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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‘Gemeenten moeten geen rode pen hanteren, maar open en faciliterend zijn’
Aalbers, Carmen - \ 2019
private sector - urban areas - urban society - initiation

Wur-onderzoek: hoe kunnen gemeenten groene bedrijfs- en burgerinitiatievenhelpen slagen?

User-documented food consumption data from publicly available apps: an analysis of opportunities and challenges for nutrition research
Maringer, Marcus ; Veer, P. van 't; Klepacz, Naomi ; Verain, M.C.D. ; Normann, Anne ; Ekman, Susanne ; Timotijevic, Lada ; Raats, Monique M. ; Geelen, M.M.E.E. - \ 2018
food consumption data - dietary intake assessment - diet apps - user-documented data - contextual data - technological innovations - data management - legal and ethical governance - research infrastructure
Background The need for a better understanding of food consumption behaviour within its behavioural context has sparked the interest of nutrition researchers for user-documented food consumption data collected outside the research context using publicly available nutrition apps. The study aims to characterize the scientific, technical, legal and ethical features of this data in order to identify the opportunities and challenges associated with using this data for nutrition research. Method A search for apps collecting food consumption data was conducted in October 2016 against UK Google Play and iTunes storefronts. 176 apps were selected based on user ratings and English language support. Publicly available information from the app stores and app-related websites was investigated and relevant data extracted and summarized. Our focus was on characteristics related to scientific relevance, data management and legal and ethical governance of user-documented food consumption data. Results Food diaries are the most common form of data collection, allowing for multiple inputs including generic food items, packaged products, or images. Standards and procedures for compiling food databases used for estimating energy and nutrient intakes remain largely undisclosed. Food consumption data is interlinked with various types of contextual data related to behavioural motivation, physical activity, health, and fitness. While exchange of data between apps is common practise, the majority of apps lack technical documentation regarding data export. There is a similar lack of documentation regarding the implemented terms of use and privacy policies. While users are usually the owners of their data, vendors are granted irrevocable and royalty free licenses to commercially exploit the data. Conclusion Due to its magnitude, diversity, and interconnectedness, user-documented food consumption data offers promising opportunities for a better understanding of habitual food consumption behaviour and its determinants. Non-standardized or non-documented food data compilation procedures, data exchange protocols and formats, terms of use and privacy statements, however, limit possibilities to integrate, process and share user-documented food consumption data. An ongoing research effort is required, to keep pace with the technical advancements of food consumption apps, their evolving data networks and the legal and ethical regulations related to protecting app users and their personal data.
Paper on quality criteria and overview of criteria applied to available data/methods - WP6 : deliverable D6.4
Raats, Monique ; Bartos, Sebastian ; Timotijevic, Lada ; Peacock, Matthew ; Hodgkins, Charo ; Touray, Morro ; Geelen, Anouk ; Maringer, Marcus ; Normann, Anne ; Verain, M.C.D. ; Zimmermann, K.L. ; Veer, P. van 't; Engberg Mikkelson, Bent - \ 2018
EU - 54 p.
Paper on quality criteria and overview of criteria applied to available data/methods - WP7 - User-documented food consumption data from publicly available apps: an analysis of opportunities and challenges for nutrition research : deliverable D7.4
Maringer, Marcus ; Veer, P. van 't; Klepacz, Naomi ; Verain, M.C.D. ; Normann, Anne ; Ekman, Susanne ; Timotijevic, Lada ; Raats, Monique ; Geelen, M.M.E.E. ; Zimmermann, K.L. - \ 2018
EU - 16 p.
Inventory of types of consumer-generated food preparation data and data collection methodologies : deliverable D6.1
Klepacz, Naomi ; Maringer, Marcus ; Ekman, Susanne ; Normann, Anne ; Geelen, M.M.E.E. ; Raats, Monique ; Zimmermann, K.L. ; Mikkelsen, Bent Egberg - \ 2018
EU - 19 p.
Report on gaps and needs - WP6, Report on the potentials and limitations for the use of user-generated domestic food preparation data to answer questions regarding determinants of nutrition and eating : deliverable D6.5
Klepacz, Naomi ; Maringer, Marcus ; Ekman, Susanne ; Normann, Anne ; Geelen, M.M.E.E. ; Raats, Monique ; Zimmermann, K.L. ; Veer, P. van 't; Mikkelsen, Bent Egberg - \ 2018
EU - 16 p.
Report on the Synthesis of the findings for WP5-7 : deliverable D4.2
Hodgkins, Charo ; Timotijevic, Lada ; Raats, Monique ; Normann, Anne ; Maringer, Marcus ; Klepacz, Naomi ; Zimmermann, K.L. ; Veer, P. van 't - \ 2018
EU - 25 p.
Position and final paper of RICHFIELDS : deliverable D1.2
Bogaardt, M.J. ; Copani, Giacomo ; Cueva, Javier de la; Finglas, Paul ; Geelen, M.M.E.E. ; Hodgkins, Charo ; Korousic, Barbara ; Mikkelsen, Bent ; Poppe, K.J. ; Pour Abdollahian, Golboo ; Puttelaar, J. van den; Raats, Monique ; Selnes, T. ; Timotijevic, Lada ; Veen, H.B. van der; Veer, P. van 't; Zimmermann, K.L. - \ 2018
EU - 49 p.
Designing a research infrastructure on dietary intake and its determinants
Bogaardt, M.J. ; Geelen, A. ; Zimmermann, K. ; Finglas, P. ; Raats, M.M. ; Mikkelsen, B.E. ; Poppe, K.J. ; van't Veer, P. - \ 2018
Nutrition Bulletin 43 (2018)3. - ISSN 1471-9827 - p. 301 - 309.
big data - consumers - diet - food - public health - research infrastructure

Research on dietary intake and its determinants is crucial for an adequate response to the current epidemic of diet-related non-communicable chronic diseases. In order to respond to this challenge, the RICHFIELDS project was tasked with designing a research infrastructure (RI) that connects data on dietary intake of consumers in Europe, and its determinants, collected using apps and wearable sensors, from behavioural laboratories and experimental facilities and from other RIs. The main output of the project, an RI design, describes interfaces (portals) to collect data, a meta-database and a data-model to enable data linkage and sharing. The RICHFIELDS project comprises three phases, each consisting of three work packages, and an overarching methodological support work package. Phase 1 focused on data generated by consumers (e.g. collected by apps and sensors) relating to the purchase, preparation and consumption of food. Phase 2 focused on data generated by organisations such as businesses (e.g. retail data), government (e.g. procurement data) and experimental research facilities (e.g. virtual supermarkets). Phases 1 and 2 provided Phase 3 with insights on data types and design requirements, including the business models, data integration and management systems and governance and ethics. The final design will be used in the coming years to build an RI for the scientific research community, policy makers and businesses in Europe. The RI will boost interdisciplinary multi-stakeholder research through harmonisation and integration of data on food behaviour.

User-documented food consumption data from publicly available apps : An analysis of opportunities and challenges for nutrition research
Maringer, Marcus ; Veer, Pieter van 't; Klepacz, Naomi ; Verain, Muriel C.D. ; Normann, Anne ; Ekman, Suzanne ; Timotijevic, Lada ; Raats, Monique M. ; Geelen, Anouk - \ 2018
Nutrition Journal 17 (2018). - ISSN 1475-2891
Contextual data - Data management - Diet apps - Dietary intake assessment - Food consumption data - Legal and ethical governance - Research infrastructure - Technological innovations - User-documented data

Background: The need for a better understanding of food consumption behaviour within its behavioural context has sparked the interest of nutrition researchers for user-documented food consumption data collected outside the research context using publicly available nutrition apps. The study aims to characterize the scientific, technical, legal and ethical features of this data in order to identify the opportunities and challenges associated with using this data for nutrition research. Method: A search for apps collecting food consumption data was conducted in October 2016 against UK Google Play and iTunes storefronts. 176 apps were selected based on user ratings and English language support. Publicly available information from the app stores and app-related websites was investigated and relevant data extracted and summarized. Our focus was on characteristics related to scientific relevance, data management and legal and ethical governance of user-documented food consumption data. Results: Food diaries are the most common form of data collection, allowing for multiple inputs including generic food items, packaged products, or images. Standards and procedures for compiling food databases used for estimating energy and nutrient intakes remain largely undisclosed. Food consumption data is interlinked with various types of contextual data related to behavioural motivation, physical activity, health, and fitness. While exchange of data between apps is common practise, the majority of apps lack technical documentation regarding data export. There is a similar lack of documentation regarding the implemented terms of use and privacy policies. While users are usually the owners of their data, vendors are granted irrevocable and royalty free licenses to commercially exploit the data. Conclusion: Due to its magnitude, diversity, and interconnectedness, user-documented food consumption data offers promising opportunities for a better understanding of habitual food consumption behaviour and its determinants. Non-standardized or non-documented food data compilation procedures, data exchange protocols and formats, terms of use and privacy statements, however, limit possibilities to integrate, process and share user-documented food consumption data. An ongoing research effort is required, to keep pace with the technical advancements of food consumption apps, their evolving data networks and the legal and ethical regulations related to protecting app users and their personal data.

Effects of loose housing and the provision of alternative nesting material on peri-partum sow behaviour and piglet survival
Bolhuis, J.E. ; Raats-van den Boogaard, A.M.E. ; Hoofs, A.I.J. ; Soede, N.M. - \ 2018
Applied Animal Behaviour Science 202 (2018). - ISSN 0168-1591 - p. 28 - 33.
Behaviour - Enrichment - Loose housing - Nest-building - Parturition - Sow
Sows are strongly motivated to perform nestbuilding behaviour before parturition. This behaviour is often restricted in commercial systems due to confinement of the sow and lack of suitable nesting material to be used on slatted floors. This study aimed to investigate effects of loose vs. crated housing and the provision of alternative nesting material on periparturient sow behaviour and piglet survival. In a 2 × 2 arrangement, sixty-eight sows were assigned to either loose housing or crates and were either or not provided with nesting material consisting of jute sacks and straw balls. All sows had a rope. Postures and manipulation of materials and pen were observed using 5 min scan sampling for the 12 h before and the 24 h after parturition. Behaviour during parturition was scored continuously and included nose-nose contact between sow and piglets and crushing incidences. No interactions between treatments were found. In the 12 h prepartum, loose housed sows showed less sitting (5 vs. 9%) and ventral lying (29 vs. 38%) and more lateral lying (33 vs. 23%) and floor manipulation (10 vs. 5%) than crated sows. During parturition, loose housed sows spent less time sitting (2 vs. 6%), had fewer postural changes (34 vs. 50), showed less fence manipulation (0.1 vs. 2%) and had more nose contact with piglets (56 vs. 19 times). Provision of nesting material increased pre-partum lying (63 vs. 57%), increased manipulation of materials (14 vs. 8%) and reduced manipulation of floor (5 vs. 10%) and fence (5 vs. 9%). During parturition, sows with nesting material showed less standing (6 vs. 10%) and more lying (90 vs. 84%). No effects were found on behaviour in the 24 h after parturition or on parturition duration (3.3 ± 0.1 h). During parturition, the times lying down and the number of piglets that died by crushing tended to be lower with provision of nesting material (0.1 vs. 0.3). In the 48 h after parturition, loose housed sows crushed more piglets. In conclusion, both loose housing and the provision of alternative nesting materials affected prepartum sow behaviour and resulted in less activity during parturition, with some tendencies for beneficial effects on (near-) crushing of piglets during this period. Thus, both loose housing and the provision of alternative nesting materials, likely particularly the jute sacks, have a beneficial effect on periparturient sow behaviour.
Report on gaps and needs : deliverable D7.5
Maringer, Marcus ; Ekman, Susanne ; Normann, Anne ; Klepacz, Naomi ; Raats, Monique ; Geelen, M.M.E.E. ; Zimmermann, K.L. ; Veer, P. van 't - \ 2017
EU
Inventory of types of purchase data and data collection methodologies for consumer generated food purchase data : deliverable D5.1
Ekman, Susanne ; Normann, Anne ; Baderstedt, Erik ; Klepacz, Naomi ; Maringer, Marcus ; Geelen, M.M.E.E. ; Verain, M.C.D. ; Raats, Monique ; Zimmermann, K.L. ; Veer, P. van 't - \ 2017
EU - 25 p.
Report on gaps and needs : deliverable D5.5
Normann, Anne ; Ekman, Susanne ; Maringer, Marcus ; Klepacz, Naomi ; Raats, Monique ; Geelen, M.M.E.E. ; Verain, M.C.D. ; Zimmermann, K.L. ; Veer, P. van 't - \ 2017
EU - 25 p.
Warmtedeken van oud-Wur-onderzoeker Van Lammeren tegen KBZ toont hoopvolle resultaten: Plevier (Prop Boomtechniek): na behandeling met de warmtedeken is de bacterie verdwenen
Lammeren, Andre van; Kuik, Fons van - \ 2017
Aging and changes in body composition
Asselt, D. van; Groot, C.P.G.M. de - \ 2017
In: Food for the Aging Population / Raats, Monique M., de Groot, Lisette C.P.G.M., van Asselt, Dieneke, Cambridge : Woodhead Publishing (Woodhead Publishing Series in Food Science, Technology and Nutrition ) - ISBN 9780081003480 - p. 171 - 184.
As we grow older changes in body composition occur. These changes include a loss of lean body mass (LBM), bone mass, body water, and a relative increase of fat mass. In view of these changes and acknowledging demographic trends, elder people are facing a growing burden of health-compromising levels of their weight, including underweight, overweight, and its combination. At all ages weight control is relevant, but in older people, it preferably occurs under professional guidance in view of the effect of body composition on mortality, morbidity, and functioning. Hereby, due attention needs to be given to the role of disease, physical activity, and other determinants of either weight gain or weight loss. For both a critical use of currently recommended cutoff points for BMI and WC is warranted in aging populations.
Food for the Aging Population
Raats, Monique ; Groot, C.P.G.M. de; Asselt, Dieneke van - \ 2017
Cambridge : Woodhead Publishing - ISBN 9780081003480 - 382 p.
Inventory of types of consumption data and data collection methodologies for consumer generated food purchase data : deliverable D7.1
Maringer, Marcus ; Ekman, Susanne ; Normann, Anne ; Klepacz, Naomi ; Verain, M.C.D. ; Raats, Monique ; Geelen, M.M.E.E. ; Zimmermann, K.L. ; Veer, P. van 't - \ 2016
EU - 30 p.
Development of a quality evaluation framework for consumer generated food consumption data : deliverable D7.3
Maringer, Marcus ; Klepacz, Naomi ; Ekman, Susanne ; Normann, Anne ; Raats, Monique ; Verain, M.C.D. ; Geelen, M.M.E.E. ; Zimmermann, K.L. ; Veer, P. van 't - \ 2016
EU - 26 p.
List of quality criteria - Development of a Quality Evaluation Framework for Consumer-Generated Domestic Food Preparation Data : deliverable D6.3
Klepacz, Naomi ; Maringer, Marcus ; Ekman, Susanne ; Normann, Anne ; Verain, M.C.D. ; Geelen, M.M.E.E. ; Raats, Monique ; Zimmermann, K.L. ; Veer, P. van 't; Mikkelsen, Bent Egberg - \ 2016
EU - 31 p.
Development of a quality evaluation framework for consumer generated food purchase data : deliverable D5.3
Normann, Anne ; Ekman, Susanne ; Klepacz, Naomi ; Maringer, Marcus ; Raats, Monique ; Geelen, M.M.E.E. ; Verain, M.C.D. ; Zimmermann, K.L. ; Veer, P. van 't - \ 2016
EU - 32 p.
Linked Data Sharing to Foster Consumer Based Science Enabled by Richfields : A Research Infrastructure on Consumer Health and Food
Zimmermann, K.L. ; Verain, M.C.D. ; Bogaardt, M.J. ; Geelen, Anouk ; Finglas, Paul ; Raats, Monique ; Mikkelsen, B.E. ; Poppe, K.J. - \ 2016
In: Proceedings of Measuring Behavior 2016. - - 7 p.
Groen strooizout kan inboet door beheerders laten kelderen
Claassen, Pieternel - \ 2016

