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| Registros recuperados: 27 | |
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| 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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| 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 |
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| 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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| 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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| 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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| 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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| Berntsen, J.; Petersen, B.M.; Olesen, J.E.. |
| Measurements of crop yield and soil carbon in the Bad Lauchstädt long-term fertiliser experiment were analysed with the FASSET model. The model satisfactorily predicted yield and soil carbon development in four treatments with no fertiliser, mineral fertiliser, farm yard manure and farm yard manure plus mineral fertiliser, respectively. However, there was a residual between the observed and simulated yield, which was correlated with year. This could be attributed to an increase in observed yields during the last six decades. Scenario analysis showed that the most probable explanation for this yield increase was the use of new crop varieties and/or pesticides, while the increase in atmospheric CO2 and changes in local N deposition were of lesser importance.... |
| Tipo: Journal paper |
Palavras-chave: Soil biology. |
| Ano: 2006 |
URL: http://orgprints.org/10591/2/10591.pdf |
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| 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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| 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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| Petersen, B.M.; Berntsen, J.. |
| One of the prime factors determining soil fertility is the content of soil organic matter. A huge amount of nitrogen (N) is bound in organic matter, and the yearly mineralisation of N in the field is only a small fraction of the total organic nitrogen.The release and incorporation of organic N is of special relevance for organic farms, where the crop supply mainly depends on N mineralised from organic matter.In order to study the long-term balance between build-up and degradation of organic matter, a simple simulation model was made, calibrated on the basis of long-term data from Sweden, U.K. and Denmark. Briefly, it is a 3-pool model (Figure 1) employing first-order kinetics, which is implemented in C-TOOL. The long-term build up or breakdown of organic N... |
| Tipo: Journal paper |
Palavras-chave: Soil biology. |
| Ano: 2003 |
URL: http://orgprints.org/4665/1/4665.PDF |
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| Berntsen, J.; Petersen, B.M.; Olesen, J.E.. |
| Measurements of crop yield and soil carbon in the Bad Lauchstädt long-term fertiliser experiment were analysed with the FASSET model. The model satisfactorily predicted yield and soil carbon development in four treatments with no fertiliser, mineral fertiliser, farm yard manure and farm yard manure plus mineral fertiliser, respectively. However, there was a residual between the observed and simulated yield, which was correlated with year. This could be attributed to an increase in observed yields during the last six decades. Scenario analysis showed that the most probable explanation for this yield increase was the use of new crop varieties and/or pesticides, while the increase in atmospheric CO2 and changes in local N deposition were of lesser importance.... |
| Tipo: Book chapter |
Palavras-chave: Soil biology. |
| Ano: 2007 |
URL: http://orgprints.org/21787/1/21787.pdf |
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| 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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| 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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| 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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| 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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| Registros recuperados: 27 | |
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