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.

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    WoSIS snapshot - September 2019
    Batjes, Niels ; Carvalho Ribeiro, Eloi ; Oostrum, Ad van - \ 2019
    ISRIC
    soil - standard - bulk density - cation exchange capacity (CEC) - soil classification - coarse fragments - clay - effective cation exchange capacity (ECEC) - electrical conductivity - organic carbon - pH - sand - silt - calcium carbonate equivalent - texture - water retention - WoSIS - WoSIS snapshot
    The World Soil Information Service (WoSIS) provides quality-assessed and standardised soil profile data to support digital soil mapping and environmental applications at broad scale levels. Since the release of the first ‘WoSIS snapshot’, in July 2016, many new soil data were shared with us, registered in the ISRIC data repository, and subsequently standardised in accordance with the licences specified by the data providers. Soil profile data managed in WoSIS were contributed by a wide range of data providers, therefore special attention was paid to measures for soil data quality and the standardisation of soil property definitions, soil property values (and units of measurement), and soil analytical method descriptions. We presently consider the following soil chemical properties (organic carbon, total carbon, total carbonate equivalent, total Nitrogen, Phosphorus (extractable-P, total-P, and P-retention), soil pH, cation exchange capacity, and electrical conductivity) and physical properties (soil texture (sand, silt, and clay), bulk density, coarse fragments, and water retention), grouped according to analytical procedures (aggregates) that are operationally comparable. Further, for each profile, we provide the original soil classification (FAO, WRB, USDA, and version) and horizon designations insofar as these have been specified in the source databases. Measures for geographical accuracy (i.e. location) of the point data as well as a first approximation for the uncertainty associated with the operationally defined analytical methods are presented, for possible consideration in digital soil mapping and subsequent earth system modelling. The present snapshot, referred to as ‘WoSIS snapshot - September 2019’, comprises 196,498 geo-referenced profiles originating from 173 countries. They represent over 832 thousand soil layers (or horizons), and over 6 million records. The actual number of observations for each property varies (greatly) between profiles and with depth, this generally depending on the objectives of the initial soil sampling programmes.
    Estimation of soil water storage change from clay shrinkage using satellite radar interferometry
    Brake, Bram te - \ 2017
    Wageningen University. Promotor(en): S.E.A.T.M. van der Zee; R.F. Hanssen, co-promotor(en): M.J. van der Ploeg; G.H. de Rooij. - Wageningen : Wageningen University - ISBN 9789463431637 - 123
    soil water - water storage - satellite imagery - satellites - interferometry - shrinkage - clay - water management - water policy - bodemwater - wateropslag - satellietbeelden - satellieten - interferometrie - krimp - klei - waterbeheer - waterbeleid

    Measurements of soil water storage are hard to obtain on scales relevant for water management and policy making. Therefore, this research develops a new measurement methodology for soil water storage estimation in clay containing soils. The proposed methodology relies on the specific property of clay soils to shrink when drying and to swell when (re-)wetted, and the capabilities of a remote sensing technique called satellite based radar interferometry (InSAR) to measure centimetre to millimetre scale displacements of the soil surface. The objective of this thesis was to develop the application of InSAR for soil water storage change estimation on the field scale to regional scale. Two relations are investigated: 1) the relation between water storage change and surface elevation change as a result of swelling and shrinkage of a clayey soil; and 2) the relation between these surface elevation changes and InSAR phase observations.

    The shrinkage potential of the soil is very important for successful application of radar interferometry to measure vertical deformation as a result of swelling and shrinkage of clay. Therefore, the shrinkage potential and the water storage change-volume change relation (called the soil shrinkage characteristic, SSC) have been quantified in the laboratory for clay aggregates from the study area in the Purmer, the Netherlands. The clay content of the sampled soil ranged from 3.4 to 23.6%. The aggregates had moderate shrinkage potential over the soil moisture content range from saturation to air-dryness. Shrinkage phases were distinguished based on the portion of water content change that was compensated by volume change. Approximately 40-50% of water was released in the normal shrinkage phase, where loss of water is fully compensated by volume change. However, the residual shrinkage phase, where volume change is smaller than water content change, started at approx. 50% normalized soil moisture content (actual moisture content with respect to the moisture content at saturation).

