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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Stochastic uncertainty and sensitivities of nitrogen flows on diary farms in The Netherlands
Oenema, J. ; Burgers, S. ; Keulen, H. van; Ittersum, M.K. van - \ 2015
Agricultural Systems 137 (2015). - ISSN 0308-521X - p. 126 - 138.
manure management-practices - nutrient management - use efficiency - systems - balances - budgets - losses - europe
Nutrient management decisions and environmental policy making must be based on sound data and proper analysis. Annual data collection and monitoring of farm and nutrient performance are wrought with uncertainties. Such uncertainties need to be addressed as it may lead to ambiguities and wrong conclusions. We developed an input-output N balance model to describe and quantify N flows in dairy farming systems. Input for this model was based on monitored data for one year (2005) from one experimental (detailed monitoring) and 14 pilot commercial dairy farms (less detailed monitoring). A Monte Carlo approach was used to quantify effects of uncertainty of input data on annual farm N surplus, soil surface N surplus and N intake during grazing, followed by a sensitivity analysis to apportion the different sources of uncertainty. Uncertainties in data input were described with probability density functions. Farm N surplus of the 14 pilot farms ranged between 81 and 294¿kg¿ha-1, soil surface N surplus between 35 and 256¿kg¿ha-1, and N intake during grazing between 27 and 108¿kg¿ha-1. The uncertainties of N flows – both relative and absolute – increased from farm N surplus (CV¿=¿8%; SD¿=¿15¿kg¿N¿ha-1) to soil surface N surplus (CV¿=¿12%; SD¿=¿16¿kg¿N¿ha-1) to N intake during grazing (CV¿=¿49%; SD¿=¿28¿kg¿N¿ha-1). Variation in uncertainty among farms in farm and soil surface N surplus and N intake during grazing was substantial and was related to the farm structure and farm characteristics such as production intensity, N fixation by clover and annual changes in stocks of roughage and manure. We found that a monitoring program based on more measurements instead of estimates and/or fixed rate values from literature will not always result in a better quantification of farm and soil surface N surplus on clover-based dairy farms. However, on farms with no N fixation, an intensive monitoring program reduced the uncertainty in farm and soil surface N surplus by 23% and the uncertainty of N intake during grazing was reduced by more than 30%. Knowledge about uncertainties of N flows is necessary to correctly interpret the N performance on dairy farms and its evolution through time. A first step is to get insights into the most uncertain N flows on a dairy farm. The next step, where possible, is to improve the estimation of the most uncertain N flows. Based on the insights from this study, these steps will underpin the validation of trends in N performance and justify decisions in environmental policy making and/or decisions for making on-farm improvements.
Nutrient regeneration by mussel Mytilus edulis spat assemblages in a macrotidal system
Broekhoven, W. van; Troost, K. ; Jansen, H.M. ; Smaal, A.C. - \ 2014
Journal of Sea Research 88 (2014). - ISSN 1385-1101 - p. 36 - 46.
la-madeleine quebec - seasonal-variation - biogeochemical fluxes - oosterschelde estuary - carrying-capacity - nitrogen - rates - phytoplankton - aquaculture - budgets
Besides exercising grazing control over phytoplankton populations, suspension-feeding bivalves can also stimulate carrying capacity by regeneration of nutrients. This study provides new data on nutrient uptake and release dynamics, and potential implications for availability and stoichiometry of nutrients, for Mytilus edulis spat collectors in the Netherlands. Uptake and release rates were measured in situ on intact spat collector ropes in a eutrophic macrotidal system in relation to development of ropes in terms of mussel biomass and associated components (fauna, flora, and organic material). There was a good fit between uptake/release rates and mussel weight based on allometric scaling functions, despite the occurrence of a substantial biomass of associated fauna, flora and organic matter on ropes. On a unit biomass basis, nutrient release rates were much higher than reported in other studies, which we attribute to greater activity of small mussels. Accounting for greater weight-specific activity of small mussels, spat collectors released more P than reported for other systems. We show that spat collectors can affect relative availabilities of N, P and Si, and we show that SMCs (Seed Mussel Collectors) likely stimulated phytoplankton production through regeneration of N and of Si, which were at limiting concentrations at different points in time. In the case of Si, stimulation would be restricted to diatoms. We conclude that SMCs are able to stimulate phytoplankton production rates, and thereby carrying capacity, and are able to influence phytoplankton composition.
