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Methods for uncertainty propagation in life cycle assessment
Groen, E.A. ; Heijungs, R. ; Bokkers, E.A.M. ; Boer, I.J.M. de - \ 2014
Environmental Modelling & Software 62 (2014). - ISSN 1364-8152 - p. 316 - 325.
sensitivity-analysis - decision-making - lca - model - input - simulation - inventory - output
Life cycle assessment (LCA) calculates the environmental impact of a product over its entire life cycle. Uncertainty analysis is an important aspect in LCA, and is usually performed using Monte Carlo sampling. In this study, Monte Carlo sampling, Latin hypercube sampling, quasi Monte Carlo sampling, analytical uncertainty propagation and fuzzy interval arithmetic were compared based on e.g. convergence rate and output statistics. Each method was tested on three LCA case studies, which differed in size and behaviour. Uncertainty propagation in LCA using a sampling method leads to more (directly) usable information compared to fuzzy interval arithmetic or analytical uncertainty propagation. Latin hypercube and quasi Monte Carlo sampling provide more accuracy in determining the sample mean than Monte Carlo sampling and can even converge faster than Monte Carlo sampling for some of the case studies discussed in this paper.
Nitrate leaching and apparent recovery of urine-N in grassland on sandy soils in the Netherlands
Corré, W.J. ; Beek, C.L. van; Groenigen, J.W. van - \ 2014
NJAS Wageningen Journal of Life Sciences 70-71 (2014). - ISSN 1573-5214 - p. 25 - 32.
nitrogen - groundwater - lysimeter - dynamics - ammonia - losses - system - input
Urine patches are an important nitrogen input source in managed pasture systems. The objective of this study was to quantify the effect of artificial urine application at different dates on nitrate leaching in a well drained sandy soil. In three subsequent years, we measured nitrate leaching and apparent urine-nitrogen recovery (ANR) in a field experiment and in two lysimeter experiments over a period of 1 year post urine application. Artificial urine patches with 400 kg ha-1of urine-N were applied at different times of the grazing seasons. For the field experiment, we compared nitrate leaching measurements with NURP model calculations. In the field experiment, greatest ANR was measured for spring and summer applications (averaging 31% of applied urine-N), and significantly declined to 0% for October applications. Nitrate leaching increased under urine patches, with a significant effect of application date. This effect was not, however, consistent over the three years. Total recovery of N in grass and of mineral N in leachate and soil was generally less than the amount of urine-N applied, with a balance deficit of 60-80% (field) or 10-70% (lysimeters). For the field experiment, the total increase in nitrate leaching corresponded reasonably well with NURP model calculations. However, the effect of application date on nitrate leaching was much smaller in the field experiment. Our results suggest that restrictions to grazing in autumn probably will be effective in decreasing the annual amount of nitrate leached, although this decrease remains hard toquantify.
Analysis of finite-buffer state-dependent bulk queues
Germs, R. ; Foreest, N. - \ 2013
OR Spektrum 35 (2013)3. - ISSN 0171-6468 - p. 563 - 583.
service processes - arrival - capacity - probabilities - computation - operations - models - input
In this paper, we consider a general state-dependent finite-buffer bulk queue in which the rates and batch sizes of arrivals and services are allowed to depend on the number of customers in queue and service batch sizes. Such queueing systems have rich applications in manufacturing, service operations, computer and telecommunication systems. Interesting examples include batch oven processes in the aircraft and semiconductor industry; serving of passengers by elevators, shuttle buses, and ferries; and congestion control mechanisms to regulate transmission rates in packet-switched communication networks. We develop a unifying method to study the performance of this general class of finite-buffer state-dependent bulk queueing systems. For this purpose, we use semi-regenerative analysis to develop a numerically stable method for calculating the limiting probability distribution of the queue length process. Based on the limiting probabilities, we present various performance measures for evaluating admission control and batch service policies, such as the loss probability for an arriving group of customers and for individual customers within a group. We demonstrate our method by means of numerical examples
Characterisation of major component leaching and buffering capacity of RDF incineration and gasification bottom ash in relation to reuse or disposal scenarios
Rocca, S. ; Zomeren, A. van; Costa, G. ; Dijkstra, J.J. ; Comans, R.N.J. ; Lombardi, F. - \ 2012
Waste Management 32 (2012)4. - ISSN 0956-053X - p. 759 - 768.
