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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Raising the steaks: How one city in the Netherlands wants to feed the world
Barbosa, Maria ; Meer, Ingrid van der; Dicke, Marcel ; Werf, Adrie van der; Goot, Atze Jan van der; Wichers, Harry - \ 2019
Development of Offshore Seaweed Cultivation : food safety, cultivation, ecology and economy : synthesis report 2018
Jansen, H.M. ; Tonk, Linda ; Werf, A. van der; Meer, I. van der; Tuinen, S. van; Burg, S. van der; Veen, J. ; Bronswijk, L. ; Brouwers, E. - \ 2019
IJmuiden : Wageningen Marine Research (Wageningen Marine Research report C012/19) - 17
Technical upscaling of seaweed cultivation : Proseaweed Dossier (project AF-16202)
Werf, A.K. van der - \ 2018
Wageningen University & Research - 3 p.
De waarde van zeewier (KennisOnline in beeld 2018)
Werf, A.K. van der; Jansen, H.M. - \ 2018
Kennisonline (WUR)
Performance of five ulva strains: productivity, chemical composition and nutrient dynamics and selection criteria for farming practices and ecosystem interactions
Jansen, H.M. ; Nederlof, M.A.J. ; Meer, I.M. van der; Werf, A.K. van der - \ 2018
- 1 p.
Growing Azolla to produce sustainable protein feed: The effect of differing species and CO2 concentrations on biomass productivity and chemical composition.
Brouwer, Paul ; Schluepmann, Henriette ; Nierop, K.G.J. ; Elderson, J. ; Bijl, P.K. ; Meer, I.M. van der; Visser, W. de; Reichart, Gert Jan ; Smeekens, S. ; Werf, A.K. van der - \ 2018
Journal of the Science of Food and Agriculture 98 (2018)12. - ISSN 0022-5142 - p. 4759 - 4768.
Background: Since available arable land is limited and nitrogen fertilizers pollute the environment, cropping systems ought to be developed that do not rely on them. Here we investigate the rapidly growing, N2 -fixing Azolla/Nostoc symbiosis for its potential productivity and chemical composition to determine its potential as protein feed. Results: In a small production system, cultures of Azolla pinnata and Azolla filiculoides were continuously harvested for over 100 days, yielding an average productivity of 90.0-97.2 kg dry weight (DW) ha-1  d-1 . Under ambient CO2 levels, N2 fixation by the fern's cyanobacterial symbionts accounted for all nitrogen in the biomass. Proteins made up 176-208 g kg-1 DW (4.9 × total nitrogen), depending on species and CO2 treatment, and contained more essential amino acids than protein from soybean. Elevated atmospheric CO2 concentrations (800 ppm) significantly boosted biomass production by 36-47%, without decreasing protein content. Choice of species and CO2 concentrations further affected the biomass content of lipids (79-100 g kg-1 DW) and (poly)phenols (21-69 g kg-1 DW). Conclusions: By continuous harvesting, high protein yields can be obtained from Azolla cultures, without the need for nitrogen fertilization. High levels of (poly)phenols likely contribute to limitations in the inclusion rate of Azolla in animal diets and need further investigation. © 2018 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Metabolic adaptation, a specialized leaf organ structure and vascular responses to diurnal N2 fixation by nostoc azollae sustain the astonishing productivity of azolla ferns without nitrogen fertilizer
Brouwer, Paul ; Bräutigam, Andrea ; Buijs, Valerie A. ; Tazelaar, Anne O.E. ; Werf, Adrie van der; Schlüter, Urte ; Reichart, Gert Jan ; Bolger, Anthony ; Usadel, Björn ; Weber, Andreas P.M. ; Schluepmann, Henriette - \ 2017
Frontiers in Plant Science 8 (2017). - ISSN 1664-462X
