biology - earthworms - arable farming - grasslands - inventories
    Regenwormen zijn belangrijk voor de bodemkwaliteit. Daarnaast zijn regenwormen een belangrijke schakel in het voedsel web van ondergrondse naar bovengrondse biodiversiteit (o.a. weidevogels). Deze Herkenningskaart is onderdeel van het pakket ‘Brede Kennisontsluiting Bodembiodiversiteit’, Op een vierkante meter bouwland is het streeftraject 80-200 regenwormen. Voor grasland is de streefwaarde 300-700. Op klei zijn de aantallen meestal hoger dan op zand. Deze brochure geeft antwoord op de vraag: welke regenworm kan ik tegenkomen.
    Can arable field margins and non-inversion tillage stimulate earthworm diversity?
    Huerta-Lwanga, E. ; Crittenden, S. ; Goede, R.G.M. de; Brussaard, L. ; Pulleman, M.M. - \ 2013
    akkerbouw - gereduceerde grondbewerking - grondbewerking - aardwormen - akkerranden - biodiversiteit - arable farming - reduced tillage - tillage - earthworms - field margins - biodiversity
    The objective of this study was to determine the effects of field margins and reduced tillage (NIT) on abundance, biomass and diversity of earthworms.
    Amazing grazing : All weather beweiding
    Lubbers, I.M. - \ 2013
    YouTube
    aardwormen - broeikasgassen - bodembiologie - emissie - universitair onderzoek - earthworms - greenhouse gases - soil biology - emission - university research
    egenwormen blijken een flink aandeel te hebben in de opwarming van de aarde. Dat blijkt uit een onderzoek dat de Wageningen Universiteit samen met internationale collega's uitvoerde. Regenwormen, bekend van hun vermogen de bodemvruchtbaarheid te verbeteren, blijken de uitstoot van broeikasgassen vanuit de bodem flink te verhogen; koolzuurgas gemiddeld met 33% en die van lachgas met 42%. Lachgas kan gemakkelijker via hun gangenstelsels ontsnappen naar de atmosfeer voordat het omgezet kan worden naar het onschadelijke stikstofgas.
    Soil biota and nitrogen cycling in production grasslands with different fertilisation histories
    Rashid, M.I. - \ 2013
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Egbert Lantinga; Ron de Goede. - S.l. : s.n. - ISBN 9789461735485 - 192
    stikstofkringloop - bodemfauna - mineralisatie - rundveemest - decompositie - bodeminvertebraten - bodem ph - aardwormen - graslanden - bodembiologie - nitrogen cycle - soil fauna - mineralization - cattle manure - decomposition - soil invertebrates - soil ph - earthworms - grasslands - soil biology
    Bodembeheer afstemmen op regen- en oorwormen
    Maas, M.P. van der; Heijne, B. ; Balkhoven, H. - \ 2013
    De Fruitteelt 103 (2013)19. - ISSN 0016-2302 - p. 8 - 9.
    bodembeheer - fruitteelt - pyrus communis - dermaptera - aardwormen - bodemstructuur - duurzaam bodemgebruik - nuttige organismen - soil management - fruit growing - pyrus communis - dermaptera - earthworms - soil structure - sustainable land use - beneficial organisms
    Op fruitbedrijven in de provincie is eind vorig jaar een onderzoek gestart naar het stimuleren van regen- en oorwormen en het verbeteren van de fosfaatvoeding in peer. Op drie locaties wordt de gangbare perenteelt vergeleken met een bodemleven- en oorwormvriendelijke teeltwijze. Hierbij komen alle aspecten van de perenteelt aan bod zoals gewasbescherming, ondergroeibeheer, bemesting en organische stofaanvoer.
    Unravelling hazards of nanoparticles to earthworms, from gene to population
    Ploeg, M. van der - \ 2013
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Nico van den Brink. - S.l. : s.n. - ISBN 9789461734440 - 192
    aardwormen - lumbricus rubellus - nanotechnologie - blootstelling - ecotoxicologie - earthworms - lumbricus rubellus - nanotechnology - exposure - ecotoxicology

    Nanotechnology is an expeditiously growing field, where engineered nanoparticles are being incorporated in many different applications, from food to waste water treatment (Dekkers et al. 2011; Gottschalk and Nowack 2011; Savage and Diallo 2005). Due to this large scale production and use of nanoparticles, their release into the environment seems inevitable (Crane et al. 2008; Handy et al. 2008a; Oberdörster et al. 2005). Actual exposure levels of nanoparticles under field conditions and the hazards of nanoparticle exposure to the environment are poorly understood, especially for the soil environment (Kahru and Dubourguier 2010; Navarro et al. 2008; Shoults-Wilson et al. 2011a).

    Given the need for better characterization of hazards of engineered nanoparticles to the environment and soil organisms in particular, the aim of the present thesis was to investigate effects of nanoparticle exposure on the earthworm Lumbricus rubellus, as a model organism for soil ecotoxicology, and to contribute to the development of effect markers for engineered nanoparticle exposure in this model.

    The present thesis was divided in different chapters. Chapter 1 provides an introduction to the topic and discusses the importance of research on the hazards of exposure to engineered nanoparticles. Furthermore, the aim and outline of the thesis are presented, with background information on the model organism, effect markers and nanoparticles.

    In chapter 2 effects of exposure to the fullerene C60 (nominal concentrations 0, 15.4 and 154 mg C60/kg soil) on survival and growth during the different life stages of L. rubellus (cocoon, juvenile, subadult and adult), as well as reproduction were quantified. These important individual endpoints for population dynamics were incorporated in a continuous-time life-history model (Baveco and De Roos 1996; De Roos 2008). In this way, effects of C60 exposure on the individual endpoints could be extrapolated to implications for population growth rate and life stage distribution, i.e. the development of the population in terms of number of individuals in the different life stages. These implications at the population level may be more relevant for the ecological impact of C60 than effects on endpoints at the individual level (Klok et al. 2006; Widarto et al. 2004). At the individual level C60 exposure caused significant adverse effects on cocoon production, juvenile growth rate and survival. When these endpoints were used to model effects on the population level, reduced population growth rates with increasing C60 concentrations were observed. Furthermore, a shift in life stage structure was shown for C60 exposed populations, towards a larger proportion of juveniles. This result implies that the lower juvenile growth rate induced by C60 exposure resulted in a larger proportion of juveniles, despite increased mortality among juveniles. Overall, this study implied serious consequences of C60 exposure for L. rubellus earthworm populations, even at the lowest level of exposure tested. Furthermore, it showed that juveniles were more sensitive to C60 exposure than adults.

    To complement the observations made on survival, growth and reproduction described in chapter 2, subsequent investigations on cellular and molecular responses of the earthworms to C60 exposure were performed (chapter 3). A set of established effect markers was used, which reflect different levels of biological organisation in the earthworm and may inform on the toxic mechanisms of adverse effects induced by C60 exposure (Handy et al. 2002; Heckmann et al. 2008). At the molecular level, four specific effect markers were selected, including markers for generic stress (heat shock protein 70 (HSP70) (van Straalen and Roelofs 2006), for oxidative stress (catalase and glutathione-S-transferase (GST) (Kohen and Nyska 2002) and for an immune response (coelomic cytolytic factor-1 (CCF-1) (Olivares Fontt et al. 2002). At the tissue level, histological analyses were used to identify damage to cells and tissues, and indications of inflammation in the tissues. In these investigations, exposure to C60 (0, 15 or 154 mg C60/kg soil) affected gene expression of HSP70 significantly. Gene expression of CCF-1 did not alter in adult earthworms exposed for four weeks, but was significantly down-regulated after lifelong exposure (from cocoon stage to adulthood) of earthworms, already to the lowest C60 exposure level. No significant trends were noted for catalase and glutathione-S-transferase (GST) gene expression or enzyme activity. Tissue samples of the C60 exposed earthworms from both experiments and exposure levels, showed a damaged cuticle with underlying pathologies of epidermis and muscles. Additionally, the gut barrier was not fully intact. However, tissue repair was also observed in these earthworms. In conclusion, this study demonstrated effects of sub-lethal C60 exposure on L. rubellus earthworms, at the level of gene expression and tissue integrity.

