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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    Population-level effects of acoustic disturbance in Atlantic cod: a size-structured analysis based on energy budgets
    Soudijn, Floor H. ; Kooten, Tobias van; Slabbekoorn, Hans ; Roos, André M. de - \ 2020
    Proceedings of the Royal Society. B: Biological Sciences 287 (2020)1929. - ISSN 0962-8452 - 1 p.
    anthropogenic noise - life history - PCoD - sound exposure

    Anthropogenic underwater noise may negatively affect marine animals. Yet, while fishes are highly sensitive to sounds, effects of acoustic disturbances on fishes have not been extensively studied at the population level. In this study, we use a size-structured model based on energy budgets to analyse potential population-level effects of anthropogenic noise on Atlantic cod (Gadus morhua). Using the model framework, we assess the impact of four possible effect pathways of disturbance on the cod population growth rate. Through increased stress, changes in foraging and movement behaviour, and effects on the auditory system, anthropogenic noise can lead to (i) increased energy expenditure, (ii) reduced food intake, (iii) increased mortality, and (iv) reduced reproductive output. Our results show that population growth rates are particularly sensitive to changes in energy expenditure and food intake because they indirectly affect the age of maturation, survival and fecundity. Sub-lethal effects of sound exposure may thus affect populations of cod and fishes with similar life histories more than lethal effects of sound exposure. Moreover, anthropogenic noise may negatively affect populations when causing persistent increases of energy expenditure or decreases of food intake. Effects of specific acoustic pollutants on energy acquisition and expenditure should therefore be further investigated.

    The role of ambient sound levels, signal-to-noise ratio, and stimulus pulse rate on behavioural disturbance of seabass in a net pen
    Hubert, J. ; Neo, Y.Y. ; Winter, H.V. ; Slabbekoorn, H. - \ 2020
    Behavioural Processes 170 (2020). - ISSN 0376-6357
    Anthropogenic noise - signal-to-noise ratio - Dicentrarchus labrax - fish behaviour
    Anthropogenic sources increasingly contribute to the underwater soundscape and this may negatively impact aquatic life, including fish. Anthropogenic sound may mask relevant sound, alter behaviour, physiology, and may lead to physical injury. Behavioural effect studies are often seen as critical to evaluate individual and population-level impact. However, behavioural responsiveness likely depends on context and characteristics of sound stimuli. We pose that ambient sound levels, signal-to-noise ratio (SNR), and pulse rate interval (PRI), could affect the behavioural response of fish. To study this, we experimentally exposed groups of tagged European seabass (Dicentrarchus labrax) to different impulsive sound treatments that varied in pulse level, elevated background level, SNR, and PRI. Upon sound exposure, the seabass increased their swimming depth. The variation in the increase in swimming depth could not be attributed to pulse level, background level, SNR or PRI. It may be that the current range of sound levels or PRIs was too narrow to find such effects.
    Population‐level consequences of seismic surveys on fishes: An interdisciplinary challenge
    Slabbekoorn, Hans ; Dalen, John ; Haan, Dick de; Winter, Hendrik V. ; Radford, Craig ; Ainslie, Michael A. ; Heaney, Kevin D. ; Kooten, Tobias van; Thomas, Len ; Harwood, John - \ 2019
    Fish and Fisheries 20 (2019)4. - ISSN 1467-2960 - p. 653 - 685.
