Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Recycling nutrients contained in human excreta to agriculture: Pathways, processes, and products
Harder, Robin ; Wielemaker, Rosanne ; Larsen, Tove A. ; Zeeman, Grietje ; Öberg, Gunilla - \ 2019
Critical Reviews in Environmental Science and Technology 49 (2019)8. - ISSN 1064-3389 - p. 695 - 743.
blackwater - carbon - feces - fertilizer - nitrogen - organic matter - Phosphorus - potassium - recovery - resource-oriented sanitation - sewage - soil amendment - source-separation - urine - wastewater

The need for better nutrient management has spurred efforts towards more comprehensive recycling of nutrients contained in human excreta to agriculture. Research in this direction has intensified throughout the past years, continuously unfolding new knowledge and technologies. The present review aspires to provide a systematic synthesis of the field by providing an accessible overview of terminology, recovery pathways and treatment options, and products rendered by treatment. Our synthesis suggests that, rather than focusing on a specific recovery pathway or product and on a limited set of nutrients, there is scope for exploring how to maximize nutrient recovery by combining individual pathways and products and including a broader range of nutrients. To this end, finding ways to more effectively share and consolidate knowledge and information on recovery pathways and products would be beneficial. The present review aims to provide a template that aims to facilitate designing human excreta management for maximum nutrient recovery, and that can serve as foundation for organizing and categorizing information for more effective sharing and consolidation.

Vascular effects of sodium and potassium intake
Gijsbers, Lieke - \ 2017
Wageningen University. Promotor(en): J.M. Geleijnse; Pieter van 't Veer. - Wageningen : Wageningen University - ISBN 9789463436267 - 161
sodium - potassium - vascular system - hypertension - blood pressure - mineral supplements - endothelium - blood vessels - heart rate - osmoregulation - human nutrition research - randomized controlled trials - cardiovascular diseases - natrium - kalium - vaatsysteem - hypertensie - bloeddruk - minerale supplementen - endotheel - bloedvaten - hartfrequentie - osmoregulatie - voedingsonderzoek bij de mens - gestuurd experiment met verloting - hart- en vaatziekten

Cardiovascular diseases (CVD) are the main cause of death worldwide. Annually, about 17.5 million people die from CVD, accounting for ~30% of deaths worldwide. Elevated blood pressure (BP) is a major risk factor for CVD and the largest single contributor to global mortality. BP is a modifiable risk factor that is largely determined by lifestyle factors, including diet. Dietary minerals, in particular sodium and potassium, play an important role in BP regulation. While adverse effects of sodium and beneficial effects of potassium on BP have repeatedly been shown in human intervention studies, evidence on other vascular effects of these dietary minerals is still scarce. Therefore, we investigated the BP effects of sodium and potassium intake in healthy humans in a broader (patho)physiological context, focusing also on endothelial function, arterial stiffness, fluid regulation and heart rate.

In Chapter 2, the effects of sodium and potassium supplementation on BP and arterial stiffness were examined by means of a randomized placebo-controlled crossover trial. Thirty-six untreated Dutch individuals with mildly elevated BP on a fully controlled diet that was relatively low in sodium (2-3 g/d) and potassium (2-3 g/d) received capsules with sodium (3 g/d), potassium (3 g/d) or placebo, for 4 weeks each, in random order. After each intervention, fasting office BP, 24-h ambulatory BP and measures of arterial stiffness were assessed. The results of this study showed that increased sodium intake strongly raised office and ambulatory systolic BP (7-8 mmHg) whereas increased potassium intake lowered systolic BP (3-4 mmHg). Potassium supplementation increased ambulatory HR, but office HR was not affected. Measures of arterial stiffness were not materially affected by increased sodium or potassium intake, possibly due to the relatively short intervention period.

