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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    A blooming business : Identifying limits to Lake Taihu's nutrient input
    Janssen, Annette B.G. - \ 2017
    Wageningen University. Promotor(en): Wolf Mooij, co-promotor(en): J.H. Janse; A.A. van Dam. - Wageningen : Wageningen University - ISBN 9789463431897 - 268
    lakes - freshwater ecology - aquatic ecosystems - nutrients - cycling - nutrient flows - biodiversity - algae - models - critical loads - limnology - spatial variation - ecological restoration - china - meren - zoetwaterecologie - aquatische ecosystemen - voedingsstoffen - kringlopen - nutriëntenstromen - biodiversiteit - algen - modellen - critical loads - limnologie - ruimtelijke variatie - ecologisch herstel - china

    Last century, Lake Taihu (China) became serious eutrophic due to excessive nutrient input. During the 1980s, the first algal blooms emerged in the lake, reaching disastrous proportions in 2007. During that year, the intake of drinking water had to be shut down and millions of people had to look for an alternative source of drinking water. This raises the question whether such problems can be avoided. Of crucial importance in avoiding and reducing toxic algal blooms is the identification of the maximum nutrient load ecosystems can absorb, while remaining in a good ecological state. In this thesis, I aim to determine the critical nutrient load for Lake Taihu. I approach the search for critical nutrient loads of Lake Taihu in five steps with diversity as an overarching topic throughout this thesis: diversity in lakes, diversity in models, diversity in spatial distribution of nutrient and water sources, diversity in the development of lakes around the earth and finally diversity within specific lakes. From the long list of available models I chose the model PCLake to use in my analysis because it is the most extensively used food web model applied for bifurcation analysis of shallow aquatic ecosystems. The approach has resulted in a range of critical nutrient loads for different parts of Lake Taihu. Furthermore, critical nutrient loads depend on management goals, i.e. the maximum allowable chlorophyll-a concentration. According to the model results, total nutrient loads need to be more than halved to reach chlorophyll-a concentrations of 30-40 μg.L-1 in most sections of the lake. To prevent phytoplankton blooms with 20 μg.L-1 chlorophyll-a throughout Lake Taihu, both phosphorus and nitrogen loads need a nearly 90% reduction. This range contrasts to the single point of recovery that is often found for small shallow lakes. The range in critical nutrient loads found for Lake Taihu can be interpreted as providing a path of recovery for which each step leads to water quality improvement in certain parts of the lake. To reach total recovery, nutrient reduction seems to be the most promising management option.

    KringloopToets: sluiten van de nutriëntenkringloop op het niveau van Noordwest-Europa : inhoudelijke en procesmatige rapportage
    Leenstra, Ferry ; Vellinga, Theun ; Bremmer, Bart - \ 2017
    Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1019) - 47
    nutriëntenstromen - voer - diervoedering - diervoeding - recycling - noordwest-europa - nutrient flows - feeds - animal feeding - animal nutrition - recycling - northwestern europe
    The Nutrient Cycle Assessment aims at visualizing nutrient flows. In policy documents closing of nutrient cycles at the level of North Western Europe is often mentioned. Province North Brabant, farmers organisation ZLTO and NGO BMF examined together with Wageningen University & Research the effects of closing the borders of North West Europe (Benelux, France, Germany, UK) for feed ingredients and animal products. The results of this exercise were discussed in a separate session with representatives of the feed industry. This report describes the conclusions of the analysis and the lessons that can be learned from this exercise for future work with the Nutrient Cycle Assessment.