Titel van krant of vakblad: Stad + Groen

Naam van de journalist(en): Santi Raats

Strooizout is een goed dooimiddel, maar het veroorzaakt verzilting van de bodem, het afsterven van planten en het roesten van metalen in bruggen, viaducten en voertuigen. Onderzoeker Pieternel Claassen van Food & Biobased Research werkt aan ‘groen’ strooizout, gemaakt uit biomassa

The pack size effect: Influence on consumer perceptions of portion sizes
Hieke, Sophie ; Palascha, Aikaterini ; Jola, Corinne ; Wills, Josephine ; Raats, Monique M. - \ 2016
Appetite 96 (2016). - ISSN 0195-6663 - p. 225 - 238.
Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While it is not possible to generalize consumer behaviour across cultures, external cues taken from pack size may affect us all. We thus examined whether pack sizes influence portion size estimates across cultures, leading to a general 'pack size effect'. We compared portion size estimates based on digital presentations of different product pack sizes of solid and liquid products. The study with 13,177 participants across six European countries consisted of three parts. Parts 1 and 2 asked participants to indicate the number of portions present in a combined photographic and text-based description of different pack sizes. The estimated portion size was calculated as the quotient of the content weight or volume of the food presented and the number of stated portions. In Part 3, participants stated the number of food items that make up a portion when presented with packs of food containing either a small or a large number of items. The estimated portion size was calculated as the item weight times the item number. For all three parts and across all countries, we found that participants' portion estimates were based on larger portions for larger packs compared to smaller packs (Part 1 and 2) as well as more items to make up a portion (Part 3); hence, portions were stated to be larger in all cases. Considering that the larger estimated portions are likely to be consumed, there are implications for energy intake and weight status.
Country Differences in the History of Use of Health Claims and Symbols
Hieke, Sophie ; Kuljanic, Nera ; Fernandez, Laura ; Lähteenmäki, Liisa ; Stancu, Violeta ; Raats, Monique ; Egan, Bernadette ; Brown, Kerry ; Trijp, Hans van; Kleef, Ellen van; Herpen, Erica van; Gröppel-Klein, Andrea ; Leick, Stephanie ; Pfeifer, Katja ; Verbeke, Wim ; Hoefkens, Christine ; Smed, Sinne ; Jansen, Léon ; Laser-Reuterswärd, Anita ; Korošec, Živa ; Pravst, Igor ; Kušar, Anita ; Klopčič, Marija ; Pohar, Jure ; Gracia, Azucena ; Magistris, Tiziana ; Grunert, Klaus - \ 2016
European Journal of Nutrition & Food Safety 6 (2016)3. - ISSN 2347-5641 - p. 148 - 168.
Health-related claims and symbols are intended as aids to help consumers make informed and healthier food choices but they can also stimulate the food industry to develop food that goes hand in hand with a healthier lifestyle. In order to better understand the role that health claims and symbols currently have and in the future potentially can have, the objective of the CLYMBOL project (“Role of health-related claims and symbols in consumer behaviour”, Grant no 311963) is to investigate consumers’ understanding of health claims and symbols, and how they affect purchasing and consumption [1].

As part of this endeavour, it is important to understand the history of use of claims and symbols in Europe. What have consumers been exposed to and how were these health-related messages used and discussed among the public? In this study, we interviewed key stakeholders across Europe about how health claims have been regulated in their country, how health symbols have been and currently are being treated, what form of monitoring there is or should be and how both health claims and symbols have been debated in the public opinion. In 26 European Union (EU) Member States, opinions from 53 key informants from up to three different stakeholder groups were gathered: national food authorities, representatives of the food industry, and consumer organisations.

While 14 Member States reported (at least partial) regulation of the use of health claims and/or symbols before the introduction of the EU Regulation (EC 1924/2006) on nutrition and health claims made on foods [2], mandatory reporting of use had only been in place in three EU Member States. A number of voluntary codes of practice for health claims and/or symbols (i.e. pre-approval or justification when challenged) was said to be in use in 15 Member States. There are only a few national databases on health claims and symbols available, the data for which is often incomplete. Only eight Member States reported having some form of database from which information about health claims and symbols could be extracted. The stakeholders interviewed expressed a strong interest in measuring the impact of health claims and symbols, particularly research into the effects on consumer behaviour (e.g. awareness and understanding, attitudes towards products carrying claims and symbols and purchase/consumption effects), public health (health outcomes and changes in national health status due to the introduction of claims and symbols on food products) and economic aspects including sales, return on investment and reputation measurements. Public debates were said to have evolved around the topics of consumer understanding of claims, acceptance as well as trust in the information presented but also the effects on vulnerable groups such as children and elderly consumers. Another field of debate was said to have been the question of the effectiveness of health claims and symbols. Lastly, stakeholders reported that public debates focussed mainly on the legislative aspects, i.e. how to apply the EU Regulation (No 1924/2006) with regards to wording issues, the evaluation process at the European Food Safety Authority (EFSA), the status of various claims and the nutrient profile modelling to be introduced in Europe.
Implications and application of the Raats superclass of soils equations
Heinen, Marius ; Bakker, Gerben - \ 2016
Vadose Zone Journal 15 (2016)8. - ISSN 1539-1663 - 12 p.

According to the Richards equation, the capacity of a soil to hold and conduct water is determined by the water retention and hydraulic conductivity characteristics. Many mathematical relationships have been proposed in the literature to describe these characteristics. Raats introduced a general functional relationship with only four parameters that included as special cases four pre-1990 models found in the literature, including the well-known relationships by Mualem-van Genuchten and Brooks and Corey. The aims of this study were (i) to discuss this general functional relationship and its four special cases, (ii) to present expressions for the differential moisture capacity, water diffusivity, and matric flux potential corresponding to the general functional relationship and its special cases, (iii) to discuss methods for determining the parameter elasticity and sensitivity, and (iv) to apply the Raats model to experimental data. Soil water retention and hydraulic conductivity data for 11 soils were used to optimize the values of the four major parameters in the Raats model. In none of the cases did the optimized coefficients indicate that the Raats model approached one of the four submodels that it includes.

Groen strooizout kan inboet door beheerders laten kelderen
Claassen, Pieternel - \ 2016
public green areas - pavements - roads - salt - salt injury - brine - salinization - biomass - biobased economy - agricultural research - biobased chemicals - environmental impact - pollution control

Strooizout is een goed dooimiddel, maar het veroorzaakt verzilting van de bodem, het afsterven van planten en het roesten van metalen in bruggen, viaducten en voertuigen. Onderzoeker Pieternel Claassen van Food & Biobased Research werkt aan ‘groen’ strooizout, gemaakt uit biomassa. Zouden we in de nabije toekomst afscheid kunnen nemen van de jaarlijkse hoge inboet van openbaar groen ten gevolge van schade door strooizout?

The role of health-related claims and health-related symbols in consumer behaviour : Design and conceptual framework of the CLYMBOL project and initial results
Hieke, S. ; Kuljanic, N. ; Wills, J.M. ; Pravst, I. ; Kaur, A. ; Raats, M.M. ; Trijp, H.C.M. van; Verbeke, W. ; Grunert, K.G. - \ 2015
Nutrition Bulletin 40 (2015)1. - ISSN 1471-9827 - p. 66 - 72.
Consumer behaviour - Food choice - Food labelling - Health claim - Health symbols

Health claims and symbols are potential aids to help consumers identify foods that are healthier options. However, little is known as to how health claims and symbols are used by consumers in real-world shopping situations, thus making the science-based formulation of new labelling policies and the evaluation of existing ones difficult. The objective of the European Union-funded project Role of health-relatedCLaimsandsYMBOLsin consumer behaviour (CLYMBOL) is to determine how health-related information provided through claims and symbols, in their context, can affect consumer understanding, purchase and consumption. To do this, a wide range of qualitative and quantitative consumer research methods are being used, including product sampling, sorting studies (i.e. how consumers categorise claims and symbols according to concepts such as familiarity and relevance), cross-country surveys, eye-tracking (i.e. what consumers look at and for how long), laboratory and in-store experiments, structured interviews, as well as analysis of population panel data. EU Member States differ with regard to their history of use and regulation of health claims and symbols prior to the harmonisation of 2006. Findings to date indicate the need for more structured and harmonised research on the effects of health claims and symbols on consumer behaviour, particularly taking into account country-wide differences and individual characteristics such as motivation and ability to process health-related information. Based on the studies within CLYMBOL, implications and recommendations for stakeholders such as policymakers will be provided.