    Although tissue injury is generally associated with an inflammatory response, as part of tissue repair (Cikutovic et al. 1999; Goven et al. 1994), the tissue damage observed for the in vivo C60 exposed earthworms in chapter 3 appeareded to occur without accompanying induced immune responses. The CCF-1 gene expression level was reduced in the C60 exposed earthworms, and histological observations did not show infiltration of damaged tissues by immune cells. In order to obtain further insight in mechanisms of effects observed at the molecular and tissue level on immune related parameters, the sensitivity of immune cells (coelomocytes) of L. rubellus earthworms towards exposure to selected nanoparticles was investigated in vitro (chapter 4). To this end, coelomocytes were isolated from unexposed adult L. rubellus earthworms and exposed to C60 in vitro. After exposure, these coelomocytes were tested for cellular viability, phagocytic activity and CCF-1 gene expression levels. The gene expression of CCF-1 was most affected, demonstrating a strong reduction, which indicated immunosuppression. Experiments with NR8383 rat macrophage cells and tri-block copolymer nanoparticles were used to compare sensitivity of the cell types and showed the usefulness of coelomocytes as a test system for nano-immunotoxicity in general. Overall, this study indicated that the absence of an immune response, in case of tissue injuries observed after in vivo C60 exposure, is likely caused by immunosuppression rather than coelomocyte mortality.

    In subsequent investigations, the experiments performed for C60 were also carried out with silver nanoparticles (AgNP), both in vivo and in vitro (chapter 5). Effects of AgNP were assessed in vivo at nominal concentrations of 0, 1.5 (low), 15.4 (medium) and 154 (high) mg Ag/kg soil and compared to effects of silver ions, added as AgNO3 (nominal concentration 15.4 mg Ag/kg soil). In a four week reproduction assay, the high AgNP and AgNO3 treatments had a significant effect on cocoon production and high AgNP exposure also caused a reduction in weight gain of the adult earthworms. No juveniles survived the high AgNP treatment, therefore only F1 earthworms from the other exposure treatments were monitored for survival and growth, until adulthood. These individual endpoints were used to model effects on the population level. The low and medium AgNP as well as the AgNO3 treatments significantly reduced the population growth rate. The high AgNP treatment caused complete failure of the population growth. Furthermore, histological examination of the earthworms from all AgNP exposure treatments demonstrated tissue damage, with injuries mainly at the external barriers, e.g. the cuticle and the gut epithelium. In addition, effects of AgNP exposure were assessed in vitro and a reduction of coelomocyte viability was observed in a concentration-dependent manner, although the EC50 was fourteen times higher compared with that for Ag ions, added as AgNO3. Furthermore, characterisation of the in vivo exposure media implied that AgNP remained present in the soil in single and aggregated state, releasing Ag to the soil pore water up to at least eleven months. The ionic fraction of Ag in soils has been suggested to be bioavailable to organisms and (largely) responsible for the observed AgNP toxicity (Coutris et al. 2012; Koo, et al. 2011; Shoults-Wilson et al. 2011b). In comparison, the AgNO3 seemed to dissolve rapidly, as is also known for this metal salt, and fixation of Ag ions by the soil presumably led to a quick reduction of Ag bioavailability (Atkins and Jones 2000; Coutris et al. 2012; Ratte 1999). This is in line with the observation that effects were more prolonged in the AgNP treatments in comparison with the AgNO3 exposed animals. In conclusion, this study indicated that AgNP exposure may seriously affect earthworm populations, with the ability to cause immunotoxicity, injury to the external barriers of the earthworm body and a reduction in growth, reproduction and juvenile survival.

    Finally, chapter 6 presents a discussion on the findings of the present thesis and provides suggestions for future research.