Aquatic ferns - Azolla/nostoc azollae symbiosis - Clock evolution - Diel cycling - Dinitrogen fixation - Heterocystous cyanobacteria - Rna-seq - Vasculature
Sustainable agriculture demands reduced input of man-made nitrogen (N) fertilizer, yet N2 fixation limits the productivity of crops with heterotrophic diazotrophic bacterial symbionts. We investigated floating ferns from the genus Azolla that host phototrophic diazotrophic Nostoc azollae in leaf pockets and belong to the fastest growing plants. Experimental production reported here demonstrated N-fertilizer independent production of nitrogen-rich biomass with an annual yield potential per ha of 1200 kg-1 N fixed and 35 t dry biomass. 15N2 fixation peaked at noon, reaching 0.4 mg N g-1 dry weight h-1. Azolla ferns therefore merit consideration as protein crops in spite of the fact that little is known about the fern’s physiology to enable domestication. To gain an understanding of their nitrogen physiology, analyses of fern diel transcript profiles under differing nitrogen fertilizer regimes were combined with microscopic observations. Results established that the ferns adapted to the phototrophic N2-fixing symbionts N. azollae by (1) adjusting metabolically to nightly absence of N supply using responses ancestral to ferns and seed plants; (2) developing a specialized xylem-rich vasculature surrounding the leaf-pocket organ; (3) responding to N-supply by controlling transcripts of genes mediating nutrient transport, allocation and vasculature development. Unlike other non-seed plants, the Azolla fern clock is shown to contain both the morning and evening loops; the evening loop is known to control rhythmic gene expression in the vasculature of seed plants and therefore may have evolved along with the vasculature in the ancestor of ferns and seed plants.
Effects of micronutrients micnobit and salt fertilization on lettuce
Blom-Zandstra, M. ; Visser, W. de; Werf, A.K. van der; Lee, Martijn van der; Vos, Ric de; Jongschaap, R.E.E. ; Dimkpa, Christian ; Bindraban, P.S. - \ 2016
Washington : Virtual Fertilizer Research Centre (VFRC Report 2016/1) - 42 p.
SPARK-UP; Seaweed Production And Refining of Kelp, Ulva and Palmaria : 2013-2016
Wald, J. ; Visser, W. de; Brandenburg, W.A. ; Jongschaap, R.E.E. ; Werf, A.K. van der; Deelman, Berth-Jan ; Helmendach-Nieuwenhuize, Carola - \ 2016
Plant Research International - 144 p.
seaweeds - biobased economy - seaweed culture - biomass production - biomass conversion - aquatic biomass - biorefinery - seaweed products - applications - applied research - cropping systems - marketing channels - zeewieren - zeewierenteelt - biomassa productie - biomassaconversie - aquatische biomassa - bioraffinage - zeewierproducten - toepassingen - toegepast onderzoek - teeltsystemen - marketingkanalen
In het SPARK-UP project, waarin de partners Arkema, PRI-WUR en North Seaweed samenwerkten aan de ontwikkeling van toepassing van zeewier in de biobased economy, is de afgelopen jaren veel werk verzet. In een bassin op het terrein van Arkema, heeft PRI een teeltsysteem opgezet en in gebruik genomen, om onder gecontroleerde omstandigheden zeewier te telen in Westerscheldewater dat in het bassin was ingenomen. Arkema heeft gewerkt aan de raffinage van wieren, met name gericht op de suikers. North Seaweed heeft zich geconcentreerd op het ontwikkelen van businesscases van geraffineerde eiwitten en alginaten uit zeewier en bij het gebruik van de hele wieren als plantversterkers.
Kweekvlees, insecten, zeewier - wat ligt er over vijf jaar op ons bord?
Dicke, Marcel ; Ende, Ernst van den; Woltering, Ernst ; Werf, Adrie van der - \ 2016