In the same study we investigated the effects of increased sodium and potassium intake on the functional measure of endothelial function (flow-mediated dilation), and on a comprehensive set of biomarkers of endothelial dysfunction and low-grade inflammation (Chapter 3). Four weeks of supplemental sodium had no effect on brachial flow-mediated dilation, or on the blood biomarkers of endothelial dysfunction and low-grade inflammation, except for an increase in serum endothelin-1 (a biomarker of endothelial dysfunction). Potassium supplementation improved flow-mediated dilation by 1.2% and tended to lower the low-grade inflammation marker interleukin-8. This suggests that potassium may beneficially influence vascular health by improving endothelial function.

In a post-hoc analysis of the same study in 35 untreated individuals, the humoral effects of supplemental sodium and potassium were assessed using a panel of markers that are involved in osmoregulation and volume regulation (Chapter 4). Results showed that supplemental sodium increased plasma natriuretic peptides and plasma copeptin, and suppressed the renin-angiotensin system. Supplemental potassium decreased plasma MR-pro-ANP, increased plasma copeptin, and stimulated the renin-angiotensin system. These findings suggest that the mineral-induced changes in BP elicit several counter regulatory mechanisms to maintain volume homeostasis.

In Chapter 5, the effect of potassium supplementation on heart rate was assessed in a meta-analysis of 22 randomized, placebo-controlled trials in healthy adults. Overall, increasing potassium intake by 2-3 g/d for at least two weeks did not affect resting heart rate. 24-h Ambulatory heart rate was not significantly affected in subgroup analysis of 4 RCTs, including ours. Other subgroup analyses for characteristics of the study and study population also showed no significant effects, and there was no evidence for a dose-response relationship. These results suggest that increasing potassium intake is not expected to adversely affect heart rate in apparently healthy adults.

In Chapter 6, BP associations for sodium and potassium intake using different dietary assessment methods were examined. Data of 993 healthy Dutch adults not on antihypertensive medication were analyzed using a cross-sectional approach. Sodium and potassium intake were estimated from two non-consecutive 24-h urinary samples (considered as the gold standard), two non-consecutive web-based 24-h recalls, and a validated 180-item food frequency questionnaire (FFQ). This study showed no significant associations of sodium intake with BP, regardless of the dietary assessment method used. Potassium intake estimated from 24-h urine and FFQ was inversely associated with BP (~1.5 mmHg reduction per 1 g/d increment). This suggests that dietary assessment methods in cross-sectional studies may be inadequate for estimating the association of sodium intake with BP, but may yield reliable results for potassium intake.

As discussed in Chapter 7, the studies presented in this thesis indicate that increasing sodium intake from a recommended level to a level that is common in Western societies for four weeks strongly raises BP in individuals with an untreated mildly elevated BP. The results for endothelial function and arterial stiffness are inconclusive, and hence more (longer-term) studies are warranted. Increasing the intake of potassium lowers BP and improves endothelial function, even in individuals on a relatively low-sodium diet. Both sodium and potassium intake affected fluid parameters, likely indicating that compensatory responses are stimulated to maintain body fluid balance. Although in our RCT ambulatory heart rate was increased after supplemental potassium, the meta-analysis showed that increasing potassium intake is unlikely to affect heart rate in apparently healthy adults. When evaluating the effectiveness of sodium and potassium intake on cardiovascular health, results obtained from observational studies should be interpreted with caution, particularly for sodium intake.

Around the world people consume on average 9-12 g of salt and 2-4 g of potassium on a daily basis. A more optimal intake of sodium and potassium can be achieved through adherence to dietary guidelines and product reformulation by food industry. This could reduce BP by more than 10 mmHg and lower the number of cardiovascular deaths by at least one-quarter in Western populations.

Potassium, the major organiser in numerous plant processes : involved in almost everything the plant turns into plant
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)4. - ISSN 2215-0633 - p. 46 - 47.
greenhouse horticulture - crop production - crop quality - potassium - plant development - nutrient requirements - glastuinbouw - gewasproductie - gewaskwaliteit - kalium - plantenontwikkeling - voedingsstoffenbehoeften
No potassium no plant: A huge number of processes are dependent on this element. Luckily, hardly any problems occur because the plant is good at looking after itself in this respect.
Measurement errors in dietary assessment using duplicate portions as reference method
Trijsburg, L.E. - \ 2016
Wageningen University. Promotor(en): Pieter van 't Veer; Anouk Geelen; Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789462576421 - 128
diet studies - nutritional assessment - questionnaires - reference standards - correction factors - validity - body mass index - regression analysis - food intake - food - protein - potassium - sodium - energy intake - methodology - dieetstudies - voedingstoestandbepaling - vragenlijsten - referentienormen - correctiefactoren - geldigheid - quetelet index - regressieanalyse - voedselopname - voedsel - eiwit - kalium - natrium - energieopname - methodologie