    In case of normal shrinkage, soil water storage change can be directly derived from soil volume change. If additionally, clay shrinkage is isotropic, the soil water storage change can be derived from vertical shrinkage measurements. The range of normal and isotropic shrinkage has been assessed in a drying field soil in the study area. To do so, soil water storage change was derived from soil moisture content sensors and groundwater level, and volume change estimates were obtained from soil layer thickness change measurements by ground anchors. Unlike for the aggregates, normal shrinkage was not observed for the field soil, but rather a large degree of linear (basic) shrinkage was observed. In the upper soil layers in the field, normalized soil moisture content below 50% has been observed when drying out. Based on the aggregate SSC, this indicates the occurrence of residual and zero shrinkage in this situation, resulting in less than normal shrinkage when the total unsaturated zone is considered. The water content change-volume change relation thus depends on the scale considered. It was also found that the relation depends on drying intensity, from comparison between shrinkage in a period with prolonged drying and shrinkage in a period with alternating drying end re-wetting.

    For the field soil, volume change larger than soil water storage change was observed when assuming isotropic shrinkage. This unrealistic result made clear that the assumption of isotropic shrinkage is invalid. Therefore a correction of the shrinkage geometry factor rs, including dependence of shrinkage geometry on soil moisture content, has been proposed. This correction yielded rs-values between 1.38 and 3. Dynamics of subsidence porosity (i.e. vertical shrinkage) calculated from the aggregate SSC, and comparison with surface elevation change data from the field study also indicated rs-values smaller than 3. Values of rs below 3, indicate that vertical shrinkage (subsidence) is dominant over horizontal shrinkage (cracking).

    Satellite based radar interferometry was applied to measure vertical deformation resulting from clay shrinkage, and evaluate the potential for soil water storage change estimation on the field scale to regional scale. Phase differences between adjacent fields were observed in interferograms over the Purmer area which were hypothesised to be caused by relative motion of the surface level. The combination of a sequence of interferograms covering short time intervals and measurements of soil surface elevation changes in time from ground anchors, indeed revealed similar dynamics in both data. Relative changes between fields in winter were explained by a different effect of frost heave in a bare soil and in a soil permanently covered by grass. Noise in interferograms over agricultural fields was successfully reduced, by multilooking over entire fields. The effect of soil type and land use on phase observation was qualitatively assessed, indicating that agricultural crop fields offer the best phase estimates in winter, while grass fields are more coherent in summer. The results underline the need for careful selection of agricultural fields or areas to base InSAR analysis on.

    The differential analysis between fields was extended to time series analysis of phase, to obtain deformation estimates with respect to a stable reference, including correction for unwanted phase contributions and temporal phase unwrapping. The correction of unwanted phase contributions specifically included the soil moisture dielectric effect. This effect was considered by predicting interferometric phase based on in situ measured soil moisture contents. The soil moisture dielectric effect was shown to be much smaller than shrinkage phase in our case study. A simple model was developed to estimate vertical shrinkage, using assumption on shrinkage behaviour (normal and isotropic shrinkage) and an approximation of water storage change from precipitation and evapotranspiration data. Using this model, temporal phase unwrapping results were corrected. The corrections for soil moisture dielectric phase and the correction of phase unwrapping both improved vertical shrinkage measurements from InSAR.

    The results in this thesis make clear that vertical clay shrinkage can be estimated from InSAR. At the same time, these results show that clay shrinkage is a considerable phase contribution to interferometric phase and can therefore cause unwrapping and interpretation errors when not accounted for. To estimate vertical clay shrinkage from InSAR, a shrinkage model including assumptions of normal and isotropic shrinkage, proved useful in the phase unwrapping procedure in this case study. However, using the same assumptions to compute water storage change from these InSAR estimates, will in many cases produce inaccurate results. Therefore, in order to use InSAR for estimating soil water storage change in clay soils, the soil shrinkage characteristic, soil moisture dependency of the shrinkage geometry factor, and the effect of variable drying and wetting conditions, need to be considered.

