|
|
|
| Registros recuperados: 28 | |
|
|
| Chatskikh, D.; Olesen, J.E.; Berntsen, J.; Regina, K.; Yamulki, S.. |
| Nitrous oxide (N2O) is a potent greenhouse gas with a high contribution from agricultural soils and emissions that depend on soil type, climate, crops and management practices. The N2O emissions therefore need to be included as an integral part of environmental assessment of agricultural production systems. A dynamical algorithm for N2O production and emission from agricultural soils was developed and included in the FASSET whole-farm model. The model simulated carbon and nitrogen (N) turnover on a daily basis. Both nitrification and denitrification was included in the model as sources for N2O production, and the N2O emissions were simulated to depend on soil microbial and physical conditions. The model was tested on experimental data of N2O emissions from... |
| Tipo: Journal paper |
Palavras-chave: Pasture and forage crops; Air and water emissions. |
| Ano: 2005 |
URL: http://orgprints.org/1808/2/1808.pdf |
| |
|
|
| 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 |
| |
|
|
| Hovmøller, M.S.; Berntsen, J.; Thomsen, I.. |
| Plantesygdomme i økologisk planteproduktion har stor indflydelse på produktkvalitet og udbytte. Specielt i korn er der gode muligheder for at forebygge svampesygdomme ved hjælp af sortsresistens, idet mange års planteforædling har bidraget til at øge niveauet af resistens mod de mest betydende svampesygdomme. Dette gælder bl.a. resistens mod bladsvampe som meldug, bygrust, skoldplet og forskellige bladpletsvampe. En sorts resistensniveau mod en given svampesygdom er imidlertid ikke konstant, men kan ændre sig over tid og have forskellig effekt i forskellige dele af landet. Det skyldes primært forskelle og dynamik i de patogenpopulationer, som forårsager de pågældende sygdomme. Derudover er sygdomsniveauet i den enkelte mark afhængig af det lokale... |
| Tipo: Newspaper or magazine article |
Palavras-chave: Crop health; Quality; Protection. |
| Ano: 2005 |
URL: http://orgprints.org/7913/1/7913.pdf |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
| |
|
| |
|
|
| Olesen, J.E.; Sørensen, P.; Thomsen, I.K.; Eriksen, J.; Thomsen, A.G.; Berntsen, J.. |
| Cycling of N in agriculture through the use of mineral fertilizers, manures and N-fixing crops gives rise to many forms of N emissions to the environment, including nitrate (NO3) leaching, ammonia (NH3) volatilization and nitrous oxide (N2O) emissions, resulting in ground water pollution, eutrophication of surface waters, soil acidification and contributions to global warming. The high rates of N input in intensive North European agricultural systems have given rise to high loss rates, and the focus in Danish agriculture during the past two decades has been on increasing the N use efficiency with the aim of reducing losses. The N use efficiency at the system level can be increased by improved handling of manure, targeted application of fertilizers and... |
| Tipo: Book chapter |
Palavras-chave: Nutrient turnover. |
| Ano: 2004 |
URL: http://orgprints.org/4668/3/4668.pdf |
| |
|
|
| Dalgaard, R.; Olesen, J.E.; Halberg, N.; Berntsen, J.. |
| De sædskiftemæssige aspekter af energiproduktion i økologisk jordbrug er belyst ved anvendelse af to forskellige tilgangsvinkler ved hjælp af henholdsvis bedriftsmodellen FASSET anvendt på markniveau og ved hjælp af en livscyklusanalyse (LCA) på bedriftsniveau. FASSET-modellen giver mulighed for at vurdere effekter af anvendelse af kløvergræs til biogas på afgrødeudbytte og på miljøeffekter (kvælstofudvaskning og drivhusgasemissioner fra marken). LCA-analyserne giver mulighed for at vurdere effekter på energiproduktion sammenholdt med øvrige kilder til drivhusgasemissioner, herunder emissionerne fra energiforbrug og indkøbt foder. I beregningerne med FASSET-modellen er der taget udgangspunkt i et rent planteavlssædskifte til økologisk jordbrug. I dette... |
| Tipo: Report chapter |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4674/1/4674.doc |
| |
|
|
| Askegaard, M.; Thomsen, I.K.; Berntsen, J.; Hovmøller, M.S.; Kristensen, K.. |
| In order to obtain a high and stable yield of organic spring barley, production should be optimized according to the specific environment. To test the performance of spring barley varieties under varying cropping conditions, a field experiment was carried out in 2003 and 2004 in a six-field mixed organic crop rotation. We investigated the choice of variety, the order in a rotation,and the application of manure (slurry and farm yard manure; 0 to 120 total-Nha�1) on grain yields of six selected varieties with different characteristics grown in either pure stands or in two spring barley mixtures, each consisting of three varieties. Average grain yield of the barley varieties varied between 3.3 t DM ha-�1 and 4.1 t DM ha-�1. Grain yields of the two... |
| Tipo: Journal paper |
Palavras-chave: Cereals; Pulses and oilseeds. |
| Ano: 2011 |
URL: http://orgprints.org/7853/2/7853.pdf |
| |
|
|
| Nielsen, N.E.; Thomsen, I.K.; Berntsen, J.. |
| Vårbyggens optagelse og udnyttelse af næringsstoffer, konkurrenceevne over for ukrudt samt sygdomsresistens har stor betydning for den økologiske planteavl. Opnåelse af en optimal ernæring forudsætter den rette kombination af et stort antal biologiske, fysiske og kemiske jord- og plantefaktorer. Kulturplanter, som sås om foråret, starter i reglen med en moderat mangel på fosfor og kalium (Nielsen et al., 2003). I pløjelaget findes hovedparten af det plantetilgængelige fosfor og i en vis udstrækning tillige kalium og mikronæringsstoffer, mens det plantetilgængelige kvælstof og svovl ofte er fordelt i hele roddybden. |
| Tipo: Journal paper |
Palavras-chave: Cereals; Pulses and oilseeds. |
| Ano: 2004 |
URL: http://orgprints.org/3278/1/F%C3%98JOenyt.pdf |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
| Registros recuperados: 28 | |
|
|
|
