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Registros recuperados: 27
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A flexible tool for simulation of soil carbon turnover Organic Eprints
Petersen, B.M.; Olesen, J.E.; Heidmann, T..
Existing models of soil organic matter (SOM) turnover are implemented within rigid and often complex modelling environments, which makes the testing of influence of SOM model structure a rather difficult task. A new soil carbon turnover simulation tool is presented (C-TOOL v. 1.0). It facilitates the construction of a wide range of user-definable SOM models based on linked SOM pools and a decay described for each pool by first order kinetics. Simulation of carbon isotopes 13C and 14C is facilitated. No programming is necessary for defining or redefining models, as the model structure is given in set-up files. The program is fast, and can utilise a range of time-steps, which enhances the computation of steady level SOM contents. The ability of C-TOOL to...
Tipo: Journal paper Palavras-chave: Nutrient turnover.
Ano: 2002 URL: http://orgprints.org/85/1/85.doc
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An approach to include soil carbon changes in life cycle assessments Organic Eprints
Petersen, B.M.; Knudsen, Marie Trydeman; Hermansen, J.E.; Halberg, Niels.
Globally, soil carbon sequestration is expected to hold a major potential to mitigate agricultural greenhouse gas emissions. However, the majority of life cycle assessments (LCA) of agricultural products have not included possible changes in soil carbon sequestration. In the present study, a method to estimate carbon sequestration to be included in LCA is suggested and applied to two examples where the inclusion of carbon sequestration is especially relevant: 1) Bioenergy: removal of straw from a Danish soil for energy purposes and 2) Organic versus conventional farming: comparative study of soybean production in China. The suggested approach considers the time of the soil CO2 emissions for the LCA by including the Bern Carbon Cycle Model. Time...
Tipo: Journal paper Palavras-chave: Nutrient turnover; Air and water emissions; Soil; Research methodology and philosophy; Environmental aspects.
Ano: 2013 URL: http://orgprints.org/22732/7/22732.pdf
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Blütenvielfalt auf dem Acker Organic Eprints
Petersen, B.M..
Früher zierten zahlreiche Blüten die Äcker. Heute sind die Äcker weitgehend blütenarm. Damit fehlt den Blütenbesuchern die Nahrungsquelle und den Landwirten die Blütenbestäuber. Blütenvielfalt bietet darüber hinaus noch viele weitere Vorteile - auch für den Landwirt. Das Merkblatt will Mut machen, wieder mehr Blüten- und Artenvielfalt auf den Acker zu bringen. Es liefert dem Landwirt dazu viele Ideen und Entscheidungshilfen.
Tipo: Book Palavras-chave: Crop husbandry; Biodiversity and ecosystem services.
Ano: 2011 URL: http://orgprints.org/25241/1/1557-bluetenvielfalt.pdf
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CN-SIM - a model for the turnover of soil organic matter. I: Long term carbon development Organic Eprints
Petersen, B.M.; Berntsen, J.; Hansen, S.; Jensen, L.S..
A computer model is presented that describes the flow of C and N in the soil. It employs a structure with conceptual compartments. Organic matter is represented by seven different compartments, two for added matter, two for soil microbial biomass, one for microbial residues, one for native organic matter, and one for inert organic matter. The latter pool probably represents both truly inert matter, and matter with a very slow turnover. This paper describes the parameterisation and performance of this model on selected long-term field data from United Kingdom, Sweden and Denmark. Statistical methods were employed to optimise parameters, and obtain proximate confidence intervals for these parameters. Very satisfactory simulations could be acquired, using the...
Tipo: Journal paper Palavras-chave: Nutrient turnover.
Ano: 2005 URL: http://orgprints.org/87/1/87.pdf
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CN-SIM - a model for the turnover of soil organic mattter. II: Short term carbon and nitrogen development Organic Eprints
Petersen, B.M.; Jensen, L.S.; Berntsen, J.; Hansen, S.; Pedersen, A.; Henriksen, T.M.; Sørensen, P.; Trinsoutrot, I..
A computer model is presented, which describes the transformations of C and N in the soil. The development has been divided into two interdependent tasks, the first being development of long-term SOC simulation capabilities, and the second being short-term simulations of C and N, as described in this paper. A number of existing, independent laboratory experiments, covering a range of amendments, have been used for this task. The amendments includes a variety of different crop residues and animal manure. These experiments have included measurements of 13C, 14C and 15N in various pools, and the model facilitates the simulation of these isotopes. Non-linear, automated optimisation procedures were utilised wherever feasible. The model generally yielded good...