    airgun - behavioural response - dynamic energy bidget - fish hearing - `population consequences of acoustic disturbance - stress physiology
    Offshore activities elevate ambient sound levels at sea, which may affect marine
    fauna. We reviewed the literature about impact of airgun acoustic exposure on fish in terms of damage, disturbance and detection and explored the nature of impact assessment at population level. We provided a conceptual framework for how to address this interdisciplinary challenge, and we listed potential tools for investigation. We focused on limitations in data currently available, and we stressed the potential benefits from cross-species comparisons. Well-replicated and controlled studies do not exist for hearing thresholds and dose–response curves for airgun acoustic exposure. We especially lack insight into behavioural changes for free-ranging fish to actual seismic surveys and on lasting effects of behavioural changes in terms of time and energy budgets, missed feeding or mating opportunities, decreased performance in predator-prey interactions, and chronic stress effects on growth, development and reproduction. We also lack insight into whether any of these effects could have population-level consequences. General “population consequences of acoustic disturbance” (PCAD) models have been developed for marine mammals, but there has been little progress so far in other taxa. The acoustic world of fishes is quite different
    from human perception and imagination as fish perceive particle motion and sound pressure. Progress is therefore also required in understanding the nature and extent to which fishes extract acoustic information from their environment. We addressed the challenges and opportunities for upscaling individual impact to the population, community and ecosystem level and provided a guide to critical gaps in our knowledge
    European seabass respond more strongly to noise exposure at night and habituate over repeated trials of sound exposure
    Neo, Y.Y. ; Hubert, J. ; Bolle, L.J. ; Winter, H.V. ; Slabbekoorn, H. - \ 2018
    Environmental Pollution 239 (2018). - ISSN 0269-7491 - p. 367 - 374.
    Anthropogenic noise - Dicentrarchus labrax - diurnal cycle - fish behaviour - Field study - Impulsive sound series - Inter-trial habituation
    Aquatic animals live in an acoustic world, prone to pollution by globally increasing noise levels. Noisy human activities at sea have become widespread and continue day and night. The potential effects of this anthropogenic noise may be context-dependent and vary with the time of the day, depending on diel
    cycles in animal physiology and behaviour. Most studies to date have investigated behavioural changes within a single sound exposure session while the effects of, and habituation to, repeated exposures remain largely unknown. Here, we exposed groups of European seabass (Dicentrarchus labrax) in an
    outdoor pen to a series of eight repeated impulsive sound exposures over the course of two days at variable times of day/night. The baseline behaviour before sound exposure was different between day and night; with slower swimming and looser group cohesion observed at night. In response to sound exposures, groups increased their swimming speed, depth, and cohesion; with a greater effect during the night. Furthermore, groups also showed inter-trial habituation with respect to swimming depth. Our findings suggest that the impact of impulsive anthropogenic noise may be stronger at night than during
    the day for some fishes. Moreover, our results also suggest that habituation should be taken into account for sound impact assessments and potential mitigating measures.
    Particle motion and pressure soundscape in outdoor vs indoor set-up
    Hubert, Jeroen ; Neo, Errol ; Campbell, James A. ; Slabbekoorn, Hans - \ 2016
    In: Proceedings of Meetings on Acoustics. - Acoustical Society of America

    Underwater sound consists of particle motion and sound pressure. Due to technical difficulties only sound pressure is measured in most sound impact studies on fish and invertebrates. However, sound pressure alone may not adequately reflect the actual acoustic stimulus, especially in tanks, basins and near-field conditions. To test the acoustic validity of different experimental settings, we measured particle motion (in velocity) and sound pressure soundscapes of two set-ups for sound impact studies on fish: an outdoor floating pen and an indoor basin. During sound exposure, there was a gradient in particle velocity as well as in the outdoor floating pen and a standing wave in the basin. The ratio between particle velocity and sound pressure was consistent in the floating pen, but not in the basin. These findings confirm the concerns about the acoustic validity and variability between particle motion and sound pressure in basins (and tanks). Therefore, we encourage researchers to measure both particle motion and sound pressure to gain insight in the actual acoustic stimulus, in order to better interpret and understand its effect on fish and aquatic invertebrates.

    Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions
    Aarts, Geert ; Benda-Beckmann, Alexander M. Von; Lucke, K. ; Özkan Sertlek, H. ; Bemmelen, Rob Van; Geelhoed, Steve C.V. ; Brasseur, Sophie ; Scheidat, Meike ; Lam, Frans Peter A. ; Slabbekoorn, Hans ; Kirkwood, Roger - \ 2016
    Marine Ecology Progress Series 557 (2016). - ISSN 0171-8630 - p. 261 - 275.
