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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Mogelijke oorzaken van een dalende opbrengst van witte klaver (Trifolium repens L.) in de tijd
Boer, H.C. de; Eekeren, N. van - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1025) - 36
trifolium repens - opbrengsten - reductie - voedingsstoffen - melkveehouderij - yields - reduction - nutrients - dairy farming
Onderzoek naar oorzaken en oplossingen van grasklaverdaling in de landbouw.
Physiology and application of sulfur-reducing microorganisms from acidic environments
Florentino, Anna Patrícya - \ 2017
University. Promotor(en): Fons Stams, co-promotor(en): Irene Sanchez Andrea; Jan Weijma. - Wageningen : Wageningen University - ISBN 9789463430975 - 264
bacteria - desulfurella - metabolism - sulfur - reduction - genome analysis - proteomes - bacteriën - metabolisme - zwavel - reductie - genoomanalyse - proteomen

Sulfur cycle is one of the main geochemical cycles on Earth. Oxidation and reduction reactions of sulfur are mostly biotic and performed by microorganisms. In anaerobic conditions – marine and some freshwater systems, dissimilatory sulfur- and sulfate-reducing bacteria and archaea are key players in the decomposition of organic carbon releasing sulfide as the product of their metabolism. Sulfide can then be used as terminal reductant by anoxygenic photosynthetic microorganisms or it can be used as electron donor for aerobic or nitrate-reducing bacteria, etc.

One particular case of the sulfur cycle is the naturally occurring oxidation of metallic sulfide-ores, which produce sulfur-rich waters with low pH and high heavy metals content. Extremophilic sulfur-reducing microorganisms are of scientific and technological interest. They are abundant in natural conditions in extreme environments, so they are environmentally relevant. Although hydrogen sulfide is corrosive and odorous, its production can be beneficial for industrial activities such as the precipitation and recovery of heavy metals. Therefore, sulfur reducers have also potential for extending the range of operating conditions of metal precipitation. This thesis describes the isolation and characterization of acidotolerant sulfur-reducing bacteria, providing a first understanding on their metabolism of sulfur compounds and insights on the beneficial microbial interactions for biotechnological purposes.

In Chapter 2, the ecology and physiology of sulfur-reducing prokaryotes is investigated. The ability of sulfur reduction is wide-spread phylogenetically over the microbial tree of life, found in more than 70 genera. Elemental sulfur reduction can occur via direct cell attachment to the solid substrate or with polysulfide as an intermediate. At least four different enzymes are described to be involved in sulfur reduction pathways, and these enzymes were also detected in several microorganisms that are potential sulfur reducers, but were not reported as such in literature so far. The ecological distribution of sulfur respiration seems to be more widespread at high temperatures with neutral pH values. However, some sulfur reducers can grow at pH as low as 1 and the strategies adopted by microorganisms to face high proton concentrations in the environment were commented in this chapter. The sulfide produced from sulfur reduction can be used to selectively precipitate metals by varying the pH values from 2 to 7, depending on the target metal. Economic calculations were presented to show that sulfur reduction is more advantageous then sulfate reduction due to the cost savings of the electron donor needed. Therefore, acidophilic sulfur reducers are of particular interest for application in selective precipitation and recovery of heavy metals from metalliferous waste streams and the suitable technologies for that purpose are also discussed.

Enrichments for sulfur reducers with various electron donors at low pH and mesophilic conditions were performed from sediments of the acidic Tinto river (Spain). A solid-media with colloidal sulfur was developed to facilitate the isolation of true elemental sulfur reducers at low pH. This strategy resulted in the isolation of a sulfur-reducing bacterium, strain TR1, belonging to the Desulfurella genus. The enrichment and isolation procedure were described in Chapter 3. The growth and activity of the isolate was tested at different pH values, temperature conditions, utilization of electron donors, and growth in the presence of heavy metals in solution. The isolate showed tolerance to metals, and growth in a broad temperature and pH, revealing its feasibility to precipitate and recover heavy metals from acidic wastewater and mining water, without the need to neutralize the water before treatment. In Chapter 4, the morphological, biochemical and physiological characterization of the isolate is provided, for which the name Desulfurella amilsii TR1 sp. nov. was proposed. D. amilsii is affiliated to the Deltaproteobacteria class showing 97% of 16S rRNA gene identity to the four species described in the Desulfurella genus. In the presence of elemental sulfur, D. amilsii utilized acetate, formate, lactate, pyruvate, stearate, arginine and H2/CO2 as substrates, completely oxidizing them to H2S and CO2. Besides elemental sulfur, thiosulfate was used as an electron acceptor and the isolate also grew in the absence of external electron donor, by disproportionation of elemental sulfur into sulfide and sulfate.