Tipo: Journal paper Palavras-chave: Nutrient turnover.
Ano: 2005 URL: http://orgprints.org/88/1/88.pdf
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C-TOOL version 1.1. A tool for simulation of soil carbon turnover. Description and users guide Organic Eprints
Petersen, B.M..
The program C-TOOL (v. 1.1) can enhance SOM model development by aiding the construction, revision and testing of soil carbon turnover models. Models can be created directly, without the aid of programmers. The program can use any time step between one day and one year, and can be run either for a predefined period or continue until specified steady-level criterions for carbon pools are reached. Development in soil carbon content at any desired time span can be simulated. Simulation of carbon isotopes 13C and 14C is facilitated, and it is possible to simulate a specific isotope tagging in order to investigate carbon flow properties in the implemented model. Standard driving variables are temperature (in air or soil), soil water content (either absolute...
Tipo: Web product Palavras-chave: Soil biology.
Ano: 2003 URL: http://orgprints.org/4664/1/4664.pdf
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Developments in greenhouse gas emissions and net energy use in Danish agriculture - How to achieve substantial CO2 reductions? Organic Eprints
Dalgaard, Tommy; Olesen, Jørgen E.; Petersen, B.M.; Petersen, Søren O.; Jørgensen, Uffe; Kristensen, Troels; Hutchings, Nicholas J.; Gyldenkerne, Steen; Hermansen, J.E..
Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990-2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50-70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers,...
Tipo: Journal paper Palavras-chave: Nutrient turnover; Air and water emissions; Buildings and machinery; Landscape and recreation; Farm nutrient management.
Ano: 2011 URL: http://orgprints.org/19044/4/19044.pdf
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Do we pay proper attention to the subsoil C turnover? Organic Eprints
Olesen, J.E.; Petersen, B.M..
The Kyoto Protocol allows carbon sequestration from changes in agricultural land use to be a mechanism for reducing anthropogenic greenhouse gas emissions. There is a specific requirement in the protocol for verification of the sequestration estimates, which may often involve the use of soil carbon simulation models and thus puts a large requirement on the validity of these models. The commonly used soil organic matter models have been calibrated on the basis of measurements of topsoil C contents under the implicit assumption that there is negligible vertical transport of soil C. We demonstrate this assumption to be wrong, and that it may lead to large deviations when modelling long-term soil organic matter development. Therefore a model with a net...
Tipo: Conference paper, poster, etc. Palavras-chave: Nutrient turnover.
Ano: 2004 URL: http://orgprints.org/4670/1/4670.doc
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Modelling dry matter production and resource use in intercrops of pea and barley Organic Eprints
Berntsen, J.; Hauggaard-Nielsen, H.; Olesen, J.E.; Petersen, B.M.; Jensen, E.S.; Thomsen, A..
The FASSET whole farm model was extended with a sub-model for competition between several plant species for light, water and nitrogen. The new model was tested on intercrops of pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.). A three-year dataset on pea and barley sole crop growth was used for calibration. Two datasets that included detailed measurements of crop production, nitrogen uptake and leaf area indices from two sites were used for testing. An arable organic experiment from three sites including several treatments over four years was also used for testing. The model predicted the increase in resource utilisation of pea and barley and effects on pea symbiotic nitrogen fixation satisfactorily. The effects of pea interspecific...
Tipo: Journal paper Palavras-chave: Crop combinations and interactions.
Ano: 2004 URL: http://orgprints.org/4052/1/4052.pdf
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Modelling long term carbon and radiocarbon development Organic Eprints
Petersen, B.M.; Berntsen, J.; Jensen, L.S.; Hansen, S..
In order to achieve predictive abilities for both short- and long-term simulations, SOM models should be developed on the basis of as large and diverse a data-set as possible. Many soil organic matter (SOM) models have parameters, where the criteria for estimating their values do not seem transparent, and few have been subject to a formal sensitivity analysis regarding the influence of parameter settings. One of the major problems in most SOM models is to estimate the soil content of very slowly decomposing or perhaps even inert organic matter ("refractory" SOM). In view of these possible limitations of present SOM models, the following model development criteria were chosen for this study: 1) use of a comprehensive data-set from both laboratory and...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil biology.
Ano: 2003 URL: http://orgprints.org/4660/1/4660.doc
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Modelling Long Term Soil Carbon and Radiocarbon Dynamics with CN-SIM Organic Eprints
Petersen, B.M.; Berntsen, J..