De Es mag niet weg! Onderzoek essenresistentie: nu sector en gebruiker aan zet
Raats, S. ; Kuik, A.J. van; Hiemstra, J.A. - \ 2013
Boom in business 2013 (2013)7. - ISSN 2211-9884 - p. 22 - 24.
fraxinus - straatbomen - genetische bronnen van plantensoorten - rassen (planten) - cultivars - klonen - plantenvermeerdering - boomkwekerijen - resistentie van variëteiten - plantenziekten - chalara fraxinea - street trees - plant genetic resources - varieties - clones - propagation - forest nurseries - varietal resistance - plant diseases
Op de Nederlandse Boominfodag 2012 maakte Jitze Kopinga bekend dat het WUR-CGN (Het Centrum voor Genetische Bronnen Nederland) een aantal redelijk resistente essenklonen bezit en dat de Wageningen Universiteit deze klonen vrijgeeft voor vermeerdering door kwekers. In november bezocht Kopinga in Vilnius een Europese projectbijeenkomst op het gebied van onderzoek naar essentaksterfte. Alle belangrijke onderzoekers in Europa waren daar aanwezig. Als het aan Kopinga ligt, overleeft de es met verve.'Maar dan moeten de sector en de gebruikers wel inzetten op vertrouwen', aldus de onderzoeker.
Effects of nutrition label format and product assortment on the healthfulness of food choice
Aschemann-Witzel, J. ; Grunert, K.G. ; Trijp, H.C.M. van; Bialkova, S.E. ; Raats, M.M. ; Hodgkins, C. ; Wasowicz-Kirylo, G. ; Koenigstorfer, J. - \ 2013
Appetite 71 (2013). - ISSN 0195-6663 - p. 63 - 74.
front-of-pack - information - consumers - impact - purchases - attention
This study aims to find out whether front-of-pack nutrition label formats influence the healthfulness of consumers’ food choices and important predictors of healthful choices, depending on the size of the choice set that is made available to consumers. The predictors explored were health motivation and perceived capability of making healthful choices. One thousand German and Polish consumers participated in the study that manipulated the format of nutrition labels. All labels referred to the content of calories and four negative nutrients and were presented on savoury and sweet snacks. The different formats included the percentage of guideline daily amount, colour coding schemes, and text describing low, medium and high content of each nutrient. Participants first chose from a set of 10 products and then from a set of 20 products, which was, on average, more healthful than the first choice set. The results showed that food choices were more healthful in the extended 20-product (vs. 10-product) choice set and that this effect is stronger than a random choice would produce. The formats colour coding and texts, particularly colour coding in Germany, increased the healthfulness of product choices when consumers were asked to choose a healthful product, but not when they were asked to choose according to their preferences. The formats did not influence consumers’ motivation to choose healthful foods. Colour coding, however, increased consumers’ perceived capability of making healthful choices. While the results revealed no consistent differences in the effects between the formats, they indicate that manipulating choice sets by including healthier options is an effective strategy to increase the healthfulness of food choices.
EURRECA-principles and future for deriving micronutrient recommendations
Claessens, M.M.A.E. ; Contor, L. ; Dhonukshe-Rutten, R.A.M. ; Groot, C.P.G.M. de; Fairweather-Tait, S. ; Gurinovic, M. ; Koletzko, B. ; Ommen, B. van; Raats, M.M. ; Veer, P. van 't - \ 2013
Critical Reviews in Food Science and Nutrition 53 (2013)10. - ISSN 1040-8398 - p. 1135 - 1146.
The EURopean micronutrient RECommendations Aligned (EURRECA) Network of Excellence (NoE) explored an approach for setting micronutrient recommendations, which would address the variation in recommendations across Europe. Therefore, a framework for deriving and using micronutrient Dietary Reference Values (DRVs) has been developed. This framework comprises four stages (defining the problem-monitoring and evaluating-deriving dietary reference values-using dietary -reference values in policy making). The aim of the present paper is to use this framework to identify specific research gaps and needs related to (1) knowledge available on specific micronutrients (folate, iodine, iron, selenium, vitamin B12, vitamin D, and zinc) and (2) the methodology presented in the framework. Furthermore, the paper describes the different outputs that support the process like protocols, guidelines, systematic review databases, and peer-reviewed publications, as well as the principal routes of dissemination of these outputs to ensure their optimal uptake in policy, practice, and research collaborations. The importance of ensuring transparency in risk assessment and risk management, systematic searching the literature, and taking into account policy options is highlighted
EURRECA-Evidence-Based methodology for deriving micronutrient recommendations
Dhonukshe-Rutten, R.A.M. ; Bouwman, J.H. ; Brown, K. ; Cavelaars, A.J.E.M. ; Collings, R. ; Grammatikaki, E. ; Groot, C.P.G.M. de; Gurinovic, M. ; Harvey, L.J. ; Hermoso, M. ; Hurst, R. ; Kremer, B. ; Ngo, J. ; Novakovic, R.N. ; Raats, M.M. ; Rollin, F. ; Serra-Majem, L. ; Souverein, O.W. ; Timotijevic, L. ; Veer, P. van 't - \ 2013
Critical Reviews in Food Science and Nutrition 53 (2013)10. - ISSN 1040-8398 - p. 999 - 1040.
dietary assessment methods - nutrient intake adequacy - nutrition policy - intake values - consumption surveys - pregnant-women - europe - health - food - patterns
The EURopean micronutrient RECommendations Aligned (EURRECA) Network of Excellence explored the process of setting micronutrient recommendations to address the variance in recommendations across Europe. Work centered upon the transparent assessment of nutritional requirements via a series of systematic literature reviews and meta-analyses. In addition, the necessity of assessing nutritional requirements and the policy context of setting micronutrient recommendations was investigated. Findings have been presented in a framework that covers nine activities clustered into four stages: stage one “Defining the problem” describes Activities 1 and 2: “Identifying the nutrition-related health problem” and “Defining the process”; stage two “Monitoring and evaluating” describes Activities 3 and 7: “Establishing appropriate methods,” and “Nutrient intake and status of population groups”; stage three “Deriving dietary reference values” describes Activities 4, 5, and 6: “Collating sources of evidence,” “Appraisal of the evidence,” and “Integrating the evidence”; stage four “Using dietary reference values in policy making” describes Activities 8 and 9: “Identifying policy options,” and “Evaluating policy implementation.” These activities provide guidance on how to resolve various issues when deriving micronutrient requirements and address the methodological and policy decisions, which may explain the current variation in recommendations across Europe
EURRECA—Framework for Aligning Micronutrient Recommendations
Veer, P. van 't; Grammatikaki, E. ; Matthys, C. ; Raats, M.M. ; Contor, L. - \ 2013
Critical Reviews in Food Science and Nutrition 53 (2013)10. - ISSN 1040-8398 - p. 988 - 998.
nutrition - requirements - challenges - phenotype - alignment - evaluate - biology - network - europe - health
There is currently no standard approach for deriving micronutrient recommendations, and large variations exist across Europe, causing confusion among consumers, food producers, and policy makers. More aligned information could influence dietary behaviors and potentially lead to a healthier population. Funded by the European Commission, EURRECA (EURopean micronutrient RECommendations Aligned) has developed methods and applications to guide Nutrient Recommendation Setting Bodies through the process of setting micronutrient reference values. The EURRECA approach is crystallized into its framework that outlines a standard process for deriving and using dietary reference values for micronutrients in a transparent, systematic, and scientific way. The 9 activities of the framework can be clustered into four stages (i) defining the problem, (ii) monitoring and evaluating, (iii) deriving dietary reference values, and (iv) using dietary reference values in policy making. The EURRECA framework should not be interpreted as a prescriptive description of a linear process, but as a structured guide for checking that all issues essential for deriving requirements have at least been considered.
EURRECA/WHO Workshop report: "Deriving micronutrient recommendations: updating best practices"
Veer, P. van 't; Heseker, H. ; Grammatikaki, E. ; Benetou, V. ; Gregoric, M. ; Margaritis, I. ; Raats, M.M. ; Wijnhoven, T.M.A. - \ 2013
Annals of Nutrition & Metabolism 62 (2013)1. - ISSN 0250-6807 - p. 63 - 67.
This paper describes the outcome of the workshop ‘Deriving Micronutrient Recommendations: Updating Best Practices’ which took place in Brussels in April 2012. The workshop was organised jointly by the European Micronutrient Recommendations Aligned (EURRECA) Network of Excellence and the World Health Organization (WHO) Regional Office for Europe. The delegates included, among others, representatives from nutrient recommendation setting bodies (NRSBs) across Europe. The current paper focuses on the gaps and needs of NRSBs as identified by the workshop participants: (i) practical tools and best practices to adapt dietary reference values, (ii) comparable nationally representative food consumption data (including updated and complete food composition databases), (iii) adequate financial resources and technical capacity, (iv) independence and transparency in expert selection, research conduct and communication of research results and (v) clear correspondence of terminology used at national levels.
Hoop doet leven voor de essentaksterfte
Raats, S. ; Kuik, A.J. van - \ 2012
Boom in business 2012 (2012)10. - ISSN 2211-9884 - p. 48 - 49.
rassen (planten) - cultivars - plantenziekten - plagenbestrijding - schimmelziekten - plantenveredelingsmethoden - landbouwkundig onderzoek - proeven - genetische bronnen - chalara fraxinea - varieties - plant diseases - pest control - fungal diseases - plant breeding methods - agricultural research - trials - genetic resources
Op zijn website van Arconox heeft Thale Roosien een voorjaarsartikel uit Baumzeitung geplaatst dat resultaten laat zien in verschil in vatbaarheid tussen verschillende klonen van Fraxinus excelsior. Hoop doet leven, volgens hem. We moeten niet teveel doemdenken over de essentaksterfte. Is er goede hoop?
Grote voordelen van vrijlopende zeug en nestmateriaal; Droomkraamhok
Lamers, J. ; Soede, N.M. ; Raats, A. ; Hoofs, A.I.J. - \ 2011
Varkens 75 (2011)12. - ISSN 0166-5952 - p. 12 - 13.
varkenshouderij - biggen - kraamhokken - ontwerp - dierenwelzijn - pig farming - piglets - farrowing pens - design - animal welfare
De Prodromi-kraamhokken lijken het gedroomde kraamhok voor zeug, big en ondernemer. Met name de Prodromi II, waar de zeugen vrij rondlopen, biedt zeug en biggen rondom het werpen alleen maar voordelen. De zeug is veel rustiger, onder andere door het aanwezige nestmateriaal. De bewegingsvrijheid stimuleert het werpen en er is veel meer contact tussen zeug en biggen
The matrix flux potential: history and root water uptake
Heinen, Marius - \ 2011
Kastanjebloedingsziekte : het vervolg : samenwerking is het credo uit de mond van betrokkenen
Raats, K. ; Kuik, A.J. van - \ 2011
Boomzorg 4 (2011)6. - p. 14 - 17.
aesculus - hippocastanaceae - houtachtige planten als sierplanten - plantenziekteverwekkende bacteriën - stadsomgeving - boomverzorging - beleid - samenwerking - ornamental woody plants - plant pathogenic bacteria - urban environment - tree care - policy - cooperation
Afgelopen maand sprak Boomzorg bezorgde boombeheerders uit Utrecht en Ridderkerk. In de laatste gemeente werd in een jaar tijd 30 procent van de kastanjes gekapt, ondanks dat het breed werd aangenomen dat de ziekte minder agressief was of zich niet meer uitbreidde. Is er een vergelijkend ziektebeeld in de twee grootste steden van Nederland? En zo ja, hoe worden ze beheerd?
Analysis of the thickness of a fresh water lens and of the transition zone
Eeman, S. ; Leijnse, A. ; Raats, P.A.C. ; Zee, S.E.A.T.M. van der - \ 2011
Advances in Water Resources 34 (2011)2. - ISSN 0309-1708 - p. 291 - 302.
geohydrologie - watervoerende lagen - zoet water - zout water - delta's - geohydrology - aquifers - fresh water - saline water - deltas - submarine groundwater discharge - porous-media - coastal aquifer - brine transport - barrier-island - interface - flow - infiltration - dispersion - intrusion
In regions with saline groundwater, fresh water lenses may develop due to rainwater infiltration. The amount of fresh water that is available for e.g. agricultural crops depends on the thickness of the lens and the extent of mixing between fresh and saline water. In this paper, we consider the mixing of fresh water and upward moving saline ground water in low-lying deltaic areas. The parameters that dominate the flow and transport problem are investigated using dimensionless groups and scaled sensitivities. We characterize the numerically simulated thicknesses of the lens and of the mixing zone by spatial moments. Rayleigh number and mass flux ratio, which is the ratio of the salt water seepage and the precipitation, determine the thickness of the fresh water lens. The local thickness of the mixing zone is mainly influenced by the dispersive/diffusive groups and the mass flux ratio. In addition, convergence of streamlines towards an outflow boundary affects the thickness, particularly in the vicinity of this boundary. Analytical and numerical steady state solutions for lens thickness are compared, taking into account upward seepage, for the two cases with and without a density difference between lens and underlying groundwater. Agreement between the numerical and analytical solutions for the lens thickness is good except when the mass flux ratio becomes small. For zero mass flux ratio, it is implicitly assumed in the analytical solution that salt water is stagnant, and that is unrealistic. Relative contributions of longitudinal and transversal hydrodynamic dispersion and diffusion to the thickness of the mixing zone are quantified numerically for different phases of lens formation. Longitudinal dispersion dominates in the early stages of lens formation, while diffusion and transversal dispersion dominate at steady state