The draft genome sequence of Desulfurella amilsii TR1 and a comparative genomic analysis with the members of Desulfurellaceae family are reported in Chapter 5. Based on average nucleotide identity and in silico DNA hybridization values, D. multipotens and D. acetivorans were revealed to belong to the same species. Reclassification was therefore suggested. Regarding sulfur metabolism, the analysed genomes encode different sulfur-reducing enzymes per genus. Hippea species encode polysulfide reductase and a sulfide dehydrogenase. The analysed genomes of Desulfurella especies do not possess the polysulfide reductase but possess the sulfide dehydrogenase. D. amilsii is the only member of the family encoding sulfur reductase. Since D. amilsii is able to grow at the lowest pH value, this enzyme was suggested to play a role in sulfur reduction when the microorganism grows in acidic conditions. Genes encoding resistance to acidic conditions were reported for all Desulfurellaceae members, countering physiological tests that showed ability to grow at low pH only for D. amilsii and D. acetivorans. Sulfur respiration by D. amilsii was studied in more detail in Chapter 6, in which the requirement for cell-sulfur interaction at acidic (pH 3.5) and circumneutral (pH 6.5) conditions was evaluated. D. amilsii was shown to benefit from contact with the insoluble substrate, as activity and number of cells decreased when sulfur was sequestered from the medium in dialysis bags of 6-8 kDa pore size. Besides, the abundance of enzymes possibly involved in sulfur respiration, acid resistance and chemolithotrophic growth were investigated by proteomics. Sulfur reductases were not detected in the dataset, but the limitations of the method might leave membrane-bound proteins underrepresented in the study. Different rhodanese-like proteins were detected in high abundance at low and neutral pH, while sulfide dehydrogenase seems to function as a ferredoxin:NADP oxidoreductase. We suggest that the sulfurtransferases might play a key role in sulfur/polysulfide reduction in D. amilsii. Proteomic data also showed that genes involved in acid resistance are constitutively expressed in this microorganism. Some proteins were exclusively detected at low pH, but with very few overlapping with proteins reported to be involved in acid resistance. Moreover, analysis of the proteome revealed the involvement of the hydrogenase HydABC for oxidation of hydrogen during chemolitotrophic growth, as well as the complete pathway for CO2 fixation via the reductive TCA cycle.

More aspects of the sulfur metabolism by D. amilsii were investigated in Chapter 7. Cultures grown on acetate with sulfur or thiosulfate as electron acceptor and cultures grown by disproportionation of elemental sulfur, all at pH 6.5, had their proteomes compared. Rhodanese-like sulfurtransferases were abundant in all the analyzed conditions, with specific differences in the sequences. In sulfur respiration and disproportionation, sulfurtransferases were the only sulfur enzymes detected and so, they are likely to play a central role in the process. The respiration of thiosulfate is likely to happen via a thiosulfate reductase and a dissimilatory sulfite reductase, highly abundant in this specific condition. Analysis on the heterotrophic cultures revealed the ability of D. amilsii to activate acetate to acetyl-CoA via the acetyl-CoA synthetase enzyme and its oxidation via the TCA cycle being this the first report of acetate activation happening via acetyl-CoA synthetase in sulfur-reducing bacteria.

The isolation and characterization of another acidotolerant sulfur respirer, Lucifera butyrica strain ALE, and its growth in co-culture with D. amilsii were described in Chapter 8. L. butyrica was shown to use a wide range of substrate, such as glucose, lactose, ethanol, glycerol glycogen, peptone, etc. When growing on glycerol, a cheap substrate, by fermentation or by respiration of elemental sulfur, L. butyrica produced acetate, ethanol and 1,3-propanediol as major products. Elemental sulfur reduction by this bacterium, however, was not efficient and led to the production of maximum 2.5 mM of sulfide. When L. butyrica grew in a co-culture with D. amilsii, the acetate produced by the first was consumed by the latter and the production of sulfide was boosted in the culture. As D. amilsii is not able to degrade glycerol, the co-culture represents a strategy to broaden the applicability of sulfur reduction at low pH with different sources of electron donors.

Maatregelen ter reductie van ammoniakemissie in bestaande varkensstallen
Vermeij, I. ; Ellen, H. ; Bokma, S. - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1010) - 21
varkenshouderij - huisvesting, dieren - ammoniakemissie - reductie - wetgeving - nederland - pig farming - animal housing - ammonia emission - reduction - legislation - netherlands
The ambition of Global Gap Add-on to reduce ammonia emission exceed the legal standards. Scrubber systems comply with the standards, but are not preferable. Alternatives to reduce ammonia emission on existing farms has been mapped out. A combination of measurements from Rav and PAS lead to different options. The reduction of protein in animal feed in addition to a housing measurement has a positive prospect. Internal deduction on farm level leads to different options. The measurements will lead to more exploitation costs on the pig farm.
Public health impact of salt reduction
Hendriksen, M.A.H. - \ 2015
University. Promotor(en): Hendriek Boshuizen, co-promotor(en): Joop van Raaij; Marianne Geleijnse. - Wageningen - ISBN 9789462575462 - 223
zout - jodiumhoudend zout - opname (intake) - reductie - gezondheid - voeding en gezondheid - modelleren - hart- en vaatziekten - hypertensie - europa - salt - iodized salt - intake - reduction - health - nutrition and health - modeling - cardiovascular diseases - hypertension - europe

The health and economic burden related to cardiovascular diseases is substantial and prevention of these diseases remains a challenge. There is convincing evidence that high salt intake affects blood pressure and the risk of cardiovascular diseases. As salt intake is far above the recommended maximum level of intake, salt reduction may help to reduce cardiovascular disease incidence. However, the effect of salt reduction initiatives on intake levels and long-term health is largely unknown. The main aim of the research described in this thesis is to assess salt intake and the potential health impact of salt reduction in the Netherlands and in Europe. This is addressed by estimating the potential effect of salt reduction strategies on salt intake, by monitoring the effect of the ongoing salt reduction initiatives in the Netherlands between 2006 and 2010 on daily salt intake and by projecting the expected long-term health benefits of salt reduction in the Netherlands and Europe.