    ESF stromende wateren en stroomgebiedsbrede ecologische systeemanalyse
    Verdonschot, P.F.M. ; Verdonschot, R.C.M. ; Besse-Lototskaya, A.A. - \ 2015
    H2O online (2015)28 augustus.
    hydrologie van stroomgebieden - kaderrichtlijn water - watersystemen - ecologische beoordeling - macrofauna - nutriëntenstromen - catchment hydrology - water framework directive - water systems - ecological assessment - macrofauna - nutrient flows
    Het halen van de doelen van de Kaderrichtlijn water (KRW) verloopt moeizaam, deels doordat de aanpak vaak te kleinschalig is en niet integraal. Stroomgebiedsbrede ecologische systeemanalyse (SESA) kan helpen bij het doorgronden van het ecologisch functioneren van watersystemen. Dat gaat uit van haalbare doelen en ondersteunt bij het afwegen van de verschillende gebruiksfuncties die oppervlaktewateren vervullen. Door de ecologische sleutel-, stress- en stuurfactoren aan elkaar te koppelen en te integreren in de stroomgebiedsbrede ecologische systeemanalyse ontstaat een integrale benadering die leidt tot doelgerichte maatregelen en een succesvollere aanpak van de KRW-waterproblematiek
    Nutriënten: bronnenanalyse en afleiding van achtergrondconcentraties als basis voor het bijstellen van KRW-doelen
    Schipper, P.N.M. ; Boekel, E.M.P.M. van; Ee, G. ; Hermans, J. - \ 2015
    H2O online (2015)10 aug..
    oppervlaktewater - nutriëntenstromen - fosfor - stikstof - waterbalans - modellen - noord-holland - surface water - nutrient flows - phosphorus - nitrogen - water balance - models - noord-holland
    In de helft van de regionale wateren blijven nutriënten een beperkende factor om KRW-doelen te bereiken. Is een groot deel daarvan misschien natuurlijk? Een belangrijke vraag, omdat de KRW de mogelijkheid geeft om achtergrondbelasting van nutriënten in de doelen te verrekenen. Uit het hieronder beschreven onderzoek weet HHNK nu per waterlichaam in zijn gebied waar de nutriënten vandaan komen en wat daarin het aandeel natuurlijke achtergrond is. Deze kennis is essentieel om KRW-doelen onderbouwd te kunnen bijstellen en om te kunnen bepalen waar welke maatregelen efficiënt zijn.
    Changes in Pig Production in China and Their Effects on Nitrogen and Phosphorus Use and Losses
    Bai, Z.H. ; Ma, L. ; Qin, W. ; Chen, Q. ; Oenema, O. ; Zhang, F.S. - \ 2014
    Environmental Science and Technology 48 (2014)21. - ISSN 0013-936X - p. 12742 - 12749.
    food-chain - integrated assessment - ammonia emission - nutrient flows - agriculture - consumption - management - performance - excretion - denmark
    China's pig production has increased manifold in the past 50 years, and this has greatly affected the nitrogen and phosphorus use and losses in the pig production sector. However, the magnitude of these changes are not well-known. Here, we provide an in-depth account of the changes in pig production-N and P use and total N and P losses in the whole pig production chain during the period 1960-2010-through simulation modeling and using data from national statistics and farm surveys. For the period of 2010-2030, we explored possible effects of technological and managerial measures aimed at improving the performances of pig production via scenario analysis. We used and further developed the NUtrient flows in Food Chains, Environment and Resources use (NUFER) model to calculate the feed requirement and consumption, and N and P losses in different pig production systems for all the years Between 1960 and 2010, pig production has largely shifted from the so-called backyard system to landless systems. The N use efficiencies at fattener level increased from 18 to 28%, due to the increased animal productivity. However, the N use efficiencies at the Whole system level decreased from 46 to 11% during this period, mainly due to the increase of landless pig farms, which rely on imported feed and have no land-base for manure disposal. The total N and P losses were 5289 and 829 Gg in 2010, which is 30 and 95 times higher than in 1960. In the business as usual scenario, the total N and P losses were projected to increase by 25 and 55% between 2010 and 2030, respectively. Analyses of other scenarios indicate that packages of technological and managerial measures can decrease total N and P losses by 64 and 95% respectively. Such improvements require major transition in the pig production sector, notably, in manure management, herd management, and feeding practices.