    Acoustics - Anthropogenic sound - Cumulative effects - Impact assessment - Individual-based model - Marine mammals - Population consequences of disturbance - Species distribution

    Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose-response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance.

    Sound exposure changes European seabass behaviour in a large outdoor floating pen: Effects of temporal structure and a ramp-up procedure
    Neo, Y.Y. ; Hubert, J. ; Bolle, L.J. ; Winter, Hendrik V. ; Cate, C. ten; Slabbekoorn, H. - \ 2016
    Environmental Pollution 214 (2016). - ISSN 0269-7491 - p. 26 - 34.
    Anthropogenic noise - Dicentrarchus labrax - Fish behaviour - Field study - Sound characteristics - Stress response
    Underwater sound from human activities may affect fish behaviour negatively and threaten the stability of fish stocks. However, some fundamental understanding is still lacking for adequate impact assessments and potential mitigation strategies. For example, little is known about the potential contribution of the temporal features of sound, the efficacy of ramp-up procedures, and the generalisability of results from indoor studies to the outdoors. Using a semi-natural set-up, we exposed European seabass in an
    outdoor pen to four treatments: 1) continuous sound, 2) intermittent sound with a regular repetition interval, 3) irregular repetition intervals and 4) a regular repetition interval with amplitude ‘ramp-up’. Upon sound exposure, the fish increased swimming speed and depth, and swam away from the sound source. The behavioural readouts were generally consistent with earlier indoor experiments, but the changes and recovery were more variable and were not significantly influenced by sound intermittency and interval regularity. In addition, the ‘ramp-up’ procedure elicited immediate diving response, similar
    to the onset of treatment without a ‘ramp-up’, but the fish did not swim away from the sound source as expected. Our findings suggest that while sound impact studies outdoors increase ecological and behavioural validity, the inherently higher variability also reduces resolution that may be counteracted
    by increasing sample size or looking into different individual coping styles. Our results also question the efficacy of ‘ramp-up’ in deterring marine animals, which warrants more investigation.
    Mapping underwater sound in the dutch part of the North Sea
    Özkan Sertlek, H. ; Aarts, Geert ; Brasseur, Sophie ; Slabbekoorn, Hans ; Cate, Carel ten; Benda-Beckmann, Alexander M. von; Ainslie, Michael A. - \ 2016
    In: The effects of Noise on Aquatic Life II / Popper, A.N., Hawkins, A., Springer Science + Business Media (Advances in Experimental Medicine and Biology ) - ISBN 9781493929801 - p. 1001 - 1006.
    Good environmental status - Shipping noise

    The European Union requires member states to achieve or maintain good environmental status for their marine territorial waters and explicitly mentions potentially adverse effects of underwater sound. In this study, we focused on producing maps of underwater sound from various natural and anthropogenic origins in the Dutch North Sea. The source properties and sound propagation are simulated by mathematical methods. These maps could be used to assess and predict largescale effects on behavior and distribution of underwater marine life and therefore become a valuable tool in assessing and managing the impact of underwater sound on marine life.

    Noise impact on European sea bass behavior : Temporal structure matters
    Neo, Yik Yaw ; Seitz, Johanna ; Kastelein, Ronald A. ; Winter, Hendrik V. ; Cate, Carel ten; Slabbekoorn, Hans - \ 2016
    In: The Effects of Noise on Aquatic Life II Springer New York LLC (Advances in Experimental Medicine and Biology ) - ISBN 9781493929801 - p. 763 - 766.