    Pilot kleirijperij en klutenplas in de Dollardkwelders : een verkenning van de lokale natuurwaarden, dimensies van de klutenplas en verwachte korte- en lange-termijn effecten
    Elschot, K. ; Baptist, M.J. - \ 2016
    Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C101/16) - 19
    vogels - watervogels - natuurwaarde - klei - eems-dollard - birds - waterfowl - natural value - clay - eems-dollard
    Emissiearme lisianthus : proef met 9 teelten op substraat bij het Improvement Centre
    Raaphorst, M.G.M. ; Eveleens-Clark, B.A. ; Burg, R. van der; Grootscholten, M. - \ 2016
    Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1401) - 42
    bloementeelt - snijbloemen - teelt onder bescherming - kasgewassen - glastuinbouw - kasproeven - duurzame landbouw - substraten - kokosvezel - klei - floriculture - cut flowers - protected cultivation - greenhouse crops - greenhouse horticulture - greenhouse experiments - sustainable agriculture - substrates - coir - clay
    Nine crops with lisianthus have been carried out on coir in cloth gutters, five of which were also on expanded clay pellets. In addition to growing on a closed system, the use of energy and plant protection products is kept limited. The crops have shown a reasonable production, although not as high as in practice. This difference may be caused by both the frugal exposure to lighting as the unfamiliarity with growing on substrate. The crops on coir have shown a better production than the crops on expanded clay pellets.
    Geo-Engineering in Lakes: A Crisis of Confidence?
    Spears, B.M. ; Maberly, S.C. ; Pan, G. ; Mackay, E. ; Lurling, M.F.L.L.W. - \ 2014
    Environmental Science and Technology 48 (2014)17. - ISSN 0013-936X - p. 9977 - 9979.
    phosphorus - sediment - clay
    The effective management of lakes suffering from eutrophication is confounded by a mosaic of interactions and feedbacks that are difficult to manipulate. For example, in lake processes can delay the relinquishment of legacy phosphorus (P) manifested within bed sediments for decades, even after effective catchment management. This recovery time is often deemed unacceptable and researchers have explored many in-lake management measures designed to “speed-up” recovery. The manipulation of biogeochemical processes (commonly targeting P) using materials to achieve a desired chemical and/or ecological response has been termed geo-engineering in lakes, and is becoming a commonly considered eutrophication management tool (Figure 1). Although this approach has been employed for many years it remains contentious largely due to variable results reported in the literature. This uncertainty risks ineffective management based on poorly designed or inappropriate applications. To address this, it is important that current levels of confidence in the approach be effectively communicated and that methods of increasing confidence are clearly demonstrated. We draw here on experiences of researchers and water managers at a global scale to demonstrate recent advances and consensus on recommendations (numbered below) for best practice. This information, although vital to underpinning successful management, has not been available in the peer reviewed literature.
    Proximal Gamma-Ray Spectroscopy to Predict Soil Properties Using Windows and Full-Spectrum Analysis Methods
    Mahmood, H.S. ; Hoogmoed, W.B. ; Henten, E.J. van - \ 2013
    Sensors 13 (2013)12. - ISSN 1424-8220 - p. 16263 - 16280.
    plant-available potassium - spectrometry - sensor - models - clay
    Fine-scale spatial information on soil properties is needed to successfully implement precision agriculture. Proximal gamma-ray spectroscopy has recently emerged as a promising tool to collect fine-scale soil information. The objective of this study was to evaluate a proximal gamma-ray spectrometer to predict several soil properties using energy-windows and full-spectrum analysis methods in two differently managed sandy loam fields: conventional and organic. In the conventional field, both methods predicted clay, pH and total nitrogen with a good accuracy (R2 = 0.56) in the top 0–15 cm soil depth, whereas in the organic field, only clay content was predicted with such accuracy. The highest prediction accuracy was found for total nitrogen (R2 = 0.75) in the conventional field in the energy-windows method. Predictions were better in the top 0–15 cm soil depths than in the 15–30 cm soil depths for individual and combined fields. This implies that gamma-ray spectroscopy can generally benefit soil characterisation for annual crops where the condition of the seedbed is important. Small differences in soil structure (conventional vs. organic) cannot be determined. As for the methodology, we conclude that the energy-windows method can establish relations between radionuclide data and soil properties as accurate as the full-spectrum analysis method.