In order to achieve predictive abilities for both short- and long-term simulations, soil organic matter (SOM) models should be developed on the basis of as large and diverse a data-set as possible. Many SOM models have parameters, where the criteria for estimating their values are not transparent, and few models have been subject to a formal sensitivity analysis regarding the influence of parameter settings. One of the major problems in most SOM models is to estimate the soil content of very slowly decomposing or perhaps even inert organic matter ("refractory" SOM). There is presently a lack of experimental methods to verify the partitioning of SOM into conceptual compartments or pools, and to determine the turnover rate and other characteristics...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil biology.
Ano: 2004 URL: http://orgprints.org/4656/1/Poster_florida.doc
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Modelling short term carbon and nitrogen development Organic Eprints
Petersen, B.M.; Jensen, L.S.; Berntsen, J.; Hansen, S.; Pedersen, A..
Carbon (C) and nitrogen (N) transformations are highly interdependent, driven by the C metabolism. Though many details of the transformations of C and N forms in soil are well known, basic knowledge about the mechanisms determining substrate availability, and the chemical and physical properties determining the stabilisation of organic matter are still lacking. The soil biota furthermore constitutes an extremely complex food web, consisting of a vast number of bacteria, fungi and fauna species, each having their own feeding preferences and characteristic life cycle. A good quantitative description of the main processes involved is required. This involves both the long-term build-up and degradation of soil organic matter, and the more short-termed N...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil biology.
Ano: 2003 URL: http://orgprints.org/4662/1/4662.doc
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Modelling soil C and 14C development Organic Eprints
Petersen, B.M.; Berntsen, J..
In order to achieve predictive abilities for both short- and long-term simulations, soil organic matter (SOM) models should be developed on the basis of as large and diverse a data-set as possible. Many SOM models have parameters, where the criteria for estimating their values are not transparent, and few models have been subject to a formal sensitivity analysis regarding the influence of parameter settings. There is presently a lack of experimental methods to verify the partitioning of SOM into conceptual compartments or pools, and to determine the turnover rate and other characteristics for each. These pool characteristics can thus only be determined indirectly by model calibration. If the model has several SOM pools, then several parameters may be...
Tipo: Conference paper, poster, etc. Palavras-chave: Soil biology.
Ano: 2004 URL: http://orgprints.org/4655/1/4655.doc
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Nitrate leaching from organic and conventional crop production farms Organic Eprints
Olesen, J.E.; Berntsen, J.; Petersen, B.M.; Kristensen, I.S..
Farm accounting data from the Institute of Food Economics and from Central Agricultural Registers in Denmark were used to define the import of nitrogen (N) to farmed fields on conventional and organic arable farms to 129 and 51 kg N ha-1 yr-1, respectively. Based on the recorded distribution of crops, a generalised crop rotation was defined for each of the two farming systems. The crop rotation for the organic farm had a high share of spring cereals and additionally 20% grass-clover in the rotation, whereas the conventional rotation was dominated by cereals, primarily winter cereals. The FASSET model was used to simulate the N balance of these two crop rotations. This included N leaching and change in the soil organic N pool. All simulations were...
Tipo: Conference paper, poster, etc. Palavras-chave: Air and water emissions.
Ano: 2004 URL: http://orgprints.org/4671/1/4671.doc
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Nitrate leaching from organic farming systems with rotational grass-clover and arable crops Organic Eprints
Berntsen, J.; Grant, R.; Olesen, J.E.; Kristensen, I.S.; Vinther, F.P.; Mølgaard, J.P.; Petersen, B.M..
Organic farming is considered an effective mean of reducing nitrogen losses compared with more intensive conventional farming systems. However, under certain conditions organic farming may also be susceptible to high nitrogen (N) losses. This is especially the case for organic dairy farms on sandy soils that use grazed grass-clover in rotation with cereals, which may lead to high rates of nitrate leaching. A study was conducted on two commercial organic farms on sand and loamy sand soils. On each farm a three year old grass-clover field was selected. Half of the field was ploughed the first year and the other half was ploughed the next year. Spring barley (Hordeum vulgare L.) was sown after the spring ploughing. Measurements showed a low N leaching...
Tipo: Journal paper Palavras-chave: Nutrient turnover; Pasture and forage crops; Farming Systems; Soil biology; Soil quality; Air and water emissions.
Ano: 2006 URL: http://orgprints.org/4642/1/4642.doc
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Nitratudvaskning fra økologiske og konventionalle planteavlsbedrifter - simuleringer med FASSET bedriftsmodellen Organic Eprints
Berntsen, J.; Petersen, B.M.; Kristensen, I.S.; Olesen, J.E..