    Regenwormen helpen u de bodem te bewerken!
    Haagsma, W.K. ; Balen, D.J.M. van; Broek, R.C.F.M. van den - \ 2012
    Westmaas : PPO AGV
    aardwormen - bodemstructuur - bodemverbeteraars - bodembiologie - akkerbouw - earthworms - soil structure - soil conditioners - soil biology - arable farming
    Regenwormen zijn zeer actief en verzetten jaarlijks 250 keer hun eigen gewicht aan grond. Zij zorgen voor: • Omzetting van organisch materiaal in humus. • Beschikbaar maken van mineralen als stikstof en fosfaat • Verbetering van de bodemstructuur • Verbetering doorlaatbaarheid bodem voor lucht en water • Verbetering van de beworteling
    Worm blij met natte zomer : Interview met Klaas van Rozen en Mirjam Pulleman
    Berg, G.A. van den; Rozen, K. van; Pulleman, M.M. - \ 2012
    Boerderij 97 (2012)49. - ISSN 0006-5617 - p. 40 - 43.
    aardappelen - oogsten - akkerbouw - aporrectodea caliginosa - aardwormen - potatoes - harvesting - arable farming - earthworms
    Het begin van zomer 2012 was nat. Half augustus zitten de wormen boven in de aardappelrug. Als de nazomer droog verloopt, is de kans op rooiproblemen groot.
    Hoe zit het met mijn regenwormen? : Project Duurzaam Bodembeheer bij peer op kleigrond in provincie Utrecht
    Maas, M.P. van der; Heijne, B. ; Anbergen, R.H.N. - \ 2012
    De Fruitteelt 102 (2012)28. - ISSN 0016-2302 - p. 10 - 11.
    fruitteelt - bodembeheer - duurzaamheid (sustainability) - aardwormen - bodemstructuur - helmintologie - cultuurmethoden - bemesting - fruit growing - soil management - sustainability - earthworms - soil structure - helminthology - cultural methods - fertilizer application
    Fruittelers hebben regenwormen nodig. Regenwormen verteren het blad zodat de schurftdruk vermindert en ze verbeteren de bodemstructuur zodat overtollig regenwater op de rij- en boomstroken sneller wordt afgevoerd. Maar hoeveel regenwormen zijn er minimaal nodig en hoeveel zijn er aanwezig? Welke maatregelen kunnen telers nemen om het aantal regenwormen te verhogen? Dat zijn enkele vragen die centraal staan in het project: Duurzaam bodembeheer bij peer op kleigrond. Het project gaat dit jaar in de provincie Utrecht van start.
    Effect of grass-clover on the ecosystem services soil structure maintenance and water regulation
    Eekeren, N.J.M. van; Bokhorst, J.G. ; Brussaard, L. ; Koopmans, C.J. - \ 2011
    In: Proceedings of the third scientific conference of the International Society of Organic Agriculture Research (ISOFAR), 28 Sept - 1 Oct 2011. - - p. 44 - 47.
    grasklaver - melkveehouderij - biologische landbouw - trifolium repens - aardwormen - bodemstructuur - bodemwaterretentie - wortels - grass-clover swards - dairy farming - organic farming - trifolium repens - earthworms - soil structure - soil water retention - roots
    White clover has a lower root biomass and a higher abundance of earthworms than grass. This might have an impact on the ecosystem services soil structure maintenance and water regulation when white clover is introduced in the grassland on organic dairy farms. We investigated the root biomass, the abundance of earthworms and a selection of soil physical parameters in white clover, grass-clover, and grass with and without N fertilizer. The treatment with clover-only had a lower root biomass, a lower C/N-ratio of the roots, a higher abundance of earthworms, a higher number of earthworm burrows, a lower penetration resistance at the 20-30 cm soil layer and a lower proportion of crumbs in the soil, than the other treatments. This confirms the literature that pure clover stimulates the ecosystem services of water regulation, but is less conducive to soil structure maintenance. However, the grass-clover mixture did not differ significantly from the grass treatments, but differed from pure clover in a higher percentage of soil crumbs. We infer that, when clover is introduced in grassland on organic dairy farms to fix atmospheric N2, the mixture of grass and clover maintains the positive impact of grass roots on soil structure but only may show a positive effect of clover-only on water regulation with a higher clover percentage in the dry matter.
    Wormen ploegen akker in drie jaar
    Faber, J.H. - \ 2011
    Kennis Online 8 (2011)juli. - p. 9 - 9.
    aardwormen - ecosysteemdiensten - bodemfauna - earthworms - ecosystem services - soil fauna
    Regenwormen en schimmels in de bodem hun werk laten doen in plaats van ploegen verbetert de grond en helpt tegen ziekten. Alleen heb je pas na vijf tot tien jaar profijt van omschakeling van ploegen naar niet-kerende bodembewerking.
    Anecic earthworms and associated ecosystem services in a ley-arable crop
    Eekeren, N.J.M. van; Bommele, L. ; Bokhorst, J.G. ; Schouten, T. ; Reheul, D. ; Brussaard, L. - \ 2010
    In: 19th World Congress of Soil Science, Soil Solutions for a Changing World, 1–6 August 2010, Brisbane, Australia. - - p. 9 - 11.
    aardwormen - graslanden - bouwland - bodemvruchtbaarheid - bodemecologie - ecosysteemdiensten - earthworms - grasslands - arable land - soil fertility - soil ecology - ecosystem services
    Een vruchtwisseling van gras en maïs zou duurzaam kunnen zijn in termen van nutriëntengebruik, maar het effect op regenwormen is nog onvoldoende bekend. Regenwormen zijn verzameld in permanent akkerland, permanent grasland en grond waarop een vruchtwisseling was toegepast. De hoeveelheid regenwormen was het hoogst in permanent grasland. Na gebruik als akkerland heeft de populatie heeft minstens drie jaar nodig om te herstellen. De populatie anenic wormen waren echter na deze periode nog niet hersteld.
    Soil macrofauna functional groups and their effects on soil structure, as related to agricultural management practices across agroecological zones of Sub-Saharan Africa
    Ayuke, F.O. - \ 2010
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Mirjam Pulleman; B. Vanlauwe; J. Six. - [S.l. : S.n. - ISBN 9789085856870 - 202
    agrarische bedrijfsvoering - gewasteelt - bodemstructuur - wormhoopjes - termietenheuvels - mierenhopen - agro-ecologische zones - isoptera - aardwormen - afrika ten zuiden van de sahara - kenya - macrofauna - farm management - crop management - soil structure - worm casts - termitaria - ant hills - agroecological zones - isoptera - earthworms - africa south of sahara - kenya - macrofauna
    This study aimed at understanding the effects of crop management practices on soil macrofauna and the links with soil aggregation and soil organic matter dynamics, which is key to the improvement of infertile or degrading soils in Sub-Sahara Africa. Soil macrofauna, especially earthworms and termites, are important components of the soil ecosystem and, as ecosystem engineers, they influence the formation and maintenance of soil structure and regulate soil processes, such as organic matter decomposition and nutrient dynamics. In comparison with natural systems, earthworm and termite diversity and abundance were low in fallow, high soil-carbon (C) and low soil-C arable treatments in 12 long-term trial fields across the sub-humid to semi-arid tropical zones in Eastern and Western Africa. Continuous crop production had significant negative effects on earthworm diversity, but little effect on termite diversity, as compared to long-term fallow. Agricultural management resulting in high soil C increased earthworm and termite diversity as compared to low-C soil.Long-term application of manure in combination with fertilizer resulted in higher earthworm diversity and biomass, associated with improved soil aggregation and enhanced C and N stabilization within this more stable soil structure. These practices therefore result in the dual benefits of improving soil physical and chemical properties. A micromorphological study of undisturbed soil thin sections showed that fallowing, conservation tillage plus residue application (in East Africa) and hand-hoeing plus manure (in West Africa) enhanced biogenic soil structure formation, resulting in a well developed soil structure and a continuous pore system characterized by many faunal channels. In contrast,intensive tillage and absence of organic inputs resulted in soil with less biogenic soil structural features. Farmers in Nyabeda, West-Kenya, were aware of the activities and nesting habits of termites, but 90% percent of the farmers perceived termites as pests.This study has shown that the soil macrofauna, especially earthworms, and, to a lesser extent termites, are important drivers of stable soil aggregation in Sub-Saharan agroecosystems, with beneficial effects on soil physical and chemical properties. However, their beneficial impact on soil aggregation is reduced with increasing management intensity and associated soil disturbance due to cultivation. This knowledge is important in designing agricultural management systems aimed at increasing long-term soil fertility in Sub-Saharan Africa.
    Soil detritivore functioning in heterogeneously contaminated soils
    Heemsbergen, D.A. - \ 2009
    VU University Amsterdam. Promotor(en): H.A. Verhoef, co-promotor(en): M.P. Berg; Jack Faber. - [S.l.] : S.n. - ISBN 9789086593972 - 156
    bodemchemie - bodemverontreiniging - aardwormen - ecotoxicologie - bodemecologie - soil chemistry - soil pollution - earthworms - ecotoxicology - soil ecology
    Bodemverontreiniging kan een belemmerende factor zijn bij de grootschalige herinrichting van uiterwaarden in het kader van het project ‘Ruimte voor de Rivier’, waarbij nieuwe kansen voor natuurontwikkeling worden gecreëerd. Onderzoek van Diane Heemsbergen aan de Vrije Universiteit Amsterdam en Alterra Wageningen UR toont aan dat regenwormen een positieve invloed op het bodemsysteem uitoefenen
    Introductie van regenwormen ter verbetering van bodemkwaliteit
    Faber, J.H. ; Hout, A. van der - \ 2009
    Wageningen : Alterra (Alterra-rapport 1905) - 59
    aardwormen - bodemstructuur - bodemwater - graslanden - bouwland - landbouw - bodemkwaliteit - earthworms - soil structure - soil water - grasslands - arable land - agriculture - soil quality