    Quantifying mineral abundances of complex mixtures by coupling spectral deconvolution of SWIR spectra (2.1–2.4 µm) and regression tree analysis
    Mulder, V.L. ; Plötze, M. ; Bruin, S. de; Schaepman, M.E. ; Mavris, C. ; Kokaly, R.F. ; Egli, M. - \ 2013
    Geoderma 207-208 (2013). - ISSN 0016-7061 - p. 279 - 290.
    modified gaussian model - reflectance spectroscopy - tetracorder algorithm - pyroxene mixtures - usgs tetracorder - clay - evolution - olivine - mars - identification
    This paper presents a methodology for assessing mineral abundances of mixtures having more than two constituents using absorption features in the 2.1–2.4 µm wavelength region. In the first step, the absorption behaviour of mineral mixtures is parameterised by exponential Gaussian optimisation. Next, mineral abundances are predicted by regression tree analysis using these parameters as inputs. The approach is demonstrated on a range of prepared samples with known abundances of kaolinite, dioctahedral mica, smectite, calcite and quartz and on a set of field samples from Morocco. The latter contained varying quantities of other minerals, some of which did not have diagnostic absorption features in the 2.1–2.4 µm region. Cross validation showed that the prepared samples of kaolinite, dioctahedral mica, smectite and calcite were predicted with a root mean square error (RMSE) less than 9 wt.%. For the field samples, the RMSE was less than 8 wt.% for calcite, dioctahedral mica and kaolinite abundances. Smectite could not be well predicted, which was attributed to spectral variation of the cations within the dioctahedral layered smectites. Substitution of part of the quartz by chlorite at the prediction phase hardly affected the accuracy of the predicted mineral content; this suggests that the method is robust in handling the omission of minerals during the training phase. The degree of expression of absorption components was different between the field sample and the laboratory mixtures. This demonstrates that the method should be calibrated and trained on local samples. Our method allows the simultaneous quantification of more than two minerals within a complex mixture and thereby enhances the perspectives of spectral analysis for mineral abundances.
    Sorption of tetracycline on organo-montmorillonites
    Liu, N. ; Wang, M.X. ; Liu, M.M. ; Liu, F. ; Weng, L.P. ; Koopal, L.K. ; Tan, W.F. - \ 2012
    Journal of Hazardous Materials 225-226 (2012). - ISSN 0304-3894 - p. 28 - 35.
    oxytetracycline - adsorption - cations - soils - clay - pharmaceuticals - metronidazole - olaquindox - mobility - surfaces
    Tetracycline (TC) is a veterinary antibiotic that is frequently detected as pollutant in the environment. Powerful adsorbents are required for removing TC. The present paper compares the TC adsorption capacity of Na-montmorillonite (Na-mont) with six organo-montmorillonites (organo-monts). Three quaternary ammonium cations (QACs) with different alkyl-chain lengths were used as modifiers. Powder X-ray diffraction indicated that the d(001) values of organo-monts increased with increasing the QACs loading and alkyl-chain length. The CECs of the organo-monts were substantially lower than that of Na-mont and decreased with QACs chain length and increased loading. The modeling of the adsorption kinetics revealed that the processes of TC adsorption on the tested samples could be well fitted by the pseudo-second-order equation. The maximum adsorption capacities of TC on the organo-monts (1000-2000 mmol/kg) were considerably higher than that on Na-mont (769 mmol/kg). Both the Langmuir and Freundlich model could fit the adsorption isotherms. The TC adsorption to the organo-monts increase significantly with decreasing the pH below 5.5 because of the electrostatic interaction, and a high QACs loading performed better than a low loading at around pH 3.
    Controlling toxic cyanobacteria: effects of dredging and phosphorus-binding clay on cyanobacteria and microcystins
    Lürling, M.F.L.L.W. ; Faassen, E.J. - \ 2012
    Water Research 46 (2012)5. - ISSN 0043-1354 - p. 1447 - 1459.