    Amplitude fluctuation - Anthropogenic sounds - Dicentrarchus labrax - Intermittency - Stress response

    Anthropogenic sounds come in different forms, varying not only in amplitude and frequency spectrum but also in temporal structure. Although fish are sensitive to the temporal characteristics of sound, little is known about how their behavior is affected by anthropogenic sounds of different temporal patterns. We investigated this question using groups of Dicentrarchus labrax (European sea bass) in an outdoor basin. Our data revealed that the temporal pattern of sound exposure is important in noise impact assessments.

    Impulsive sounds change European seabass swimming patterns: influence of pulse repetition interval
    Neo, Y.Y. ; Ufkes, E. ; Kastelein, R.A. ; Winter, H.V. ; Cate, C. ten; Slabbekoorn, H. - \ 2015
    Marine Pollution Bulletin 97 (2015)1-2. - ISSN 0025-326X - p. 111 - 117.
    startle-response - trawling vessel - fish - habituation - behavior - noise - variability - avoidance - zebrafish - recovery
    Seismic shootings and offshore pile-driving are regularly performed, emitting significant amounts of noise that may negatively affect fish behaviour. The pulse repetition interval (PRI) of these impulsive sounds may vary considerably and influence the behavioural impact and recovery. Here, we tested the effect of four PRIs (0.5–4.0 s) on European seabass swimming patterns in an outdoor basin. At the onset of the sound exposures, the fish swam faster and dived deeper in tighter shoals. PRI affected the immediate and delayed behavioural changes but not the recovery time. Our study highlights that (1) the behavioural changes of captive European seabass were consistent with previous indoor and outdoor studies; (2) PRI could influence behavioural impact differentially, which may have management implications; (3) some acoustic metrics, e.g. SELcum, may have limited predictive power to assess the strength of behavioural impacts of noise. Noise impact assessments need to consider the contribution of sound temporal structure.
    Temporal structure of sound affects behavioural recovery from noise impact in European seabass
    Neo, Y.Y. ; Seitz, J. ; Kastelein, R.A. ; Winter, H.V. ; Cate, C. ten; Slabbekoorn, H. - \ 2014
    Biological Conservation 178 (2014). - ISSN 0006-3207 - p. 65 - 73.
    zebrafish danio-rerio - seismic air-guns - dicentrarchus-labrax - fish distribution - startle response - atlantic salmon - high-intensity - rainbow-trout - teleost fish - marine fish
    Human activities in and around waters generate a substantial amount of underwater noise, which may negatively affect aquatic life including fish. In order to better predict and assess the consequences of the variety of anthropogenic sounds, it is essential to examine what sound features contribute to an impact. In this study, we tested if sounds with different temporal structure resulted in different behavioural changes in European seabass. Groups of four fish were exposed in an outdoor basin to a series of four sound treatments, which were either continuous or intermittent, with either consistent or fluctuating amplitude. The behavioural changes of the fish were analyzed by a video-tracking system. All sound treatments elicited similar behavioural changes, including startle responses, increased swimming speed, increased group cohesion and bottom diving. However, with all other sound conditions being the same, intermittent exposure resulted in significantly slower behavioural recovery to pre-exposure levels compared to continuous exposure. Our findings imply that the temporal structure of sound is highly relevant in noise impact assessments: intermittent sounds, such as from pile driving, may have a stronger behavioural impact on fish than continuous sounds, such as from drilling, even though the latter may have higher total accumulated energy. This study urges regulatory authorities and developers to pay more attention to the influence of temporal structure when assessing noise impacts. However, more studies are needed to examine other sound parameters and to determine the generality of our observations in other species and in other outdoor water bodies
    Ontwikkeling van een autonome precisiespuit voor de aardbeienteelt in de volle grond : ontwerp, bouw, validatie en demonstratie van een prototype
    Kempenaar, C. ; Michielsen, J.G.P. ; Nieuwenhuizen, A.T. ; Slabbekoorn, J.J. ; Zande, J.C. van de; Evenhuis, A. ; Bosch, G.B.M. van den; Molhoek, W.M.L. - \ 2013
    Wageningen : Plant Research International, Business Unit Agrosysteemkunde (Rapport / Plant Research International 540) - 55
    spuitapparaten - gewasbescherming - aardbeien - vollegrondsteelt - precisielandbouw - landbouwtechniek - dosering - spuiten - trekkers - sprayers - plant protection - strawberries - outdoor cropping - precision agriculture - agricultural engineering - dosage - spraying - tractors
    In dit rapport worden de eerste fasen van de ontwikkeling van een autonome precisiespuit in de aardebeienteelt beschreven. Dit traject is een initiatief van een groep aardbeientelers in West Brabant, Homburg Holland uit Stiens en Wageningen UR – PRI, om te komen tot een systeem waarmee autonoom gewasbeschermingsmiddelen op een zo nauwkeurig mogelijke manier toegediend kunnen worden in aardbeien. Op grond van praktijkeisen is gekozen voor een kleine New Holland landbouwtrekker van 50 pk (type Boomer) als basis voor het eerste prototype van de autonome precisiespuit. Voor het variabel kunnen doseren van middel is gekozen voor de SensiSpray Horti, een sensor gestuurde precisiespuit met luchtondersteuning van Homburg Holland en Probotiq.