municipal solid-waste - refuse-derived fuel - energy recovery - trace-elements - transport - behavior - input
Thermal treatment of refuse derived fuel (RDF) in waste-to-energy (WtE) plants is considered a promising solution to reduce waste volumes for disposal, while improving material and energy recovery from waste. Incineration is commonly applied for the energetic valorisation of RDF, although RDF gasification has also gained acceptance in recent years. In this study we focused on the environmental properties of bottom ash (BA) from an RDF incineration (RDF-I, operating temperature 850-1000 degrees C) and a RDF gasification plant (RDF-G, operating temperature 1200-1400 degrees C), by evaluating the total composition, mineralogy, buffering capacity, leaching behaviour (both at the material's own pH and as a function of pH) of both types of slag. In addition, buffering capacity results and pH-dependence leaching concentrations of major components obtained for both types of BA were analysed by geochemical modelling. Experimental results showed that the total content of major components for the two types of BA was fairly similar and possibly related to the characteristics of the RDF feedstock. However, significant differences in the contents of trace metals and salts were observed for the two BA samples as a result of the different operating conditions (i.e. temperature) adopted by the two RDF thermal treatment plants. Mineralogy analysis showed in fact that the RDF-I slag consisted of an assemblage of several crystalline phases while the RDF-G slag was mainly made up by amorphous glassy phases. The leached concentrations of major components (e.g. Ca, Si) at the natural pH of each type of slag did not reflect their total contents as a result of the partial solubility of the minerals in which these components were chemically bound. In addition, comparison of total contents with leached concentrations of minor elements (e.g. Pb, Cu) showed no obvious relationship for the two types of BA. According to the compliance leaching test results, the RDF-G BA would meet the limits of the Italian legislation for reuse and the European acceptance criteria for inert waste landfilling. RDF-I BA instead would meet the European acceptance criteria for non hazardous waste landfilling. A new geochemical modelling approach was followed in order to predict the leaching behaviour of major components and the pH buffering capacity of the two types of slags on the basis of independent mineralogical information obtained by XRD analysis and the bulk composition of the slag. It was found that the combined use of data regarding the mineralogical characterization and the buffering capacity of the slag material can provide an independent estimate of both the identity and the amount of minerals that contribute to the leaching process. This new modelling approach suggests that only a limited amount of the mineral phases that control the pH, buffering capacity and major component leaching from the solid samples is available for leaching, at least on the time scale of the applied standard leaching tests. As such, the presented approach can contribute to gain insights for the identification of the types and amounts of minerals that control the leaching properties and pH buffering capacity of solid residues such as RDF incineration and gasification bottom ash.
Spike-Interval Triggered Averaging Reveals a Quasi-Periodic Spiking Alternative for Stochastic Resonance in Catfish Electroreceptors
Lankheet, M.J.M. ; Klink, P.C. ; Borghuis, B.G. ; Noest, A.J. - \ 2012
PLoS ONE 7 (2012)3. - ISSN 1932-6203 - 11 p.
white-noise analysis - interspike intervals - binocular-rivalry - nervous-system - organs - responses - neuron - input - motoneurons - cells
Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals.
The crop yield gap between organic and conventional agriculture
Ponti, T. de; Rijk, H.C.A. ; Ittersum, M.K. van - \ 2012
Agricultural Systems 108 (2012). - ISSN 0308-521X - p. 1 - 9.