Measurement errors in dietary assessment using duplicate portions as reference method

Laura Trijsburg

Background: As Food Frequency Questionnaires (FFQs) are subject to measurement error, associations between self-reported intake by FFQ and outcome measures should be corrected for measurement error with data from a reference method. Whether the correction is adequate depends on the characteristics of the reference method used in the validation study. The duplicate portion method (DP), compared to the often used 24h recall (24hR), seems a promising reference method as correlated errors between FFQ and DP, such as memory bias, errors in portion size estimations and food composition databases, are not expected.

Aim: This thesis aimed to determine the validity of the DP compared to the 24hR as a reference method for FFQ validation. The second aim was to explore the validity of nutrient densities for DP, 24hR and FFQ. The third aim was to determine the factors associated with misreporting of energy, protein and potassium as estimated by DP, 24hR and FFQ.

Methods: Within the DuPLO-study, a Dutch validation study which is part of the NQplus study, two DPs, two FFQs, two blood and urinary biomarkers and one to fifteen 24hRs (web-based and/or telephone-based) were collected in 198 subjects, within 1.5 years. Also, one or two doubly labelled water measurements were available for 69 participants. Multivariate measurement error models were used to assess proportional scaling bias, error correlations with the FFQ, validity coefficients and attenuation factors. Furthermore linear regression analysis was used to determine the association between misreporting and various factors.

Results: The DP was less influenced by proportional scaling bias, had lower correlated errors with the FFQ and showed higher attenuation factors than the 24hR for potassium, sodium and protein. Also, the DP seemed a better reference method than the 24hR for the assessment of validity coefficients for the FFQ for various fatty acids. The attenuation factors for the FFQ, using either the DP or 24hR as reference method, agreed reasonably well. Furthermore, the DP showed, when using plasma fatty acids as reference, slightly better ranking of participants according to their intake of n-3 fatty acids (0.33) and the n‑3/LA ratio (0.34) than the 24hR (0.22 and 0.24, respectively). Less group level bias was observed for protein and sodium densities compared to their absolute intakes for FFQ, 24hR and DP, but not for potassium. Overall the validity coefficients and attenuation factors for DP, 24hR and FFQ did not improve for nutrient densities compared to absolute intakes, except for the attenuation factor for sodium density. Lastly, BMI proved to be the most consistent determinant associated with misreporting (group level bias) of energy, protein and potassium for DP, 24hR and FFQ. Men tended to underreport protein by the DP, FFQ and 24hR and persons of older age underreported potassium but only by the 24hR and FFQ. Other explorative determinants did not show a consistent association with misreporting of energy or nutrients by the different dietary assessment methods.

Conclusion: With respect to error correlations and attenuation factors the DP performed slightly better than the 24hR as a reference method for validating FFQs in epidemiological research. Furthermore, the use of nutrient densities does not necessarily improve the validity of the dietary intake estimates from DP, 24hR and FFQ. Moreover, it was shown that BMI is an important determinant of misreporting of energy, protein and potassium for these three assessment methods.