The nitrogen footprint of food products in the European Union
Leip, A. ; Weiss, F. ; Lesschen, J.P. ; Westhoek, H. - \ 2014
The Journal of Agricultural Science 152 (2014)S1. - ISSN 0021-8596 - p. 20 - 33.
greenhouse-gas emissions - water footprint - agriculture - land - budgets - carbon - capri
Nitrogen (N) is an essential element for plants and animals. Due to large inputs of mineral fertilizer, crop yields and livestock production in Europe have increased markedly over the last century, but as a consequence losses of reactive N to air, soil and water have intensified as well. Two different models (CAPRI and MITERRA) were used to quantify the N flows in agriculture in the European Union (EU27), at country-level and for EU27 agriculture as a whole, differentiated into 12 main food categories. The results showed that the N footprint, defined as the total N losses to the environment per unit of product, varies widely between different food categories, with substantially higher values for livestock products and the highest values for beef (c. 500 g N/kg beef), as compared to vegetable products. The lowest N footprint of c. 2 g N/kg product was calculated for sugar beet, fruits and vegetables, and potatoes. The losses of reactive N were dominated by N leaching and run-off, and ammonia volatilization, with 0·83 and 0·88 due to consumption of livestock products. The N investment factors, defined as the quantity of new reactive N required to produce one unit of N in the product varied between 1·2 kg N/kg N in product for pulses to 15–20 kg N for beef.
Wijzer met groen in de stad; Van bestaansvoorwaarde naar verdienmodel. Achtergronddocument
Dijkshoorn-Dekker, M.W.C. ; Blaeij, A.T. de; Polman, N.B.P. ; Michels, R. ; Ballemans, M. - \ 2013
Den Haag : LEI Wageningen UR (LEI Wageningen UR 14-070) - 21
openbaar groen - stedelijke gebieden - bedrijfsvoering - omgevingsverrijking - regelingen - budgetten - publiek-private samenwerking - public green areas - urban areas - management - environmental enrichment - regulations - budgets - public-private cooperation
Het mkb-bedrijf heeft continu te maken met nieuwe ontwikkelingen, die zowel van invloed zijn op het bedrijf als p de omgeving. Deze hebben ook effect op het groen in de stedelijke omgeving. Om de meerwaarde van groen voor een bedrijf te kunnen bepalen is het van belang deze ontwikkelingen hierin mee te nemen.
Databank Gemeentelijk Groenbeheer geeft inzicht: Hoe doet de buurman dat?
Hop, M.E.C.M. ; Spijker, J. - \ 2013
Vitale Groene Stad 2013 (2013)2. - p. 40 - 41.
openbaar groen - kosten - groenbeheer - budgetten - kennisoverdracht - public green areas - costs - management of urban green areas - budgets - knowledge transfer
De crisis gaat ook aan het gemeentelijk groen niet ongemerkt voorbij. Beheerafdelingen proberen het gemeentelijk groen zo goed mogelijk te beheren met afnemende budgetten. Moet je bezuinigen op groen, dan is het handig om te weten wat realistische mogelijkheden daarvoor zijn. Een kijkje in de keuken bij andere gemeenten kan zeer verhelderend werken.
Gazons duurder dan borders met rozen of vaste planten?
Hop, M.E.C.M. - \ 2013
Stad + groen : vakblad over openbaar groen en het vergroenen van de buitenruimte 2013 (2013)2. - ISSN 2352-4634 - p. 88 - 93.
stadsomgeving - openbaar groen - groenbeheer - kosten-batenanalyse - overblijvende planten - gazon - beplantingen - budgetten - opinies - urban environment - public green areas - management of urban green areas - cost benefit analysis - perennials - lawns and turf - plantations - budgets - opinions
In de eerste uitgave van Vitale Stad stond een artikel over gazons die duurder zouden zijn dan borders met vaste planten of sierheesters. Volgens dit artikel zouden vaste planten dus goedkoper zijn dan gazons. Als wij die vraag stellen aan de gemiddelde groenbeheerder, krijgt je een compleet ander antwoord. Hoe zit het nu eigenlijk?