    Het is goed mogelijk om regenwormen te introduceren zodanig dat populaties zich blijvend vestigen. Op een termijn van enkele jaren kunnen geïntroduceerde regenwormen de eigenschappen van de bodem verbeteren door meer aggregaatvorming, grotere porositeit, betere doorluchting en waterinfiltratie en meer vochtleverend vermogen van de bodem. Daarmee hebben introducties in agrarisch grasland en akkerland potentie voor toepassing als teeltondersteunende maatregel. De succesfactoren bij de maatregel zijn echter nog onvoldoende bekend voor onmiddellijke toepassing in de praktijk. Dit rapport geeft een overzicht van de resultaten van introducties in Nederland en elders in gematigde streken. De gegevens van Nederlandse introducties komen voort uit historisch onderzoek en recent uitgevoerde veldinventarisaties. Op basis van literatuurstudie worden succes- en faalfactoren kort op een rijtje gezet, evenals de effecten van introducties op de kwaliteit van de bodem in grasland en akkerland.
    De bijdrage van ecologisch milieubeheer aan de kwaliteit van natuurgebieden
    Eijsackers, H.J.P. - \ 2008
    De Levende Natuur 109 (2008)2. - ISSN 0024-1520 - p. 45 - 50.
    ecosystemen - bodemverontreiniging - zware metalen - bioremediëring - aardwormen - ecotoxicologie - natuurgebieden - ecosystems - soil pollution - heavy metals - bioremediation - earthworms - ecotoxicology - natural areas
    Natuurbeheer heeft drie relaties met milieubeheer. Namelijk: 1. via man-made ecosystemen; 2. via de invloed van negatieve milieuomstandigheden op de natuur; 3. via de mogelijkheid om natuurlijke processen in te zetten om verontreiniging in natuurgebieden op te ruimen. In dit artikel komen alle drie de aspecten aan bod via het voorbeeld van waterbodemverontreiniging en slibproblematiek door zware metalen, PAK's en PCB's in veengebieden en uiterwaarden. Het verkent de mogelijkheden van regenwormen als inzet voor natuurlijke reiniging en probeert van daaruit oplossingsrichtingen voor beleid en beheer aan te reiken
    Bodemvitaliteit in de biologische kasteelt : effect van grondbewerking en introductie van regenwormen op de bodemstructuur
    Cuijpers, W.J.M. ; Burgt, G.J.H.M. van der - \ 2008
    Driebergen : Louis Bolk Instituut - 31 p.
    biologische landbouw - bodemvruchtbaarheid - bodemstructuur na grondbewerking - grondbewerking - gewasopbrengst - aardwormen - bemesting - glastuinbouw - glasgroenten - organic farming - soil fertility - tilth - tillage - crop yield - earthworms - fertilizer application - greenhouse horticulture - greenhouse vegetables
    In 2006 en 2007 a research was done to investigate the effect on soil structure of tillage, organic manure and introduction of worms. There were no repetitions of the treatments, so the results can only be indicative. A less intensive soil tillage improved the overall soil structure, measured on the parameters penetration resistance, water infiltration and bulk density. The yield increased substantially. The effect on the soil structure was temporally. Short after soil tillage (April – May) differences could be measured, but in October no differences could be observed. Farmyard manure instead of compost, in combination with a 50% reduction of basis fertilizer nitrogen application out of additional fertilizers did not reduce the yield although total nitrogen application and nitrogen availability were substantially reduced. Out of this research it can not be concluded whether this is caused by an improved soil quality due to FYM or by a surplus of nitrogen in the ‘standard’ way of manure and fertilizer application. The introduction of Aporrectodea calliginosa is more successful then that of Dendrobaena veneta. Because of this, and because of the different function of these worms in the soil ecosystem, little effect of D. veneta on soil structure may be expected.
    Verkenning van de mogelijkheden om de opname van bodemfosfaat door blijvend grasland te verhogen
    Boer, H.C. de - \ 2008
    Wageningen : Animal Sciences Group (Rapport / Animal Sciences Group 144) - 15
    fosfaten - mobilisatie - graslanden - aardwormen - micro-organismen - mycorrhizae - phosphates - mobilization - grasslands - earthworms - microorganisms - mycorrhizas
    This literature study gives an overview of the possibilities to increase the soil phosphorus uptake of permanent grassland by practical measures
    Soil biodiversity and nitrogen cycling under agricultural (de-)intensification
    Postma-Blaauw, M.B. - \ 2008
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Ron de Goede; Jaap Bloem; Jack Faber. - [S.l.] : S.n. - ISBN 9789085048909 - 198
    bodemfauna - biodiversiteit - aardwormen - nematoda - stikstof - kringlopen - intensivering - mineralisatie - agrarische bedrijfsvoering - nederland - bodembiodiversiteit - agro-ecosystemen - agrobiodiversiteit - soil fauna - biodiversity - earthworms - nematoda - nitrogen - cycling - intensification - mineralization - farm management - netherlands - soil biodiversity - agroecosystems - agro-biodiversity
    Bodemorganismen spelen een sleutelrol in de recycling van nutriënten door hun bijdrage aan de afbraak van organisch materiaal (decompositie), het beschikbaar maken van voedingstoffen (mineralisatie) die benut kunnen worden voor plantengroei en bioturbatie van de bodem. In de intensieve landbouw wordt deze rol ten dele overgenomen door het gebruik van kunstmest en grondbewerking. Deze landbouwpraktijken hebben het nadelige gevolg dat onder andere de diversiteit aan bodemorganismen afneemt, en nutrientenverliezen, met name stikstof, naar het milieu toenemen. Daarom hebben wetenschappers zich recentelijk in toenemende mate gericht op het creëren en ondersteunen van vormen van landbouw die op de lange termijn duurzaam zijn. Een efficiëntere benutting van nutrienten in agro-ecosystemen kan wellicht bereikt worden wanneer de bodemgemeenschap een grotere rol in de nutriëntencyclus gaat spelen.
    Schurftbestrijding in de biologische fruitteelt (Repco)
    Heijne, B. ; Jong, P.F. de - \ 2007
    fruitteelt - biologische landbouw - gewasbescherming - plantenziekten - biologische bestrijding - nuttige organismen - aardwormen - fruit growing - organic farming - plant protection - plant diseases - biological control - beneficial organisms - earthworms
    Doel van het EU-project Repco is methoden te ontwikkelen, die beheersing van schurft in de biologische teelt mogelijk maken zonder het gebruik van koper, bijvoorbeeld door regenwormen te bevorderen die bladeren eten waar de ziekte in overwintert
    Regenwormen en structuurproblemen
    Rozen, K. van - \ 2006
    Kennisakker.nl 2006 (2006)15 april.
    zware kleigronden - bodemstructuur - verliezen bij het oogsten - rooien - aardappelen - bodemwatergehalte - aardwormen - flevoland - akkerbouw - clay soils - soil structure - harvesting losses - grubbing - potatoes - soil water content - earthworms - flevoland - arable farming
    In natte perioden leidt een toenemende activiteit van hoge aantallen regenwormen tot negatieve veranderingen van de bodemstructuur in aardappelruggen. Problemen bij de aardappeloogst op de zwaardere gronden in de Flevopolders is het gevolg. De aardappelruggen worden kleverig en hard en het rooien verloopt moeizaam. Het onderzoek richt zich op structuurverbetering van de bodem en beheersing van de populatie regenwormen. In vitro onderzoek op het PPO-AGV resulteerde in perspectiefvolle resultaten om de structuurprobleem te voorkomen. Maar hierop volgend veldonderzoek gaf niet de gewenste resultaten. In 2001 werden betrouwbaar meer grote kluiten gemeten bij een behandeling met Stalosan F in het veld, het enige product die in in vitro onderzoek het effect benaderde van een situatie met klei zonder regenwormen.
    Dynamiek versluiert; veldeffecten van metalen in dynamische ecosystemen
    Klok, C. - \ 2006
    Bodem 16 (2006)3. - ISSN 0925-1650 - p. 120 - 121.
    ecosystemen - toxicologie - aardwormen - bodemfauna - overstromingen - stroomvlakten - zware metalen - ecotoxicologie - ecosystems - toxicology - earthworms - soil fauna - floods - floodplains - heavy metals - ecotoxicology
    Deze bijdrage richt zich op de invloed van overstroming op de kans dat effecten van vervuiling zichtbaar worden op regenwormpopulaties
    Kluiten regenwormen aanpakken met gips
    Rozen, K. van; Ester, A. - \ 2005
    Kennisakker.nl 2005 (2005)15 feb.
    aardappelen - rooien - verliezen bij het oogsten - tarra - kluiten - bodemstructuur - zware kleigronden - aardwormen - landbouwkundig onderzoek - flevoland - akkerbouw - potatoes - grubbing - harvesting losses - tare - clods - soil structure - clay soils - earthworms - agricultural research - flevoland - arable farming
    Oogsten van aardappelen zonder grondtarra; in de Flevopolder gloort weer hoop aan de horizon. De laatste jaren werd de klei in aardappelruggen met hoge aantallen regenwormen versmeerd, waardoor moeilijk afbreekbare kluiten ontstonden. Een probleem waarvan de omvang ieder jaar weer afhangt van de hoeveelheid neerslag die tijdens het teeltseizoen op het aardappelveld valt. Gips biedt weerstand tegen deze vorm van kluitvorming, zo blijkt uit veldonderzoek van PPO-agv in Lelystad.
    Relatie tussen appelschurft en bladvertering door regenwormen
    Heijne, B. ; Jong, P.F. de; Anbergen, R.H.N. - \ 2005
    venturia inaequalis - biologische bestrijding - aardwormen - nuttige organismen - organismen ingezet bij biologische bestrijding - boomgaarden - venturia inaequalis - biological control - earthworms - beneficial organisms - biological control agents - orchards
    Meerdere ziekten, zoals door Venturia inaequalis veroorzaakte appelschurft, overwinteren in afgevallen blad. Door ervoor te zorgen dat het blad snel verteert, wordt de inoculum-hoeveelheid in het voorjaar verkleind. Daardoor zou het beter mogelijk zijn om aantasting het volgend jaar te beperken. Het doel is om regenwormen te stimuleren om sneller blad op te eten. Beschrijving van het onderzoek in een biologische boomgaard, resultaten en de praktijk
    Bladvertering door regenwormen bevorderen : onderzoek
    Heijne, B. ; Anbergen, R.H.N. ; Jager, A. de - \ 2005