The process of setting micronutrient recommendations: a cross-European comparison of nutrition-related scientific advisory bodies
Timotijevic, L. ; Barnett, J. ; Brown, K. ; Shepherd, R. ; Fernandez-Celemin, L. ; Domolki, L. ; Ruprich, J. ; Dhonukshe-Rutten, R.A.M. ; Sonne, A.M. ; Hermoso, M. ; Koletzko, B. ; Frost-Andersen, L. ; Timmer, A. ; Raats, M.M. - \ 2011
Public Health Nutrition 14 (2011)4. - ISSN 1368-9800 - p. 716 - 728.
folic-acid - health-policy - risk - science - perspectives - expertise - politics - context - trial
Objective - To examine the workings of the nutrition-related scientific advisory bodies in Europe, paying particular attention to the internal and external contexts within which they operate. Design - Desk research based on two data collection strategies: a questionnaire completed by key informants in the field of micronutrient recommendations and a case study that focused on mandatory folic acid (FA) fortification. Setting - Questionnaire-based data were collected across thirty-five European countries. The FA fortification case study was conducted in the UK, Norway, Denmark, Germany, Spain, Czech Republic and Hungary. Results - Varied bodies are responsible for setting micronutrient recommendations, each with different statutory and legal models of operation. Transparency is highest where there are standing scientific advisory committees (SAC). Where the standing SAC is created, the range of expertise and the terms of reference for the SAC are determined by the government. Where there is no dedicated SAC, the impetus for the development of micronutrient recommendations and the associated policies comes from interested specialists in the area. This is typically linked with an ad hoc selection of a problem area to consider, lack of openness and transparency in the decisions and over-reliance on international recommendations. Conclusions - Even when there is consensus about the science behind micronutrient recommendations, there is a range of other influences that will affect decisions about the policy approaches to nutrition-related public health. This indicates the need to document the evidence that is drawn upon in the decisions about nutrition policy related to micronutrient intake
Tilia zorgt voor hommeles (interview met Cornelissen & Sondeijker)
Raats, K. ; Cornelissen, B. ; Sondeijker, J. - \ 2010
Boomzorg 2010 (2010)juli. - p. 34 - 35.
bombus - apidae - energiebehoeften - tilia tomentosa - tilia - bomen - concurrentie tussen dieren - doodsoorzaken - biologische mededinging - energy requirements - trees - animal competition - causes of death - biological competition
In de zeventiende eeuw stond voor bijenhouders het advies al op schrift: ‘breng uw bijen niet naar lindes!’ Maar nog altijd zien boombeheerders ieder jaar het verschijnsel dat met name hommels massaal de dood vinden onder de lindeboom.
The nutritional requirements of infants. Towards EU alignment of reference values: the EURRECA network
Hermoso, M. ; Tabacchi, G. ; Iglesia-Altaba, I. ; Bel-Serrat, S. ; Moreno-Aznar, L.A. ; Garcia-Santos, Y. ; Rosario Garcia-Luzardo, M. Del; Santana-Salguero, B. ; Pena-Quintana, L. ; Serra-Majem, L. ; Hall Moran, V. ; Dykes, F. ; Decsi, T. ; Benetou, V. ; Plada, M. ; Trichopoulou, A. ; Raats, M.M. ; Doets, E.L. ; Berti, C. ; Cetin, I. ; Koletzko, B. - \ 2010
Maternal and Child Nutrition 6 (2010)2. - ISSN 1740-8695 - p. 55 - 83.
breast-fed infants - nutrient intake values - vitamin-d deficiency - espghan committee - human-milk - complementary foods - randomized intervention - cobalamin status - iron-deficiency - drinking-water
This paper presents a review of the current knowledge regarding the macro- and micronutrient requirements of infants and discusses issues related to these requirements during the first year of life. The paper also reviews the current reference values used in European countries and the methodological approaches used to derive them by a sample of seven European and international authoritative committees from which background scientific reports are available. Throughout the paper, the main issues contributing to disparities in micronutrient reference values for infants are highlighted. The identification of these issues in relation to the specific physiological aspects of infants is important for informing future initiatives aimed at providing standardized approaches to overcome variability of micronutrient reference values across Europe for this age group.
EURRECA's General Framework to make the process of setting up micronutrient recommendations explicit and transparent
Dhonukshe-Rutten, R.A.M. ; Timotijevic, L. ; Cavelaars, A.J.E.M. ; Wit, L.S. de; Doets, E.L. ; Raats, M.M. ; Tabacchi, G. ; Wijnhoven, T.M.A. ; Roman, B. ; La Cruz, J.N. De; Gurinovic, M. ; Groot, C.P.G.M. de; Veer, P. van 't - \ 2010
Proceedings of the Nutrition Society 69 (2010). - ISSN 0029-6651 - p. E34 - E34.
EURRECA is a Network of Excellence with the objective of addressing the problem of national variations in micronutrient recommendations and working towards a framework of advice to better inform policy-makers. It became apparent that the network needed a framework that puts the process of recommendation setting in the context of science, policy and society. Although variability in recommendations originates from the scientific evidence-base used and its interpretation (e.g. health outcomes, types and methods of evaluation of evidence, quantification of risk/benefit), the background information provided in the recommendation reports does not easily facilitate the disentangling of the relative contribution of these different aspects because of lack of transparency. The present report portrays the general framework (see Figure) that has been developed by and for EURRECA in order to make the process of setting up micronutrient recommendations explicit and transparent. Low resolution version High resolution version In explaining the link from science to policy applications, the framework distinguishes four principal components or stages (see Figure). These stages are: a) Defining the nutrient requirements: A judgement about the (best) distribution(s) of the population requirement is necessary for estimating nutrient requirements. Many assumptions need to be made about the attributes of the population group. Furthermore, several factors (consumer behaviour as well as physiology) are to be included to characterize optimal health. b) Setting the nutrient recommendations: All available evidence is needed to formulate recommendations. Incorporating different endpoints provide the basis to formulate an optimal diet in terms of (non-)nutrients and food(group)s. c) Policy options: Policy options should be formulated on how the optimal diet can be achieved. They concern the advice of scientist and/or expert committees to the policy makers. Current policy options are setting up a task force, food based dietary guidelines, general health education, educational programme for specific group(s), voluntary or mandatory fortification, labelling, supplementation (general or for specific groups), inducing voluntary action in industry, legislation on micronutrient composition in food products, fiscal change, monitoring and evaluation of intake (via food consumption surveys) and/or nutritional status. d) Policy applications: Policies and planning, usually done by government, that lead to nutritional interventions or programmes. They usually require consideration of scientific, legal, regulatory, ethical and cultural issues, economic implications, and political and social priorities. This framework illustrates three dimensions of the process of setting (micro)nutrient requirements: 1) The logical sequence of scientific thinking from setting physiological requirements for nutritional health leading to evidence-based derivation of Nutrient Intake Values. 2) In the early stages nutritional and epidemiological science is the dominant source and in the later stages evidence from consumer and social sciences as well as stakeholder influences is used in deriving the options for changing the distribution of nutrient intakes. 3) The wider socio-political context: a feedback loop between health perception, actual health and food intake exists and is directly affected by the food industry and many other stakeholders. Moreover, from the viewpoint of policymakers, there are concerns for health promotion and disease prevention because of population health indices, costs of health care, and economic interests in the agro-food sector. In conclusion: A systematic approach for development and regular review of micronutrient requirements in Europe, transparently based on scientific evidence and best practices, enables national and international authorities/bodies to use the best available information obtained through evidence-based nutrition and accomplish well-considered food policy. Funded by an EU FP6 Network of Excellence (EURRECA, grant no. FP 6–036196-2). G. T. performed part of the work under a short-term contract for WHO Europe.
European micronutrient recommendations aligned: a general framework developed by EURRECA
Dhonukshe-Rutten, R.A.M. ; Timotijevic, L. ; Cavelaars, A.J.E.M. ; Raats, M.M. ; Wit, L.S. de; Doets, E.L. ; Roman, B. ; Ngo-de la Cruz, J. ; Gurinovic, M. ; Groot, C.P.G.M. de; Veer, P. van 't - \ 2010
In: 3rd European Public Health Conference, Amsterdam, The Netherlands, 10 - 13 November, 2010. - - p. 125 - 125.
In Europe, micronutrient recommendations have been established by (inter)national committees of experts and are used by public health-policy decision makers to monitor and assess the adequacy of the diets of population groups. Current micronutrient recommendations are, however, heterogeneous, whereas the scientific basis for this is not obvious. Alignment of setting micronutrient recommendations is necessary to improve the transparency of the process, the objectivity and reliability of recommendations that are derived by diverse regional and (inter)national bodies. Objective: To align transparent decision making for evidence-based policy making, stakeholder involvement and alignment of policies across Europe. Results: The General Framework as proposed by Eurreca envisions the derivation of nutrient recommendations as scientific methodology, embedded in a policy-making process that also includes consumer issues, and acknowledges the influences of the wider sociopolitical context by distinguishing the principal components of the framework: (a) defining the nutrient requirements for health, (b) setting nutrient recommendations, (c) policy options and (d) policy applications. Conclusion: The General Framework can serve as a basis for a systematic and transparent approach to the development and review of micronutrient requirements in Europe, as well as the decision making of scientific advisory bodies, policy makers and stakeholders involved in this process of assessing, developing and translating these recommendations into public health nutrition policy.
European micronutrient recommendations aligned: a general framework developed by Eurreca
Dhonukshe-Rutten, R.A.M. ; Timotijevic, L. ; Cavelaars, A.J.E.M. ; Raats, M.M. ; Wit, L.S. de; Doets, E.L. ; Tabacchi, G. ; Roman, B. ; Ngo-de la Cruz, J. ; Gurinovic, M. ; Groot, C.P.G.M. de; Veer, P. van 't - \ 2010
European Journal of Clinical Nutrition 64 (2010)S2. - ISSN 0954-3007 - p. S2 - S10.
nutrient intake values - energy
Background: In Europe, micronutrient recommendations have been established by (inter)national committees of experts and are used by public health-policy decision makers to monitor and assess the adequacy of the diets of population groups. Current micronutrient recommendations are, however, heterogeneous, whereas the scientific basis for this is not obvious. Alignment of setting micronutrient recommendations is necessary to improve the transparency of the process, the objectivity and reliability of recommendations that are derived by diverse regional and (inter)national bodies. Objective: This call for alignment of micronutrient recommendations is a direct result of the current sociopolitical climate in Europe and uncovers the need for an institutional architecture. There is a need for evidence-based policy making, transparent decision making, stakeholder involvement and alignment of policies across Europe. Results: In this paper, we propose a General Framework that describes the process leading from assessing nutritional requirements to policy applications, based on evidence from science, stakeholder interests and the sociopolitical context. The framework envisions the derivation of nutrient recommendations as scientific methodology, embedded in a policy-making process that also includes consumer issues, and acknowledges the influences of the wider sociopolitical context by distinguishing the principal components of the framework: (a) defining the nutrient requirements for health, (b) setting nutrient recommendations, (c) policy options and (d) policy applications. Conclusion: The General Framework can serve as a basis for a systematic and transparent approach to the development and review of micronutrient requirements in Europe, as well as the decision making of scientific advisory bodies, policy makers and stakeholders involved in this process of assessing, developing and translating these recommendations into public health nutrition policy
Institutional contexts in which micronutrient reference values are developed across Europe
Timotijevic, L. ; Raats, M.M. ; Barnett, J. ; Brown, K. ; Fernandez, L. ; Domolki, L. ; Ruprich, J. ; Dhonukshe-Rutten, R.A.M. ; Sonne, A.M. ; Hermoso, M. ; Koletzko, B. ; Frost-Andersen, L. - \ 2010