farming-systems - rice intensification - food security - management - productivity - phosphorus - nitrogen - quality - input - world
A key issue in the debate on the contribution of organic agriculture to the future of world agriculture is whether organic agriculture can produce sufficient food to feed the world. Comparisons of organic and conventional yields play a central role in this debate. We therefore compiled and analyzed a meta-dataset of 362 published organic–conventional comparative crop yields. Our results show that organic yields of individual crops are on average 80% of conventional yields, but variation is substantial (standard deviation 21%). In our dataset, the organic yield gap significantly differed between crop groups and regions. The analysis gave some support to our hypothesis that the organic–conventional yield gap increases as conventional yields increase, but this relationship was only rather weak. The rationale behind this hypothesis is that when conventional yields are high and relatively close to the potential or water-limited level, nutrient stress must, as per definition of the potential or water-limited yield levels, be low and pests and diseases well controlled, which are conditions more difficult to attain in organic agriculture. We discuss our findings in the context of the literature on this subject and address the issue of upscaling our results to higher system levels. Our analysis was at field and crop level. We hypothesize that due to challenges in the maintenance of nutrient availability in organic systems at crop rotation, farm and regional level, the average yield gap between conventional and organic systems may be larger than 20% at higher system levels. This relates in particular to the role of legumes in the rotation and the farming system, and to the availability of (organic) manure at the farm and regional levels. Future research should therefore focus on assessing the relative performance of both types of agriculture at higher system levels, i.e. the farm, regional and global system levels, and should in that context pay particular attention to nutrient availability in both organic and conventional agriculture
Making More Food Available: Promoting Sustainable Agricultural Production
Rabbinge, R. ; Bindraban, P.S. - \ 2012
Journal of Integrative Agriculture 11 (2012)1. - ISSN 2095-3119 - p. 1 - 8.
deforestation - systems - energy - input
Effect of production system, alternative treatments and calf rearing system on udder health in organic dairy cows
Wagenaar, J.P. ; Klocke, P. ; Butler, G. ; Smolders, E.A.A. ; Nielsen, J.H. ; Canever, A. ; Leifert, C. - \ 2011
NJAS Wageningen Journal of Life Sciences 58 (2011)3-4. - ISSN 1573-5214 - p. 157 - 162.
intramammary infections - clinical mastitis - teat seal - milk - management - input - herds - pathogens - efficacy - farms
In the last decade the main goals of organic dairying have been to attain acceptable levels of milk production, increase opportunities for animals to perform species own behaviour, resulting in improved animal welfare and animal health, and minimize the use of therapeutic interventions, including the reduction of the (preventive) use of antibiotics. Maintaining animal health without the use of therapeutic interventions is a major challenge for organic dairy farmers. In particular, udder health remains a major problem in both conventional and organic farming. In the QualityLowInputFood (QLIF) project udder health status and management were assessed in different production systems and European regions. These studies suggest that good udder health can be maintained in organic or low-input farming management systems. Novel strategies to control mastitis were evaluated and the potential of using internal teat sealers for the control of environment-associated pathogens was shown. Also oral application of a herd profile based single homeopathic remedy combined with homeopathic silica had a significant effect on cows with a relative low somatic cell count before drying-off. Suckling systems in calf rearing, as an integrated management approach, did not result in better udder health. None of the studies presented identified new variables affecting udder health. QLIF studies also demonstrated the importance of comparing udder health parameters in contrasting organic, low input and conventional production systems, since clear differences in antibiotic use against mastitis could be identified not only between organic and conventional systems, but also among dairy systems used in different EU-countries. Although alternative treatments used in organic systems could not be shown to be fully effective, results suggest that the use of individual or combined alternative strategies to improve udder health on organic or low-input farms warrants further investigation. Based on the results obtained it is recommended that future research should focus on identifying the reasons for variability in udder health between organic farms that use different management protocols to identify ‘best current practice’ when carrying out this research.
Luenberger boundary observer synthesis for Sturm-Liouville systems
Vries, D. ; Keesman, K.J. ; Zwart, H.J. - \ 2010
International Journal of Control 83 (2010)7. - ISSN 0020-7179 - p. 1504 - 1514.
waste-water - input
A static Luenberger observer of a system with Sturm-Liouville operator is synthesised with the aid of a boundary control formulation. To this aim, approximate observability, detectability and stability of the system is studied and design results are worked out for a typical biochemical case study
Factors limiting the grain protein content of organic winter wheat in south-eastern France: a mixed-model approach
Casagrande, M. ; David, C. ; Valantin-Morison, M. ; Makowski, D. ; Jeuffroy, M.H. - \ 2009
Agronomy for Sustainable Development 29 (2009)4. - ISSN 1774-0746 - p. 565 - 574.