Ky’osimba Onaanya: understanding productivity of East African Highland banana
Taulya, G. - \ 2015
Wageningen University. Promotor(en): Ken Giller, co-promotor(en): Peter Leffelaar; P.J.A. van Asten. - Wageningen : Wageningen University - ISBN 9789462575615 - 167
bananen - musa - droogte - voedingsstoffenbeschikbaarheid - kalium - stikstof - kunstmeststoffen - afrika - uganda - gewasgroeimodellen - beslissingsmodellen - drogestofverdeling - groeianalyse - licht - fenotypische variatie - bananas - musa - drought - nutrient availability - potassium - nitrogen - fertilizers - africa - uganda - crop growth models - decision models - dry matter distribution - growth analysis - light - phenotypic variation

Over 30 million people in East Africa depend on East African highland bananas for food and income. The bananas are grown with limited additions of nutrients and no irrigation, despite widespread poor soil fertility and regular dry seasons. This thesis describes the effect of increasing rainfall and application of potassium and nitrogen fertilizers on banana growth and yields. In areas that receive less than 1100 mm of rainfall per year, additional rainfall increases yields by 65%. Application of potassium increases yields by 88%, while nitrogen is not required. A framework for computing banana growth and yield in response to the amount of water stored in the soil is described. Where the soil water storage capacity is low, mulching increases yields by 10% but it has no effect in areas where the soil water storage is high. This framework is envisaged to guide improvements in banana management and productivity in East Africa.