Firstly, we used data from the Dutch National Food Consumption Survey 2007-2010 and the Dutch Food Composition Database 2010 to study the effect of two potential salt reduction scenarios on salt intake from processed foods. In the first scenario, sodium levels in processed foods were reduced towards their minimum feasible sodium level. In the second scenario, foods were substituted by a low-salt alternative within the same food category. This study demonstrated that daily salt intake from foods could be reduced below the recommended maximum intake of 6 g/d, provided these strategies are successfully implemented.

Secondly, the effect of the ongoing salt reduction initiatives in the Netherlands between 2006 and 2010 was evaluated. Dutch adults in two cross-sectional studies (n=317 in 2006 and n=342 in 2010) collected a single 24h urine sample. Despite the initiatives of the food industry to reduce sodium levels in processed foods, no statistically significant difference in daily salt intake was observed between 2006 (8.7 g/d) and 2010 (8.5 g/d).

Thirdly, the long-term health impact of salt reduction was assessed for the Netherlands using the RIVM Chronic Disease Model and for Europe using the Dynamic Model for Health Impact Assessment (DYNAMO-HIA). A two-step approach was used: the effect of salt reduction on blood pressure was estimated, which was subsequently translated into occurrence of cardiovascular diseases. Substantial changes in incident stroke (6.0%) and acute myocardial infarction (4.4%) can be expected in the Netherlands if sodium contents in processed foods were reduced to the minimum feasible level. The potential health impact of population-wide adherence to the salt intake guideline of the World Health Organization (maximum of 5 g/d) ranged for nine European countries between 10.1% in Finland to 23.1% in Poland for stroke, and between 6.6% in Finland to 15.5% in Poland for ischemic heart diseases.

Finally, a methodological comparison of seven population health models on salt reduction revealed that these models vary in underlying assumptions. We demonstrated that these differences in assumptions may substantially affect the health impact estimates.

In conclusion, technologically feasible salt reductions in processed foods or changes in dietary behaviour may, if implemented successfully, lead to a substantial lowering of daily salt intake, and thereby contribute to considerable health gain. Cross-country comparisons of health impact of salt reduction strategies might benefit from more transparency on the necessary assumptions in the various population health impact models for salt reduction used worldwide.

Anaerobic oxidation of methane : evaluation of alternative conditions
Suarez Zuluaga, D.A. - \ 2015
University. Promotor(en): Cees Buisman, co-promotor(en): Jan Weijma. - Wageningen : Wageningen University - ISBN 9789462574823 - 131
microorganisms - methane - oxidation - sulfates - reduction - bioreactors - micro-organismen - methaan - oxidatie - sulfaten - reductie - bioreactoren

Microorganisms capable of performing anaerobic oxidation of methane (AOM) coupled to sulphate reduction have high doubling times which make their enrichment difficult. However, due to higher energy gain, they might be rapidly enriched using alternative electron acceptors. In chapter 2, it was shown that up to 50 times higher conversion rates were obtained with thiosulphate when compared to sulphate. However, it was also presented that thiosulphate was not be exclusively used by microorganisms that reduce it, but that it was also disproportionated into sulphate and sulphide (Chapter 2).

In Chapter 3, a 5 litre membrane bioreactor was fed not only with methane and sulphate but also with acetate and thiosulphate. As previous experiments using these additional substrates had allowed to obtain either faster conversion rates or enrichment of methanotrophic microorganisms; it was expected that AOM rates in the reactor would increase relatively fast. However, the microorganisms that were enriched were not AOM related. They microbial community that showed the highest activity rates in the reactor was comprised by thiosulphate disproportionated bacteria and green sulphur bacteria. The former disproportionated thiosulphate into sulphate and sulphide while the latter converted the sulphide into elemental sulphur.

Chapter 4, unlike the previous chapters, focused on studying the occurrence of AOM in a fresh water ecosystem. Such system was located next to a natural gas source which captured methane for domestic purposes. It was presented how, with the different electron acceptors added, AOM and trace methane oxidation occurred. However, net AOM was only measured in the presence of sulphate as electron acceptor. Furthermore, the microorganisms that were enriched in the presence of methane and sulphate were also detected.