De groeiende wereldbevolking moet op zoek naar alternatieve voedselbronnen. NRC-redacteur Carlijn Vis bespreekt vier toekomstbestendige voedselsoorten.

North-Sea-Weed-Chain: sustainable seaweed from the North Sea; an exploration of the value chain
Groenendijk, F.C. ; Bikker, P. ; Blaauw, R. ; Brandenburg, W.A. ; Burg, S.W.K. van den; Harmsen, P.F.H. ; Jak, R.G. ; Kamermans, P. ; Krimpen, M.M. van; Prins, H. ; Stuiver, M. ; Werf, A.K. van der; Scholl, M.M. ; Wald, J. - \ 2016
IMARES (Report / IMARES C055/16) - 94 p.
seaweeds - seaweed culture - seaweed products - feasibility studies - economic viability - public-private cooperation - economic cooperation - projects - biobased economy - zeewieren - zeewierenteelt - zeewierproducten - haalbaarheidsstudies - economische haalbaarheid - publiek-private samenwerking - economische samenwerking - projecten
Zeewier is een potentieel belangrijke voedselbron en grote duurzame koolstofbron voor de biobased economy. Met de groeiende wereldbevolking is het noodzakelijk om voor ons voedsel meer te kijken naar de zee als ‘landbouwgebied’. Boeren op zee is een grote uitdaging. Het vereist grote investeringen in infrastructuur. Voordat ondernemers hierin kunnen investeren moeten realistische vooruitzichten zijn op kweekmogelijkheden en winstgevende eindproducten. Dit project had tot doel de verschillende schakels in de keten van zeewierproductie tot vermarkting tegen het licht te houden. Duurzaamheid van de productie is hierbij leidend geweest.
Lipid Yield and Composition of Azolla filiculoides and the Implications for Biodiesel Production
Brouwer, Paul ; Werf, Adrie van der; Schluepmann, Henriette ; Reichart, Gert Jan ; Nierop, Klaas G.J. - \ 2016
Bio Energy Research 9 (2016)1. - ISSN 1939-1234 - p. 369 - 377.
Azolla - Biochemicals - Biodiesel - Feedstock - Fern - Lipids

The aquatic fern Azolla is one of the fastest-growing nitrogen-fixing plants on Earth and therefore considered as a potential source of biomass for bioenergy production. The lipid fraction from Azolla filiculoides was analyzed to investigate whether it suited biodiesel production. Since the productivity of Azolla is further increased at higher CO2 concentrations, A. filiculoides biomass was produced at 800 ppm CO2 mimicking a cultivation system utilizing CO2 waste from industry. The harvested biomass contained 7.92 ± 0.14 % dry weight (dw) crude lipids. Drying conditions did not significantly affect lipid composition or yields, indicating that drying conditions may be energetically optimized without the risk of product loss. Total lipid extracts contained 4.2 ± 0.38 % free fatty acids. Of the crude lipid fraction, 41 ± 13 % consisted of fatty acids that were converted into fatty acid methyl esters upon saponification in methanol. Unique mid-chain (di)hydroxy compounds constituted 7.2 ± 2.8 % of the crude lipids. Based on the fatty acid profile, it was estimated that Azolla biodiesel meets requirements set by the EN14214 standard on fuel density, cetane number, and iodine value. The cold filter plugging point (CFPP), however, is expected to be too high due to relatively high concentrations of lignoceric acid and the presence of the mid-chain (di)hydroxy compounds. To produce high-quality biodiesel from Azolla lipids, therefore, a fractionation step will be required removing these compounds. As an advantage, the long-chain alcohols and (di)hydroxy fatty acids obtained after fractionation may provide a valuable secondary product stream with applications to chemical industry and nutrition.