nitrogen-fertilizer - farming systems - weed management - yield - crop - input - sustainability - number
Organic agriculture could achieve the objectives of sustainable agriculture by banning the use of synthetic fertilizers and pesticides. However, organic crops generally show lower performances than conventional ones. In France, organic winter wheat production is characterized by low grain protein content. There is a crucial need for better understanding the variability of grain protein content, because millers require batches with values over 10.5% of dry matter. Here, a regional agronomic diagnosis was carried out to identify the limiting factors and crop management practices explaining the variability of grain protein content. The studied field network was a set of 51 organic winter wheat plots in south-eastern France. The mixed-model method was used for identifying and ranking the limiting factors and the crop management practices responsible for variation in limiting factors. Our results show that the grain protein content variation was mostly explained by the baking quality grade of the cultivar, crop nitrogen status and weed density at flowering. There was a positive correlation between grain protein content and both crop nitrogen status and weed density. To a lesser extent, climatic factors also explained grain protein content variability. A lower water stress increased grain protein content, whereas an increase in the photothermal quotient and daily temperature over 25 degrees C reduced grain protein content. In south-eastern France, grain protein content of organic winter wheat could be increased by improving fertilization management, using an improved baking quality grade cultivar, choosing a legume fodder crop as preceding crop, or by avoiding late sowing dates.
Quantitative analysis of natural resource management options at different scales
Keulen, H. van - \ 2007
Agricultural Systems 94 (2007)3. - ISSN 0308-521X - p. 768 - 783.
land-use - european-community - farming system - policy - food - netherlands - nitrate - instruments - groundwater - input
Natural capital (land, water, air) consists of many resources, each with its own quality, dynamics and renewability, but with strong interactions. The increasing competition for the natural resources, especially land and water, calls for a basic redirection in the analysis of land use. In this paper, the land use analysis cycle is introduced and recent methodological developments for supporting some of its distinct phases are illustrated. Tools are available to quantify the production possibilities for various crops at plot or field scale, though the accuracy of the estimates decreases as less of the production factors are under control. Illustrations are given for quantitative analysis of management options at the farm level. In terms of explorative studies these tools appear highly successful and where the socio-economic environment is conducive, results of such analysis can indeed form the basis for formulation of development options. Tools have been developed for quantitative analysis at (sub-)regional level, that allow exploration of the outer envelope of development possibilities. The examples still largely bear an academic character, but as the demand by policy makers for integrated land use analysis studies increases, they may serve as building blocks for development of operational methodologies for land use policy formulation and analysis. Their potential impacts on planning procedures and achievement of land use objectives are high, particularly when they are further developed in settings that allow participation and involvement of the various user groups
N leaching across European forests: derivation and validation of empirical relationships using data from intensive monitoring plots
Salm, C. van der; Vries, W. de; Reinds, G.J. ; Dise, N.B. - \ 2007
Forest Ecology and Management 238 (2007)1-3. - ISSN 0378-1127 - p. 81 - 91.
nitrogen deposition - c/n ratios - ecosystems - input
Empirical relationships to predict the leaching flux of dissolved inorganic nitrogen in forested ecosystems as a function of N-deposition and stand and site characteristics have been derived using an updated version of the UN-ECE/EC intensive monitoring database, including data for the period up to the year 2000. These relationships were validated on an independent database with literature data. For the model development, reliable N budgets were available for 57 forest sites in Europe for a median period of 5 years. Multiple regression analysis showed that the measured N leaching fluxes could be well explained by a number of different empirical relationships. The simplest model included only the N throughfall flux and explained 30% of the variance in observed leaching fluxes. The most complex model showed a positive relationship between N leaching fluxes and N throughfall flux, temperature and the pH of the mineral topsoil and a negative relationship with the C/N ratio of the organic layer. This relationship explained 42% of the observed variance in leaching fluxes. The empirical equations explained 47-64% of the observed variation in leaching flux in an independent validation database. The best relationships were the one that included only N throughfall as a predictor, and a relationship that also included the C/N ratio of the organic layer as a factor to express differences in reaction above or below a critical C/N ratio. The median error was 211 mol/(ha year) for the relationship with N throughfall and 240 mol/(ha year) for the relationship that also included the C/N ratio. The median relative errors were 70 and 50%, respectively, for the two relationships. These large errors are mainly due to a general overestimation of N leaching fluxes at sites with a nitrogen-leaching fraction below 0.3. These are primarily Nordic sites with low total N-deposition levels and mid-latitude sites with relatively high C/N ratios.