Naar een herziening van kali-advies grasland
Bussink, D.W. ; Schöll, L. van; Draai, H. van der; Middelkoop, J.C. van; Holshof, G. - \ 2014
Wageningen : NMI-AGRO / Wageningen UR (Soil for life 1421.N.10) - 63
graslanden - kalium - bemesting - grondanalyse - mestbehoeftebepaling - grasslands - potassium - fertilizer application - soil analysis - fertilizer requirement determination
Voor een optimale grasgroei moet K op het juiste moment in voldoende mate aanwezig zijn. Tegelijkertijd dient een te hoog aanbod van K te worden voorkomen om nadelige effecten voor de diergezondheid te vermijden. Het vigerende kalibemestingsadvies is gebaseerd op proeven uit de jaren vijftig en zestig met zware eerste sneden. Het advies is na 1976 vrijwel niet meer gewijzigd. Sindsdien is de landbouw sterk gewijzigd en zijn er nieuwe methoden voor grondonderzoek ontwikkeld.
Extreem weer remt opbrengst snijmais
Colenbrander, E. ; Groten, J.A.M. - \ 2014
Melkvee Magazine 13 (2014)2. - p. 32 - 33.
zea mays - weer - gewasopbrengst - maïskuilvoer - bemesting - kalium - dosering - weather - crop yield - maize silage - fertilizer application - potassium - dosage
Een opbrengst van 50 ton per hectare. Een dergelijk resultaat is mogelijk als de weersomstandigheden meezitten. Maar het weer wordt extremer en er dreigt kalitekort. Er is ook goed nieuws: er komen telkens nieuwe rassen, die nog beter scoren in opbrengst en voederwaarde.
Effects of sodium and sulfur on catalytic performance of supported iron catalysts for the Fischer-Tropsch synthesis of lower olefins
Torres Galvis, H.M. ; Koeken, A.C.J. ; Bitter, J.H. ; Davidian, T. ; Ruitenbeek, M. ; Dugulan, A.I. ; Jong, K.P. de - \ 2013
Journal of Catalysis 303 (2013). - ISSN 0021-9517 - p. 22 - 30.
synthesis gas - selectivity - nanoparticles - potassium - promotion - manganese - size
The Fischer–Tropsch synthesis of lower olefins (FTO) is an alternative process for the production of major chemical building blocks from natural gas, coal, or biomass-derived synthesis gas. The addition of low concentrations of sulfur plus sodium to Fe/a-Al2O3 resulted in catalysts with high C2–C4 olefins selectivity (~50%C), enhanced catalytic activity, and decreased methane production (
Bemesting Alstroemeria: Invloed van EC en K:Ca verhoudingin de teelt van Alstroemeria op kokossubstraat
Helm, F.P.M. van der; Labrie, C.W. ; Mourik, N.M. van; Groot, M. de; Voogt, W. - \ 2013
Bleiswijk : Wageningen UR Glastuinbouw (Rapporten WUR GTB 1249) - 74
alstroemeria - alstroemeriaceae - bemesting - teelt - substraten - kokosnootproducten - elektrische geleidbaarheid - kalium - calcium - glastuinbouw - nederland - fertilizer application - cultivation - substrates - coconut products - electrical conductivity - potassium - greenhouse horticulture - netherlands
In 2010 is budget beschikbaar gesteld door het Productschap Tuinbouw voor een 2 jaar durend onderzoek om te bepalen wat de juiste verhouding K:Ca bij verschillende EC-niveau’s is gedurende het jaar. Er is een twee jaar durende kasproef uitgevoerd waarin een K:Ca verhouding van 5:1, 1:1 en 1:3 is gerealiseerd bij een EC van 2 (laag) en 3 (hoog) mS/ cm. In het onderzoek gaf de hoge EC op een kokossubstraat bij een K:Ca verhouding van 1:1 of lager betrouwbaar meer productie in stuks en in kilo’s geoogst gewicht dan een lage EC. De productie bij een K:Ca verhouding van 5:1 was altijd lager, de EC had hierop geen invloed. Daarnaast was bij een hoge EC en een K:Ca verhouding van 1:3 in de voedingsoplossing zowel productie en takgewicht per 80 cm het hoogste. Ook was de lengte van het gewas in de zomer duidelijk hoger als gevolg van een lagere K:Ca in de voedingsoplossing. Met het oog op ziektegevoeligheid gaf een voedingsoplossing met een K:Ca verhouding van 1:3 een robuuster gewas dat minder vatbaar was voor vochtblaadjes en bloemschade door klimaat wisselingen en hoge instraling. Daarnaast was bij hoge EC het gewas gevoeliger voor vochtblaadjes, maar dit effect was minder sterk dan het effect van een hoge K:Ca verhouding. Ten slotte gaf de lage EC in dit onderzoek meer problemen met uitval door Fusarium.
Adviesbasis voor de bemesting van akkerbouwgewassen
Haan, J.J. de; Geel, W.C.A. van - \ 2013 2013 (2013)20 maart.
akkerbouw - gewassen - mest - organische meststoffen - samenstelling - werkwijze - stikstof - fosfaat - kalium - bemesting - arable farming - crops - manures - organic fertilizers - composition - mode of action - nitrogen - phosphate - potassium - fertilizer application