Progress has been made towards a coherent public health nutrition policy across Europe; however this remains a challenge mainly due to the variety of public health nutrition (PHN) policy traditions between countries and the diversity in scientific bases used to inform policy(1) This is particularly apparent in the misalignment of micronutrient reference values (MRV) across European countries and regions(2). MRV often inform food and nutrition policies which are becoming an increasingly more important part of public health policies due to the burden associated with nutrition-related diseases. Desk research and a questionnaire completed by key informants were used to collect data relating to the processes used to develop current MRV in thirty-one European countries, employing methods reported previously(2). Data were collected on the process of scientific decision-making, including information on the transparency and openness of the process. Considerable diversity was observed across Europe in the institutional context and nutrition policy imperatives driving the process of developing MRV. In those countries that have an established tradition of PHN policy the presence of advisory bodies is seen as key in developing MRV and advising government departments charged with applying science into policy and practice. This position is partly predicated by the institutional context (whether there is a dedicated department in charge of public health and how it is linked with other departments, the diversity of bodies and organisations involved in setting the agendas and making decisions in PHN, the broader governance context etc.), the PHN tradition and the historical context. Although the implication for nutrition policy is that there is a dedicated scientific institution or basis that acts as policy advisor and consequently facilitates development of dedicated national-level nutrition policies, it raises the issue of the extent to which scientific advisory committees are open, transparent and inclusive in the process. It appears that there is a considerable divide in terms of the openness and transparency of the process between the countries with an emerging democracy and those with established and increasingly participatory governance structures; also, in the complexity of the governance system in charge of developing MRV and hence the extent to which these levels are specifically tailored to national needs. In those countries with a more developed institutional architecture, scientific advisory bodies appear to be more than just a source of technical and scientific advice, instead acting as a link between evidence and policy. In particular, the remaining question is to what extent this model of informing national level of PHN policy can service the policy imperatives and the needs of wider society for the development of PHN policy that includes the framing of a wider section of society. In addition, the selection of the advisory panel members is not always clear and could lead to MRV that are eminence rather than evidence based.
Soil sodicity as a result of periodical drought
Zee, S.E.A.T.M. van der; Shah, S.H.H. ; Uffelen, C.G.R. van; Raats, P.A.C. ; Ferro, N. dal - \ 2010
Agricultural Water Management 97 (2010)1. - ISSN 0378-3774 - p. 41 - 49.
irrigation - water - alkali
Soil sodicity development is a process that depends nonlinearly on both salt concentration and composition of soil water. In particular in hot climates, soil water composition is subject to temporal variation due to dry–wet cycles. To investigate the effect of such cycles on soil salinity and sodicity, a simple root zone model is developed that accounts for annual salt accumulation and leaching periods. Cation exchange is simplified to considering only Ca/Na exchange, using the Gapon exchange equation. The resulting salt and Ca/Na-balances are solved for a series of dry/wet cycles with a standard numerical approach. Due to the nonlinearities in the Gapon equation, the fluctuations of soil salinity that may be induced, e.g. by fluctuating soil water content, affect sodicity development. Even for the case that salinity is in a periodic steady state, where salt concentrations do not increase on the long term, sodicity may still grow as a function of time from year to year. For the longer term, sodicity, as quantified by Exchangeable Sodium Percentage (ESP), approaches a maximum value that depends on drought and inflowing water quality, but not on soil cation exchange capacity. Analytical approaches for the salinity and sodicity developing under such fluctuating regimes appear to be in good agreement with numerical approximations and are very useful for checking numerical results and anticipating changes in practical situations
General framework for EURRECA
Dhonukshe-Rutten, R.A.M. ; Timotijevic, L. ; Cavelaars, A.J.E.M. ; Wit, L.S. de; Doets, E.L. ; Raats, M.M. ; Tabacchi, G. ; Wijnhoven, T.M.A. ; Roman, B. ; Cruz, J. de la; Gurinovic, M. ; Groot, C.P.G.M. de; Veer, P. van 't - \ 2009
Food-drug interactions in older people
Witkamp, R.F. - \ 2008
In: Food for the Ageing Population / Raats, M., de Groot, C.P.G.M., van Staveren, W.A., London : Woodhead Publishing - ISBN 9781845691936 - p. 458 - 477.
As a general rule, the use of medication increases considerably with advancing years. In many cases, the elderly are using drugs for chronic and degenerative disease for longer periods of time. Polypharmacy, the combined use of several drugs, is generally regarded as a high risk, especially in a population that is already at risk because of various other factors. Not surprisingly, adverse drug reactions are a major problem in elderly persons and a common cause of admission to hospital. Compared to drug–drug interactions, the possible effects of food on drug actions or side-effects or, vice versa, the effects of drug use on (micro-)nutrient status are receiving far less attention. Drug-nutrient interactions can be bi-directional. The vast majority of the literature concentrates on the general mechanisms of food effects on drugs. By contrast, much less is known on the effects of drugs on micronutrient uptake, storage or elimination. Effects of medication on nutrient status are easily overlooked, as they generally develop slowly and may go together with other social, nutritional, clinical and other changes. It seems conceivable that drug-induced nutrient deficiencies are relatively more frequent in the elderly than in younger patients. This chapter discusses the most important examples and mechanisms of drug-nutrient interactions. Attention is also paid to general age-related changes in drug effects. In the elderly, dietary habits may change, food intake tends to decrease and requirements of macro- and micronutrients may be different. The use of medicinal preparations, including OTC products and food supplements is on average very high in the elderly population. The sparse systematic information that is available on drug-induced changes in nutrient status, for example B12 and D, is often limited to studies in younger people and comprise one drug at a time. It seems highly conceivable that drug-nutrient interactions are under-diagnosed in the elderly population and that there may be much more under the water line. This will be particularly true for specific groups such as frail elderly persons taking several drugs at a time, or persons having a low dietary intake. Health care professionals should be aware that an elderly person’s new symptoms can be attributable to an underlying drug–nutrient interaction.
Food for the ageing population
Raats, M.M. ; Groot, C.P.G.M. de; Staveren, W.A. van - \ 2008
London : Woodhead Publishing (Woodhead publishing in food science, technology and nutrition ) - ISBN 9781845691936 - 652
ouderenvoeding - ouderen - ouderdom - verouderen - elderly nutrition - elderly - old age - aging
The world’s ageing population is increasing and food professionals will have to address the needs of older generations more closely in the future. This unique volume reviews the characteristics of the ageing population as food consumers, the role of nutrition in healthy ageing and the design of food products and services for the elderly. Chapters in Part one discuss aspects of the elderly’s relationship with food such as appetite and ageing, ageing and sensory perception, food and satisfaction with life, and the social significance of meals. The second part of the book reviews the role of nutrition in extending functionality into later years, with chapters on topics such as undernutrition and conditions such as Alzheimer's disease, bone and joint health and eye-related disorders. Concluding chapters address the issues of food safety and the elderly, designing new foods and beverages for the ageing and nutrition education programmes.
How we will produce the evidence-based EURRECA toolkit to support nutrition and food policy
Ashwell, M. ; Lambert, J. ; Alles, M.S. ; Branca, F. ; Bucchini, L. ; Brzozowska, A. ; Groot, C.P.G.M. de; Dhonukshe-Rutten, R.A.M. ; Dwyer, J.T. ; Fairweather-Tait, S. ; Koletzko, B. ; Pavlovic, M. ; Raats, M.M. ; Serra-Majem, L. ; Smith, R. ; Ommen, B. van; Veer, P. van 't; Rosen, J. von; Pijls, L.T.J. - \ 2008
European Journal of Nutrition 47 (2008)1. - ISSN 1436-6207 - p. 2 - 16.
europe - recommendations - values - energy
Background There is considerable variation in the recommended micronutrient intakes used by countries within Europe, partly due to different methodologies and concepts used to determine requirements and different approaches used to express the recommendations. As populations become more mobile and multinational, and more traditional foods become available internationally, harmonised recommendations based on up to date science are needed. This was recognised by the European Commission's (EC) Directorate-General (DG) Research in their 2005 call for proposals for a Network of Excellence (NoE) on 'nutrient status and requirements of specific vulnerable population groups'. EURopean micronutrient RECommendations Aligned (EURRECA), which has 34 partners representing 17 European countries, started on its 5-year EC-funded programme in January 2007. The programme of work was developed over 2 years prior to submitting an application to the EC. The Network's first integrating Meeting (IM) held in Lisbon in April 2007, and subsequent consultations, has allowed further refinement of the programme. Aim This paper presents the rationale for the EURRECA Network's roadmap, which starts by establishing the status quo for devising micronutrient recommendations. The Network has the opportunity to identify previous barriers and then explore 'evidence-based' solutions that have not been available before to the traditional panels of experts. The network aims to produce the EURRECA 'toolkit' to help address and, in some cases, overcome these barriers so that it can be used by those developing recommendations. Results The status quo has been largely determined by two recent initiatives; the Dietary Reference Intake (DRI) reports from the USA and Canada and suggestions for approaches to international harmonisation of nutrient-based dietary standards from the United Nations University (UNU). In Europe, the European Food Safety Authority (EFSA) has been asked by the EC's Directorate-General for Health and Consumer Protection to produce values for micronutrient recommendations. Therefore, EURRECA will draw on the uniqueness of its consortium to produce the sustainable EURRECA toolkit, which will help make such a task more effective and efficient. Part of this uniqueness is the involvement in EURRECA of small and medium-sized enterprises (SMEs), consumer organisations, nutrition societies and other stakeholders as well as many scientific experts. The EURRECA toolkit will contain harmonised best practice guidance for a more robust science base for setting micronutrient recommendations. Hence, in the future, the evidence base for deriving nutrient recommendations will have greater breadth and depth and will be more transparent. Conclusions The EURRECA Network will contribute to the broader field of food and nutrition policy by encouraging and enabling the alignment of nutrient recommendations. It will do this through the development of a scientific toolkit by its partners and other stakeholders across Europe. This will facilitate and improve the formulation of micronutrient recommendations, based on transparently evaluated and quantified scientific evidence. The Network aims to be sustainable beyond its EC funding period.
Current micronutrient recommendations in Europe: towards understanding their differences and similarities
Doets, E.L. ; Wit, L.S. de; Dhonukshe-Rutten, R.A.M. ; Cavelaars, A.J.E.M. ; Raats, M.M. ; Timotijevic, L. ; Brzozowska, A. ; Wijnhoven, T.M.A. ; Pavlovic, M. ; Holm Totland, T. ; Andersen, L.F. ; Ruprich, J. ; Pijls, L.T.J. ; Ashwell, M. ; Lambert, J.P. ; Veer, P. van 't; Groot, C.P.G.M. de - \ 2008
European Journal of Nutrition 47 (2008)1. - ISSN 1436-6207 - p. 17 - 40.
nutrient intake values - nivs - energy
Background Nowadays most countries in Europe have established their own nutrient recommendations to assess the adequacy of dietary intakes and to plan desirable dietary intakes. As yet there is no standard approach for deriving nutrient recommendations, they may vary from country to country. This results in different national recommendations causing confusion for policy-makers, health professionals, industry, and consumers within Europe. EURRECA (EURopean micronutrient RECommendations Aligned) is a network of excellence funded by the European Commission (EC), and established to identify and address the problem of differences between countries in micronutrient recommendations. The objective of this paper is to give an overview of the available micronutrient recommendations in Europe, and to provide information on their origin, concepts and definitions. Furthermore this paper aims to illustrate the diversity in European recommendations on vitamin A and vitamin D, and to explore differences and commonalities in approaches that could possibly explain variations observed. Methods A questionnaire was developed to get information on the process of establishing micronutrient recommendations. These questionnaires were sent to key informants in the field of micronutrient recommendations to cover all European countries/regions. Also the latest reports on nutrient recommendations in Europe were collected. Standardisation procedures were defined to enable comparison of the recommendations. Recommendations for vitamin A and vitamin D were compared per sex at the ages 3, 9 months and 5, 10, 15, 25, 50 and 70 years. Information extracted from the questionnaires and reports was compared focusing on: (1) The concept of recommendation (recommended daily allowance (RDA), adequate intake (AI) or acceptable range), (2) The year of publication of the report (proxy for available evidence), (3) Population groups defined, (4) Other methodological issues such as selected criteria of adequacy, the type of evidence used, and assumptions made. Results Twenty-two countries, the World Health Organization (WHO)/the Food and Agriculture Organization of the United Nations (FAO) and the EC have their own reports on nutrient recommendations. Thirteen countries based their micronutrient recommendations on those from other countries or organisations. Five countries, WHO/FAO and the EC defined their own recommendations. The DACH-countries (Germany, Austria and Switzerland) as well as the Nordic countries (Norway, Sweden, Finland, Denmark and Iceland) cooperated in setting recommendations. Greece and Portugal use the EC and the WHO/FAO recommendations, respectively and Slovenia adopted the recommendations from the DACH-countries. Rather than by concepts, definitions, and defined population groups, variability appears to emerge from differences in criteria for adequacy, assumptions made and type of evidence used to establish micronutrient recommendations. Discussion The large variation in current micronutrient recommendations for population groups as illustrated for vitamin A and vitamin D strengthens the need for guidance on setting evidence based, up-to-date European recommendations. Differences in endpoints, type of evidence used to set recommendations, experts¿ opinions and assumptions are all likely to contribute to the identified variation. So far, background information was not sufficient transparent to disentangle the relative contribution of these different aspects. Conclusion EURRECA has an excellent opportunity to develop tools to improve transparency on the approaches used in setting micronutrient recommendations, including the selection of criteria for adequacy, weighing of evidence, and interpretation of data