TechnoGIN, a tool for exploring and evaluating resource use efficiency of cropping systems in East and Southeast Asia
Ponsioen, T.C. ; Hengsdijk, H. ; Wolf, J. ; Ittersum, M.K. van; Rötter, R.P. ; Son, T.T. ; Laborte, A.G. - \ 2006
Agricultural Systems 87 (2006)1. - ISSN 0308-521X - p. 80 - 100.
irrigated lowland rice - land-use options - european-community - quantification - coefficients - fertility - input
Agricultural research in East and Southeast Asia is increasingly challenged by the search for land-use options that best match multiple development objectives of rural societies (e.g., increased income,, food security, and reduced environmental pollution). In order to support the identification of sustainable land-use options and to support decision making with respect to land use, a tool was developed for quantifying inputs and outputs of cropping systems at the field level. TechnoGIN, the tool described in this paper, integrates systems analytical and expert knowledge and different types of agronomic data enabling the assessment of inputs and Outputs of a broad range of cropping systems and the evaluation of their resource use efficiencies. By using methods of spatial aggregation in combination with linear programming, results can also be used to explore trade-offs in resource-use efficiencies at higher levels such as the farm household, municipality and province. New features in TechnoGIN compared with similar tools include the annual rotation of up to three crops, the distinction between aerobic and anaerobic growing conditions of crops, and the procedure for estimating crop nutrient uptake. TechnoGIN is illustrated with results from the Tam Duong district in North Vietnam. The design of TechnoGIN enables easy access to its data, parameters and assumptions, and rapid generation and evaluation of input-output relationships of cropping systems in order to add new information and to improve data. TechnoGIN raises awareness about the assumptions incorporated and thus supports data collection and setting of the research agenda with respect to agro-ecological processes for which knowledge is incomplete, and is relevant For showing trade-offs between production, economic and environmental impacts of different land-use systems. (c) 2005 Elsevier Ltd. All rights reserved.
An interdisciplinary approach to regional land use analysis using GIS, with applications to the Atlantic Zone of Costa Rica
Jansen, H.P.G. ; Bouman, B.A.M. ; Schipper, R.A. ; Hengsdijk, H. ; Nieuwenhuyse, A. - \ 2005
Agricultural Economics 32 (2005)1. - ISSN 0169-5150 - p. 87 - 104.
quantification - systems - tropics - models - impact - input
Policy makers and other stakeholders concerned with regional rural development increasingly face the need for instruments that can improve transparency in the policy debate and that enhance understanding of opportunities for and limitations to development. To this end, a methodology called SOLUS (Sustainable Options for Land Use) was developed by an interdisciplinary team of scientists over a 10-year period in the Atlantic Zone of Costa Rica. The main tools of SOLUS include a linear programming (LP) model, two expert systems that define technical coefficients for a large number of production activities, and a geographic information system (GIS). A five-step procedure was developed for GIS to spatially reference biophysical and economic parameters, to create input for the expert systems and the LP model, to store and spatially reference model output data, and to create maps of both model input and output data. SOLUS can be used to evaluate the potential effects of alternative policies and incentive structures on the performance of the agricultural sector. A number of practical applications demonstrate SOLUS's capability to quantify trade-offs between economic objectives (income, employment) and environmental sustainability (soil nutrient balances, pesticide use, greenhouse gas emissions). GIS-created maps visualize the spatial aspects of such trade-offs and indicate hotspots where local goals may conflict with regional goals.
The tradeoff analysis model: integrated bio-physical and economic modeling of agricultural production systems
Stoorvogel, J.J. ; Antle, J.M. ; Crissman, C. ; Bowen, W. - \ 2004
Agricultural Systems 80 (2004)1. - ISSN 0308-521X - p. 43 - 66.
land-use - farm-level - variability - indicators - impact - input
There is an increasing call for tools that provide insight into the complex nature of agricultural systems and that deal with a broad range of sustainability issues related to policy intervention, technological innovations, and changes in environmental conditions (e.g., climate change). Sustainability indicators are useful, but only if their number is limited and the interactions between indicators are taken into consideration. In this context, we propose a methodology for an integrated analysis of tradeoffs between economic and environmental indicators. The analysis to quantify these relationships should be based on a multi-disciplinary approach and as such requires the usage of bio-physical as well as econometric-process simulation models. The communication between these very different models is based on explicit definitions of spatial and temporal scales and model integration software. The methodology is based on spatially explicit econometric simulation models linked to spatially referenced bio-physical simulation models to simulate land use and input use decisions. The methodology has been applied for the potato-pasture production system in the Ecuadorian Andes. Results of the analysis are presented in the form of tradeoff curves between different indicators, but also as maps, and risks diagrams. Besides an analysis of the current status, the approach allows for the analysis of alternative scenarios showing the effect of those scenarios on the position and slope of the tradeoff curve. (C) 2003 Elsevier Ltd. All rights reserved.
Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income: a case study for vegetable farms in South Uruguay
Dogliotti Moro, S. ; Rossing, W.A.H. ; Ittersum, M.K. van - \ 2004
Agricultural Systems 80 (2004)3. - ISSN 0308-521X - p. 277 - 302.
land-use systems - organic-matter - quantification - impact - model - input
Rapid changes in the social and economic environment in which agriculture is developing, together with the deterioration of the natural resource base threatens sustainability of farm systems in many areas of the world. For vegetable farms in South Uruguay, survival in the long term depends upon the development of production systems able to reduce soil erosion, maintain or improve physical and biological soil fertility, and increase farmer's income to socially acceptable levels. We propose a model-based explorative land use study to support the re-orientation of vegetable production systems in South Uruguay. In this paper we present a new method to quantitatively integrate agricultural, environmental and socio-economic aspects of agricultural land use based on explicit design objectives. We describe the method followed to design and evaluate a wide variety of land use activities for Canelon Grande (South Uruguay) and we illustrate the usefulness of this approach in an ex-ante evaluation of new farming systems using data from 25 farms in this region. Land use activities resulted from systematic combination of crops and inter-crop activities into crop rotations, different crop management techniques (i.e., mechanisation, irrigation and crop protection) and animal production. We identified and quantified all possible rotations and estimated inputs and outputs at crop rotation scale, explicitly considering interactions among crops. Relevant inputs and outputs (i.e., soil erosion, balance of soil organic matter and nutrients, environmental impact of pesticides, labour and machinery requirements, and economic performance) of each land use activity were quantified using different quantitative methods and following the target-oriented approach. By applying the methodology presented in this paper we were able to design and evaluate 336,128 land use activities suitable for the different soil types in Canelon Grande and for farms with different availability of resources, i.e., land, labour, soil quality, capital and water for irrigation. After theoretical evaluation, a large subset of these land use activities showed promise for reducing soil erosion, maintaining soil organic matter content of the soil and increasing farmer's income, allowing improvement of current farming systems in the region and providing a widely diverse set of strategic options for farmers in the region to choose from. This method can be used as a stand-alone tool to explore options at the field and farm scale or to generate input for optimisation models to explore options at the farm or regional scale. (C) 2003 Elsevier Ltd. All rights reserved.
An evaluation of whole farm nitrogen balances and related indices for efficient nitrogen use
Schröder, J.J. ; Aarts, H.F.M. ; Berge, H.F.M. ten; Keulen, H. van; Neeteson, J.J. - \ 2003
European Journal of Agronomy 20 (2003)1-2. - ISSN 1161-0301 - p. 33 - 44.
ammonia volatilization - livestock production - systems - netherlands - groundwater - crops - input - agriculture - indicate - nitrate
Quantification of nitrogen (N) flows creates awareness among farmers, can help them to re-evaluate N management and may reduce nitrate loss to groundwater. Hence, whole-farm balances play a crucial role in legislation on N management in Netherlands. This paper reviews the strengths and weaknesses of whole-farm balances for assessment of the environmental impact of agriculture. The usefulness and reliability of a balance strongly depends on its completeness. The surplus per unit area indicates the environmental impact, provided that all relevant terms are included. However, the surplus per unit area, the surplus per unit output and the output per unit input, as derived from the balance, may not represent accurate indicators of the operational management skills of a farmer, as these estimates not only depend on the conversion of N within the farm, but also on the extent to which the farm relies on animal feed produced outside the farm and the extent to which processing of crops takes place outside the farm. Without additional information on the processes underlying the whole-farm level and N fluxes at spatial scales above the level of an individual farm, whole-farm balances do not reveal the nature and magnitude of losses, nor do they provide sufficient clues how to improve the efficiency of N use
Uncertainties in the fate of nitrogen: II. a quantitative assessment of the uncertainties in major nitrogen fluxes in the Netherlands
Vries, W. de; Kros, J. ; Oenema, O. ; Klein, J.J.M. de - \ 2003
Nutrient Cycling in Agroecosystems 66 (2003)1. - ISSN 1385-1314 - p. 71 - 102.