Time-dependent, species-specific effects of N:P stoichiometry on grassland plant growth
Fujita, Y. ; Ruiter, P.C. de; Wassen, M.J. ; Heil, G.W. - \ 2010
Plant and Soil 334 (2010)1-2. - ISSN 0032-079X - p. 99 - 112.
nutrient availability - wetland graminoids - 2nd-year growth - phosphorus - nitrogen - fens - acquisition - budgets - limitation - vegetation
N and P have different eutrophication effects on grassland communities, yet the underlying mechanisms are poorly understood. To examine plant growth in response to the varying (relative) supply of N and P, we conducted a two-year greenhouse experiment. Five grasses and three herbs were grown with three N:P supply ratios at two overall nutrient supply levels. During the first year the plant growth was relatively low at both high and low N:P supply ratios, whereas during the second year the growth was especially low at a high N:P supply ratio. This second-year low growth was attributed to the high root death rate, which was influenced by a high N:P supply ratio rather than by the nutrient supply level. Species responded differently, especially in P uptake and loss at a high N:P supply ratio. Each species seemed to have a different strategy for P limitation, e.g. an efficient P uptake or a high P resorption rate. Species typical of P-limited grasslands had neither better P uptake nor better P retention at a high N:P supply ratio. This study quantitatively demonstrates an increased plant root death triggered by strong P limitation. This finding indicates a possible extra effect of N eutrophication on ecosystem functioning via changed N:P stoichiometry
Economic and nutrient discharge tradeoffs of excreta-fed aquaculture in the Mekong Delta, Vietnam
Nhan, D.K. ; Verdegem, M.C.J. ; Binh, N.T. ; Duong, L.T. ; Milstein, A. ; Verreth, J.A.J. - \ 2008
Agriculture, Ecosystems and Environment 124 (2008)3-4. - ISSN 0167-8809 - p. 259 - 269.
multiple-regression analysis - crop-animal systems - fish yield - ponds - agriculture - thailand - farmers - budgets - profit - inputs
The present study quantifies the effects on production, nutrient discharge and economic return of the use of pig and human excreta in pond tanning. On-farm data from various studies were integrated and analyzed applying single and multiple regression methods. Pond-dissolved oxygen concentration, water exchange and nutrient discharge interacted and were strongly affected by input level. Increased input levels coincided with farmers exchanging more water and discharging more chemical oxygen demand (COD), nitrogen (N), phosphorus (P) and total suspended solids (TSS). Fish yield and the accumulation of organic carbon, N and P in pond sediments increased with the excreta input level. Using a regression model, it was predicted that with an excreta input of 5 kg N ha(-1) day(-1), a fish yield of 8380 kg and an economic return of 52 million VND ha(-1) year(-1) can be obtained while about 2060 kg COD, 645 kg N, 210 kg P and 39,200 kg TSS ha(-1) year(-1) will be discharged. At this input level, it was estimated that about 9% of input-N will be recovered in harvested fish while 52% will accumulate in the pond sediment. Hence, fish culture reduces nutrient discharge from excreta by 61% while generating income for resource-poor farmers. However, in the long run such a system will become unsustainable when more farmers take up this farming practice. The challenges are to reduce nutrient discharges from ponds while maintaining high production and profitability and to use the nutrients accumulated pond sediments more efficiently. (c) 2007 Elsevier B.V. All rights reserved.