De Adviesbasis voor de bemesting van akkerbouwgewassen bevat de meest actuele bemestingsadviezen. Deze adviezen zijn vastgesteld door de Commissie Bemesting Akkerbouw/Vollegrondsgroenteteelt, die bestaat uit vertegenwoordigers van bedrijfsleven, onderzoek en voorlichting. De adviezen hebben een landbouwkundige grondslag, dat wil zeggen gebruik van het advies leidt tot een economisch optimaal resultaat. De vermelde adviezen gelden voor een gemiddelde situatie. Op basis van eigen ervaringen en kennis kunnen ze aan de eigen specifieke situatie worden aangepast. De Adviesbasis geeft hiervoor handvaten in de vorm van voetnoten en aanvullende opmerkingen.
Adviesbasis voor de bemesting van akkerbouwgewassen : mineralengehalten in geoogst product
Haan, J.J. de; Geel, W.C.A. van - \ 2013 2013 (2013)20 maart.
akkerbouw - adviescentra - mineralen - stikstof - fosforpentoxide - kalium - bemesting - mineralenboekhouding - arable farming - advisory centres - minerals - nitrogen - phosphorus pentoxide - potassium - fertilizer application - nutrient accounting system
Tabel met mineralengehalten (N, P2O5 en K2O) in geoogst product voor diverse akkerbouwgewassen t.b.v bemestingsadvies.
Adviesbasis voor de bemesting van akkerbouwgewassen - rekenvoorbeeld bodem- en gewasgericht advies
Haan, J.J. de; Geel, W.C.A. van - \ 2013 2013 (2013)20 maart.
bemesting - fosfaat - kalium - akkerbouw - berekening - fertilizer application - phosphate - potassium - arable farming - calculation
In deze bijlage van de bemestingsadviesbasis vindt u rekenvoorbeelden hoe om te gaan met gewas- en bodemgerichte adviezen voor fosfaat en kali.
Beste toepassing van bicarbonaat
Jong, P.F. de - \ 2013
De Fruitteelt 103 (2013)13. - ISSN 0016-2302 - p. 18 - 18.
fruitteelt - kalium - bicarbonaten - gewasbescherming - plantenziektebestrijding - toepassing - bladbespuiting - spuiten - landbouwkundig onderzoek - fruit growing - potassium - bicarbonates - plant protection - plant disease control - application - foliar spraying - spraying - agricultural research
Kaliumbicarbonaat is een zout en is beter bekend als bakpoeder. Naast deze toepassing is gebleken dat het ook een werking heeft op plantenziekten. Momenteel heeft Karma met kaliumbicarbonaat als werkzame stof een toelating in fruit.
Effect of sodium chloride intake on urine volume, urinary urea excretion, and milk urea concentration in lactating dairy cattle
Spek, J.W. ; Bannink, A. ; Gort, G. ; Hendriks, W.H. ; Dijkstra, J. - \ 2012
Journal of Dairy Science 95 (2012)12. - ISSN 0022-0302 - p. 7288 - 7298.
nitrogen-excretion - ammonia emissions - water restriction - renal-function - cows - sheep - metabolism - protein - agriculture - potassium
Milk urea nitrogen (MUN; mg of N/dL) has been shown to be related to excretion of urinary urea N (UUN; g of N/d) and total excretion of urinary N (UN; g of N/d) in dairy cows. In the present experiment, it was hypothesized that MUN and the relationship between MUN and UUN or UN is affected by urine volume as a result of dietary sodium chloride intake. Twelve lactating Holstein-Friesian dairy cows (mean ± SD: milk production 28.1 ± 3.23 kg/d and 190 ± 41 d in milk), of which 4 were fitted with catheters in the urine bladder and jugular vein, were randomly assigned to 4 dietary levels of sodium chloride (3, 9, 14, and 19 g of Na/kg of DM) according to a triple 4 × 4 Latin square design. Cows were fed at 95% of ad libitum intake, excluding salt addition. Milk was analyzed for MUN and protein content; urine was analyzed for total N, urea, and creatinine content; feces were analyzed for total N and DM content; and blood plasma was analyzed for urea and creatinine content. Creatinine clearance rate (CCR; L/min) and renal urea reabsorption ratio were estimated based on plasma concentrations of urea and creatinine, and total excretion of urea and creatinine in urine. Intake of DM and N, milk production, and milk protein content were (mean ± SD), on average, 21.4 ± 1.24 kg/d, 522 ± 32.0 g/d, 25.4 ± 2.53 kg/d, and 3.64 ± 0.186%, respectively. A linear relationship was found between Na intake and urine production [urine (kg/d; mean ± SE) = 7.5 ± 4.33 + 0.136 ± 0.0143 × Na intake (g/d)] and between Na intake and MUN [MUN (mg/dL; mean ± SE) = 13.5 ± 0.35 - 0.0068 ± 0.00104 × Na intake (g/d)]. Despite the decrease in MUN with increased Na intake, UN excretion increased linearly with Na intake. Excretion of UUN was not affected by dietary Na content. A linear plateau relationship was observed between CCR and renal urea reabsorption. An increase in CCR coincided with an increase in calculated renal urea reabsorption until a CCR breakpoint value (mean ± SD) of 1.56 ± 0.063 L/min was reached. We conclude that Na intake is negatively related to MUN, whereas UUN is not affected. Variation in mineral intake levels that affect urine volume should, therefore, be taken into account when using MUN as an indicator of UUN in dairy cattle.