    Impacts of urban expansion on nitrogen and phosphorus flows in the food system of Beijing from 1978 to 2008
    Ma, L. ; Guo, J. ; Velthof, G.L. ; Li, Y. ; Chen, Q. ; Ma, W. ; Oenema, O. ; Zhang, F. - \ 2014
    Global environmental change : human and policy dimensions 28 (2014). - ISSN 0959-3780 - p. 192 - 204.
    environmental implications - nutrient flows - china - cities - consumption - chain - urbanization - metabolism - ecology - balance
    Rapid growth of metropolitan areas is associated with increased flows of nitrogen (N) and phosphorus (P) in the food production–consumption system. However, quantitative analyses of these flows during urban expansion and information about their controlling factors are scarce. Here, we report on N and P flows in the food system of Beijing, which experienced a remarkable growth in population number between especially 1978–2008, using a combination of statistical data bases, surveys and the NUFER model (nutrient flow in the food system, environment and resource). The N (or P) cost of food is defined as the amount of ‘new’ N (or P) used in food production for the delivery of 1 kg N (or P) in the food entering household. ‘New’ N (P) includes fertilizer N (P), biological N fixation, atmospheric N deposition, and imports of N (P) via feed and food. Recycled N (P) includes N (P) in crop residues, manures and wastes. We found that the rapid increase in temporary migrants greatly increased food imports to Beijing metropolitan areas and thereby led to an apparent decrease of the N and P cost of food. The input of ‘new’ N to the food system of Beijing metropolitan areas increased from 180 to 281 Gg, and for P from 33.5 to 50.4 Gg during 1978–2008, as a result of increases in population and changes in food consumption patterns per capita. The food and feed imports in per cent of total ‘new’ N and P inputs increased from 31 to 63% for N and from 18 to 46% for P during 1978–2008. The N and P cost of the food was relatively low compared to the mean of China, and decreased over time. About 52% of the new N input and 85% of the new P input was not recycled in 2008, it accumulated as wastes (in crop residues, animal excreta, and human excreta and household wastes). The N and P use efficiencies in crop and animal production were low, i.e., only 17% for N and 11% for P in 2008. Total losses of ammonia (NH3) and nitrous oxide (N2O) to air and of N to groundwater and surface waters increased by a factor of about 3, and losses of P to groundwater and surface waters increased by a factor of 37 in the period 1978–2008. Key measures for decreasing N and P accumulation and losses are (1) developing satellite towns, (2) expelling animal production to rural areas, and (3) effective collection of the wastes and animal manure, and the utilization of these in rural areas outside Beijing. These findings may also portend changes in other metropolitan areas in China and elsewhere in the rapidly developing world.
    Nitrogen and Phosphorus Use Efficiencies in Dairy Production in China
    Bai, Z.H. ; Ma, L. ; Oenema, O. ; Chen, Q. ; Zhang, F.S. - \ 2013
    Journal of Environmental Quality 42 (2013)4. - ISSN 0047-2425 - p. 990 - 1001.
    nutrient flows - farming system - food-chain - management - agriculture - losses - feed - performance - industry
    Milk production has greatly increased in China recently, with significant impacts on the cycling of nitrogen (N) and phosphorus (P). However, nutrient flows within the changing dairy production system are not well quantified. The aim of this study was to increase the quantitative understanding of N and P cycling and utilization in dairy production through database development and simulation modeling. In 2010, of the entire 1987 and 346 thousand tons (Gg) of N and P input, only 188 Gg N and 31 Gg P ended up in milk. The average N and P use efficiencies were 24 and 25%, respectively, at the whole system level. Efficiencies differed significantly between the four dairy systems. Losses of N from these systems occurred via NH3 volatilization (33%), discharge (27%), denitrification (24%), NO3 leaching and runoff (16%), and N2O emission (1%). Industrial feedlots use less feed per kg milk produced than traditional systems, and rely more on high-quality feed from fertilized cropland; they have very poor recycling of manure nutrients to cropland. As industrial feedlot systems are booming, overall mean N and P use efficiencies will increase at herd level but will decrease at the whole dairy production system level unless manure N and P are used more efficiently through reconnecting China's feed and dairy production sectors.