Crop residue, manure and fertilizer in dryland maize under reduced tillage in northern China: I grain yields and nutrient use efficiencies
Wang, X.B. ; Cai, D.X. ; Hoogmoed, W.B. ; Perdok, U.D. ; Oenema, O. - \ 2007
Nutrient Cycling in Agroecosystems 79 (2007)1. - ISSN 1385-1314 - p. 1 - 16.
nitrogen use efficiency - soil fertility - water-use - management - systems - rice - wheat - plain - budgets - losses
The rapidly increasing population and associated quest for food and feed in China has led to increased soil cultivation and nitrogen (N) fertilizer use, and as a consequence to increased wind erosion and unbalanced crop nutrition. In the study presented here, we explored the long-term effects of various combinations of maize stover, cattle manure and nitrogen (N) and phosphorus (P) fertilizer applications on maize (Zea mays L.) yield and nutrient and water use efficiencies under reduced tillage practices. In a companion paper, we present the effects on nutrient balances and soil fertility characteristics. The ongoing factorial field trial was conducted at Shouyang Dryland Farming Experimental Station in northern China from 1993 onwards. The incomplete, determinant-optimal design comprised 12 treatments, including a control treatment, in duplicate. Grain yields and N, P, and potassium (K) uptakes and N, P and K use efficiencies were greatly influenced by the amount of rain during the growing season (GSR), and by soil water at sowing (SWS). There were highly significant interactions between GSR and added stover and manure, expressed in complex annual variations in grain yield and N, P and K use efficiencies. Annual mean grain yields ranged from 3,000 kg ha¿1 to 10,000 kg ha¿1 and treatment mean yields from 4,500 kg ha¿1 to 7,000 kg ha¿1. Balanced combination of stover (3,000¿6,000 kg), manure (1,500¿6,000 kg) and N fertilizer (105 kg) gave the highest yield. Stover and manure were important for supplying K, but the effects differed greatly between years. Overall mean N recovery efficiency (NRE) ranged from 28% to 54%, depending on N source. NRE in wet years ranged from 50% to 90%. In conclusion, balanced combinations of stover, manure and NP fertilizer gave the highest yield and NRE. Reduced tillage with adding stover and manure in autumn prior to ploughing is effective in minimizing labor requirement and wind erosion. The potentials of split applications of N fertilizer, targeted to the need of the growing crop (response farming), should be explored to further increase the N use efficiency.
KB-WOT Fisheries Research : programme for 2007
Dickey-Collas, M. ; Beek, F.A. van - \ 2007
IJmuiden : Centrum voor Visserijonderzoek (CVO) (CVO report 07.006) - 53
visserij - visserijbeleid - visserijbeheer - toegepast onderzoek - programmaontwikkeling - programma's - budgetten - mariene ecologie - nederland - aquatische ecosystemen - fisheries - fishery policy - fishery management - applied research - program development - programs - budgets - marine ecology - netherlands - aquatic ecosystems
LNV programma 406 omvat de wettelijke taken die door DLO uitgevoerd worden en betrekking hebben op de visserij. Binnen dit programma is er een Kennisbasis budget dat bedoeld is voor het ontwikkelen en onderhouden van expertise om dit programma uit te kunnen voeren. Dit rapport beschrijft hoe het budget voor 2007 (€ 621000) aan onderzoeksprojecten is toegekend. Van ieder onderzoeksproject wordt een beschrijving gegeven. De projecten zijn onderverdeeld in vijf thema’s: 1) invloed van veranderende leefomgeving op mariene ecosystemen, 2) impact van visserij op ecosysteem, 3) visserijbeheer, 4) onderhoud sleutelexpertise en 5) kleine onderzoeksprojecten. Het rapport geeft bovendien een doorkijk naar de behoefte aan Kennisbasis budget voor de periode van 2008-2010
Report of the KB-WOT fisheries programme carried out in 2006
Dickey-Collas, M. ; Beek, F.A. van - \ 2007
IJmuiden : IMARES (Report / Wageningen IMARES no. C044/07) - 19
visserij - visserijbeheer - mariene ecologie - budgetten - onderzoeksondersteuning - nederland - fisheries - fishery management - marine ecology - budgets - research support - netherlands
LNV programma 406 omvat de wettelijke taken die door DLO uitgevoerd worden en betrekking hebben op de visserij. Binnen dit programma is er een Kennisbasis budget dat bedoeld is voor het ontwikkelen en onderhouden van expertise om dit programma uit te kunnen voeren. Dit rapport beschrijft hoe het budget voor 2006 (€ 621000) gebruikt is voor de diverse onderzoeksprojecten. Van ieder onderzoeksproject wordt een beschrijving gegeven, daarnaast worden de resultaten, de opgedane kennis en een verantwoording van de financiering gegeven. De projecten zijn onderverdeeld in vijf thema’s: 1) invloed van veranderende leefomgeving op mariene ecosystemen, 2) impact van visserij op ecosysteem, 3) visserijbeheer, 4) onderhoud sleutelexpertise en 5) kleine onderzoeksprojecten
Evaluating farm performance using agri-environmental indicators: Recent experiences for nitrogen management in The Netherlands
Langeveld, J.W.A. ; Verhagen, A. ; Neeteson, J.J. ; Keulen, H. van; Conijn, J.G. ; Schils, R.L.M. ; Oenema, J. - \ 2007
Journal of Environmental Management 82 (2007)3. - ISSN 0301-4797 - p. 363 - 376.
