|
|
|
| Registros recuperados: 28 | |
|
|
| 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 |
| |
|
|
| Berntsen, J.; Petersen, B.M.; Olesen, J.E.; Eriksen, J.; Søegaard, K.. |
| The FASSET farm model was used to simulate production in an experiment where a grass-clover or a grass ley was either cut or grazed with dairy cows receiving low or high N sup-plements. The six different ley types were ploughed in and followed by three years with spring cereals with undersown catch crops. The original model was extended with a new grass and clover model, which included the capability to simulate rhizodeposition and root growth. The new model predicted the observed annual carbon (C) and nitrogen (N) production satisfactorily. The simulated first year residual effects of a cut grass or grass-clover ley varied between 0 and 34, while the residual effect of a grazed grass or grass-clover ley varied between 71 and 150 fertilizer equivalents... |
| Tipo: Journal paper |
Palavras-chave: Denmark. |
| Ano: 2005 |
URL: http://orgprints.org/4592/1/4592.pdf |
| |
|
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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.; 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
| Hovmøller, M.S.; Berntsen, J.; Kristensen, K.. |
| Significant increase in severity of powdery mildew,leaf rust and net blotch with increasing N-content in plant leaves 30 days after germination (all years where the relevant diseases were present at a substantial level). This may explain: · Most of the environmental main effects (field) on disease. · Effect of treatments, i.e., treament 4 resulted in reduced N/increased K content in leaves, which coincided with reduced levels of disease. We observed no clear effect of P, Ca, S, and Zn content in leaves on disease. Micronutrients as Cu, Mo and Mn showed significant effects on powdery mildew in one year but not the other; further interpretation may not be possible due to inter-correlation among the effect of micro-nutrients. The diseases had a... |
| Tipo: Working paper |
Palavras-chave: Crop health; Quality; Protection Farm nutrient management. |
| Ano: 2006 |
URL: http://orgprints.org/7914/1/7914.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 |
| |
|
|
| Olesen, J.E.; Berntsen, J.. |
| Crop models can be powerful tools to analyse the effect of changes in management of cropping systems on productivity and environmental impact, provided the models have been thoroughly tested. The FASSET model was found to adequately reproduce effects of management (manure and catch crops) and of site (soil and climate) on crop yields and nitrate leaching from a 4- crop rotation with a grass-clover green manure crop in one out of four years. Scenario analyses shown that the nitrate leaching increased relatively more with increasing N fixation in the grass-clover than did the crop yields. The yields could be increased and the nitrate leaching reduced by using catch crops and/or using the grass-clover for biogas instead of a green manure, assuming that the... |
| Tipo: Newspaper or magazine article |
Palavras-chave: Nutrient turnover; Production systems. |
| Ano: 2004 |
URL: http://orgprints.org/4673/1/4673.doc |
| |
|
|
| 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 |
| |
|
| |
|
| |
| Registros recuperados: 28 | |
|
|
|