nitraten - monitoring - milieueffect - stikstofkringloop - onzekerheid - nederland - bodemchemie - emissie - uitspoelen - soil chemistry - nitrates - emission - leaching - environmental impact - nitrogen cycle - uncertainty - netherlands - soil type - oxide production - grassland soil - peat soils - denitrification - ecosystem - model - cycle - input - nitrification
Enhanced levels of nitrogen in the environment may have several adverse effects, including decreased plant species diversity in (semi) natural terrestrial ecosystems, eutrophication of surface waters, pollution of groundwater due to nitrate leaching and global warming due to nitrous and nitrogen oxide emissions. To determine the effectiveness of policies aimed at the reduction of emission of ammonia, nitrous and nitrogen oxide, nitrate leaching and nitrogen runoff, it is essential to have information on the fate of nitrogen in both agricultural and non-agricultural soils on a regional and national scale and its inherent uncertainties. In this paper, the authors quantified the uncertainties in the emission, uptake, accumulation, denitrification, leaching and runoff of nitrogen at a national scale and for specific land use–soil type combinations. Furthermore, they identified which parameters contribute most to the overall uncertainty in the emission of ammonia to the atmosphere and the leaching / runoff to groundwater and surface water. To gain quantitative insight into the propagation of the uncertainty, a model was developed representing all crucial processes in the nitrogen chain by simple process descriptions. Uncertainties were quantified for the Netherlands as a whole, including terrestrial systems, both agricultural and non-agricultural land, and aquatic systems
Enhanced levels of nitrogen in the environment may have several adverse effects, including decreased plant species diversity in ( semi) natural terrestrial ecosystems, eutrophication of surface waters, pollution of ground-water due to nitrate leaching and global warming due to nitrous and nitrogen oxide (N2O and NOx) emissions. To determine the effectiveness of policies aimed at the reduction of emission of ammonia (NH3), N2O and NOx, nitrate (NO3) leaching and nitrogen (N) runoff, it is essential to have information on the fate of nitrogen in both agricultural and non-agricultural soils on a regional and national scale and its inherent uncertainties. In this paper, we quantified the uncertainties in the emission, uptake, accumulation, denitrification, leaching and runoff of nitrogen at a national scale and for specific land use-soil type combinations. Furthermore, we identified which parameters contribute most to the overall uncertainty in the emission of ammonia to the atmosphere and the leaching/runoff to groundwater and surface water. To gain quantitative insight into the propagation of the uncertainty, a model was developed representing all crucial processes in the N chain by simple process descriptions. Uncertainties were quantified for the Netherlands as a whole, including terrestrial systems, both agricultural and non-agricultural land, and aquatic systems. For agricultural and non-agricultural land, plots were distinguished, consisting of a multiple of 500 3 500 m and of 250 3 250 m grid cells, respectively, with unique combinations of soil use, soil type and groundwater table class that were derived from existing digital maps. Model parameters were assigned by using relationships with soil type, groundwater level class and land use. The uncertainty was quantified by means of a Monte Carlo analysis, whereas statistical approaches were used to identify which parameters contribute most to the overall uncertainty of the fate of nitrogen. The 90% confidence interval for the fluxes of N compounds to air, groundwater and surface water (in Gg N.yr(-1)) ranged between 102 and 194 for ammonia emission, between 18 and 51 for N2O emissions, between 32 and 108 for NO3 inflow to groundwater and between 2 and 38 for N inflow to surface water. The uncertainty in NH3 emission was mainly caused by the uncertainty in the NH3 emission fractions for animal manure, whereas the uncertainty in N2O emission was mainly due to the uncertainty in the fractions relating total nitrification and denitrification to N2O emissions. The uncertainty in inflow to groundwater and runoff to surface water was mainly caused by the uncertainty in denitrification in the soil and in upper groundwater and in non-agricultural soils also by the N accumulation in the soil. In view of the need to monitor and evaluate the impact of N reduction policies and measures, it is essential to put more effort in activities yielding a reduction of these large uncertainties, such as additional data gathering and process research under field circumstances.