    Behoefte en verbruik van micronutriënten in de diervoeding = Requirement and consumption of micro nutrients in animal feed
    Krimpen, M.M. van; Vuuren, A.M. van; Bikker, P. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 673) - 31
    rundveehouderij - varkenshouderij - pluimveehouderij - rundveevoeding - varkensvoeding - pluimveevoeding - mineralenvoeding - voer - kwantitatieve kenmerken - nutriëntenstromen - wereldeconomie - schaarste - cattle husbandry - pig farming - poultry farming - cattle feeding - pig feeding - poultry feeding - mineral nutrition - feeds - quantitative traits - nutrient flows - world economy - scarcity
    In this report, the requirements of some micro nutrients for cattle, pigs and poultry are summarized. Moreover, the global consumption of micro nutrients that are added to animal diets is calculated and compared with the total global use for all applications.
    Bio-energie en bodemkwaliteit : : terugwinning van nutriënten en organische stof bij kleinschalige bio-energie systemen in ontwikkelingslanden
    Bonten, L.T.C. ; Wosten, J.H.M. ; Rijssenbeek, W.L.M.M. ; Franken, Y.J. - \ 2012
    Bodem 22 (2012)5. - ISSN 0925-1650 - p. 24 - 26.
    bodemkwaliteit - duurzaamheid (sustainability) - landbouwproductie - brandstofgewassen - nutriëntenstromen - ontwikkelingslanden - bio-energie - biobased economy - soil quality - sustainability - agricultural production - fuel crops - nutrient flows - developing countries - bioenergy - biobased economy
    Bio-energie kan een bijdrage leveren aan een duurzamere energievoorziening. Grootschalige export van biomassa voor energieproductie, uit vooral tropische landen, gaat echter gepaard met de export van nutriënten en organische stof, en heeft uitputting van de bodem tot gevolg. Bij lokale productie van bio-energie kunnen nutriënten en organische stof wellicht teruggewonnen worden.
    Tracing the spatial propagation of river inlet water into an agricultural polder area using anthropogenic gadolinium
    Rozemeijer, J. ; Siderius, C. ; Verheul, M. ; Pomarius, H. - \ 2012
    Hydrology and Earth System Sciences 16 (2012)8. - ISSN 1027-5606 - p. 2405 - 2415.
    watervoorziening - rivierwater - watertekort - zoet water - waterkwaliteit - landbouwgrond - tracer technieken - zeldzame aardelementen - nutriëntenstromen - water supply - river water - water deficit - fresh water - water quality - agricultural land - tracer techniques - rare earth elements - nutrient flows - quality - impact - irrigation - hydrology - nitrogen
    Diverting river water into agricultural areas or nature reserves is a frequently applied management strategy to prevent fresh water shortage. However, the river water might have negative consequences for chemical and ecological water quality in the receiving water bodies. This study aimed to obtain a spatial image of the diverted river water propagation into a hydrologically complex polder area, the polder Quarles van Ufford in The Netherlands. We used anthropogenic gadolinium (Gd-anomaly) as a tracer for river water that was diverted into the polder. A clear reduction in the river water contribution was found between very dry conditions on 5 August 2010 and very wet conditions on 22 October. Despite the large river water impact on 5 August, the diverted river water did not propagate up into the small agricultural headwater ditches. Gadolinium proved to be an effective tracer for diverted river water in a polder system. We applied our results to upgrade the interpretation of water quality monitoring data and to validate an integrated nutrient transport model
    Nutrient flows in small-scale bio-energy use in developing countries
    Bonten, L.T.C. ; Wösten, J.H.M. - \ 2012
    Wageningen : Alterra (Alterra-rapport 2304) - 42
    bio-energie - voedingsstoffenretentie - voedingsstoffen - brandstofgewassen - energieomzetting - biomassa - nutriëntenstromen - ontwikkelingslanden - biobased economy - bioenergy - nutrient retention - nutrients - fuel crops - energy conversion - biomass - nutrient flows - developing countries - biobased economy
    This study explored the opportunities for the retention and return of nutrients in local bio-energy production using energy crops (oil palm, jatropha and cassava), fuel wood, manure, rice husks and a common pest plant (water hyacinth). For all bio-energy systems some return of nutrients is possible, but the differences between conversion technologies and between feed stocks can be large. Anaerobic digestion retains most nutrients, while combustion and gasification loses all nitrogen. Palm oil has the lowest potential for nutrient return of the energy crops; however it is the most efficient, together with cassava, regarding the required nutrient input per mega joule of bio-energy. Jatropha is the least efficient energy crop, it requires the most nutrients to produce a mega joule of energy.