Uptake of water from soils by plant roots
Raats, P.A.C. - \ 2007
Transport in Porous Media 68 (2007)1. - ISSN 0169-3913 - p. 5 - 28.
zero-sink uptake - aggregated soil - mass-flow - diffusion - systems - models - distributions - nutrients - constant - equation
Uptake of water by plant roots can be considered at two different Darcian scales, referred to as the mesoscopic and macroscopic scales. At the mesoscopic scale, uptake of water is represented by a flux at the soil¿root interface, while at the macroscopic scale it is represented by a sink term in the volumetric mass balance. At the mesoscopic scale, uptake of water by individual plant roots can be described by a diffusion equation, describing the flow of water from soil to plant root, and appropriate initial and boundary conditions. The model involves at least two characteristic lengths describing the root¿soil geometry and two characteristic times, one describing the capillary flow of water from soil to plant roots and another the ratio of supply of water in the soil and uptake by plant roots. Generally, at a certain critical time, uptake will switch from demand-driven to supply-dependent. In this paper, the solutions of some of the resulting mesoscopic linear and nonlinear problems are reviewed. The resulting expressions for the evolution of the average water content can be used as a basis for upscaling from the mesoscopic to the macroscopic scale. It will be seen that demand-driven and supply-dependent uptake also emerge at the macroscopic scale. Information about root systems needed to operationalize macroscopic models will be reviewed briefly.
Vadose zone dynamics and the legacy of Wilford R. Gardner
Walter, M.T. ; Parlange, J.Y. ; Raats, P.A.C. - \ 2007
Transport in Porous Media 68 (2007)1. - ISSN 0169-3913 - p. 1 - 4.
soil water - evaporation - storage - roots - plant
Foliekas reëel alternatief bij koudere teelten: hoge lichtdoorlatendheid, lange levensduur en warmte-absorptie
Kierkels, T. ; Raats, P. ; Hemming-Hoffmann, S. - \ 2007
Onder Glas 4 (2007)4. - p. 45 - 47.
kassen - folie - bouwconstructie - bouwmaterialen - bekleding, bouw - polyethyleen - polyethyleenfilm - polyvinylchloride - lage-energie teelt - lichtdoorlating - kostenanalyse - glastuinbouw - energiebesparing - greenhouses - foil - building construction - building materials - cladding - polyethylene - polyethylene film - poly(vinyl chloride) - low energy cultivation - light transmission - cost analysis - greenhouse horticulture - energy saving
Foliekassen kampen met een imagoprobleem. Onderzoekers van Wageningen UR en KEMA denken dat tuinders met koudere teelten er verstandig aan zouden doen zo’n kas te overwegen. Elkellaags polyetheen geeft financiële voordelen ten opzichte van glas bij verschillende gewassen. Dubbellaags PE bespaart 30% energie maar springt er financieel slechter uit. F-Clean heeft veel voordelen, maar is wel duur. Toch is het eindplaatje bij F-Clean financieel positiever dan glas. Het wachten is op nieuwe folies. Die zijn in aantocht. Ze combineren hoge lichtdoorlatendheid, lange levensduur en warmteabsorptie met een gunstige prijs. Een groot voordeel van foliekassen is tevens de lagere investering
Special issue on responsible management of water in agriculture Wesseling-van Schilfgaarde-Bouwer special issue of agricultural water management - Preface
Raats, P.A.C. - \ 2006
Agricultural Water Management 86 (2006)1-2. - ISSN 0378-3774 - p. 1 - 1.
Haalbaarheid foliekassen voor energie-extensieve gewassen : "stand van zaken en opties voor de toekomst
Raats, P.H. ; Hemming, S. ; Ruijs, M.N.A. ; Janse, J. - \ 2006
Arnhem : KEMA/A&F/PPO Glastuinbouw/LEI - 41
lage-energie teelt - kassen - teelt onder bescherming - bouwconstructie - kostenanalyse - folie - bouwmaterialen - glastuinbouw - kastechniek - energiebesparing - low energy cultivation - greenhouses - protected cultivation - building construction - cost analysis - foil - building materials - greenhouse horticulture - greenhouse technology - energy saving
Foliekassen zouden een geschikt alternatief kunnen vormen voor economisch rendabele teelt van deze energie-extensieve gewassen in Nederland. Bij dubbellaags toepassen van foliedekmateriaal wordt een energiebesparing van ongeveer 25% verwacht. Bij toepassen van eenvoudiger foliekasconstructies voor volle grond teelten wordt een toename van de gewasopbrengst verwacht. De Nederlandse markt voor foliekassen is echter nog klein en er is weinig bekend over de kosten, levensduur, energiehuishouding, optimale materialen en constructie van deze kassen in de Nederlandse weercondities, verwarmingspraktijk (ketelverwarming en CO2-dosering) en aardgasaansluitcapaciteiten. Het doel van deze inventarisatie is het beschrijven van folies en foliekasconstructies voor energie-extensieve teelten, het bepalen van gewassen die mogelijk in aanmerking komen voor teelt in foliekassen, het vaststellen van de markt en economische betekenis van deze gewassen en het analyseren van de kosten van foliekassen
The role of grass stems as structural foraging deterrents and their effects on the foraging behaviour of cattle
Drescher, M.F. ; Heitkönig, I.M.A. ; Raats, J.G. ; Prins, H.H.T. - \ 2006
Applied Animal Behaviour Science 101 (2006)1-2. - ISSN 0168-1591 - p. 10 - 26.
functional-response - mammalian herbivores - mechanistic model - diet selection - sward height - ingestive behavior - bite dimensions - residual stems - grazing cattle - herbage intake
Little quantitative information is available about the role of stems as structural foraging deterrents for large grazers and the actual mechanisms by which such deterrents affect foraging behaviour. We measured bite size, bite rate and the rate of forage intake of cattle foraging on artificial micro-swards of the tropical, broad-leaved guinea grass. These micro-swards varied in total forage mass density, in forage quality, defined as the proportion of high-quality plant parts (leaves) and of foraging deterrents (stems), and in the spatial pattern of plant parts. We hypothesized that stems interfere with the process of grasping of leaves and predicted that decreasing forage quality, by reducing bite size and bite rate, depresses the slope and the asymptotic maximum of the functional response curve. Further we hypothesized that increasing cluster size of leaves increases the accessibility of leaves to cattle, thus alleviating the negative effects of decreasing forage quality, and predicted that increasing leaf cluster size has positive effects on bite size and on the rate of forage intake. The slope of the functional response curve decreased with decreasing forage quality, mainly because of depressed bite size. These effects were also found when the amount of leaves in the grass sward was kept constant while only the amount of stems increased. Thus, the observed effects are not merely the result of decreased availability of leaves, but at least in part caused by the increasing interference of stems with the grasping of leaves. Leaf cluster size had a positive effect on bite size. However, this effect did not show in the rate of forage intake, because for small leaf clusters high bite rates compensated for decreased bite sizes. Instead of the familiar negative relationship of bite rate with bite size, we found a positive relationship. We speculate that this effect is the result of decreased chewing times for small bites and increased time needed to grasp these bites, effectively changing the limitation of bite rate from chewing time to a limitation by the time needed to grasp bites.
Chemistry of subsurface drain discharge from an agricultural polder soil
Hesterberg, D. ; Vos, B. de; Raats, P.A.C. - \ 2006
Agricultural Water Management 86 (2006)1-2. - ISSN 0378-3774 - p. 220 - 228.
multicomponent solute transport - precipitation dissolution - calcite supersaturation - homogeneous reactions - concentration waves - nonlinear sorption - field experiment - sandy aquifer - groundwater
Protecting groundwater and surface water quality in drained agricultural lands is aided by an understanding of soil physical and chemical processes affecting leaching of plant nutrients and other chemical constituents, and discharge from subsurface drains. Our objectives were to determine which chemical processes most affected discharge of redox-active components and macroelements (mainly base cations) from a subsurface drain, and to assess soil characterization needs for more accurate reactive-transport modeling. We measured the chemical composition of discharge water samples collected for 150 days from a 0.075-ha agricultural field plot on a calcareous polder soil. In light of previously reported two-dimensional, hydrological modeling of subsurface NO3 and Cl discharge, variations in the dissolved concentrations of Mn, Fe, Ca, Mg, Na, K, HCO3, and S could be qualitatively understood in terms of hydrology along with oxidation¿reduction (redox), precipitation/dissolution, and cation exchange processes. Elevated concentrations of Mn and Fe in the presence of NO3 during periods of peak flow were consistent with mixing of porewaters from reduced and oxidized soil zones. Discharge samples were supersaturated with respect to pure calcite, and responded only weakly to changes in pH over the measured range of pH 7.2¿8.2. Dissolved concentrations of Na, Mg, K, and S depended on their relative affinities for the soil exchanger phase and initial NH4Cl-extractable concentrations throughout the soil profile. Quantitative prediction of reactive components in drain discharge would require coupling of two-dimensional hydrological modeling with modeling of depth-dependent precipitation/dissolution and cation exchange processes, and redox kinetics.
Contributions by Jans Wesseling, Jan van Schilfgaarde, and Herman Bouwer to effective and responsible water management in agriculture
Raats, P.A.C. ; Feddes, R.A. - \ 2006
Agricultural Water Management 86 (2006)1-2. - ISSN 0378-3774 - p. 9 - 29.
hydraulic conductivity - irrigation management - unconfined aquifers - rapid-infiltration - salinity sensors - minimizing salt - drain water - air entry - soil - flow
The first three, successive Editors-in-Chief of Agricultural Water Management, Jans Wesseling, Jan van Schilfgaarde, and Herman Bouwer, were of Dutch origin, received their early training immediately after World War II, and started their careers in the early 1950s: Jans in The Netherlands and Jan and Herman in the USA. In this paper we review the circumstances and the highlights of their contributions to responsible management of water in agriculture. Following a sketch of the state of agricultural water management research around 1950, both in The Netherlands and in the USA, we describe their training, document their early scientific contributions, especially in the realm of agricultural drainage, and highlight their later service as research managers. The three careers reflect the great progress in the second half of the 20th century: the scope of water management research widened, computational capabilities became more powerful, experimental methods became more sophisticated. With increasing attention for environmental implications of water management, the focus of research changed from mainly water quantity to both water quantity and quality. The review of the careers of the first three Editors-in-Chief shows that the journal Agricultural Water Management from its inception and throughout its first quarter century was in very good hands.
A mysterious, pleiotropic growth defect caused by deletion of a glyoxal oxidase gene in Botrytis cinerea
Kan, J.A.L. van; Stefanato, F. ; Raats, E.M. - \ 2004
In: Book of Abstracts XIII International Botrytis Symposium, Antalya, Turkey, 25-31 October 2004 - p. 97 - 97.
A Botrytis cinerea gene was cloned encoding a glyoxal oxidase homologue (BcGLYOX1). The gene product is presumably secreted and contains a chitin-binding domain homologous to plant lectins. BcGLYOX1 was anticipated to be required for production of oxalic acid and for virulence of this plant pathogenic fungus. Mutants constructed by gene replacement retained the ability to produce oxalic acid, indicating that BcGLYOX1 is not essential for oxalate production. Unexpectedly however, BcGLYOX1-deficient mutants lost the ability to germinate and grow on minimal media containing a range of carbon sources. The mutants were consequently non-pathogenic on a range of host tissues. The growth defect was fully restored by supplementing the medium with arginine at concentrations as low as 50 mM. Spontaneous suppressor mutants that regain the ability to grow on simple sugars in the absence of arginine were obtained at a frequency of about 10-6. introduction of the wild type gene into the mutant only partly restored the wild type growth phenotype. We conclude that the BcGLYOX1 mutation results in a severe defect in primary or secondary metabolism, which can be overcome by arginine supplementation. The mechanisms underlying the behaviour of the mutants, the relief of the phenotype by arginine, as well as the emergence of spontaneous suppressors remain elusive.