nutrient management - pilot farms - dairy farms - balances - systems - soil - agriculture - budgets - impact - level
Intensive agriculture, characterized by high inputs, has serious implications on the environment. Monitoring and evaluation of projects aiming at designing, testing and applying more sustainable practices require instruments to asses agronomic as well as environmental performance. Guidelines for Good Agricultural Practice (GAP) or Good Farming Practice (GFP) define sustainable practices but give limited insight into their environmental performance. Agri-environmental indicators (AEIs) provide information on environmental as well as agronomic performance, which allows them to serve as analytical instruments in research and provide thresholds for legislation purposes. Effective AEIs are quantifiable and scientifically sound, relevant, acceptable to target groups, easy to interpret and cost-effective. This paper discusses application of four AEIs for nitrogen (N) management in three Dutch research projects: `De Marke¿, `Cows and Opportunities¿ and `Farming with a future¿. `De Marke¿ applied Nitrogen Surplus and Groundwater Nitrate Concentration in the design and testing of environmentally sound dairy systems. `Cows and Opportunities¿, testing and disseminating dairy systems designed at `De Marke¿, mainly applied Nitrogen Surplus, while `Farming with a future¿ used Nitrogen Surplus, Groundwater Nitrate Concentration and Residual Mineral Soil Nitrogen to support arable farmers in complying with Dutch legislation (MINAS). Nitrogen Surplus is quantifiable, appealing and easy to interpret, but lacks scientific soundness or a good relationship with groundwater quality. Nitrogen Use Efficiency is sensitive to changes in management, while Residual Mineral Soil Nitrogen is appealing and cheap, but has difficulties in scaling. Groundwater Nitrate Concentration lacks clear rules for sampling, is labor consuming, expensive and mainly used in combination with other indicators. AEIs enhanced improvements in N management by facilitating (i) definition of project goals, (ii) design of desired systems, (iii) evaluation of applied systems and (iv) improving effective communication. AEI applications in other countries show a similar pattern as found in The Netherlands. Limitations to AEI application relate to inconsistencies between different indicators, heterogeneity of soil characteristics and linkages of N, carbon and water management. AEIs should be applied in an integrated evaluation, at a scale that reflects the farm's spatial variability. Simple AEIs like Nitrogen Surplus should be supported by other indicators and/or model calculations. The paper concludes that AEIs proved their value in design, implementation and testing of farming systems, but they should be used with care, always keeping in mind that indicators are simplifications of complex and variable processes.
Exploring the trophic structure in organically fertilized and feed-driven tilapia culture environments using multivariate analyses
Muendo, P.N. ; Milstein, A. ; Dam, A. ; Gamal, N.E. ; Stoorvogel, J.J. ; Verdegem, M.C.J. - \ 2006
Aquaculture Research 37 (2006)2. - ISSN 1355-557X - p. 151 - 163.
oreochromis-niloticus - chemical fertilizers - aquaculture ponds - fish ponds - water - nitrogen - polyculture - phosphorus - manures - budgets
Reports of similar yields in manure and feed-driven tilapia culture environments raise questions on food utilization in these environments. The possibility that similar production rates are because of utilization of different foods was investigated using exploratory techniques of multivariate analyses. Using factor analysis, trophic pathways through which food becomes available to fish were explored, and using anova models, water quality, sediment quality and tilapia growth and yields were compared. Conceptual graphic models of the main ecological processes occurring in feed-driven and organically fertilized environments are presented and discussed. In both environments, autotrophic and heterotrophic pathways are important processes that result in the availability of natural foods that are utilized by the fish. Extrapolated fish yield data indicate that with equal nutrient input and stocking density, organically fertilized environments could achieve production rates similar to those in feed-driven environments. The general assumption that supplemental or complete foods are well utilized by tilapia in outdoor stagnant ponds remains challenged, and further research on tilapia feeding behaviour and food selection in feed-and organic fertilizer-driven environments is needed.