Relatie effectiviteit bicarbonaat en contacttijd (poster)
Jong, P.F. de; Steeg, P.A.H. van der; Anbergen, R.H.N. - \ 2012
fruitgewassen - kalium - bicarbonaten - plantenziektebestrijding - toepassing - bladbespuiting - landbouwkundig onderzoek - fruit crops - potassium - bicarbonates - plant disease control - application - foliar spraying - agricultural research
Poster over de effectiviteit van bicarbonaat tegen schurft in de fruitteelt.
Dietary acid load and risk of hypertension: The Rotterdam Study
Engberink, M.F. ; Bakker, S.J.L. ; Brink, E.J. ; Baak, M.A. van; Rooij, F.J.A. van; Hofman, A. ; Witteman, J.C.M. ; Geleijnse, J.M. - \ 2012
American Journal of Clinical Nutrition 95 (2012). - ISSN 0002-9165 - p. 1438 - 1444.
blood-pressure response - base-balance - excretion - calcium - protein - humans - potassium - trials - metaanalysis - association
Background: Mild metabolic acidosis, which can be caused by diet, may result in elevated blood pressure (BP). Design: The analyses included 2241 participants aged =55 y who were free of hypertension at baseline (1990–1993) and who had complete dietary and BP data. Dietary data were obtained from a 170-item food-frequency questionnaire. We used 2 measures to characterize dietary acid load: 1) potential renal acid load (PRAL) by using an algorithm including protein, phosphorus, potassium, calcium, and magnesium, and 2) estimated net endogenous acid production (NEAP) based on protein and potassium. HRs for 6-y incidence of hypertension were obtained in tertiles of PRAL and NEAP with adjustment for age, sex, BMI, smoking, education, and intakes of alcohol, fiber, and total energy. Results: We identified 1113 incident cases of hypertension during 8707 person-years of follow-up. The median dietary acid load ranged from -14.6 to 19.9 mEq/d across categories of PRAL. Hypertension risk was not significantly associated with dietary acid load. The multivariate HRs (95% CIs) in consecutive tertiles of PRAL were 1.00 (reference), 1.01 (0.87, 1.17), and 1.02 (0.88, 1.18) (P trend = 0.83). The median dietary acid loads were 30.4, 36.7, and 43.7 mEq/d, respectively, in consecutive tertiles of NEAP. Corresponding HRs for NEAP were 1.00 (reference), 0.92 (0.80, 1.07), and 0.94 (0.81, 1.10) (P-trend = 0.46). Conclusion: The findings from this prospective cohort study provided no evidence of an association between dietary acid load and risk of hypertension in older adults
Predicting urinary creatinine excretion and its usefulness to identify incomplete 24h urine collections
Keyzer, W. de; Huybrechts, I. ; Dekkers, A.L.M. ; Geelen, A. ; Crispim, S.P. ; Hulshof, P.J.M. ; Andersen, L.F. ; Rehurkova, I. ; Ruprich, J. ; Volatier, J.L. ; Maele, G. van; Slimani, N. ; Veer, P. van 't; Boer, E. de; Henauw, S. de - \ 2012
The British journal of nutrition 108 (2012)6. - ISSN 0007-1145 - p. 1118 - 1125.
4-aminobenzoic acid - european centers - completeness - potassium - diet - validation - stability - recalls - protein - sodium
Studies using 24 h urine collections need to incorporate ways to validate the completeness of the urine samples. Models to predict urinary creatinine excretion (UCE) have been developed for this purpose; however, information on their usefulness to identify incomplete urine collections is limited. We aimed to develop a model for predicting UCE and to assess the performance of a creatinine index using para-aminobenzoic acid (PABA) as a reference. Data were taken from the European Food Consumption Validation study comprising two non-consecutive 24 h urine collections from 600 subjects in five European countries. Data from one collection were used to build a multiple linear regression model to predict UCE, and data from the other collection were used for performance testing of a creatinine index-based strategy to identify incomplete collections. Multiple linear regression (n 458) of UCE showed a significant positive association for body weight (ß = 0·07), the interaction term sex × weight (ß = 0·09, reference women) and protein intake (ß = 0·02). A significant negative association was found for age (ß = - 0·09) and sex (ß = - 3·14, reference women). An index of observed-to-predicted creatinine resulted in a sensitivity to identify incomplete collections of 0·06 (95 % CI 0·01, 0·20) and 0·11 (95 % CI 0·03, 0·22) in men and women, respectively. Specificity was 0·97 (95 % CI 0·97, 0·98) in men and 0·98 (95 % CI 0·98, 0·99) in women. The present study shows that UCE can be predicted from weight, age and sex. However, the results revealed that a creatinine index based on these predictions is not sufficiently sensitive to exclude incomplete 24 h urine collections.