A mysterious, pleiotropic growth defect caused by deletion of a glyoxal oxidase gene in Botrytis cinerea
Kan, J.A.L. van; Stefanato, F. ; Raats, E.M. - \ 2004
In: Book of Abstracts 7th European Conference on Fungal Genetics, Copenhagen, Denmark, 17-20 April 2004 - p. 168 - 168.
A Botrytis cinerea gene was cloned encoding a glyoxal oxidase homologue (BcGLYOX1). The gene product is presumably secreted and contains a chitin-binding domain homologous to plant lectins. BcGLYOX1 was anticipated to be required for production of oxalic acid and for virulence of this plant pathogenic fungus. Mutants constructed by gene replacement retained the ability to produce oxalic acid, indicating that BcGLYOX1 is not essential for oxalate production. Unexpectedly however, BcGLYOX1-deficient mutants lost the ability to germinate and grow on minimal media containing a range of carbon sources. The mutants were consequently non-pathogenic on a range of host tissues. The growth defect was fully restored by supplementing the medium with arginine at concentrations as low as 50 mM. Spontaneous suppressor mutants that regain the ability to grow on simple sugars in the absence of arginine were obtained at a frequency of about 10-6. introduction of the wild type gene into the mutant only partly restored the wild type growth phenotype. We conclude that the BcGLYOX1 mutation results in a severe defect in primary or secondary metabolism, which can be overcome by arginine supplementation. The mechanisms underlying the behaviour of the mutants, the relief of the phenotype by arginine, as well as the emergence of spontaneous suppressors remain elusive.
Parameterizing the soil - water - plant root system
Feddes, R.A. ; Raats, P.A.C. - \ 2004
In: Unsaturated-zone modeling; Progress, challenges and applications / Feddes, R.A., de Rooij, G.H., van Dam, J.C., Dordrecht : Kluwer Academic Publishers (Wageningen UR Frontis Series 6) - ISBN 1402029187 - p. 95 - 141.
bodemwater - plant-water relaties - modellen - klimaatverandering - soil water - plant water relations - climatic change - models
Root water uptake is described from the local scale, to the field scale and to the regional and global scales. The local macroscopic model can be incorporated in Soil-Plant-Atmosphere Continuum (SPAC) numerical models, like the SWAP, HYSWASOR, HYDRUS, ENVIRO-GRO and FUSSIM models. These SPAC models in turn can be used for upscaling, first to the field scale and from there to the regional and global scales. As Global Climate Models (GCMs) show a strong sensitivity to continental evaporation, closer root water-uptake modeling might improve soil vegetation control instead of uncontrolled continental evaporation
Deletion of a glyoxal oxidase gene causes a severe conditional growth defect in Botrytis cinerea
Stefanato, F. ; Raats, E.M. ; Kan, J.A.L. van - \ 2003
In: Book of Abstracts of Offered Papers 8th International Congress of Plant Pathology, Christchurch, New Zealand, 2-7 February 2003 [S.l.] : S.n. - ISBN 0864761511 - p. 231 - 231.
A mutant of Botrytis cinerea in a putative glyoxal oxidase gene is unable to grow on multiple carbon sources, but the phenotype can be circumvented by arginine supplementation
Kan, J. van; Stefanato, F. ; Raats, E. ; Visser, J. - \ 2002
In: Book of Abstracts 6th European Conference on Fungal Genetics, Pisa, Italy, 6-9 April 2002. - Pisa, Italy : University of Pisa, 2002 - p. 100 - 100.
Physical properties of composting material: Gas permeability oxygen diffusion coefficient and thermal conductivity
Ginkel, J.T. van; Haneghem, I.A. van; Raats, P.A.C. - \ 2002
Biosystems Engineering 81 (2002)1. - ISSN 1537-5110 - p. 113 - 125.
Composting is one of the oldest bio-technological processes used by human beings. It can be defined as the partial decomposition of heterogeneous organic matter by a mixed microbial population in a moist, warm and aerobic environment. In the organic matter, a dense population of various micro-organisms is found. The micro-organisms use organic matter, minerals, water and oxygen for their growth and metabolic activity. Each microbial species has an optimal temperature at which growth and multiplication rates are maximal. The oxygen concentration plays a dominant role in these processes. To optimize the composting process, the above-mentioned aspects must be known in detail. A simulation model offers an appropriate tool to reach this goal. Such a model must especially describe distributions of temperature and oxygen concentrations because these are considered as the most important process parameters. Reliable results can only be obtained if the physical properties of the composting material are well known under various conditions. In this paper, measurements of gas permeability, oxygen diffusivity, and thermal conductivity of the composting material are presented. Generally it is found that the gas permeability decreases as the gas velocity increases. For raw material, the gas permeability decreases with the wetness, whereas for older material there is no clear relationship. For composting material which has been turned once, the gas permeability is larger than for raw material. The oxygen diffusion coefficient is proportional to the gas-filled volume fraction to the power 1.5. There is no clear relationship between the oxygen diffusion coefficient and the age of the material. It is found that at a given temperature and for volume fractions of solid phase of 0.33 or less, the thermal conductivity increases linearly with the volume fraction of the liquid phase. The thermal conductivity is not influenced by the age of the composting material. The thermal conductivity increases with temperature.
On hydrostatics and matristatics of swelling soils
Grant, C.D. ; Groenevelt, P.H. ; Bolt, G.H. - \ 2002
In: Environmental mechanics: Water, mass and energy Transfer in the Biosphere / Raats, P.A.C., Smiles, D., Warrick, A.W., - p. 95 - 105.
Chloride transport in a recently reclaimed Dutch polder
Vos, J.A. de; Raats, P.A.C. ; Feddes, R.A. - \ 2002
Journal of Hydrology 257 (2002). - ISSN 0022-1694 - p. 59 - 77.
bodemwaterbeweging - drainage - ontginning - polders - grondwaterspiegel - waterkwaliteit - chloride - modellen - flevoland - soil water movement - water table - water quality - reclamation - models
Water flow and nitrate leaching in a layered silt loam
Vos, J.A. ; Hesterberg, D.L.R. ; Raats, P.A.C. - \ 2000
Soil Science Society of America Journal 64 (2000). - ISSN 0361-5995 - p. 517 - 527.
Nitrate (NO3) leaching was studied for a winter leaching period in a layered calcareous silt loam with tile-drains at about 1-m depth and 12-m spacing. Groundwater levels, drain discharge rates, and NO3 concentrations in the drainage water were monitored, and the soil hydraulic characteristics were measured for the different soil layers. The data were interpreted using the two-dimensional water flow and solute transport model SWMS_2D. This model uses Darcy's law for water flow and the convection–dispersion equation for solute transport for both the saturated and unsaturated zones. A nitrogen-production term of 39 kg N ha-1 was used to account for the net N mineralization in the topsoil during the leaching period. The model was calibrated by varying the hydraulic conductivity at saturation (Ks) for the different soil layers, using the measured groundwater level–drain discharge rate relationship as calibration target. Peaks in NO3 concentrations in the drainage water are well explained by the temporal two-dimensional behavior of convective transport. Measured NO3 leaching was 11 kg N ha-1 yr-1 and simulated NO3 leaching was 15 kg N ha-1 yr-1 in the relatively dry winter leaching period 1991–1992. The two-dimensional transport model SWMS_2D is a useful tool to evaluate the relative effects of management practices to reduce N leaching.
Dutch connections in John Philip's career
Raats, P.A.C. - \ 2000
In: Eos Transactions AGU, Vol. 81(48) : "Heat and mass transfer in the vadose zone: John Philip and his influence", America. - [S.l.] : [s.n.], 2000 - p. 498 - 498.
Major 20th Century achievements in soil physics
Raats, P.A.C. - \ 2000
Agronomy Abstracts (2000). - ISSN 0375-5495 - p. 219 - 219.
Kinematics of subsidence of soils with a non-conservative solid phase
Raats, P.A.C. - \ 2000
In: Geophysical Research Abstract, Vol. 2 : HSA 5 on "Hydrology and soil processes", Nice, France 2000. - [S.l.] : [s.n.], 2000 - p. 284 - 284.
Hysteretic hydraulic properties of a coarse sand horticultural substrate
Heinen, M. ; Raats, P.A.C. - \ 1999
In: Characterization and measurement of the hydraulic properties of unsaturated porous media / van Genuchten, M.T., Leij, F.J., Wu, L., - p. 467 - 476.
Hydraulic properties of root zone substrates used in greenhouse horticulture
Otten, W. ; Raats, P.A.C. ; Kabat, P. - \ 1999
In: Characterization and measurement of the hydraulic properties of unsaturated porous media / van Genuchten, M.T., Leij, F.J., Wu, L., - p. 477 - 488.
Spatial and temporal dynamics of water in the root environment of potted plants on a flooded bench fertigation system
Otten, W. ; Raats, P.A.C. ; Baas, R. ; Challa, H. ; Kabat, P. - \ 1999
Netherlands Journal of Agricultural Science 47 (1999)1. - ISSN 0028-2928 - p. 51 - 65.
The relationship between evapotranspiration of potted Ficus benjamina plants on a flooded bench fertigation system and the distribution of water in the root zone was studied in detail for a range of fertigation schedules. The physical characteristics of the peat-based potting medium were described by models commonly used in soil physics. The functioning of the substrate in practical situations was greatly affected by hysteresis in the water retention characteristic. Daily evapotranspiration of Ficus benjamina plants ranged from 0.4 to 4.1 kg/msuperscript 2 per day, of which 19-41% was lost by evaporation. Water uptake by plant roots resulted in near hydrostatic equilibrium conditions as long as the volumetric water content was above 0.22. Lower average water contents resulted in locally drier conditions in the root environment. The absorption of water during irrigation depended on the soil physical conditions and increased with decreasing volumetric water content before flooding. The majority of the water absorption occurred within the first minutes, making frequent fertigation more effective than increasing the duration. Actual buffer capacity of the potting medium was defined and by combining measured absorption during flooding with data on evapotranspiration, the derivation of minimum requirements of the fertigation schedule is demonstrated.
Stability criteria for certain flows in unsaturated soils
Raats, P.A.C. - \ 1999
Geophysical Research Abstracts 1 (1999)2. - ISSN 1029-7006 - p. 325 - 325.
Hydraulic properties of root zone substrates used in greenhouse horticulture
Otten, W. ; Raats, P.A.C. ; Kabat, P. - \ 1999
In: Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, Part 1: proceedings of an International Workshop organized by the U.S. Salinity Laboratory, USDA-ARS and the Department of Soil & Environmental Sciences of the University of California, Riverside, CA, USA, 22-24 October, 1997 / M.Th. van Genuchten, F.J. Leij, L. Wu. - Riverside : University of California, 1999 - p. 477 - 488.
Hysteretic hydraulic properties of a coarse sand horticultural substrate
Heinen, M. ; Raats, P.A.C. - \ 1999
In: Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, Part 1: proceedings of an International Workshop organized by the U.S. Salinity Laboratory, USDA-ARS and the Department of Soil & Environmental Sciences of the University of California, Riverside, CA, USA, 22-24 October, 1997 / M.Th. van Genuchten, F.J. Leij, L. Wu. - Riverside : University of California, 1999 - p. 467 - 476.
Unconventional flow of water from dry to wet caused by hysteresis : A numerical experiment
Heinen, M. ; Raats, P.A.C. - \ 1999
Water Resources Research 35 (1999). - ISSN 0043-1397 - p. 2587 - 2590.
Bulk density and porosity distributions in a compost pile
Ginkel, J.T. van; Raats, P.A.C. ; Haneghem, I.A. van - \ 1999
Netherlands Journal of Agricultural Science 47 (1999). - ISSN 0028-2928 - p. 105 - 121.
This paper mainly deals with the description of the initial distribution of bulk density and porosity at the moment a compost pile is built or rebuilt. A relationship between bulk density and vertical position in a pile is deduced from theoretical and empirical considerations. Formulae to calculate the air filled volume fraction and the true densities of the solid phase and of the organic matter are derived. The true density of dry matter is used in the computation of porosity distributions. The relationships between bulk density and height and between air-filled volume fraction and height are shown to be valid for composting material consisting of chopped wheat straw and chicken manure. The check of this validity is limited to total bulk density values ranging from 150 to 950 kg/msuperscript 3, with values of dry matter content varying between 18 and 28% (w.b.). Moreover, the gravimetric dry matter content must be constant throughout the total cross section of the pile. The error in the calculated bulk densities and air-filled volume fractions was found to be 12% at a reliability level of 95%. It was concluded that the presented equations will give reasonable results for other values of dry matter content and other kinds of chopped fibrous materials as long as the gravimetric dry matter content remains independent of height.
Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger
Sterk, G. ; Stroosnijder, L. ; Raats, P.A.C. - \ 1999
In: Wind erosion: An International Symposium, 3-5 June 1997 : Manhattan, Kansas, USA 1997
Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger G. Sterk, L. Stroosnijder, and P.A.C. Raats Abstract The objective of this paper is to present the main results and conclusions from three years of field research on wind erosion processes and control techniques in the Sahelian zone of Niger. Sediment transport was quantified with sediment catchers, and storm based maps of mass transport were made by applying geostatistics. The maps were used to calculate soil losses from the plot. In total, 45.9 Mg ha-1 were lost during four storms. Samples of trapped material were collected and analyzed on total element (TE) contents of K, C, N, and P. The losses of these elements during two storms were equal to approximately 3% of the TE masses that were present in the top 0.10 m of the soil. Wind erosion can be reduced by applying erosion control techniques. A survey in seven villages revealed that mulching with crop residues is the main control technique applied by farmers. Field tests with flat pearl millet stalks showed that small quantities of 1000 and 1500 kg ha-1 can significantly reduce sediment transport during most storms. But, the availability of crop residues for mulching is limited due to other uses. Therefore, future research should concentrate on enhancement of biomass production for wind erosion control purposes.