There are several hypotheses which attempted to explain the AOM coupled to sulphate reduction. One of them indicates that it is a process that involves two microorganisms working in a syntrophic relationship. The first microorganism would convert the methane into carbon dioxide and pass the electrons to the second one. Consequently, the second microorganism would convert the sulphate into hydrogen sulphide. In such a structure, the way that electrons are released by the conversion performed by the first microorganism is unknown. It is possible, that electrons are not transfer via electron shuttles or chemical compounds, but that they are transferred directly from one microorganism to the other. A methodology which could be used to determine if the AOM consortia uses direct electron transfer mechanisms was evaluated in Chapter 5. Different kinds of granular biomass were used for this evaluation and, the granule types that would potentially be capable of using direct electron transfer mechanisms were detected.

Minder gasvormige emissies op melkveebedrijf : praktijkervaringen met voer- en diermanagement als sturing voor methaan en ammoniak
Sebek, L.B. ; Goselink, R.M.A. ; Evers, A.G. ; Vrolijk, M. ; Haan, M.H.A. de - \ 2015
Wageningen : Wageningen UR Livestock Research (Rapport / Koeien & Kansen nr. 75) - 32
broeikasgassen - melkveehouderij - ammoniakemissie - emissie - reductie - methaan - greenhouse gases - dairy farming - ammonia emission - emission - reduction - methane
Dit rapport beschrijft wat het voor de melkveehouder betekent om reductiemaatregelen voor methaan in de bedrijfsvoering te implementeren. Het gaat om de beleving en de praktijkervaring van de 16 Koeien & Kansen deelnemers en hun bedrijfsadviseurs. De effectiviteit van de toegepaste maatregelen is in een ander Koeien & Kansen rapport beschreven (Goselink, 2015). De beschreven maatregelen zijn gericht op de reductie van de on farm emissie van het broeikasgas methaan in wisselwerking met de maatregelen om de emissie van ammoniak te verminderen. De bruikbaarheid voor de brede praktijk van de in Koeien & Kansen toegepaste reductiemaatregelen is onderzocht. Aangevuld met een omgevingsanalyse geeft dat een beeld van wat de Nederlandse melkveehouder nodig heeft om actief aan de slag te gaan met de reductie van de gasvormige emissies methaan en ammoniak.
Kruiden verdringen antibiotica
Wolkers, H. ; Groot, M.J. ; Kleerebezem, M. ; Rebel, J.M.J. - \ 2015
WageningenWorld (2015)2. - ISSN 2210-7908 - p. 34 - 39.
veehouderij - diergezondheid - geneeskrachtige kruiden - dierziektepreventie - natuurlijke producten - antibiotica - reductie - dierenwelzijn - varkens - pluimvee - rundvee - melkvee - diervoeding - dierlijke productie - livestock farming - animal health - herbal drugs - animal disease prevention - natural products - antibiotics - reduction - animal welfare - pigs - poultry - cattle - dairy cattle - animal nutrition - animal production
Vanwege beperking van het antibioticagebruik vallen veehouders steeds vaker terug op kruiden, bacteriedrankjes en andere natuurlijke middelen om dieren gezond te maken én te houden. Hoewel harde medische claims niet altijd voorhanden zijn, boeken boeren soms spectaculaire resultaten met natuurlijke preparaten.
Geen extra chips na zoutarm eten
Janssen, A.M. - \ 2015
WageningenWorld (2015)2. - ISSN 2210-7908 - p. 6 - 6.
voedingsmiddelen - zoutgehalte - smaak - voedingsonderzoek bij de mens - reductie - gezondheidsgevaren - gezondheidsbevordering - behoeftenbevrediging - foods - salinity - taste - human nutrition research - reduction - health hazards - health promotion - need gratification
Minder zout in etenswaren zorgt ervoor dat mensen daadwerkelijk minder zout eten; ze zoeken geen zoutcompensatie op andere momenten van de dag.
Aromameter onthult smaakverlies groente en fruit
Woltering, E.J. - \ 2015
WageningenWorld (2015)2. - ISSN 2210-7908 - p. 5 - 5.
groenten - fruit - smaak - bemonsteren - meting - apparatuur - innovaties - houdbaarheid (kwaliteit) - reductie - aroma - verandering - vegetables - taste - sampling - measurement - apparatus - innovations - keeping quality - reduction - change
Een tomaat in de koelkast verliest al snel onomkeerbaar zijn smaak. Dat blijkt uit metingen met een nieuw apparaat, ontwikkeld door Wageningen UR. Dat kan snel en nauwkeurig veranderingen in het aroma vaststellen.
Tomaten belichten met minder elektriciteit
Dieleman, J.A. ; Janse, J. ; Gelder, A. de; Kempkes, F.L.K. ; Visser, P.H.B. de; Lagas, P. ; Meinen, E. ; Warmenhoven, M.G. ; Elings, A. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1338) - 76
glastuinbouw - cultuurmethoden - tomaten - solanum lycopersicum - belichting - led lampen - energiegebruik - efficiëntie - elektriciteit - reductie - gewasproductie - greenhouse horticulture - cultural methods - tomatoes - illumination - led lamps - energy consumption - efficiency - electricity - reduction - crop production
Over the last 10 years, the use of electricity for assimilation lighting has increased considerably. It is now an important part of the energy use of the horticultural sector. To reverse this trend, in the lighting season 2013/2014, we conducted a trial with the aim to reduce the electricity use in a lighted tomato crop by 35% while maintaining production levels. Two treatments were applied: (1) Reference cultivation: clear glass and lighting by 50% HPS lamps and 50% LED intermittent lighting (210 µmol/m2/s), (2) energy efficient cultivation: diffuse greenhouse cover and lighting by 50% LED top lighting and 50% intermittent LED lighting (210 µmol/m2/s). In the energy efficient cultivation, 37% less electricity was used in the period October - May. However, energy use for heating in this treatment was higher to compensate for the lack of radiative heat. The light sum the plants received (sunlight + artificial lighting) was 6% lower in the energy efficient cultivation compared to the reference cultivation due to the lower number of lighting hours. However, the production difference was only 0.3 kg/m2, less than 1%! Detailed plant measurements showed hardly any differences between the treatments in light interception, light absorption by the leaves, photosynthesis and the production and distribution of assimilates. The analysis of the crop growth model showed that the effect of the lower number of lighting hours in the energy efficient cultivation was fully compensated by the positive effects of the diffuse greenhouse cover which has a higher light transmission.