Norms for multivariate diagnosis of nutrient imbalance in the East African highland bananas (musa
Wairegi, L. ; Asten, P. van - \ 2011
Journal of Plant Nutrition 34 (2011)10. - ISSN 0190-4167 - p. 1453 - 1472.
recommendation integrated system - crops - dris - soil - potassium - nutrition - nitrogen - biomass - potato - growth
Despite low yields and soil fertility problems, fertilizer use in the East African Highland banana (AAA-EA) production is absent. High fertilizer costs increase the need for site-specific fertilizer recommendations that address deficiencies. This study aimed to derive and compare norms for AAA-EA bananas, using Compositional Nutrient Diagnosis (CND), Diagnosis and Recommendation Integrated System (DRIS), and a DRIS that includes a filling value (DRIS-Rd), and study nutrient interactions. Data on foliar nitrogen, phosphorus, potassium, calcium, and magnesium concentrations, and plant performance were obtained from 300 plots in Uganda. CND indices were closely related to DRIS and DRIS-Rd indices (R2 > 0.965). Four nutrient interactions were common in both low and high bunch weight subpopulations. Although the three approaches can be used to determine nutrient imbalances in AAA-EA bananas, we recommend CND for ease of use. Diagnosis of nutrient deficiencies should be based on methods that identify plant nutritional imbalances.
Doeltreffend kali-bemestingsadvies voor snijmais = Effective potassium fertilisation recommendation for sillage maize
Schooten, H.A. van; Schöll, L. van; Dijk, W. van; Middelkoop, J.C. van; Boer, D.J. den - \ 2011
Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 500)
maïs - kalium - bemesting - gewasopbrengst - normen - voedergewassen - mineralenboekhouding - voedingsstoffengehalte - maize - potassium - fertilizer application - crop yield - standards - fodder crops - nutrient accounting system - nutrient content
The current potassium fertilisation recommendation for silage maize is outdated and does not take into account the potential of production of plots and residual (K) effect from cover crops or grass. That is why a study was conducted on the background and efficiency of the current recommendations. This report describes the results and conclusions of this study. Recommendations for further research were formulated from the conclusions.
Mineralenconcentraat op het melkveebedrijf en het akkerbouwbedrijf : knelpunten en mogelijkheden verkend op bedrijfsniveau, 2009 en 2010
Verloop, J. ; Akker, H. van den - \ 2011
Wageningen : Plant Research International (Rapport / Plant Research International 393) - 24
bemesting - vloeibare meststoffen - concentraten - akkerbouw - melkveehouderij - stikstof - kalium - fosfaat - kunstmeststoffen - mesttechnologie - fertilizer application - liquid manures - concentrates - arable farming - dairy farming - nitrogen - potassium - phosphate - fertilizers - fertilizer technology
Het doel van deze studie was het verkennen van ervaringen bij gebruik van mineralenconcentraten, het in kaart brengen van knelpunten en oplossingen daarvoor en communiceren over de ervaringen. De meeste gebruikers concluderen dat concentraat als meststof een plaats verdient. Toepassing biedt perspectief in suikerbiet, wintertarwe, gerst, maïs, stamslaboon, waspeen en aardappel (akkerbouw) en in gras (melkveehouderij). De onderlinge verhouding van stikstof en fosfaat is van sommige van de geproduceerde concentraten te laag. Dit is met name voor melkveehouders met een fosfaatoverschot een belemmering. De kali-aanvoer met concentraat beperkt de ruimte voor kunstmest-N vervanging op melkveebedrijven met een kali-getal voldoende en hoger in de bodem. Als kali in concentraat op melkveebedrijven in een behoefte voorziet, dan draagt dit aanzienlijk bij aan het financieel rendement van het gebruik van concentraat. In veel akkerbouwgewassen is de kali-behoefte hoog. Concentraat kan hierin voor een groot deel voorzien, waardoor gebruik van concentraat bijdraagt aan besparing op bemestingskosten.
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