    Rijenbemesting in aardappelen : rijenbemesting versus breedwerpig en perspectief van nieuwe meststoffen : verslag van een veldproef op zuidwestelijke zeeklei in 2011
    Slabbekoorn, J.J. - \ 2012
    Westmaas : Praktijkonderzoek Plant & Omgeving, onderdeel van Wageningen UR, Business Unit AGV - 44
    akkerbouw - aardappelen - precisielandbouw - teeltsystemen - bemesting - proeven op proefstations - stikstofhoudende verbindingen - stikstofmeststoffen - lichte-matig zware kleigronden - rijpadensysteem - toedieningshoeveelheden - broeikaseffect - arable farming - potatoes - precision agriculture - cropping systems - fertilizer application - station tests - nitrogenous compounds - nitrogen fertilizers - clay loam soils - controlled traffic farming - application rates - greenhouse effect
    In opdracht van het Pogramma Precisielandbouw (PPL) is door PPO te Westmaas (ZH) op kleigrond een stikstof bemestingsproef uitgevoerd. De precisietoepassing van stikstofhoudende meststoffen draagt bij aan PPL doelen van energie-besparing en reductie van broeikas-emmissie in de zin dat mogelijkheden worden onderzocht om kunstmeststikstof te vervangen.
    Ontwikkeling van een autonome precisiespuit voor de aardbeienteelten in de volle grond : fase 1 en 2: ontwerp en bouw van prototype
    Kempenaar, C. ; Michielsen, J.G.P. ; Nieuwenhuizen, A.T. ; Slabbekoorn, J.J. ; Zande, J.C. van de - \ 2012
    Wageningen : Plant Research International, Business Unit Agrosysteemkunde - 24
    landbouwtechniek - spuiten - toedieningswijzen - spuitapparaten - controlled droplet application - kleinvolume spuiten - pesticiden - aardbeien - aangepaste technologie - landbouwkundig onderzoek - agricultural engineering - spraying - application methods - sprayers - controlled droplet application - low volume spraying - pesticides - strawberries - appropriate technology - agricultural research
    In dit rapport worden de eerste fasen van de ontwikkeling van een autonome precisiespuit in de aardbeienteelt beschreven. Dit traject is een initiatief van een groep aardbeientelers in West Brabant, Homburg Holland uit Stiens en Wageningen UR–PRI, om te komen tot een systeem waarmee autonoom gewasbeschermingsmiddelen op een zo nauwkeurig mogelijke manier toegediend kunnen worden in aardbeien. De partners in deze publiek private samenwerking hebben hiertoe een ontwikkeltraject opgezet waarin vier fasen onderscheiden worden: ontwerp, bouw, testen en aanpassen, en demonstreren van de autonome spuit. Het initiatief is gestart in 2009 en het samenwerkingscontract loopt door tot en met 2014.