Azolla domestication towards a biobased economy?
Brouwer, Paul ; Brautigam, A. ; Kulahoglu, C. ; Tazelaar, A.O.E. ; Kurz, S. ; Nierop, K.G.J. ; Werf, A.K. van der; Weber, A.P.M. ; Schluepmann, H. - \ 2014
New Phytologist 202 (2014)3. - ISSN 0028-646X - p. 1069 - 1082.
Due to its phenomenal growth requiring neither nitrogen fertilizer nor arable land and its biomass composition, the mosquito fern Azolla is a candidate crop to yield food, fuels and chemicals sustainably. To advance Azolla domestication, we research its dissemination, storage and transcriptome. Methods for dissemination, cross-fertilization and cryopreservation of the symbiosis Azolla filiculoides–Nostoc azollae are tested based on the fern spores. To study molecular processes in Azolla including spore induction, a database of 37 649 unigenes from RNAseq of microsporocarps, megasporocarps and sporophytes was assembled, then validated. Spores obtained year-round germinated in vitro within 26 d. In vitro fertilization rates reached 25%. Cryopreservation permitted storage for at least 7 months. The unigene database entirely covered central metabolism and to a large degree covered cellular processes and regulatory networks. Analysis of genes engaged in transition to sexual reproduction revealed a FLOWERING LOCUS T-like protein in ferns with special features induced in sporulating Azolla fronds. Although domestication of a fern–cyanobacteria symbiosis may seem a daunting task, we conclude that the time is ripe and that results generated will serve to more widely access biochemicals in fern biomass for a biobased economy.
Rietteelt als mogelijke bouwsteen voor een duurzaam water- en bodembeheer in natte veengebieden
Korevaar, H. ; Werf, A.K. van der - \ 2014
Wageningen : Plant Research International, Business Unit Agrosysteemkunde (Rapport / Plant Research International 544) - 48
phragmites - landgebruik - bodembeheer - waterzuivering - biomassa - ecosysteemdiensten - bodemdaling - veenweiden - haalbaarheidsstudies - utrecht - land use - soil management - water treatment - biomass - ecosystem services - subsidence - peat grasslands - feasibility studies
De teelt van riet is één van de mogelijke alternatieven voor het huidige landgebruik en systeem van waterbeheer in de veenweidegebieden en kan helpen de bodemdaling te beperken. In deze haalbaarheidsstudie komen aan bod: de thema's water, bodem, broeikasgassen, natuurwaarden, maatschappelijke aspecten, en economische aspecten. Vervolgens komen de mogelijke functies aan bod: waterzuivering, waterberging, bodemdaling, buffering van natuur, oeverbescherming, biodiversiteit, biomassateelt en recreatie. De marktprijs van rietbiomassa is momenteel te laag om rietteelt rendabel te maken. Een betaling voor ecosysteemdiensten is nog niet genoeg ontwikkeld om daarmee een goede beloning voor o.a. waterzuiverinbg, klimaatadaptaie en bodemdaling te genereren.
Balancing carbon sequestration and GHG emissions in a constructed wetland
Klein, J.J.M. de; Werf, A.K. van der - \ 2014
Ecological Engineering 66 (2014). - ISSN 0925-8574 - p. 36 - 42.
waste-water treatment - phragmites-australis - methane emission - nitrous-oxide - emergent macrophytes - ecosystem services - restored wetlands - greenhouse gases - fresh-water - denitrification
In many countries wetlands are constructed or restored for removing nutrients from surface water. At the same time vegetated wetlands can act as carbon sinks when CO2 is sequestered in biomass. However, it is well known that wetlands also produce substantial amounts of greenhouse gasses CH4 and N2O. Especially N2O, resulting from nitrification and denitrification, is a very potent GHG. To assess the environmental sustainability of constructed wetlands the benefit of carbon sink and the downside of GHG emissions have to be evaluated. Since nutrient and carbon cycles in wetlands are complex and variable among wetlands and in time such a balance always contains uncertainties. Several studies have addressed this issue and indicated that CW can be either a sink or a source of CO2 equivalents depending on the time scale of research and the environmental and management conditions involved. Here we balance carbon sequestration with CH4 and N2O emissions in a multi-functional constructed wetland, dominated by emergent Phragmites vegetation. Detailed measurements were combined with a nitrogen budget, and all fluxes were expressed as a range indicating the uncertainties in measurements and extrapolation techniques. Measured methane emissions were variable and showed clear relationship with temperature and density of the emergent vegetation. Average CH4 emissions in the vegetation were 7.8 at 15 °C and 24.5 mg m-2 h-1 at 24 °C. Estimated N2O emissions ranged from 0.5 to 1.9 g m-2 y-1. After converting the fluxes to CO2 equivalents we concluded that the Lankheet constructed wetland is most likely a sink of CO2 in the present conditions. Annual net sequestration of CO2 amounts 0.27–2.4 kg m-2 y-1 which represents 12–67% of the CO2 fixation in the biomass. N2O emissions represent a substantial part of the total effect of GHG emissions (12–29%) and should not be disregarded in budget studies. We acknowledge the limitations and uncertainties of our estimates, however, we are confident that our findings contribute to assessing the environmental sustainability of constructed wetlands.
Azolla: from floating fern to renewable resource
Werf, Adrie van der - \ 2013
azolla - fuel crops - aquatic biomass - biomass production - new crops

Documentary september 2013

Azolla aandacht in EenVandaag documentaire “Groene en Republikeinse Dromen voor de Koning”
Werf, Adrie van der - \ 2013

EenVandaag verzamelt, in aanloop naar de inhuldiging van Willem-Alexander, dromen van 'gewone' Nederlanders. Vandaag de droom van poolreiziger Marc Cornelissen, die hoopt dat de waterprins zich ontpopt tot groene koning.