    De Fruitteelt 95 (2005)6. - ISSN 0016-2302 - p. 12 - 13.
    aardwormen - lumbricidae - bladeren - vermicompostering - gewasbescherming - fruitteelt - boomgaarden - earthworms - lumbricidae - leaves - vermicomposting - plant protection - fruit growing - orchards
    In een EU-project werkt PPO-fruit aan de verbetering van de bladvertering door regenwormen. Als het blad verteerd is, is de ziektedruk veel lager
    Kluiten regenwormen aanpakken met gips
    Rozen, K. van; Ester, A. - \ 2005
    Boerderij/Akkerbouw 90 (2005)4. - ISSN 0169-0116 - p. 12 - 13.
    aardappelen - rooien - verliezen bij het oogsten - tarra - kluiten - bodemstructuur - zware kleigronden - aardwormen - landbouwkundig onderzoek - flevoland - potatoes - grubbing - harvesting losses - tare - clods - soil structure - clay soils - earthworms - agricultural research - flevoland
    Veel meer tarra in aardappelen, soms zelfs gedwongen stoppen met rooien, regenwormen blijken de boosdoeners. Waar veel wormen zijn, komen kluiten. Gips helpt, aldus PPO-agv
    Meer calcium, kleinere kluit
    Rozen, K. van; Ester, A. ; Mierlo, T. van - \ 2004
    Boerderij/Akkerbouw 89 (2004)3. - ISSN 0169-0116 - p. 16 - 17.
    solanum tuberosum - aardappelen - rooien - oogsten - bodemstructuur - kluiten - versmeren - klei - aardwormen - grondverbeteraars - bodemverbeteraars - bekalking - gips - bodemchemie - kunstmeststoffen - ammoniumsulfaat - bemesting - flevoland - solanum tuberosum - potatoes - grubbing - harvesting - soil structure - clods - puddling - clay - earthworms - soil amendments - soil conditioners - liming - gypsum - soil chemistry - fertilizers - ammonium sulfate - fertilizer application - flevoland
    In de Flevopolder komen grote aantallen regenwormen voor, wat bij het aardappelrooien kan leiden tot grote kluiten en versmering. In emmerproeven met grond uit de Flevopolder werd onderzocht in hoeverre toediening van kalk- en zuurwerkende meststoffen deze structuurproblemen kan helpen voorkomen. Vooral gips en zwavelzure ammoniak blijken minder grote kluiten te geven
    Uit de bodem- en natuurprogramma's : Effecten van zware metalen op de Das. Interactie tussen versnippering en vergiftiging
    Klok, T.C. - \ 2004
    Wageningen : Alterra (Informatieblad 384/396.01) - 2
    zware metalen - dassen (zoogdieren) - aardwormen - wegen - bodemverontreiniging - fragmentatie - habitats - verontreiniging - habitatfragmentatie - ecotoxicologie - heavy metals - badgers - earthworms - roads - soil pollution - fragmentation - habitats - pollution - habitat fragmentation - ecotoxicology
    In dit infoblad wordt de invloed van bodemvervuiling door cadmium en koper op de Das besproken. Deze effecten worden gerelateerd aan de effecten van versnippering. Uit deze studie komt naar voren dat in leefgebieden met een lage kwaliteit als gevolg van vervuiling het aannemelijk is dat dassen langer moeten foerageren en grotere afstanden afleggen om in hun dagelijkse voedselbehoefte te voorzien. Dit omdat een verlies van voedingsstoffen door nierschade moet worden gecompenseerd door langer te foerageren terwijl een lagere dichtheid aan regenwormen gecompenseerd kan worden door meer gebieden te bezoeken. Hierdoor zal in een leefgebied dat wordt doorsneden door wegen de verkeerssterfte kunnen toenemen
    Multipele stress op populaties van Oligochaeta in de uiterwaarden
    Ma, W.C. - \ 2004
    natuurbescherming - bodem - verontreiniging - aardwormen - oligochaeta - natuurbeheer - natuur - uiterwaarden - ecotoxicologie - nature conservation - soil - pollution - earthworms - oligochaeta - nature management - nature - river forelands - ecotoxicology
    Over de betekenis van verontreiniging binnen de natuurlijke randvoorwaarden van populaties is nog zeer weinig bekend. Om hierin meer inzicht te krijgen is een veldonderzoek uitgevoerd aan de regenwormenfauna (Oligochaeta) in het uiterwaardgebied de Afferdensche en Deestsche Waarden langs de Waal. Een belangrijk doel van het onderzoek was het ontwikkelen van praktisch toepasbare aanknopingspunten voor het beheer van bodem en natuur in Nederland. De resultaten bieden gelegenheid om ecologische risico's van verontreiniging af te wegen tegen de ecologische effecten veroorzaakt door natuurlijke stress
    The role of earthworms in strategies against scab (Venturia inaequalis) in apple orchards - Literature study on methods for sampling, cultivation and stimulation in the field of earthworms relevant for apple leaf decomposition (part of WP 6.5 in REPCO)
    Jager, A. de; Heijne, B. - \ 2004
    Randwijk : PPO Fruit (Rapport PPO 2004-40) - 25 p.
    appels - aardwormen - venturia inaequalis - boomgaarden - ziektebestrijding - apples - earthworms - venturia inaequalis - orchards - disease control
    Soil macrofauna community structure along a gradient of land use intensification in the humid forest zone of southern Cameroon.
    Madong à Birang, - \ 2004
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): W.A.M. Didden; S. Hauser. - Wageningen : S.n. - ISBN 9789085040316 - 200
    bodemfauna - bodeminvertebraten - aardwormen - formicidae - isoptera - zwerflandbouw - landgebruik - bossen - humide klimaatzones - kameroen - macrofauna - soil fauna - soil invertebrates - earthworms - formicidae - isoptera - shifting cultivation - land use - forests - humid zones - cameroon - macrofauna
    The impact of land use systems on soil macrofauna community structures is described as well as their relationships with the vegetation and soil parameters in the humid forest zone of southernCameroon. 36 Earthworm species were found. A completely different earthworm assemblage was found at high LUI while low and medium LUI blocks had species in common in the various functional groups. Earthworm surface casting decreased when fallow plots were converted to cultivated fields. This reduction depended on the type of fallow. 223 Termite species were recorded.There was no significant effect of LUI but in contrast, a strong effect of LUS on termite species richness and abundance. 80 Ant species were found. LUI and LUS had striking effects on ant communities with highest richness in the low LUI block. Ant species assemblages were location specific.Soil macrofaunal species richness was more responsive to soil and vegetation parameters than macrofaunal abundances.The knowledge gathered on the present state of earthworm, termite and ant communities and the effects of land use change on these macrofauna in southernCameroonconstitutes the baseline information necessary for the design and /or implementation of measures of conservation in which farmers should play a pivotal role.
    Toxiciteitonderzoek van regenwormen 2003 : toxiciteit van biologische en chemische producten op de regenworm Aporrectodea caliginosa in vitro
    Rozen, K. van; Ester, A. - \ 2003
    Wageningen : Praktijkonderzoek Plant & Omgeving B.V. - 15
    aardappelen - oogsten - neerslag - oogstschade - gewasverliezen - aardwormen - schuifweerstand - smering - bodemkwaliteit - potatoes - harvesting - precipitation - crop damage - crop losses - earthworms - sliding friction - lubrication - soil quality
    In Oostelijk en Zuidelijk Flevoland komen sinds de jaren ’90 problemen voor met de oogst van aardappelen. Na veel neerslag kan in het najaar plaatselijk veel regenwormen in de vochtige aardappelruggen voorkomen. De activiteit van regenwormen resulteert in versmering van de klei, dit resulteert onder drogende weersomstandigheden in een harde, betonachtige structuur. Ondanks een luchtig wormengangenstelsel onder het oppervlak kit het oppervlak van de klei dermate, dat het rooien van deze aardappelruggen bij zowel natte als droge omstandigheden leidt tot grote hoeveelheden tarra in het geoogste product. Vanuit het HPA en SPF (bijeenkomst 7 januari 2003) is verzocht om biologische en chemische producten te testen op de toxiciteit op regenwormen. In dit rapport is het onderzoek in vitro beschreven
    Oligochaeta
    Didden, W.A.M. - \ 2003
    In: Bioindicators & Biomonitors-Principles, concepts and applications / Markert, B.A., Breure, A.M., Zechmeister, H.G., Amsterdam : Elsevier - ISBN 9780080441771 - p. 555 - 576.
    lumbricidae - aardwormen - bodemverontreiniging - biologische indicatoren - ecotoxicologie - biologische monitoring - lumbricidae - earthworms - soil pollution - biological indicators - ecotoxicology - biomonitoring
    Het voorkomen van de regenworm Allolobophora cupulifera in Nederland (oligochaeta: lumbricidae)
    Ma, W.C. ; Bodt, J.M. de - \ 2002
    Nederlandse Faunistische Mededelingen 16 (2002). - ISSN 0169-2453 - p. 57 - 62.
    oligochaeta - aardwormen - zoögeografie - land van maas en waal - alblasserwaard - uiterwaarden - bodemecologie - bodemfauna - regenworm - Gelderland - Zuid-Holland - oligochaeta - earthworms - zoogeography - land van maas en waal - alblasserwaard - river forelands
    In dit artikel worden de eerste twee Nederlandse vindplaatsen van de zeldzame regenworm A. cupulifera beschreven. Deze vochtminnende regenworm werd gevonden in het veenweidegebied van de polder Kortenbroek in de Alblasserwaard en in de uiterwaardengebied Afferdensche en Deestsche Waarden
    Reconciling scientific approaches for organic farming research
    Baars, T. - \ 2002
    Wageningen University. Promotor(en): L. 't Mannetje; N.G. Röling; A. Elgersma. - Driebergen etc. : Louis Bolk Institute [etc.] - ISBN 9789058087713 - 345
    biologische landbouw - landbouwkundig onderzoek - methodologie - experimenteel veldonderzoek - filosofie - trifolium repens - weidevlinderbloemigen - poaceae - grassen - planteninteractie - dierlijke meststoffen - plantenplagen - bodembiologie - plantenparasitaire nematoden - aardwormen - kalium - nederland - biologisch-dynamische landbouw - wetenschap - organic farming - agricultural research - methodology - field experimentation - philosophy - trifolium repens - pasture legumes - poaceae - grasses - plant interaction - animal manures - plant pests - soil biology - plant parasitic nematodes - earthworms - potassium - netherlands - biodynamic farming - science