    Duurzame aardappelteelt in ieders belang : thema Aardappeldemodag 2012: duurzaam naar topopbrengst
    Slabbekoorn, Hanja ; Tramper, Marcel - \ 2012
    potatoes - sustainability - arable farming - demonstrations - knowledge transfer - extension
    Using crop reflectance to determine sidedress N rate in potato saves N and maintains yield
    Evert, F.K. van; Booij, R. ; Jukema, J.N. ; Berge, H.F.M. ten; Uenk, D. ; Meurs, E.J.J. ; Geel, W.C.A. van; Wijnholds, K.H. ; Slabbekoorn, J.J. - \ 2012
    European Journal of Agronomy 43 (2012). - ISSN 1161-0301 - p. 58 - 67.
    nitrogen status - fertilizer nitrogen - light reflectance - chlorophyll meter - vegetation index - management - soil - sensor - corn - recommendations
    A low basal N application combined with in-season adjustment of the sidedressNrate has been proposed as a means to saveN in growing potato (Solanum tuberosum L.). We hypothesize that a measurement of canopy reflectance provides information which can be used to adjust sidedressNrate. The objective of our work was to develop and test a canopy reflectance-based Nsidedress system for potato in humid climates. In four years of experiments with ware potato on a sandy soil it was determined that the reflectance index WDVI correlates well with N uptake, that sidedressN should be applied at around the time of canopy closing, and that the sidedressNrate should be calculated as the difference between a (fixed) desired N uptake and a reflectance-based measurement of N uptake. The calculated N saving in these experiments was between 10 and 109 (average 56) kg N ha-1. The reflectance-based Nsidedress system was tested at an additional two locations, with ware potatoes on a loamy soil and with starch potatoes on a sandy soil, in two further years of experiments. N saving in these experiments was between 8 and 88 (average 44) kg N ha-1. In both sets of experiments, yields with the sidedress system were generally at the same level as yields obtained with recommended Nrates (basal N only). We conclude that the reflectance-based sidedressN system allows saving of N while maintaining yield
    Sensorgestuurd variabel N-bijmesten van consumptieaardappelen 2011 : proef RH11.24 uitgevoerd op Rusthoeve Colijnsplaat
    Schans, D.A. van der; Slabbekoorn, J.J. ; Blok, D. - \ 2012
    Lelystad : Praktijkonderzoek Plant & Omgeving, Business Unit Akkerbouw, Groene Ruimte en Vollegrondsgroenten - 31
    bemesting - aardappelen - consumptieaardappelen - beslissingsondersteunende systemen - stikstof - veldproeven - akkerbouw - mestgiften - precisielandbouw - fertilizer application - potatoes - table potatoes - decision support systems - nitrogen - field tests - arable farming - dressings - precision agriculture
    In het teeltseizoen 2011 is op proefboerderij De Rusthoeve een stikstofbemestingsproef uitgevoerd in het gewas aardappelen. Het doel van deze proef was om de stikstofbenutting bij verschillende N giften vast te stellen en de stikstof adviezen van twee N bijmestsystemen te vergelijken met de optimale N bijmest strategie. Uit de proefresultaten blijkt dat het advies van de CropScan sensor en het advies op basis van Aardappel monitoring elkaar niet veel ontlopen. Beide systemen hebben achteraf gezien evenwel onterecht een N bijmest advies gegeven. Ook verschilden de adviezen bij een lage basisgift nauwelijks van die bij een hoge basisgift.