    3D-modellering van nutriëntentransport door bodem en grondwater
    Janssen, G. ; Griffioen, J. ; Grift, B. van der; Groenendijk, P. - \ 2011
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 44 (2011)6. - ISSN 0166-8439 - p. 27 - 29.
    nutriëntenstromen - bodem - grondwater - transportprocessen - bodemwaterbeweging - nutriëntenuitspoeling - waterkwaliteit - modellen - nutrient flows - soil - groundwater - transport processes - soil water movement - nutrient leaching - water quality - models
    Deltares heeft samen met Alterra een concept ontwikkeld voor driedimensionale modellering van nutriëntentransport. Door ANIMO te koppelen aan RT3D wordt de kennis over nutriëntenprocessen in de bodem gekoppeld aan transportprocessen in het diepere grondwater. Hiermee kan men de bijdrage van de uitspoeling uit de bodem aan de oppervlaktewaterkwaliteit, de afhankelijkheden tussen gebieden en de mate van bedreiging van bijvoorbeeld grondwaterlichamen en drinkwaterwinningen beter inschatten en voorspellen. Tegelijkertijd wordt een voorzet gegeven voor de invulling van een onderdeel van de kwaliteitsmodellering in het hydrologische modelspoor van het Nationaal Hydrologisch Instrumentarium.
    Verspreiding inlaatwater in beeld met nieuwe tracer
    Rozemeijer, J. ; Siderius, C. ; Verheul, M. ; Pomarius, H. - \ 2011
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 12 (2011). - ISSN 0166-8439 - p. 33 - 35.
    oppervlaktewaterkwaliteit - tracers - tracer technieken - nieuwe producten - nutriëntenstromen - watersystemen - hydrologie van stroomgebieden - maas - land van maas en waal - surface water quality - tracers - tracer techniques - new products - nutrient flows - water systems - catchment hydrology - river meuse - land van maas en waal
    Inlaatwater heeft in de polder Quarles van Ufford zelfs in een droge periode geen invloed op de waterkwaliteit van kleine landbouwsloten. Dat blijkt uit metingen van de concentratie gadolinium, die zijn uitgevoerd voor het project Monitoring Stroomgebieden. Hiermee komt voor dit gebied een einde aan de twijfel over de invloed van inlaatwater op de oppervlaktewaterkwaliteit en is er meer duidelijkheid over de belasting vanuit de landbouw.
    Nog steeds fosfaat in vaatwasmiddel
    Smit, A.L. - \ 2011
    Kennis Online 8 (2011)augustus. - p. 8 - 8.