Med udgangspunkt i regnskabsdata fra Fødevareøkonomisk Institut (FØI) og data fra Centrale Registre (CR) blev importen af kvælstof (N) i gødning til marken til konventionelle og økologiske planteavlere estimeret til hhv. 129 og 51 kg N ha-1 år-1. Desuden blev der med udgangspunkt i den aktuelle afgrødefordeling opstillet et generelt sædskifte for hver af de to systemer. Det opstillede sædskifte for den økologiske planteavl havde en høj andel af vårsæd og desuden 20% kløvergræs, mens den konventionelle planteavl var domineret af kornafgrøder primært i form af vintersæd. Med baggrund i disse model-sædskifter blev N-balancen på markniveau beregnet ved anvendelse af FASSET modellen. Dette inkluderede også N-udvaskning og ændring i jordens Npulje. Alle...
Tipo: Report Palavras-chave: Nutrient turnover; Production systems; Farming Systems; Air and water emissions.
Ano: 2004 URL: http://orgprints.org/4605/1/4605.pdf
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Nitratudvaskning fra økologiske og konventionelle planteavlsbedrifter - simuleringer med FASSET bedriftsmodellen Organic Eprints
Berntsen, J.; Petersen, B.M.; Kristensen, I.S.; Olesen, J.E..
Med udgangspunkt i regnskabsdata fra Fødevareøkonomisk Institut (FØI) og data fra Centrale Registre (CR) blev importen af kvælstof (N) i gødning til marken til konventionelle og økologiske planteavlere estimeret til hhv. 129 og 51 kg N ha-1 år-1. Desuden blev der med udgangspunkt i den aktuelle afgrødefordeling opstillet et generelt sædskifte for hver af de to systemer. Det opstillede sædskifte for den økologiske planteavl havde en høj andel af vårsæd og desuden 20% kløvergræs, mens den konventionelle planteavl var domineret af kornafgrøder primært i form af vintersæd. Med baggrund i disse model-sædskifter blev N-balancen på markniveau beregnet ved anvendelse af FASSET modellen. Dette inkluderede også N-udvaskning og ændring i jordens N-pulje. Alle...
Tipo: Report Palavras-chave: Nutrient turnover; Soil; Soil biology; Soil quality; Air and water emissions.
Ano: 2004 URL: http://orgprints.org/4653/1/4653.pdf
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Omsætning i jordpuljen på forskellige bedriftstyper Organic Eprints
Petersen, B.M.; Berntsen, J..
En af de vigtigste faktorer, der bestemmer jordens frugtbarhed, er dens indhold af organisk stof. Der er bundet store mængder af kvælstof heri, og den årlige omsætning i marken af kvælstof udgør kun en lille brøkdel af den totale mængde. Dette indlæg fokuserer på langtidseftervirkningen, som et resultat af jordens dyrkningshistorie.
Tipo: Report chapter Palavras-chave: Nutrient turnover.
Ano: 2002 URL: http://orgprints.org/4666/1/bmp_n_temadag.doc
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Omsætning i jordpuljen på forskellige bedriftstyper Organic Eprints
Petersen, B.M.; Berntsen, J..
Indlægget fokuserer på langtidseftervirkningen som et resultat af jordens dyrkningshistorie og anvender modellering som redskab.
Tipo: Conference paper, poster, etc. Palavras-chave: Nutrient turnover.
Ano: 2002 URL: http://orgprints.org/86/1/86.doc
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Samme udvaskning af kvælstof ved økologisk og konventionel planteavl Organic Eprints
Petersen, B.M.; Berntsen, J.; Kristensen, I.S.; Olesen, J.E..
I forbindelse med den faglige evaluering forud for Vandmiljøplan II (VMP II) blev det anslået, at økologisk jordbrug i gennemsnit reducerede udvaskningen med 10 kg kvælstof (N) per ha. Det fremgik, at dette tal var behæftet med stor usikkerhed. Da der i forbindelse med genberegning af udvaskningsniveauet fra dansk landbrug i 2002 skete en opjustering af det generelle udvaskningsniveau før VMP II, vurderedes dette ikke at skulle ske for økologisk jordbrug. Forskellen i nitratudvaskning mellem økologiske og konventionelle arealer blev derfor revurderet til at være 28 kg N per ha.DJF har nu genanalyseret forskellene mellem økologiske og konventionelle planteavlsbrug for repræsentative sædskifter, driftsledelser og gødningsimport (Berntsen et al., 2004)....
Tipo: Journal paper Palavras-chave: Air and water emissions.
Ano: 2004 URL: http://orgprints.org/4663/1/4663.PDF
Registros recuperados: 27
Primeira ... 12 ... Última
 

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