    oppervlaktewaterkwaliteit - meren - herstelbeheer - eutrofiëring - cyanobacteriën - lanthaan - klei - vergelijkend onderzoek - aquatische ecologie - surface water quality - lakes - restoration management - eutrophication - cyanobacteria - lanthanum - clay - comparative research - aquatic ecology - rare-earth-elements - lake restoration - organic-matter - shallow lakes - sediment removal - northern poland - urban lake - blooms - water - fresh
    Sediment dredging and Phoslock(®) addition were applied individually and in combination in an enclosure experiment in a Dutch hypertrophic urban pond. These measures were applied to control eutrophication and reduce the risk of exposure to cyanobacterial toxins. Over the 58 days course of the experiment, cyanobacteria (predominantly Microcystis aeruginosa) gradually decreased until they dropped below the level of detection in the combined treated enclosures, they were reduced in dredged enclosures, but remained flourishing in controls and Phoslock(®) treated enclosures. Cyanobacteria were, however, less abundant in the enclosures (medians chlorophyll-a 30-87 µg l(-1)) than in the pond (median chlorophyll-a 162 µg l(-1)), where also a thick surface scum covered one-third of the pond for many weeks. Soluble reactive phosphorus (SRP), total phosphorus and total nitrogen concentrations were significantly lower in the combined dredged and Phoslock(®) treated enclosures than in controls. Median SRP concentrations were 24 µg P l(-1) in the combined treatment, 58 µg P l(-1) in dredged enclosures, and 90 µg P l(-1) in controls and 95 µg P l(-1) in Phoslock(®) treated enclosures. Hence, the combined treatment was most effective in decreasing SRP and TP, and in lowering cyanobacterial biomass. Microcystin (MC) concentrations were analyzed by LC-MS/MS. MC concentrations and cyanobacterial biomass were positively correlated in all treatments. Mean MC concentrations in controls (71 µg l(-1)), Phoslock(®) treated enclosures (37 µg l(-1)) and dredged enclosures (25 µg l(-1)) exceeded the provisional guideline of 20 µg l(-1), whereas mean MC concentrations were 13 µg l(-1) in the combined treated enclosures. All samples contained the MC variants dmMC-RR, MC-RR, MC-YR, dmMC-LR and MC-LR; traces of MC-LY and nodularin were detected in few samples. The different treatments did not change the relative contribution of the variants to the MC pool; MC profiles in all treatments and the pond showed dominance of MC-RR followed by MC-LR. In the surface scum of the pond, total MC concentration was extremely high (64000 µg l(-1) or 1300 µg g(-1) DW), which poses a serious health hazard to children playing on the banks of the pond. Based on our results and pond characteristics, we propose combined sediment dredging and Phoslock(®) addition, fish removal and strong reduction of duck feeding by the neighborhood as most promising measures controlling cyanobacterial hazards in this pond.
    Akkerbouw in de kleiregio’s
    Ham, A. van den - \ 2012
    LMM e-nieuws 2012 (2012)april.
    akkerbouw - bodemtypen (naar textuur) - klei - bedrijfsresultaten in de landbouw - bedrijfsgrootte in de landbouw - agrarische bedrijfsvoering - arable farming - soil types (textural) - clay - farm results - farm size - farm management
    In dit artikel worden de structuurkenmerken en de gevolgen voor het bodemoverschot van akkerbouwbedrijven in de diverse kleiregio’s beschreven. De kleiregio wordt ingedeeld in vier subregio's. Dat zijn het Noordelijk kleigebied, het Centraal kleigebied, het Zuidwestelijk kleigebied en het Rivierkleigebied. In de drie eerstgenoemde subregio's is een aanzienlijk aandeel akkerbouw aanwezig, voor het rivierkleigebied zijn in het Bedrijven-Informatienet van het LEI te weinig bedrijven beschikbaar. Op basis van de gegevens van de landbouwtelling t/m 2008 is duidelijk dat er verschillen zijn in de structuur van de akkerbouwbedrijven tussen deze drie kleigebieden.
    Crop traits relevant for selecting potato genotypes adapted to low nitrogen availability
    Tiemens-Hulscher, M. ; Lammerts Van Bueren, E. ; Struik, P.C. - \ 2012
    akkerbouw - aardappelen - solanum tuberosum - biologische landbouw - biologische plantenveredeling - rassenproeven - stikstofmeststoffen - dosering - zandgronden - klei - gewasopbrengst - arable farming - potatoes - solanum tuberosum - organic farming - organic plant breeding - variety trials - nitrogen fertilizers - dosage - sandy soils - clay - crop yield
    Organic and conventional growers require potato varieties that give reliable and stable yields under low nitrogen input conditions. However, breeders lack suitable selection criteria to select for such varieties. In this research we analysed genetic variation of relevant crop characteristics and physiological processes associated with nitrogen efficiency under low nitrogen input. The aim is to identify crop traits that reflect variation in the ability to deal with low availability of nitrogen and to transform these traits into practical selection criteria. In 2008 and 2009 field trials were conducted on an organic site (sandy soil) and on a conventionally managed site (clay soil). In 2010 and 2011, both trial fields were on an organic farm (a sandy soil and a clay soil).
    Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: An experimental and mechanistic modeling study
    Regelink, I.C. ; Temminghoff, E.J.M. - \ 2011
    Environmental Pollution 159 (2011)3. - ISSN 0269-7491 - p. 716 - 721.
    dissolution kinetics - nickel sorption - soil - zn - pyrophyllite - interface - clay - stability - minerals - gibbsite
    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At pH =7.2 both adsorption and Ni-Al LDH precipitation occurred. In batch experiments with the sandy soil up to 70% of oxalate-extractable Al was taken up in LDH formation during 56 days. In a long term column experiment 99% of influent Ni was retained at pH 7.5 due to Ni adsorption (˜34%) and Ni-Al LDH precipitation (˜66%) based on mechanistic reactive transport modeling. The subsequent leaching at pH 6.5 could be largely attributed to desorption. Our results show that even in sandy aquifers with relatively low Al content, Ni-Al LDH precipitation is a promising mechanism to immobilize Ni. © 2010 Elsevier Ltd. All rights reserved.
    Natural handicaps in Dutch agricultural areas : assessment of less favoured areas based on economic criteria
    Vellinga, Th.V. ; Reeuwijk, P. van; Haan, M.H.A. de; Evers, A.G. ; Wolf, P.L. de; Smit, A. ; Brouwer, F. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 443)
    zandgronden - winderosie - klei - grondbewerking - gewasopbrengst - inventarisaties - economische aspecten - sandy soils - wind erosion - clay - tillage - crop yield - inventories - economic aspects
    Smit en Brouwer (2009) hebben bodems met een landbouwkundige handicap geselecteerd aan de hand van biofysische criteria. De relevante biofysische criteria waren gerelateerd aan bodemeigenschappen: drainage, textuur, aanwezigheid van stenen en chemische eigenschappen. Textuur en aanwezigheid van stenen zijn onderverdeeld in verschillende klassen: grof materiaal, grof en middelgrof zand, zware klei, veengronden, zwel en krimpverschijnselen en het opkomen van stenen uit de ondergrond. Verzilting is de enige chemische eigenschap die relevant is voor Nederland. Naast een selectie van gebieden op grond van biofysische eigenschappen, moet ook een verfijnde selectie worden uitgevoerd. Deze verfijnde selectie is gebaseerd op de verschillen in saldo per hectare tussen gebieden met en zonder de landbouwkundige gevolgen van de biofysische eigenschappen. De belangrijkste landbouwkundige gevolgen voor de verschillende categorieën waren de gevoeligheid voor winderosie bij grof en middelgrof zand; de beperkingen van de bewerkbaarheid van de grond en de beperkingen in het bouwplan op de zware kleigronden en lagere netto productie en de onmogelijkheid om maïs te verbouwen op veengronden
    Infoblad beheer en herstel van Kievitsbloemlanden : Rivierenlandschap 2010
    Corporaal, A. - \ 2010
    S.n.
    fritillaria - vegetatie - natuurbescherming - vegetatiebeheer - bodem - klei - ecologisch herstel - fritillaria - vegetation - nature conservation - vegetation management - soil - clay - ecological restoration
    Informatieblad over beheer en herstel van Kievitsbloemlanden. Voor het beheer van kievitsbloemlanden moet naar het hele systeem worden gekeken.
    Fate of airborne metal pollution in soils as related to agricultural management: 2. Assessing the role of biological activity in micro-scale Zn and Pb distributions in A, B and C horizons
    Fernandez, C. ; Labanowski, J. ; Jongmans, T. ; Bermond, A. ; Cambier, P. ; Lamy, I. ; Oort, F. van - \ 2010
    European Journal of Soil Science 61 (2010)4. - ISSN 1351-0754 - p. 514 - 524.