    Part I : Reflection on research methods in organic grassland and animal production at the Louis Bolk Institute, The Netherlands

    Key words: organic agriculture, anthroposophy, methodology, research strategy, experiential science, multidisciplinary science, Goethean science

    This dissertation focuses on the research question: what is peculiar to agricultural research when its purpose is to support the conscious development of organic agriculture? What approaches, designs and methods are used for such research? Since the 1990s the Louis Bolk Institute has become one of the important actors in the field of organic research and development. The author analysed the methodological aspects of seven case studies, each following the same format: background of the project, methods used, a reflection on the methods and, to a limited extent, agronomic results. Each of these sheds light on an aspect of the Louis Bolk Institute's approach to research.

    Organic farming is experienced as a new paradigm and its research methods need to do justice to it. Three criteria were formulated for this purpose: the self regulation of farming systems, the involvement of farmers and the respect for the integrity of life. Two conceptual frameworks are used to analyse the research methods: (1) a four-quadrant matrix. Epistemological, ontological and methodological changes in the way of thinking are relevant in discussions about holism versus reductionism and positivism versus constructivism. The second framework is (2) a triangle which can show the relationship between the underlying values, the involvement of the actors and the nature of the scientific process.

    The scientific position which is defended in this dissertation can ultimately best be described as a 'radical holistic research strategy'.

    Research approaches applied in the case studies are: interdisciplinary research, experiential science and mutual learning, farmer-to-farmer learning, exploring tacit knowledge, bio-ethical evaluation, Goethean science and systemic development. In the four quadrant matrix two new additional research methods are positioned: (1) Goethean science is included as a holistic counterpart to multidisciplinary system ecology; (2) experiential science is included for comparison with mono-disciplinary experimental research. The constructivist character of both Goethean science and experiential science particularly distinguishes these methods from mainstream science.

    The meta-reflection on the research showed some important new elements of research. There was a systemic orientation in terms of a cohesive set of management measures and actions. This systemic orientation also encompasses holism in terms of Goethean science. In addition there is the experiential science based on intuitive action and pattern recognition. The reflection on the methods made it clear that their acceptance was influenced by the underlying scientific philosophy.

    The entire research strategy is thus based on two different interpretations of knowledge. Experiential science focuses on the actions of the farmer and is based on the epistemology of action. In addition there is an epistemology of knowledge, where it relates to interdisciplinary research and Goethean science. There are barriers to the acceptance of these scientific methods in the current lack of suitable statistical evaluation methods, and also in the absence of accepted methods for explicitly exploring reality as constructed by people.


    Part II : Effects of manure types and white clover (Trifolium repens) cultivars on the productivity of grass-clover mixtures grown on a humid sandy soil

    Key words: organic agriculture, grass-clover, white clover cultivars, animal manure, potassium, nematodes, earthworms

    This Part describes the agronomic results of the multidisciplinary grassland study. This project concerned the effects of clover varieties and spring applications of animal manure on the yield of grass-white clover mixtures on a moist sandy soil (1993-1996). To be aware of the context of the findings in a multidisciplinary approach, attention was paid to: chemical soil fertility, damage to clover by slugs and soil borne nematodes. To increase the understanding of soil fertility, earthworm dynamics were also measured. At the end of the period the botanical composition of all plots was assessed. Factors measured besides total yield and clover yield were N, P and K yield. It was found that these 'context'- measurements were important for the overall explanation of the scientific results. Data were used for modelling several relationships between yield parameters. The overall findings of this project led to an understanding and description of the main aspects of manure with regard to grass-white clover growth on a moist sandy soil.

    It was concluded that on a moist sandy soil the amount of inorganic and organic N, the N release and the K input were the main manure factors relating to fluctuations in total yields on white clover development and on N yields in the first six years after sward establishment. The inorganic N component in manure can be used strategically to improve the growth of the herbage in spring. Maintenance of soil fertility in terms of P, K and Ca levels is an important key factor for a successful organic grass-clover sward.

    Carbon rich FYM derived from a deep litter stable and composted before application increased the earthworm population, reduced the number of nematodes and maintained the highest level of soil pH, all factors which might positively affect white clover growth in the long term. FYM applied in spring resulted in the typical extended growth season in the second part of the growing season. On a sandy soil the high concentration of K in the FYM positively affects the potential white clover growth.

    The choice of a persistent white clover cultivar is another important factor affecting herbage and N yields of an organic grass-clover sward. However, winter losses were not found to be the main cause of white clover reductions over the years. Losses in the growing season were related to slugs which reduced white clover leaf area. The literature shows that the cyanide concentration in DM herbage affects the susceptibility of white clover to pests.
    Interactions between soil organic matter dynamics and soil structure as affected by farm management
    Pulleman, M. - \ 2002
    Wageningen University. Promotor(en): J. Bouma; N. van Breemen. - S.l. : S.n. - ISBN 9789058087317 - 146
    organisch bodemmateriaal - bodemstructuur - agrarische bedrijfsvoering - biologische landbouw - aardwormen - landgebruik - mineralisatie - nederland - soil organic matter - soil structure - farm management - organic farming - earthworms - land use - mineralization - netherlands

    In the last century, agriculture has focussed primarily on attaining maximum yields of crop production with the use of large amounts of fertilizers, biocides and pesticides. Growing public awareness of the detrimental effects of modern agriculture on soil productivity, food quality and the environment, however, resulted in a demand for "sustainable land management". Soil processes play a crucial role in determining the sustainability of land management. In agricultural land, soil organic matter (SOM) content is a key indicator of soil quality and sustainability for its effects on physical, chemical and biological soil properties that regulate crop yields, nutrient emissions, leaching of agrochemicals and the susceptibility to soil erosion. More recently, the elevated atmospheric CO 2 concentration and associated global warming receive much attention. Since SOM can act as a sink for atmospheric C, concern about the "greenhouse effect" provides a second reason to adopt management practices that increase SOM levels.