Identification of the hydraulic characteristics of a layered silt loam
Vos, J.A. de; Simunek, J. ; Raats, P.A.C. ; Feddes, R.A. - \ 1999
In: Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, Part 1: proceedings of an International Workshop organized by the U.S. Salinity Laboratory, USDA-ARS and the Department of Soil & Environmental Sciences of the University of California, Riverside, CA, USA, 22-24 October, 1997 / M.Th. van Genuchten, F.J. Leij, L. Wu. - Riverside : University of California, 1999 - p. 783 - 798.
Susceptibility and predictability of conditions for preferential flow
Wang, Z. ; Feyen, J. ; Ritsema, C.J. - \ 1998
Water Resources Research 34 (1998)9. - ISSN 0043-1397 - p. 2169 - 2182.
Preferential flow in the field might be caused by various factors and is difficult to observe in situ. This experimental study was designed to identify the combined effects of air entrapment, surface desaturation (suction head), soil layering, and water repellency (hydrophobicity) of the porous media on unstable preferential flow (or fingering) in the vadose zone. The predictability of unstable flow was studied on the basis of two existing criteria for gravity fingering: (1) a velocity criterion proposed by Hill and Parlange [1972] and (2) a pressure head criterion by Raats [1973] and Philip [1975]. Two-dimensional transparent chambers (60 cm high, 41.5 cm wide, and 2.8 cm thick and 90 cm deep, 74.5 cm wide, and 1.8 cm thick) were used to visualize water infiltration into a water-wettable sand, a water-wettable loam, differently layered sand and loam, and a water-repellent sand. The results suggested that infiltration into the homogeneous sand and a sand-over-loam system, without the effects of airentrapment and surface desaturation, was unconditionally stable. Infiltration in the loam vias also stable as observed in the limited chambers. The flow was unconditionally unstable in a fine- over-coarse stratified sublayer and conditionally unstable inthe homogeneous sand under the effects of air entrapment and surface desaturation. In multiple-layered systems, infiltration flow was semiunstable; fingers developed in the sand layer and were stabilized in the loam. In the repellent sand the wetting front was unstable under low pending conditions; however, it was stabilized when the pending depth exceeded the water-bubbling (entry) value of the hydrophobic medium. Both the velocity and pressure head criteria predicted fingering in the sand (layers) with the effects of gravity. However, the criteria failed to predict stable flow in the loam, indicating that the capillary (stabilizing) effects on the flow need to be included in theoretical developments. Finally, the observed width and speed of the fingers and the system flux were found to be always higher under air-draining fingering conditions than with fingering under air-confined conditions.
Spatial and material description of some processes in rigid and non-rigid saturated and unsaturated soils
Raats, P.A.C. - \ 1998
In: Proceedings of the Biot Conference on Poromechanics. Poromechanics. A Tribute to Maurice A. Biot, Louvain-la-Neuve, 14-16 September 1998. Balkema, Rotterdam / Thimus, J.F., Abousleiman, Y., Cheng, A.H.D, Coussy, O., Detournay, E., - p. 135 - 140.
Unconventional flow: water flow from dry to wet.
Heinen, M. ; Raats, P.A.C. - \ 1998
In: International Water Repellency Workshop, Wageningen, The Netherlands - p. 61 - 61.
Appearance and disappearance of phreatic surfaces in coarse porous media used as root zone substrates in greenhouse horticulture.
Heinen, M. ; Raats, P.A.C. - \ 1998
In: Annual Meeting American Society of Agronomy, Crop Science Society of America and Soil Science Society of America - p. 175 - 175.
Transport across single and series arrays of membranes.
Raats, P.A.C. - \ 1998
In: Annual Meeting American Society of Agronomy, Crop Science Society of America and Soil Science Society of America - p. 188 - 188.
Some fundamental aspects of retention and movement of water in hydrophobic soils.
Raats, P.A.C. - \ 1998
In: International Water Repellency Workshop, Wageningen, The Netherlands - p. 29 - 29.
Kinematics of subsidence of soils with a non-conservative solid phase.
Raats, P.A.C. - \ 1998
In: 16th World Congress of Soil Science: new concepts and theories in soil physics, Montpellier, France 1 - p. 33 - 33.
Spatial and material description of some processes in rigid and non-rigid saturated and unsaturated soils.
Raats, P.A.C. - \ 1998
In: Poromechanics: a tribute to Maurice A. Biot / Thimus, J.F., Rotterdam : Balkema - p. 135 - 140.
Verslag van Workshop 4.13 Modellering heterogeen transport van water, gassen en opgeloste stoffen , gehouden op het Nationaal Symposium Bodemonderzoek, op 18 en 19 december 1995 in de Blije Werelt te Lunteren
Raats, P.A.C. - \ 1997
In: Symposiumverslag Bodem Breed '95 - Actief bodembeheer: noodzaak voor beleid, uitdaging voor de wetenschap - p. 24 - 26.
Transport processes in the soil-plant-atmosphere system
Raats, P.A.C. - \ 1997
Unknown Publisher
Hydraulic properties of root zone substrates used in greenhouse horticulture
Raats, P.A.C. - \ 1997
In: Abstract of a talk presented at the International workshop on Characterization and measurement of the hydraulic properties of unsaturated porous media , organized by the US Salinity Laboratory, USDA-ARS and the Department of Soil and Environmental Sciences of the University of Califormai, Riverside, USA, 22-24 October 1997, Riverside, USA - p. 135 - 135.
Identification of the hydraulic properties of a layered silt loam
Vos, J.A. de; Simunek, J. ; Raats, P.A.C. - \ 1997
In: Abstract of a poster presented at the International workshop on Characterization and measurement of the hydraulic properties of unsaturated porous media , U.S. Salinity Laboratory, USDA-ARS & Department of Soil & Environment Sciences, University of California, Riverside, USA, 22-24 October 1997 - p. 49 - 49.
Wind erosion in the Sahelian zone of Niger : processes, models, and control techniques
Sterk, G. - \ 1997
Agricultural University. Promotor(en): Leo Stroosnijder, co-promotor(en): P.A.C. Raats. - S.l. : Sterk - ISBN 9789054856726 - 152
winderosie - bodemvruchtbaarheid - modellen - onderzoek - niger - wind erosion - soil fertility - models - research
<p>In the Sahelian zone of Niger, severe wind erosion occurs mainly in the first half of the rainy season (May - July), when violent winds preceding thunderstorms result in intense sediment transport. Quantification of this wind erosion is difficult due to a high degree of temporal and spatial variability in wind-blown particle mass fluxes. Using improved techniques to collect field data in Niger and developed models revealed that a single wind erosion event may result in severe losses of soil particles and nutrients from unprotected fields. The many technical measures available to reduce wind erosion do not always fit into the Sahelian farming systems. A survey revealed that mulching with crop residues is the main control technique applied by Nigerien farmers, but the quantity of crop residues available for soil conservation is limited, as stover has also other important uses. Field tests with flat pearl millet stalks showed that small quantities can significantly reduce sediment transport during moderate storms. However, sediment transport may actually be intensified by small quantities of mulch during severe storms, because of increased turbulence around the stalks.
Dynamics of water and nutrients in closed, recirculating cropping systems in glasshouse horticulture : with special attention to lettuce grown in irrigated sand beds
Heinen, M. - \ 1997
Agricultural University. Promotor(en): R.A. Feddes; P.A.C> Raats. - S.l. : S.n. - ISBN 9789054856672 - 270
slasoorten - tuinbouw - teelt onder bescherming - teeltsystemen - voedingsstoffen - water - evaporatie - glastuinbouw - lettuces - horticulture - protected cultivation - cropping systems - nutrients - evaporation - greenhouse horticulture
<p>Due to the high leaching fractions commonly practised in glasshouse horticulture, environmental pollution is clearly a major concern. Switching from soil-based to closed, recirculating substrate-based cropping systems potentially offers a good solution to this problem. As an alternative to the usual trial-and-error method in designing these new systems and optimizing fertigation strategies, this thesis uses the approach of modelling processes in the root zone supported with some detailed experiments. For this purpose a two-dimensional simulation model is developed.<p>Water movement is described by the mixed volumetric water content-pressure head Richards equation, which is solved numerically using the control volume finite element method. When the entire flow domain is unsaturated, the solution is obtained by the alternating direction implicit method. Otherwise, the incomplete Cholesky conjugate gradient method is used. Nutrient transport occurs by convection, dispersion and diffusion. Water and nutrient uptakes by the roots are described by scaled-up versions of microscopic steady-rate solutions for uptake by a single root.<p>As a test case, large bedding cropping systems filled with coarse sand (median diameter 0.6 mm) were used. The hydraulic properties of the sand were determined by the equilibrium hanging water column and transient multi-step outflow methods. Hysteresis was taken into account. The main validation data were volumetric water content measured by the TDR method, pressure head, and drainage outflow. Water use, transpiration, root length density distribution and root radius were obtained in experiments as well, while other parameters were obtained from the literature. Additionally, data on lettuce growth and nutrient uptake are presented and in some cases compared with data obtained in nutrient film technique experiments and from the literature. Dry matter productions in the two systems were comparable, but nutrient uptake differed.<p>A reasonable agreement between simulated and measured data was obtained. The model was applied in some case studies. Coarse porous media usually have enough water available for long periods of evapotranspiration. However, high solute concentrations may develop near the surface of the substrate since solutes are left behind when water evaporates and the flow through these regions is limited. Therefore, it is advised to schedule fertigation based on salinity control rather than on water supply control. Saturated conditions at the bottom occur only for short periods, and aeration problems in coarse porous media are unlikely.
Water flow and nutrient transport in a layered silt loam soil
Vos, J.A. de - \ 1997
Agricultural University. Promotor(en): P.A.C. Raats; R.A. Feddes. - S.l. : De Vos - ISBN 9789054857495 - 287
infiltratie - hydraulisch geleidingsvermogen - kwel - nitraten - fosfaten - fosforpentoxide - derivaten - modellen - onderzoek - infiltration - hydraulic conductivity - seepage - nitrates - phosphates - phosphorus pentoxide - derivatives - models - research
<br/>Theory, numerical models, and field and laboratory measurements are used to describe and predict water flow and nutrient transport in a layered silt loam soil. One- and two-dimensional models based on the Darcy equation for water flow and the convection-dispersion equation for solute transport are evaluated. Pressure heads simulated with the one-dimensional water balance model SWATRE are too large. The two-dimensional SWMS_2D model simulates water flow well for the winter leaching periods. The layering of the soil profile and the height of the phreatic surface determine flow paths to the subsurface drain. The hydraulic conductivity at saturation ranged from 200 cm d <sup>-1</SUP>in the 0-25 cm depth topsoil to 10 cm d <sup>-1</SUP>in the 95-120 cm depth subsoil. Under wet conditions solutes are transported laterally from the 0-25 cm topsoil towards the drain. Under drier conditions drainage water originates mainly from the 75-120 cm depth soil layers. Water flow and solute transport through the larger pores and solute exchange between the soil and water in these pores appear to be important, which was confirmed by a bromide tracer experiment. The upward diffusion of 220 kg ha <sup>-1</SUP>yr <sup>-1</SUP>chloride (Cl) was a major term in the Cl mass balance. Estimates of yearly averaged nitrogen (N) losses for integrated and conventional arable farming plots were 45 and 72 kg N ha <sup>-1</SUP>yr <sup>-1</SUP>respectively. At an integrated plot measured N leaching ranged from 0 to 50 kg ha <sup>-1</SUP>yr <sup>-1</SUP>. High nitrate (N0 <sub>3</sub> ) concentrations in the drainage water were often measured during wet periods with shallow phreatic surfaces. Spatial differences in N content of 30 kg ha <sup>-1</SUP>were measured as a function of the distance from the drain, probably as a result of denitrification. Smaller drain spacing, precise application of fertilisers and irrigation water, and controlled drainage can reduce N0 <sub>3</sub> leaching to groundwater and surface water.
The Richards equation, and its simplifications and generalizations.
Raats, P.A.C. - \ 1997
In: Abstracts of a keynote lecture at the EUROMECH Colloquium 366 on Porous Media: Theory and Experiments organized by the Institute of Mechanics of the University of Essen, Essen, Germany - p. 41 - 41.
Hydraulic properties of root zone substrates used in greenhouse horticulture.
Raats, P.A.C. - \ 1997
In: Abstr. at the Int. Workshop on 'Characterization and measurement of the hydraulic properties of unsaturated porous media' (1997) 135 pp
Identification of hydraulic properties of a layered silt loam.
Vos, J.A. de; Simunek, J. ; Raats, P.A.C. - \ 1997
In: Abstr. of a poster presented at the Int. Workshop on 'Characterization and measurement of the hydraulic properties of unsaturated porous media, Riverside, CA, USA - p. 49 - 49.
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