Research Guidance: De rode draad bij (systeem) innovaties
Ravensbergen, Peter - \ 2005
agricultural sector - research - knowledge - change - research support - budgets - knowledge transfer - system innovation - scientific research
Short Communication. Rhizons improved estimation of nutrient losses because of seepage in aquaculture ponds
Muendo, P.N. ; Stoorvogel, J.J. ; Gamal, N.E. ; Verdegem, M.C.J. - \ 2005
Aquaculture Research 36 (2005)13. - ISSN 1355-557X - p. 1333 - 1336.
fish ponds - water - phosphorus - hydrology - nitrogen - budgets - shallow - lake
History and prospect of catchment biogeochemistry: a european perspective based on acid rain
Breemen, N. van; Wright, R.F. - \ 2004
Ecology 85 (2004)9. - ISSN 0012-9658 - p. 2363 - 2368.
verzuring - oppervlaktewater - zure regen - luchtverontreiniging - biogeochemie - monitoring - stroomgebieden - aquatisch milieu - acidification - surface water - acid rain - air pollution - biogeochemistry - monitoring - watersheds - aquatic environment - experimental lakes area - experimental acidification - ecosystem experiments - nitrogen saturation - ammonium-sulfate - soil-water - forest - deposition - project - budgets
Hydrochemical monitoring of catchments provided a philosophical framework as well as hard data to understand and quantify the linked biological and abiotic processes that explain how atmospheric deposition of S and N changed soils and waters in nonagricultural areas across Europe. Initially, as a tool to collect relevant data in a representative and systematic way, hydrochemical monitoring provided evidence for widespread surface water acidification related to atmospheric pollution and long-range air transport. Recognizing the strong effect biota can have on their chemical environment, in the context of catchment biogeochemistry, these data provided new insights into individual processes of soil and water acidification and helped to quantify the relative importance of natural and anthropogenic sources of H+. Furthermore, combined with large-scale ecosystem manipulation and modeling, catchment biogeochemistry offered an effective tool to investigate risks of acidification and of nitrogen saturation of soils and waters
Nutrient dynamics in mangrove areas of the Red River Estuary in Vietnam
Wösten, J.H.M. ; Willigen, P. de; Tri, N.H. ; Lien, T.V. ; Smith, S.V. - \ 2003
Estuarine Coastal and Shelf Science (2003)1-2. - ISSN 0272-7714 - p. 65 - 72.
budgets
Nutrient dynamics of mangrove in the 107 kmr large estuary of the Red River Delta in Vietnam are studied using the existing LOICZ-CABARET budget model. The methodology and assumptions underlying this model are described. Input data for evaporation, rainfall, river discharge, and concentrations of salt, phosphorus and nitrogen are obtained during measurement campaigns in Vietnam. The calculated P-balance of the estuary together with measured data on the C/P ratio of mangroves yield a calculated mangrove biomass growth rate of 80 kg dry matter per ha per day. Direct measurements of mangrove growth show a rate of 31 kg dry matter per ha per day. Considering the uncertainties involved in this study where nutrient exchange with mineral particles is ignored, the nutrient budget model established for the Red River Estuary proves to give acceptable results. The model demonstrates that the mangroves in the estuary act as clear sinks of nutrients and sequester some 26000 kg N per day and some 3100 kg P per day for their biomass production. Next the model is used in an explorative way to investigate effects of realistic future scenarios. Increasing river discharge in combination with constant or proportionally increasing river nutrient concentration results in increasing nutrient concentrations in the estuary. Increasing river discharge in combination with decreasing river nutrient concentration results in decreasing nutrient concentrations in the estuary. Constant river discharge in combination with increasing river nutrient concentration results in increasing nutrient concentrations in the estuary. The scenario analysis helps to understand the different interactions in the nutrient dynamics of the Red River mangrove area.