    fosfor - fosfaatuitspoeling - nutriëntenstromen - voedingsstoffenbalans - visualisatie van stroming - kringlopen - nederland - phosphorus - phosphate leaching - nutrient flows - nutrient balance - flow visualization - cycling - netherlands
    Haalbaarheidsstudie terugwinning van mestnutriënten : Fase 1: Processchema en nutriëntenstromen = Feasibility study on nutrient recovery from animal manure : Phase 1: Process scheme and nutrient flows
    Starmans, D.A.J. ; Melse, R.W. ; Sanders, J.P.M. - \ 2011
    Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 446) - 21
    rundveehouderij - varkenshouderij - varkensmest - rundveemest - dierlijke meststoffen - mestverwerking - nutriëntenstromen - co-vergisting - scheidingstechnologie - haalbaarheidsstudies - digestaat - biobased economy - cattle husbandry - pig farming - pig manure - cattle manure - animal manures - manure treatment - nutrient flows - co-fermentation - separation technology - feasibility studies - digestate - biobased economy
    A process scheme for a new manure treatment system for pig and cattle manure was formulated which aims to produce manure nutrient flows with added value. The basic process behind the treatment system is fermentation of manure, which is preceded by both stripping ammonia and chemical digestion of the organic solids. The fermented manure is separated in a thin and a thick phase, which is further treated.
    A quantification of phosphorus flows in the Netherlands through agricultural production, industrial processing and households
    Smit, A.L. ; Middelkoop, J.C. van; Dijk, W. van; Reuler, H. van; Buck, A.J. de; Sanden, P.A.C.M. van de - \ 2010
    Wageningen : Plant Research International (Rapport / Plant Research International 364) - 55
    fosfor - fosfaatuitspoeling - nutriëntenstromen - voedingsstoffenbalans - visualisatie van stroming - kringlopen - nederland - phosphorus - phosphate leaching - nutrient flows - nutrient balance - flow visualization - cycling - netherlands
    To investigate the possibilities for a more sustainable use of phosphorus it was necessary to have a complete picture of the national phosphorus flows in the Netherlands. In this report a material flow analysis was performed by dividing the national system into a number of subsystems: agricultural subsystems (arable, grazing, intensive livestock) but also non-agricultural subsystems (food industry, non-food industry, feed industry, household, waste management, environment) were included. Quantification of the various phosphorus flows between the subsystems was done for the year 2005 and was based on various data sources. The results showed that in the reference year 2005 a surplus of around 60 Mkg of P existed, roughly half of this amount accumulated in agricultural soil. The remaining part ended up in ground or surface water (around 7 Mkg) or was sequestered in one way or another (e.g. landfill, incineration ashes, sewage sludge etc.). Recycling from society (households and industry) back to agriculture was minimal. Options for a more sustainable use of phosphorus in the Netherlands are discussed.
    Integrated soil fertility management: Operational definition and consequences for implementation and dissemination
    Vanlauwe, B. ; Bationo, A. ; Chianu, J. ; Giller, K.E. ; Merckx, R. ; Mokwunye, U. ; Ohiokpehai, O. ; Pypers, P. ; Tabo, R. ; Shepherd, K.D. ; Smaling, E.M.A. ; Woomer, P.L. ; Sanginga, N. - \ 2010
    Outlook on Agriculture 39 (2010)1. - ISSN 0030-7270 - p. 17 - 24.