Ziektebeheersing substraatloze teeltsystemen : naar een robuust systeem tegen ziekten en plagen
Stijger, C.C.M.M. ; Janse, J. ; Vermeulen, T. ; Weel, P.A. van - \ 2014
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1335) - 45
bladgroenten - slasoorten - teeltsystemen - hydrocultuur - vloeibare kunstmeststoffen - ziektebestrijding - nutrientenbeheer - risicofactoren - monitoring - reductie - plagenbestrijding - leafy vegetables - lettuces - cropping systems - hydroponics - liquid fertilizers - disease control - nutrient management - risk factors - reduction - pest control
De belangrijkste kennislacune rond substraatloze teeltsystemen is het beheersen van de kwaliteit van het voedingswater. Hoge kwaliteit vergt, naast een goede balans van nutriënten, vooral het voorkomen van ziekte- en plaagontwikkeling. Het voorkomen of beheersen van de verspreiding speelt daarbij een grote rol. De bedrijfszekerheid van nieuwe teeltsystemen staat of valt bij de beheersbaarheid van ziekten en plagen. De ziekte- en plaagbeheersing in substraatloze systemen volgen andere principes dan de reguliere (steenwol of grondgebonden) teelt. De gebruikte watervolumes zijn enorm, fysieke barrières ontbreken maar ook een buffer/balans ontbreekt waarmee een direct effect is te benoemen op het risico op ziekte( en plaagverspreiding. De ziekte- en plaagrisico’s bepalen het gebruik van (chemische) gewasbeschermingsmiddelen, spui, maar bovenal het succes van een substraatloze teelt. Het verlagen van het risico op ziekten en plagen en het voorkomen, monitoren en vertragen van een snelle verspreiding daarvan is onderwerp van dit project. Het onderzoek waarin in dit verslag wordt gerapporteerd heeft zich gericht op de kennisvragen rond ziektebeheersing en de ontwikkeling van indicatoren en teeltstrategieën ter voorkoming van ziekten in een robuust substraatloos (water) systeem. Behalve dat een chemische aanpak vanwege het gebruik van grote volumes water in deze nieuwe teeltsystemen vaak geen economisch haalbare oplossing is, is een chemische aanpak voor ziekte- en plaagproblematiek bovendien geen toekomstgerichte oplossing. Daarom heeft het onderzoek zich gericht, naast het voorkomen van aantastingen, vooral op mogelijke natuurlijke en fysische bestrijdingsmaatregelen. In het onderzoek dat heeft gelopen van juni 2013 tot en met mei 2014 zijn in totaal vier achtereenvolgende slateelten uitgevoerd.
Enkeldops validatiemetingen driftreducerende spuitdoppen en rijsnelheid : veldmetingen 2011-2012
Stallinga, H. ; Zande, J.C. van de; Michielsen, J.G.P. ; Velde, P. van - \ 2014
Wageningen : Plant Research International, Business Unit Agrosysteemkunde (Rapport / Plant Research International 600) - 152
akkerbouw - spuitdoppen - drift - snelheid - verstuiven (insectenbestrijding) - spuiten - spuitapparaten - meting - modellen - reductie - arable farming - fan nozzles - velocity - drift spraying - spraying - sprayers - measurement - models - reduction
Bij veldmetingen (Zande et al., 2005) werd bij gebruik van een standaard spleetdop (TeeJet XR11004 bij 3 bar spuitdruk) bij een rijsnelheidsverhoging van 6 km/h naar 12 km/h op de strook 2½-3½ m vanaf de buitenste dop een toename van de drift van 46% gevonden. Tijdens dezelfde metingen werd bij een voorkamer spleetdop (TeeJet DG11004 bij 3 bar spuitdruk) in combinatie met een kantdop (Lechler IS8004) een toename gevonden van 364%. Bij validatiemetingen voor het IDEFICS model werd bij een rijsnelheidsverhoging van 0,5 m/s tot 1,5 m/s een gemiddelde toename in driftdepositie van 20% gevonden (Holterman et al., 1997). Van een aantal geselecteerde spuitdoppen uit de driftreductieklassen 50,75, 90 en 95 (TCT,2012) zijn in 2012 de druppelgrootte spectra gemeten (Zande et al., 2012) en is de drift uitgerekend met het driftmodel IDEFICS (Holterman et al., 1997). De spuitdopselectie bestond uit verschillende doptypen zoals venturi spleetdoppen, tweewaaier spleetdoppen en hispeed spleetdoppen. De drift van de geselecteerde doppen werd berekend bij de standaard rijsnelheid van 6 km/h en bij de hogere snelheden van 8, 10, 12 en 18 km/h. Resultaat van deze modelberekeningen was dat de gemiddelde toename in drift door toename van de snelheid 20% was. Doel van deze berekeningen was of aangegeven kon worden of spuitdoppen of een hogere rijsnelheid resulteert in een andere klassenindeling. Gevonden werd dat door toename van de rijsnelheid bij de meeste doppen de driftdepositie toe nam. Omdat eerdere veldmetingen van de drift afwijken van de modelberekeningen door toename van de rijsnelheid zijn enkeldops drift metingen uitgevoerd ter validatie van het driftmodel IDEFICS. Om het driftmodel IDEFICS te valideren voor rijsnelheidseffecten en doptype zijn met de doppen uit bovenstaande studie enkeldops driftmetingen uitgevoerd in 2011-2012. Naast meting van de drift naar de grond is ook de drift naar de lucht gemeten. Bij de metingen zijn twee meetmethoden vergeleken: een passieve methode met bolcollectoren (standaard) en door middel van met actieve aanzuiging (filters). Doel daarvan is om te kijken wat de verschillen zijn en of er een correlatie tussen de twee methoden is. In deze rapportage worden de meetmethodieken beschreven in hoofdstuk 2 en de resultaten in hoofdstuk 3. Het rapport eindigt met discussie (hoofdstuk 4) en conclusies (hoofdstuk 5).