Cornelissen neemt ons mee naar Wageningen, waar grote experimenten gaande zijn met kroos. Dat wordt nu nog gezien als ‘plaag’, maar kan de 'blessing in disguise' worden. Het groeit zo snel, dat er veevoer, diesel en andere producten van gemaakt kan worden. Cornelissen schetst ons het Nederland van de toekomst met een Groene in plaats van Oranje Koning.

Daarnaast de droom van republikein Bart Pol. die droomt van het grootste cadeau dat Prins Willem-Alexander Nederland volgens hem kan geven: een Republiek.

Azolla aandacht in “eenvandaag” documentaire “Groene en Republikeinse Dromen voor de Koning”

Plant strategies and cultural practices to improve the uptake of indigenous soil P and the efficiency of fertilization
Smit, A.L. ; Blom, M. ; Werf, A.K. van der; Bindraban, P.S. - \ 2013
Washington D.C. : VFRC (VFRC report 2013/4) - 36
bemesting - mineralenopname - gewassen, groeifasen - veldgewassen - akkerbouw - groenteteelt - fertilizer application - mineral uptake - crop growth stage - field crops - arable farming - vegetable growing
Several indications can be found which support the hypothesis that plant properties and cultural measures can stimulate P-uptake in early plant stages and could lead to a better use of indigenous soil P as well as higher efficiency of mineral inputs
De invloed van ozon op de alternatieve ademhaling en carbon use efficiency : evaluatie van de bevindingen van crops advance
Werf, A.K. van der; Dueck, T.A. ; Snel, J.F.H. - \ 2011
Wageningen : Plant Research International (Rapport / Plant Research International 391) - 20
plantenontwikkeling - tuinbouwgewassen - ozon - stress - ademhaling - rozen - glastuinbouw - plant development - horticultural crops - ozone - respiration - roses - greenhouse horticulture
Door Crops Advance zijn waarnemingen gedaan en is onderzoek uitgevoerd waaruit blijkt dat de aanwezigheid van ozon, met name in de kritische vroeg vegetatieve groeifase van gewassen, veel grotere schade tot gevolg heeft dan tot dusver bekend is of aangenomen wordt. Een verband werd gelegd tussen het tijdstip waarop rozen worden gestekt en de groei en productie gedurende een aantal jaren. Planten die gestekt en opgekweekt werden op een tijdstip met verhoogde stress (met hogere ozonconcentraties), groeiden minder in de latere teelt(en). Voor Nederland is door het RIVM een jaarlijkse toename (2%) in ozon voorspeld, waardoor de mogelijke consequenties voor de tuinbouw alsmaar groter kunnen worden.
Surface water sanitation and biomass production in a large constructed wetland in the Netherlands
Meerburg, B.G. ; Vereijken, P.H. ; Visser, W. de; Verhagen, A. ; Korevaar, H. ; Querner, E.P. ; Blaeij, A.T. de; Werf, A.K. van der - \ 2010
Wetlands Ecology and Management 18 (2010)4. - ISSN 0923-4861 - p. 463 - 470.
phragmites-australis - waste-water - nutrient removal - impact - river - flow - agriculture - macrophytes - plants
In Western-Europe, agricultural practices have contributed to environmental problems such as eutrophication of surface and ground water, flooding, drought and desiccation of surrounding natural habitats. Solutions that reduce the impact of these problems are urgently needed. Common reed (Phragmites australis) is capable of sanitizing surface water and may function as green energy source because of its high productivity. Here, the results of an experiment in a constructed wetland in the Netherlands are presented where two different sanitation treatments were compared. Depending on the residence time and volume per unit area, reed is capable to reduce the total amount of nitrogen in the water with average efficiencies from 32 to 47% and the total amount of phosphorous with 27–45%. Although biomass production still varies largely between different parts of the constructed wetland, a rapid increase in biomass was observed since planting. Constructed wetlands with reed provide opportunities to improve water quality and reed produces enough biomass to serve as green energy source. Moreover, these wetlands also function as a flood water reservoir and are possibly advantageous for biodiversity. The optimal moment of reed harvesting depends on the goal of the owner. This moment should be chosen wisely, as it may have consequences for reed filter regeneration, biomass production, biodiversity, methane emission and water sanitation efficiency.
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