    organic-matter - earthworm activity - heavy-metals - fractionation - bioavailability - extraction - turnover - tillage - casts - clay
    This work assesses relationships between characteristic aggregate microstructures related to biological activity in soils under different long-term land use and the distribution and extractability of metal pollutants. We selected two neighbouring soils contaminated with comparable metal loads by past atmospheric deposition. Currently, these soils contain similar stocks, but different distributions of zinc (Zn) and lead (Pb) concentrations with depth. One century of continuous land use as permanent pasture (PP) and conventional arable (CA) land, has led to the development of two soils with different macro- and micro-morphological characteristics. We studied distributions of organic matter, characteristic micro-structures and earthworm-worked soil by optical microscopy in thin sections from A, B and C horizons. Concentrations and amounts of total and EDTA-extractable Zn and Pb were determined on bulk samples from soil horizons and on size-fractions obtained by physical fractionation in water. Large amounts of Zn and Pb were found in 2–20-µm fractions, ascribed to stable organo-mineral micro-aggregates influenced by root and microbial activity, present in both soils. Unimodal distribution patterns of Zn, Pb and organic C in size-fractions were found in horizons of the CA soil. In contrast, bimodal patterns were observed in the PP soil, because large amounts of Zn and Pb were also demonstrated in stable larger micro-aggregates (50–100-µm fractions). Such differing distribution patterns characterized all those horizons markedly influenced by earthworm activity. Larger earthworm activity coincided with larger metal EDTA-extractability, particularly of Pb. Hence, land use-related biological activity leads to specific soil microstructures affecting metal distribution and extractability, both in surface and subsurface horizons
    Effects of lanthanum and lanthanum-modified clay on growth, survival and reproduction of Daphnia magna
    Lürling, M.F.L.L.W. ; Tolman, Y. - \ 2010
    Water Research 44 (2010)1. - ISSN 0043-1354 - p. 309 - 319.
    waterkwaliteit - meren - klei - eutrofiëring - daphnia magna - lanthaan - zeldzame aardelementen - fosfor - aquatische ecologie - waterzuivering - water quality - lakes - clay - eutrophication - daphnia magna - lanthanum - rare earth elements - phosphorus - aquatic ecology - water treatment - phosphorus binding clay - rare-earth-elements - microcystis-aeruginosa - cyanobacterial toxins - suspended clay - waters - blooms - phosphate
    The novel lanthanum-modified clay water treatment technology (Phoslock) seems very promising in remediation of eutrophied waters. Phoslock is highly efficient in stripping dissolved phosphorous from the water column and in intercepting phosphorous released from the sediments. The active phosphorous-sorbent in Phoslock is the Rare Earth Element lanthanum. The purpose of this study was: 1) to establish a dose response relationship between Phoslock and the growth of Daphnia magna, 2) to determine the amount of lanthanum released from Phoslock, and 3) to test the effects of lanthanum on life-history characteristics of D. magna in artificial P-free and P-containing medium.
    The novel lanthanum-modified clay water treatment technology (Phoslock (R)) seems very promising in remediation of eutrophied waters. Phoslock (R) is highly efficient in stripping dissolved phosphorous from the water column and in intercepting phosphorous released from the sediments. The active phosphorous-sorbent in Phoslock (R) is the Rare Earth Element lanthanum. A leachate experiment revealed that lanthanum could be released from the clay, but only in minute quantities of 0.13-2.13 mu g l(-1) for a worst-case Phoslock (R) dosage of 250 mg l(-1). A life-history experiment with the zooplankton grazer Daphnia magna revealed that lanthanum, up to the 1000 mu g l(-1) tested, had no toxic effect on the animals, but only in medium without phosphorous. In the presence of phosphorous, rhabdophane (LaPO4 center dot nH(2)O) formation resulted in significant precipitation of the food algae and consequently affected life-history traits. With increasing amounts of lanthanum, in the presence of phosphate, animals remained smaller, matured later, and reproduced less, resulting in lower population growth rates. Growth rates were not affected at 33 mu g La l(-1), but were 6% and 7% lower at 100 and 330 mu g l(-1), respectively, and 20% lower at 1000 mu g l(-1). A juvenile growth assay with Phoslock (R) tested in the range 0-5000 mg l(-1), yielded EC50 (NOEC) values of 871 (100) and 1557 (500) mg Phoslock (R) l(-1) for weight and length based growth rates, respectively. The results of this study show that no major detrimental effects on Daphnia are to be expected from Phoslock (R) or its active ingredient lanthanum when applied in eutrophication control. (C) 2009 Elsevier Ltd. All rights reserved.