Via diergezondheidsmanagement naar minimaliseren van antibioticumgebruik werkt! : ervaringen van biologische varkenshouders
Bokma-Bakker, M.H. ; Eijck, I. - \ 2014
Wageningen UR, Livestock Research
varkenshouderij - antibiotica - reductie - biologische landbouw - diergezondheid - dierziektepreventie - dierenwelzijn - huisvesting, dieren - kraamstallen - pig farming - antibiotics - reduction - organic farming - animal health - animal disease prevention - animal welfare - animal housing - farrowing houses
Diverse biologische varkenshouders hebben geëxperimenteerd met een ‘nieuwe’ aanpak van het diergezondheidsmanagement en verdere vermindering van antibioticagebruik op het bedrijf. De resultaten zijn veelbelovend. In deze brochure willen we een aantal opvallende ervaringen van varkenshouders met u delen.
Recirculatie Cymbidium
Kromwijk, J.A.M. ; Voogt, W. - \ 2014
potplanten - cymbidium - emissie - drainagewater - recirculatiesystemen - reductie - glastuinbouw - landbouwkundig onderzoek - pot plants - emission - drainage water - recirculating systems - reduction - greenhouse horticulture - agricultural research
Het doel van dit onderzoek is het verminderen van emissie bij teelt van Cymbidium.
Recirculatie potorchidee
Kromwijk, J.A.M. ; Schoenmakers, M. - \ 2014
orchideeën als sierplanten - potplanten - stikstof - emissie - reductie - kennisoverdracht - drainagewater - normen - ornamental orchids - pot plants - nitrogen - emission - reduction - knowledge transfer - drainage water - standards
De aanleiding van dit onderzoek is dat de emissie van stikstof bij de teelt van potorchidee relatief hoog is en loopt op bedrijven zonder recirculatie uiteen van 700 tot ruim 1000 kg N/ha/jaar. Om te kunnen voldoen aan de norm is recirculatie nodig. Het doel van dit onderzoek is het beantwoorden van kennisvragen en oplossen van knelpunten bij recirculatie bij potorchidee.
Sturen met hoge EC verbetert smaak en kwaliteit vruchtgroenten : zoektocht naar minder water, meststoffen en spui
Velden, P. van; Beerling, E.A.M. - \ 2014
Onder Glas 11 (2014)12. - p. 24 - 25.
glastuinbouw - groenten - cultuurmethoden - kweekmedia - emissie - irrigatie - reductie - gewaskwaliteit - tomaten - waterbehoefte - greenhouse horticulture - vegetables - cultural methods - culture media - emission - irrigation - reduction - crop quality - tomatoes - water requirements
Een tandje bijzetten om het nog beter te doen. Dat is de inzet van nieuwe proeven die het water- en meststoffenverbruik en de spui naar beneden moeten brengen. Dat klinkt een beetje als een verplicht nummer, tot blijkt dat de kwaliteit van het eindproduct omhoog kan. Misschien zelfs met behoud van productie. Overdrain als verzekering is een achterhaald idee.
Visie Internationale Agrologistiek : inventarisatie naoogst verliezen en verbeterde voedselzekerheid in opkomende landen en de mogelijke bijdrage van het Nederlandse bedrijfsleven
Scheer, F.P. ; Gogh, J.B. van; Ravensbergen, P. ; Burgh, M. van der; Waarts, Y.R. ; Rutten, M.M. ; Aramyan, L.H. - \ 2014
Wageningen : Wageningen UR - Food & Biobased Research (Report / Wageningen UR Food & Biobased Research 1430) - ISBN 9789461736994 - 84
logistiek - ketenmanagement - agro-industriële sector - gegevens verzamelen - deskundigen - reductie - voedselopslagverliezen - overgangseconomieën - logistics - supply chain management - agroindustrial sector - data collection - experts - reduction - food storage losses - transition economies
Energiemonitor van de Nederlandse glastuinbouw 2013
Velden, N.J.A. van der; Smit, P.X. - \ 2014
Den Haag : LEI Wageningen UR (LEI-rapport / LEI Wageningen UR 014-025) - ISBN 9789086156900 - 54
glastuinbouw - energie - broeikasgassen - kooldioxide - duurzaamheid (sustainability) - emissie - reductie - nederland - greenhouse horticulture - energy - greenhouse gases - carbon dioxide - sustainability - emission - reduction - netherlands
In de Nederlandse glastuinbouw vindt een energietransitie plaats. Deze transitie wordt ingegeven door het effect van het energiegebruik op het klimaat, de stijgende energieprijzen, de slinkende voorraden fossiele brandstof, de afnemende voorzieningszekerheid, het imago van de glastuinbouw en de duurzaamheidswensen van afnemers en consumenten in binnen- en buitenland. Tussen de glastuinbouwsector en de overheid zijn in diverse convenanten afspraken gemaakt over de CO2-emissie, de CO2-emissieruimte, de energie-efficiëntie en het aandeel duurzame energie. In 2013 kwam via de SER het Energieakkoord voor duurzame groei tot stand. Hierin is voor de glastuinbouw een inzet voor energiebesparing opgenomen. Het transitieprogramma 'Kas als Energiebron' (KaE) is het beleids- en uitvoeringsprogramma om de energiedoelen te realiseren. Dit transitieprogramma is een publiek-private samenwerking (PPS), waarin de glastuinbouw en de Nederlandse overheid invulling geven aan de ambitie om in 2020 in nieuwe kassen klimaatneutraal en economisch rendabel te telen. In juli 2014 zijn de doelen en ambities uit eerdere convenanten bijeengebracht in de Meerjarenafspraak Energietransitie Glastuinbouw. Hierin is de reductie van de CO2-emissie meer centraal komen te staan.
Microbial (per)chlorate reduction in hot subsurface environments
Liebensteiner, M. - \ 2014
University. Promotor(en): Fons Stams, co-promotor(en): Bart Lomans. - Wageningen : Wageningen University - ISBN 9789462571259 - 172
perchloraten - chloraten - reductie - microbiologie - micro-organismen - ondergrondse lagen - perchlorates - chlorates - reduction - microbiology - microorganisms - subsurface layers