    The beneficial effects of SOM are partly indirect via its influence on soil structure. SOM binds mineral particles into stable soil aggregates, which are important for aeration, water storage and rootability of the soil. In turn, stable aggregates can reduce SOM decomposition by physical protection of aggregate-occluded organic matter. To define management practices for sustainable land use and increased C sequestration, a better understanding of the interactions between SOM and soil structure, and how they are affected by management, is needed. Differences in organic matter inputs and soil disturbance in different management systems result in different processes of soil structure formation (biogenic versus physicogenic), which are reflected in different morphological characteristics. In general, however, SOM-soil structure interactions have been studied using physically fractionated soil separates, without regarding differences in structural morphology. This thesis was aimed to improve understanding of the mechanisms and consequences for SOM stabilization of biogenic aggregate formation as opposed to physicogenic aggregate formation in different management systems. Therefore, differences in soil structure morphology resulting from different aggregate formation processes were emphasized. To exclude interference of differences in soil type and texture, one soil series was selected. This soil series has developed in marine loam deposits and is located in the southwestern part of the Netherlands (Zeeland). (Chapter 1).

    Chapter 2 describes a regional survey of land-use history and current SOM content in the considered soil series. SOM contents of 45 fields were determined and information about land use in the past 63 yr was provided by the farmers. Four land use types were distinghuished: conventional-arable, conventional-grass, organic-arable and organic-grass, resulting in a range of SOM contents from 17 to 88 g kg -1. Regression analysis showed that SOM content was increased by long-term grass, and to a lesser extent, by organic farming when compared to conventional arable farming.

    For more detailed study of management effects on the interactions between SOM dynamics and soil structure, three long-term farming systems (>70 yr) were selected: a permanent pasture (PP), a conventional arable system (CA), and an organic arable system (OA). Due to the lack of soil tillage and arable cropping, the soil under permanent pasture represents optimal conditions for this particular soil type in terms of organic inputs, soil structure and biological activity. The differences in management resulted in a significant increase in (i) the impact of earthworms on soil structure, (ii) stable macroaggregation, and (iii) C and N mineralization in the order: CA < OA < PP (Chapter 3). However, as for conventional arable farming, organic arable farming had resulted in severe soil compaction, which negatively affects crop growth.

    Chapter 4 describes an incubation experiment to determine C mineralization protection in undisturbed soil aggregates from the permanent pasture and the conventional arable system. The difference in respiration between undisturbed and crushed (<250mm) aggregates was used as an estimate of macroaggregate protected C. Under permanent pasture, C mineralization did not significantly increase due to crushing of the highly porous macroaggregates. In contrast, mineralization was considerably restricted in the macroaggregates from the conventional arable soil, which could be explained by a limited gas exchange due to the low porosity of the, dominantly physicogenic, macroaggregates. However, macroaggregates from the conventional arable soil were not very water-stable and are probably easily disrupted under field conditions, leading to rapid decomposition of the released SOM. The amount of C protected in microaggregates was estimated from the additional CO 2 evolution due to grinding (< 50mm) of crushed soil material. The results suggested that microaggregate protected C was high compared to macroaggregate protected C, especially under permanent pasture.

    To study management effects on SOM stabilization at the microaggregate scale, microaggregates were isolated from total soil samples and SOM distribution was determined using physical fractionation techniques (Chapter 5). Similar amounts of microaggregates (53-250mm) were isolated from permanent pasture and conventional and organic arable land. In all three systems, the main part of total soil organic C was present in these microaggregates. However, microaggregates under permanent pasture, especially in the top 10 cm, were more stable, contained a larger fraction of total soil C and more fine mineral particles, and had a higher C:N ratio than microaggregates in both arable soils. This indicated that microaggregates under permanent pasture more effectively protect SOM against decomposition than microaggregates in arable land. Differences in microaggregate characteristics between the two arable systems were mostly not significant. Microscopic analysis of undisturbed thin sections suggested that the high earthworm activity under permanent pasture plays an important role in the formation of stable microaggregates that are relatively enriched in C and fine mineral particles.

    To study the impact of earthworms on the relation between soil structure and SOM dynamics in the three farming systems, aggregates were separated by hand into biogenic (worm casts) and physicogenic macroaggregates, based on morphological characteristics (Chapter 6). Small differences in total organic C content and C respiration were found between different aggregate types within each farming system. Quantification of particulate organic matter (POM) and microaggregates in thin sections, however, showed that biogenic aggregates of the permanent pasture contained distinctly larger amounts of POM and microaggregates, which were enriched in organic and fine mineral material, than physicogenic aggregates. In the arable soils, POM and microaggregates were rarely observed in physicogenic aggregates and hardly more abundant in biogenic aggregates, showing that the effects of earthworms on soil microstructure are dependent on management.

    The morphological approach used in this study revealed that the formation of stable, highly SOM-enriched microaggregates can be initiated by the activities of earthworms. Current concepts of aggregate- and SOM dynamics do not account for differences in biogenic and physicogenic aggregate formation. This thesis provides strong indications that present conceptual models of aggregate formation and physical protection are incomplete. Therefore, I distinguished two different pathways of microaggregate formation: "Passive" microaggregate formation, which is the basis of current conceptual models of microaggregate formation, without interference of earthworms, and "active" microaggregate formation, that takes place in the earthworm gut and ageing casts after excretion (Chapter 7). Under permanent pasture biogenic aggregate formation by earthworms led to (i) larger amounts of microaggregates within macroaggregates, (ii) greater SOM storage in microaggregates, and (iii) stabilization of relatively little decomposed SOM. However, earthworms could not exert this active microaggregate formation effectively in arable land. The proposed extension of conceptual models of SOM-aggregate interactions needs further development, under a wider set of conditions, to further clarify the conditions and management practices that favour the beneficial effects of biogenic aggregate formation on SOM storage.