Modelling heavy metal and phosphorus balances for farming systems
Keller, A.N. ; Schulin, R. - \ 2003
Nutrient Cycling in Agroecosystems 66 (2003). - ISSN 1385-1314 - p. 271 - 284.
cadmium accumulation - regional-scale - fertilizers - netherlands - management - soils - agroecosystems - uncertainty - budgets - feeds
Accounting for agricultural activities such as P fertilization in regional models of heavy metal accumulation provides suitable sustainable management strategies to reduce nutrient surpluses and metal inputs in agricultural soils. Using the balance model PROTERRA-S, we assessed the phosphorus ( P), cadmium (Cd) and zinc (Zn) flux balances in agricultural soils of a rural region in Switzerland for different farm types and crop types. The P requirements of crops on arable farms were mainly supplied by commercial fertilizers and sewage sludge, while on animal husbandry farms P fertilizer demands were met by animal manure alone. Metal accumulation in soil was very different between the balance units. Estimated net Cd fluxes ranged between 1.0 and 2.3 g ha(-1) yr(-1) for arable farm types, 0.6 and 2.0 g ha(-1) yr(-1) for dairy and mixed farm types, and 9.1 and 17.8 g ha(-1) yr(-1) for animal husbandry farm types. Largest net Zn fluxes of 17.9 - 39.8 kg ha(-1) yr(-1) were estimated for animal husbandry farms, whereas for arable farm types net Zn fluxes of 101 - 260 g ha(-1) yr(-1) and for dairy and mixed farm types of 349 - 3360 g ha(-1) yr(-1) were found. The results indicate that P management is a primary factor determining the variation of these net Cd and net Zn fluxes. The latter were highly sensitive to the Zn/P concentration ratio in animal manure, atmospheric deposition and crop concentrations. Variation of net Cd fluxes resulted mainly from uncertainty in crop concentrations, atmospheric deposition, leaching parameters and uncertainty in Cd/P concentration ratio of commercial fertilizers. In addition, element balances were sensitive to empirical assumptions on fertilization strategy of farmers, such as the partitioning of manure between balance units.
Monitoringsonderzoek recreatie duingebied Meijendel - deel XII. Analyse van het recreatieverkeer en het recreatiebezoek in de periode maart 2001 - februari 2002
Beunen, R. ; Webster, M.J. ; Jaarsma, C.F. - \ 2002
Wageningen : Wageningen UR (Nota Vakgroep Ruimtelijke Planvorming 92) - ISBN 9789067546850 - 98
recreatieonderzoek - recreatie - onderzoek - methodologie - projecten - monitoring - dichtheid - wegtransport - verkeer - tellen - budgetten - tijd - duinen - eolisch zand - nederland - karteringen - gegevensanalyse - zuid-holland - leisure research - recreation - research - methodology - projects - density - road transport - traffic - counting - budgets - time - dunes - aeolian sands - netherlands - surveys - data analysis
Budgettaire consequenties introductie Programma Beheer
Meeuwissen, T.W.M. ; Mulder, M. - \ 1999
onbekend : LEI (Rapport LEI 4.99.20) - ISBN 9789052425290 - 89
milieubeleid - milieuwetgeving - natuurbescherming - subsidies - economie - beleid - budgetten - nederland - financieren - environmental policy - environmental legislation - nature conservation - subsidies - economics - policy - budgets - netherlands - financing
In opdracht van het Ministerie van Landbouw, Natuurbeheer en Visserij is door het LEI in samenwerking met de werkgroep Budgetneutraliteit van de projectgroep Programma Beheer een rekenmodel ontwikkeld waarmee vervolgens de budgettaire consequenties van de introductie van het Programma Beheer zijn berekend. De resultaten van drie berekeningen staan in dit rapport beschreven. Het ten behoeve van die berekeningen gemaakte rekenmodel zal worden overgedragen aan het Ministerie van LNV om dienst te doen bij de onderbouwing van programmeringsafspraken en begrotingsvoorstellen.
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