The microbial reduction of chlorate and perchlorate has been known for long as a respiratory process of mesophilic bacteria that thrive in diverse environments such as soils, marine and freshwater sediments. Chlorate and perchlorate are found in nature deriving from anthropogenic and natural sources and can, in the absence of oxygen, be reduced by respective microorganisms to chloride coupled to energy conservation and growth. These classical chlorate- and perchlorate-reducing microorganisms employ enzymes that reduce perchlorate (or chlorate) to the intermediate chlorite, followed by the disproportionation of chlorite to chloride and dioxygen. The latter has been regarded as key reaction for complete (per)chlorate reduction, catalyzed by the enzyme chlorite dismutase, which forms oxygen under anaerobic conditions. This de novo produced oxygen is reduced by terminal oxidases in the metabolism of facultative anaerobic (per)chlorate-reducing microorganisms and can be used by oxygenases for the activation of recalcitrant substrates, as was shown earlier for hydrocarbons.

The potentially stimulating effect of chlorate and perchlorate on microorganisms indigenous to petroleum reservoirs was discussed, seeking new strategies for microbial enhanced oil recovery (based on subsurface growth stimulation and partial hydrocarbon degradation) and reservoir souring control (by inhibiting sulfate-reducing prokaryotes and diminishing sulfide formation).

This thesis reports the capability of hyperthermophilic and thermophilic prokaryotes that originate from subsurface environments to grow by the reduction of chlorate and/or perchlorate. In contrast to the classical metabolism of mesophilic (per)chlorate-reducing microorganisms this study demonstrated that a chlorite-disproportionating enzyme is commonly absent in (hyper)thermophilic (per)chlorate reducers. The absence of this enzyme that was previously defined as prerequisite for (per)chlorate reduction is overcome by the chemical reactivity of reduced sulfur compounds with chlorite generated. In the here more closely investigated hyperthermophilic archaea (Archaeoglobus fulgidus and Aeropyrum pernix) and thermophilic Firmicutes (Carboxydothermus hydrogenoformans and Moorella glycerini strain NMP) chlorite is formed by the activity of molybdopterin oxidoreductases. The respective enzymes are remotely related to perchlorate reductases of mesophilic bacteria and nitrate reductases of the bacterial Nar-type. In contrast to classical bacterial Nar-type enzymes, above-mentioned enzymes seem to have their catalytic subunits outside of the cell. As a consequence the reduction of (per)chlorate forms chlorite extracellularly where it reacts with reduced sulfur species present in the medium/environment (e.g. sulfide), forming chloride anions and oxidized sulfur species (SxOyz-).