    Polycyclic aromatic hydrocarbon-polluted dredged peat sediments and earthworms: a mutual interference
    Eijsackers, H.J.P. ; Jonge, S. de; Muijs, B. ; Slijkerman, D. ; Gestel, C.A.M. van - \ 2001
    Ecotoxicology 10 (2001)1. - ISSN 0963-9292 - p. 35 - 50.
    aardwormen - polycyclische koolwaterstoffen - bodemverontreiniging - bagger - sediment - nederland - ecotoxicologie - noord-holland - bodemecologie - bodemfauna - milieu - polycyclische aromatische koolwaterstoffen - veen - earthworms - polycyclic hydrocarbons - soil pollution - dredgings - sediment - netherlands - ecotoxicology - noord-holland
    In lowland areas of the Netherlands, any peat sediments will gradually become enriched with anthropogenically derived Polycyclic Aromatic Hydrocarbons. Due to Dutch policy standards these (anaerobic) sediments are not allowed to be dredged and placed onto land. Under aerobic conditions, however, biodegradation of PAH is greatly enhanced. This degradation is further stimulated by colonisation of the sediments by earthworms. Laboratory experiments show that although earthworms do not avoid PAH-contaminated sediment, their burrowing-activity is reduced. Furthermore, these sediments have no significant ecotoxicological impacts on earthworms. Experimental introduction of earthworms into PAH-contaminated OECD-soil will result in a decrease in overall PAH content. In field surveys no significant differences in earthworm numbers between locations with fresh and old sediment could be found. It is concluded that dredging of PAH-contaminated sediment poses a very limited environmental threat, and that puttingthese sediments on land will improve PAH-biodegradation, partly through the colonisation by and activities of earthworms.
    Cadmium uptake by earthworms as related to the availability in the soil and the intestine
    Oste, L.A. ; Dolfing, J. ; Ma, W.C. ; Lexmond, T.M. - \ 2001
    Environmental Toxicology and Chemistry 20 (2001)8. - ISSN 0730-7268 - p. 1785 - 1791.
    bodemchemie - cadmium - aardwormen - zware metalen - ecotoxicologie - soil chemistry - heavy metals - cadmium - earthworms - ecotoxicology
    The free metal concentration in the soil solution is often considered a key parameter for metal uptake by and toxicity to soft-bodied soil organisms. The equilibrium partitioning theory, which assumes a relationship between the contaminant concentration in pore water and the contaminant concentration in the body tissue, can be used to describe uptake by earthworms. This theory has proved useful for organic chemicals, but its applicability is less clear for metals. In this study, the Cd concentration in soil pore water (pw) was varied by increasing the soil pH by the addition of lime (Ca(OH)2) and by adding manganese oxide (MnO2), which has a high metal binding capacity. Both lime (0.135 /w) and MnO2 (1 /w) decreased [Cd2 ]pw by a factor of 25, while Cdworm was reduced only by a factor of 1.3 in lime-treated soils and 2.5 in MnO2-treated soils. Cadmium uptake was weakly related to the free metal concentration (R2adj = 0.66). Adding pH as an explanatory variable increased R2adj to 0.89, indicating that Cd uptake from pore water is pH dependent, which might be attributed to competition of protons and Cd at the surface of the earthworm body. However, previous earthworm experiments in reconstituted groundwater showed a conspicuously smaller pH dependency of Cd uptake. The differences in metal uptake between earthworms in lime- and MnO2-treated soils are therefore more likely to reflect the predominance of pH-independent intestinal uptake of Cd. Equilibrating the soil with a solution of 0.01 M CaCl2 and 0.1 M triethanolamine (buffered at pH 7.2), simulating the conditions prevailing in the worm intestine, yielded free Cd concentrations that were closely (R2adj = 0.83) and linearly related to the Cd concentration in the earthworm tissue.
    Effect of beringite on cadmium and zinc uptake by plants and earthworms: more than a liming effect?
    Oste, L.A. ; Dolfing, J. ; Ma, W.C. ; Lexmond, T.M. - \ 2001
    Environmental Toxicology and Chemistry 20 (2001)6. - ISSN 0730-7268 - p. 1339 - 1345.
    aardwormen - bodemverontreiniging - zware metalen - cadmium - zink - ecotoxicologie - earthworms - soil pollution - heavy metals - cadmium - zinc - ecotoxicology
    Metal-contaminated soils are potentially harmful to plants, animals, and humans. Harmful effects are often related to the free-metal concentration in the soil solution. Immobilization is a potentially useful method to improve the quality of metal-contaminated soils by transforming free-metal ions into species that are less mobile and less toxic. The effect of many immobilizing products can be attributed to sorption on the surface of the material. Alkaline materials also enhance adsorption to soil particles by decreasing proton competition. Immobilization should preferably be evaluated independently of soil pH to discriminate between these processes. In this study, the immobilizing effect of beringite, an alkaline alumino silicate, was compared with that of lime. Plants (Swiss chard [Beta vulgaris L. var. cicla]) were grown on a soil contaminated with cadmium and zinc and treated with graded amounts of beringite or lime. Metal availability, as determined by a 0.01 M CaCl2 extraction, and metal uptake by plants strongly decreased in all treated soils. Beringite did not reduce metal availability more than liming when the obtained pH levels were similar. The effect of beringite can, therefore, be explained as a liming effect, at least for the duration of our experiment (10 weeks). The effect of beringite and lime on metal accumulation by earthworms (Eisenia veneta and Lumbricus rubellus) was small or not significant, although the CaCl2-extractable metal concentration in treated soils decreased by more than 90ÐWe conclude that immobilizing agents based on a liming effect can decrease metal uptake by plants, but they will hardly affect metal uptake by earthworms. Hence, these materials can reduce negative ecological effects of metal contamination on plants and herbivores, but not on earthworm predators.
    Soil structure and earthworm activity in an marine silt loam under pasture versus arable land
    Jongmans, A.G. ; Pulleman, M.M. ; Marinissen, J.C.Y. - \ 2001
    Biology and Fertility of Soils 33 (2001). - ISSN 0178-2762 - p. 279 - 285.
    bodemstructuur - organisch bodemmateriaal - aardwormen - soil structure - soil organic matter - earthworms
    Agricultural management influences soil organic matter (SOM) and earthworm activity which interact with soil structure. We aimed to describe the change in earthworm activity and related soil (micro)structure and SOM in a loamy Eutrodept as affected by permanent pasture (PP) and conventional arable (CA). Thin sections were studied and biogenic calcite spheroids, worm casts, infillings and groundmass coatings were quantified. In both soils, sedimentary stratification was absent up till 50 cm depth, and equal amounts of biogenic calcite spheroids were counted, suggesting similar earthworm activity in the past. Currently the percentage volume of optically recognizable biologically influenced groundmass was 54␒n PP and 10␒n CA. The Ah of PP had an organic matter content of 66 mg kg-1 whereas the content was 22 mg kg-1 in the Ah of the CA soil. Low earthworm activity in the CA soil has led to the formation of a physicogenetic soil structure with mainly angular blocky aggregates, fissure and angular blocky microstructures. The percentage volume of unsorted coatings counted in thin sections was 5°indicating soil structure deterioration. SOM was evenly distributed through the groundmass. In contrast, high earthworm activity in the PP soil has caused a biogenic structure consisting of granular and subangular blocky aggregates and spongy and granular microstructures with abundant channels. SOM was incorporated as fine (10-100 ?m) particulate organic matter in worm casts and infillings and intimately mixed with clay material. Such encapsulated SOM indicates the presence of microaggregates within biogenic macroaggregates, in which SOM may be physically protected against rapid decomposition.
    Ecologische risico's van bodemverontreinigingen in toemaakdek in de gemeente De Ronde Venen
    Bosveld, A.T.C. ; Klok, T.C. ; Bodt, J.M. ; Rutgers, M. - \ 2000
    Wageningen : Alterra (Alterra-rapport 151) - 92
    sorex araneus - limosa limosa - lumbricus - vuilnis - bodemverontreiniging - zware metalen - lood - polycyclische koolwaterstoffen - aromatische koolwaterstoffen - bodemfauna - milieueffect - aardwormen - vogels - zoogdieren - nederland - ecotoxicologie - bioaccumulatie - utrecht - veenweiden - sorex araneus - limosa limosa - lumbricus - refuse - soil pollution - heavy metals - lead - polycyclic hydrocarbons - aromatic hydrocarbons - soil fauna - environmental impact - earthworms - birds - mammals - netherlands - ecotoxicology - bioaccumulation - utrecht - peat grasslands
    De gemeente De Ronde Venen ligt in het gebied de Venen in het Groene Hart. De veengronden in dit gebied zijn vanaf de achttiende eeuw regelmatig opgehoogd met stadsafval om hun draagkracht en vruchtbaarheid te verbeteren. De opgebrachte laag wordt toemaakdek genoemd. In dit toemaakdek komen hoge concentraties zware metalen en PAK voor. Om de ecologische risico's van deze verontreinigingen in kaart te brengen is onderzoek gedaan naar de concentraties van de afzonderlijke verontreinigingen en de effecten die deze verontreinigingen hebben op bodemorganismen en daarvan voor hun voedsel afhankelijke vogels en zoogdieren.
    Earthworm management in tropical agroecosystems
    Lavelle, P. ; Brussaard, L. ; Hendrix, P. - \ 1999
    Wallingford : CABI Publishing - ISBN 9780851992709 - 300
    aardwormen - rupsenteelt - dierecologie - bodembiologie - bedrijfsvoering - ecologie - landbouw - tropen - agro-ecosystemen - earthworms - vermiculture - animal ecology - soil biology - management - ecology - agriculture - tropics - agroecosystems
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