    Aardappeldemodag 2012: Duurzaam naar topopbrengst (Interview met Thie-Arend Brouwer, Hanja Slabbekoorn en Marcel Tramper)
    Delleman, J. ; Brouwer, T.A. ; Slabbekoorn, J.J. ; Tramper, M. - \ 2012
    Aardappelwereld 66 (2012)2. - ISSN 0169-653X - p. 4 - 5.
    aardappelen - demonstraties (vertoning) - landbouwtentoonstellingen - akkerbouw - gewasopbrengst - oogsttoename - duurzaamheid (sustainability) - potatoes - demonstrations - agricultural shows - arable farming - crop yield - yield increases - sustainability
    Op 22 augustus 2012 zal de Aardappeldemodag te Westmaas weer plaatsvinden. In deze tiende editie staat het thema 'Duurzaam naar topopbrengst' centraal.
    Rijenbemesting in relatie tot schilkwaliteit tafelaardappelen, 2010
    Slabbekoorn, J.J. - \ 2011
    Lelystad : PPO AGV - 41
    akkerbouw - aardappelen - precisielandbouw - bemesting - kwaliteit na de oogst - schillen - kaliummeststoffen - magnesiummeststoffen - teeltsystemen - teelt in rijen - rijenbemesting - arable farming - potatoes - precision agriculture - fertilizer application - postharvest quality - rinds - potassium fertilizers - magnesium fertilizers - cropping systems - alley cropping - band placement
    De consument wil een stabiele, goede kwaliteit verse aardappel gedurende het gehele seizoen. Met kwaliteit bedoelen we presentatie, inwendige kwaliteit, smaak en geschiktheid voor consumptietoepassing. Om op heterogene kleipercelen een homogener kwaliteitsproduct te telen kan precisielandbouw helpen, door plaatsspecifiek te bemesten, aaltjes en andere ziekten en plagen te bestrijden, plantafstanden te variëren, loofvernietiging toe te passen enz. We willen de effecten van een aantal bestaande en nieuwe teelt: en bemestingsadviezen beoordelen op resultaat en vervolgens vertalen naar een onderbouwd advies. Verschillende meststoffen kunnen een effect hebben op de schilkwaliteit. Ook de wijze van toediening van de meststoffen, breedwerpig of in de de rij, kan invloed hebben op schilkwaliteit of opbrengst. Als in de praktijk ook nog sprake is van (pleksgewijze) toediening van middelen tegen aaltjes of ritnaalden, wat is dan het effect van de combinatie van al deze middelen, meststoffen en wijze van toediening op groei van het gewas, opbrengst en (schil)kwaliteit?
    Dosering van drijfmest en vloeibare kunstmest in één werkgang met de zodebemester-PPL
    Holshof, G. ; Geel, W.C.A. van; Slabbekoorn, J.J. - \ 2011
    Lelystad : PPO AGV - 23
    bemesting - graslanden - bodeminjecteurs - landbouwtechniek - vloeibare meststoffen - drijfmest - precisielandbouw - fertilizer application - grasslands - soil injectors - agricultural engineering - liquid manures - slurries - precision agriculture
    In opdracht van Slootsmid en Landbouwcommunicatie BV hebben PPO-AGV en Wageningen Livestock Research een veldproef op grasland uitgevoerd om een door de opdrachtgever ontwikkelde mesttoedieningsmachine te testen op grasland. De ontwikkelde machine maakt het mogelijk om vloeibare kunstmeststoffen (N-houdende, maar ook andere) in één werkgang in combinatie met drijfmest toe te dienen. De machine wordt door de opdrachtgever als zodebemester-PPL aangeduid. Het bleek dat het goed mogelijk is om vloeibare kunstmeststof (inclusief spuiloog) in combinatie met drijfmest toe te dienen met de zodebemester-PPL, waarbij de dosering van de vloeibare kunstmest en de drijfmest afzonderlijk van elkaar kunnen worden ingesteld. Het was met de gebruikte machine niet mogelijk om grote hoeveelheden (>1,4 m3 per ha) van laag-geconcentreerde vloeibare N-meststoffen zoals mineralenconcentraat toe te dienen. Daarvoor zou de capaciteit van de pomp voor de vloeibare kunstmeststoffen (een slangenpomp) op de zodebemester-PPL moeten worden verhoogd.
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