    smallholder farms - western kenya - exploring diversity - resource-allocation - nutrient flows - variability - tropics - maize
    Traditional farming systems in Sub-Saharan Africa depend primarily on mining soil nutrients. The African green revolution aims to intensify agriculture through the dissemination of integrated soil fertility management (ISFM). This paper develops a robust and operational definition of ISFM based on detailed knowledge of African farming systems and their inherent variability and of the optimal use of nutrients. The authors define ISFM as a set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs and improved germplasm, combined with the knowledge on how to adapt these practices to local conditions, aimed at maximizing agronomic use efficiency of the applied nutrients and improving crop productivity. All inputs need to be managed in accordance with sound agronomic principles. The integration of ISFM practices into farming systems is illustrated with the dual-purpose grain legume-maize rotations in the savannas and fertilizer micro-dosing in the Sahel. Finally, the dissemination of ISFM practices is discussed
    Meetgebieden in de gebieden Drentse Aa, Schuitenbeek, Krimpenerwaard en Quarles van Ufford : een eerste data-analyse ten behoeve van het tussenrapport Monitoring Stroomgebieden
    Roelsma, J. ; Bogaart, P.W. ; Siderius, C. - \ 2010
    Wageningen : Alterra (Alterra-rapport 1957) - 84
    stroomgebieden - waterkwaliteit - monitoring - voedingsstoffengehalte - stikstof - fosfaat - nederland - nutriëntenstromen - drenthe - veluwe - krimpenerwaard - land van maas en waal - watersheds - water quality - monitoring - nutrient content - nitrogen - phosphate - netherlands - nutrient flows - drenthe - veluwe - krimpenerwaard - land van maas en waal
    Een eerste data-analyse ten behoeve van het tussenrapport Monitoring Stroomgebieden
    ANIMO-RT3D 1.0 On line koppeling van Animo en RT3D voor dynamische modellering van nutriëntentransport op regionale schaal
    Janssen, G. ; Grift, B. van der; Griffioen, J. ; Groenendijk, P. - \ 2010
    Utrecht : Deltares - 82
    nutriëntenstromen - transportprocessen - nutriëntenuitspoeling - bodem - grondwater - modellen - koppeling - nutrient flows - transport processes - nutrient leaching - soil - groundwater - models - linkage
    ANIMO-RT3D is het acroniem voor een gekoppeld transportmodel voor nutriënten tussen de onverzadigde en verzadigde zone. ANIMO is ontwikkeld door Alterra en beschrijft in detail het verloop van de koolstof-, stikstof- en fosforcyclus in de bodem, onder invloed van dynamische meteorologische (neerslag, temperatuur, verdamping) en agrarische (landbouwmanagement) omstandigheden. RT3D is een generiek 3D reactief-transportmodel voor de verzadigde zone. De in dit rapport beschreven modelkoppeling, waarin ANIMO en RT3D on-line zijn gekoppeld, is bedoeld om het koppelingsprincipe te testen en om aan te tonen dat een dergelijke koppeling mogelijk is.
    Network analysis of N flows and food self-sufficiency - a comparative study of crop-livestock systems of the highlands of East and southern Africa
    Rufino, M.C. ; Tittonell, P.A. ; Reidsma, P. ; Lopez-Ridaura, S. ; Hengsdijk, H. ; Giller, K.E. ; Verhagen, A. - \ 2009
    Nutrient Cycling in Agroecosystems 85 (2009)2. - ISSN 1385-1314 - p. 169 - 186.
    soil fertility gradients - smallholder farms - western kenya - exploring diversity - nutrient flows - management - heterogeneity - efficiencies - strategies - ecosystem
    Smallholder farming systems in sub-Saharan Africa are often nutrient-limited, and therefore imports must be increased to compensate exports and losses. To explore whether the properties of nutrient cycling networks relate to the systems’ capability to sustain rural families, we investigated N flows within contrasting crop-livestock systems in Ethiopia, Kenya and Zimbabwe applying concepts from ecological network analysis. Farm households were conceptualised as networks, the compartments were the household and their farming activities which were connected by the N flows. Indicators assessing network size, activity and cycling, and the organisation and diversity of the N flows were compared with system productivity and food self-sufficiency. Results showed that organisation and diversity of N flows to, from and within the farm households differed more between farms of different resource endowments than across sites. The amount of N cycled per household was small and comparable across sites: less than 25 kg N year-1, and for the poor households less than 5 kg N year-1. Poor households with soil N stocks that were 50–60% smaller than wealthier households depended more on external inputs (e.g. a dependence of 65% vs. 45% in Zimbabwe). Productivity was positively related to network size, its organisation and N cycling, but utilisation efficiencies were different across sites in relation to soil N stock and the importance of livestock for N flows. Greater size of the N flow network and its organisation led to increased productivity and food self-sufficiency, reducing dependence, which may increase the adaptability and reliability of smallholder crop-livestock systems
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