    Humus- en vegetatiereeksen als hulpmiddel voor natuurbeheer : enkele voorbeelden op basis van de SBB-referentiepunten
    Waal, R.W. de; Hommel, P.W.F.M. - \ 2010
    Wageningen : Alterra (Alterra-rapport 2049) - 53
    bodemchemie - humushorizonten - vegetatietypen - indicatoren - duingebieden - veengebieden - hoogveengebieden - klei - bodem-plant relaties - beekdalen - natuurgebieden - soil chemistry - humus horizons - vegetation types - indicators - duneland - peatlands - moorlands - clay - soil plant relationships - brook valleys - natural areas
    In dit rapport zijn voor enkele belangrijke fysiotopen (standplaatstypen) de humusgegevens aan de vegetatiegegevens gekoppeld in de vorm van enkele karakteristieke vegetatie-humusreeksen. Het betreft hier fysiotopen in duinvalleien, laagvenen, beekdalen, zeekleigebieden en hoogvenen. De gegevens zijn afkomstig van het Staatsbosbeheer-project Terreincondities, het z.g. referentieproject. Door vegetatie- en humusgegevens van natuurterreinen, aangevuld met enkele eenvoudig veldkenmerken van de standplaats, naast de reeks te leggen wordt het mogelijk om meer inzicht te krijgen in de toekomstige ontwikkelingen van de vegetatie. Door dit inzicht kan een effectiever beheer in deze natuurterreinen gevoerd worden.
    Winning van zand en klei: iedereen blij? : evaluatie Kwaliteitsteam en kwaliteitsadviezen ontgrondingen provincie Gelderland
    Pleijte, M. ; Kersten, P.H. ; Dirksen, J. - \ 2009
    Wageningen : Alterra (Alterra-rapport 1914) - 76
    zandafgravingen - mijnbouw - afgegraven land - klei - regionaal beleid - kwaliteit - ruimtelijke ordening - nederland - gebiedsontwikkeling - ruimtelijke analyse - gelderland - sand pits - mining - mined land - clay - regional policy - quality - physical planning - netherlands - area development - spatial analysis - gelderland
    In het Zand- en kleiwinningsplan Gelderland kondigt de provincie de instelling van een Provinciaal Kwaliteitsteam Ontgrondingen aan, dat werkende weg een eigen methodiek zal ontwikkelen. Inmiddels bestaat dit kwaliteitsteam 3 jaar en heeft 16 adviezen uitgebracht. In dit rapport staat een evaluatie van de kwaliteit van de werkwijze en van de adviezen van het Provinciaal Kwaliteitsteam Ontgrondingen centraal. Geconcludeerd wordt dat de werkwijze en adviezen volstaan, maar dat zij verder kunnen worden geprofessionaliseerd. Dit rapport biedt handvatten aan de provincie om die professionalisering verder vorm te geven.
    Rapportage bemesting 2007 : deelrapport sector bloembollen : telen met toekomst
    Dam, A.M. van - \ 2008
    Wageningen : Praktijkonderzoek Plant & Omgeving B.V. - 12
    bemesting - teeltsystemen - bloembollen - bodemtypen - klei - zand - fertilizer application - cropping systems - ornamental bulbs - soil types - clay - sand
    Voor u ligt de rapportage bemesting van het praktijknetwerk Telen met toekomst voor de open teelten voor het jaar 2007. Het is het laatste jaarverslag van dit vierjarige onderzoeksproject. In 2008 wordt Telen met toekomst op een andere wijze voortgezet. Dit rapport geeft het resultaat van de analyse van de bemesting van het vierde jaar van de kernbedrijven in Telen met toekomst, waarbij de resultaten getoetst worden tegen de gebruiksnormen 2008. Tevens wordt een beoordeling gegeven van ontwikkelingen in de toepassing van de Best Practices Bemesting
    Mest in voorjaar 't proberen waard
    Slabbekoorn, J.J. ; Dekker, P.H.M. - \ 2006
    Boerderij/Akkerbouw 92 (2006)26. - ISSN 0169-0116 - p. 16 - 17.
    drijfmest - klei - stikstofmeststoffen - landbouwbeleid - landbouwkundig onderzoek - herfst - lente - slurries - clay - nitrogen fertilizers - agricultural policy - agricultural research - autumn - spring
    Uitrijden van mest op klei in het voorjaar in plaats van in het najaar is over het algemeen beter omdat klei de stikstof in het voorjaar beter vasthoudt. Het maken van de overstap van najaar naar voorjaar blijkt vaak goed te werken, ook binnen de seizoenen zijn verschuivingen te maken
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