The hyperthermophilic archaeon Archaeoglobus fulgidus reduces these chemically formed sulfur species concomitantly to (per)chlorate reduction, which regenerates sulfide for the continuous reduction of (per)chlorate. This interaction of biotic and abiotic reactions during (per)chlorate reduction establishes an intraspecies “sulfur loop” that enables complete reduction of perchlorate to chloride.

Whereas A. pernix also relies on the chemical reactivity of chlorite with thiosulfate, this archaeon does not employ systems for regenerating the reducing agents biologically; which is reflected by the accumulation of sulfate during perchlorate reduction. The Crenarchaeon A. pernix, formerly known as a strictly aerobic microorganism, expands the trait of microbial (per)chlorate reduction up to 100°C.

In addition to the intraspecies “sulfur loop” of A. fulgidus, there were indications that the reduction of perchlorate may also proceed syntrophically, as indicated by a thermophilic bacterial consortium. In the respective culture, it seems that one microorganism reduces perchlorate, forming chlorite, which is chemically reduced by sulfide to chloride anions and oxidized sulfur compounds. Another group of microorganisms uses the respective sulfur compounds as electron acceptors and regenerates sulfide. Sulfur (of different redox states) depicts the mediating agent in this interspecies “sulfur loop”, but may possibly be substituted in nature by other compounds such as ferrous/ferric iron.

Here presented (per)chlorate reduction sensu lato, which lacks the action of a chlorite-disproportionating enzyme may be widely spread among prokaryotes. For example enzymes closely resembling the designated (per)chlorate-reducing enzyme in Archaeoglobus fulgidus are also found in other strictly anaerobic thermophiles, of which C. hydrogenoformans and M. glycerini NMP were already confirmed to grow by the reduction of (per)chlorate as well.

The substrate ambiguity of particular periplasmic DMSO enzymes may enable a broader group of microorganisms of (per)chlorate reduction sensu lato, in case sulfide is present in the environment. A broadened substrate spectrum of respective enzymes (beyond their canonical function) may possibly have had evolutionary advantages. Chlorine oxyanions are naturally formed and have been introduced on Earth for ages already. The reduction of (per)chlorate and formation of chlorite in ancient anaerobic microorganisms may even have contributed to the evolution of proteins adapted to oxidizing conditions on early Earth and preceded the evolution of oxygenic photosynthesis.

It is shown that subsurface-inhabiting (hyper)thermophiles are able to grow by the reduction of (per)chlorate, which is also of interest for applications in the field of oil recovery. The finding that (per)chlorate reduction is interfering with the sulfur metabolism of a major contributor to reservoir souring in hot oil fields, A. fulgidus, draws promising scenarios for future attempts in developing novel souring control strategies.

(Per)chlorate reduction by A. fulgidus was also coupled to the oxidation of butyrate, a volatile fatty acid commonly present in petroleum reservoirs. For sustainable applications in the oil recovery business, it is desirable to rely, as little as possible, on external substrates. In this respect the fact that A. fulgidus couples (per)chlorate reduction to the oxidation of butyrate is advantageous. Possibly the microorganism can also degrade long-chain alkanes and alkenes coupled to (per)chlorate reduction, a feature that was shown earlier coupled to sulfate reduction.

All together a shift of A. fulgidus from sulfate reduction to (per)chlorate reduction in oil fields would not only diminish souring, but maintain/stimulate in-situ growth of the microorganism (based on intrinsic carbon sources) which has additionally advantageous effects for improved sweeping efficiencies during water flooding.

Kwaliteit van groente en snijbloemen uit gronddoekgoten verbluffend goed : Vermindering emissie water en meststoffen
Rodenburg, J. ; Helm, F.P.M. van der; Janse, J. - \ 2014
Onder Glas 11 (2014)9. - p. 30 - 31.
glastuinbouw - snijbloemen - groenten - teeltsystemen - materialen - goten - plantenontwikkeling - substraten - groeimedia - emissie - reductie - greenhouse horticulture - cut flowers - vegetables - cropping systems - materials - ducts - plant development - substrates - growing media - emission - reduction
Na succesvolle proefresultaten van gronddoekgoten bij de teelt van lisianthus, breidde Wageningen UR Glastuinbouw dit voorjaar het onderzoek uit naar sla, radijs en zomerbloemen. Gedurende vier maanden testte studente Jou-Fu Wang de producten op zowel kwaliteit als groei. De uitkomsten waren boven verwachting goed en bieden kansen voor de toekomst.
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