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| Registros recuperados: 14 | |
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| Pedersen, Anders; Thorup-Kristensen, Kristian; Kristensen, Hanne Lakkenborg; Berntsen, Jørgen. |
| Dynamic plant/soil models are used to predict crop production, N dynamics and nitrate leaching loss of different cropping systems. To do this, the models simulate various aspects of plant biology, soil biology and soil physics. Correct simulation of root growth is critical for the simulation of nitrate leaching losses. Measurements have been made on crop root growth on two soil types, and the data used to improve the simulation of root growth within the FASSET model. The paper presents the results from root measurements on winter wheat, spring barley and sugar beets, and the root modelling approach we have developed. |
| Tipo: Journal paper |
Palavras-chave: Soil biology. |
| Ano: 2004 |
URL: http://orgprints.org/3879/1/3879.rtf |
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| Olesen, Jørgen E.; Chatskikh, Dmitri; Berntsen, Jørgen; Hutchings, Nicholas J.. |
| Danmark har underskrevet Kyoto-protokollen, som forpligter til en reduktion i samfundets udledning af drivhusgasser på 21 procent i perioden fra 1990 til 2010. Med hensyn til reduktion af landbrugets udledning af drivhusgasser har fokus hidtil været på reduktion af kvælstofanvendelsen. I den nationale opgørelse beregnes lattergasudledningen som 1,25 procent af den udbragte kvælstofmængde. De nye modelberegninger, som præsenteres her, viser at dette er en alt for simpel måde at beregne lattergasudledningen på. Der er dels store forskelle mellem jordtyper, og dels er den procentvise udledning større ved høje kvælstofniveauer end ved lave niveauer. Det sidste forhold kan gøre økologisk jordbrug interessant som redskab i klimapolitikken, da... |
| Tipo: Journal paper |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4077/1/4077.doc |
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| Chatskikh, Dmitri; Olesen, Jørgen E.; Berntsen, Jørgen. |
| A dynamic algorithm to simulate the N2O production and emission from nitrification and denitrification has been included in the field component of the FASSET whole-farm model. Firstly, the model was tested on experimental data of N2O emissions from typical North European grasslands with mineral soils (Denmark, Finland, UK), differing in climatic conditions, soil properties and management. A good agreement was obtained between simulated and measured seasonal N2O emissions grazed and mown grasslands. The predicted annual N2O emissions were generally in accordance with the emission factor of 1.25% suggested by IPCC. Secondly, the model was tested under different climatic and management scenarios applicable for Denmark. The reasonable calculations of potent... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4131/1/4131.doc |
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| Berntsen, Jørgen. |
| Registerdata er blevet anvendt til modelberegninger med DJF’s bedriftsmodel FASSET. Beregningerne viste, at på et udsnit af typiske danske jorde var udvaskningen fra både økologiske og konventionelle planteavlere ca. 36 kg N/ha. Forskellen mellem økologisk og konventionel planteavl kom dog til udtryk i ændringer i organisk stof i jorden. Mens økologerne opbyggede ca. 13 kg N/ha om året, tærede de konventionelle ca. 6 kg N/ha om året på jordens organiske stof. Modellen blev yderligere brugt til at gennemregne effekten af forskellig driftspraksis. Anvendelse af efterafgrøder var klart det mest effektive virkemiddel til at reducere kvælstofudvaskningen. I gennemsnit over et helt sædskifte blev udvaskningen således reduceret med ca. 9 kg N/ha. Det svarede... |
| Tipo: Newspaper or magazine article |
Palavras-chave: Nutrient turnover; Production systems; Farming Systems. |
| Ano: 2004 |
URL: http://orgprints.org/4604/1/4604.doc |
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| Berntsen, Jørgen; Hauggard-Nielsen, Henrik; Olesen, Jørgen E.; Molt Petersen, Bjørn; Jensen, Erik Steen; Thomsen, Anton. |
| 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: Production systems. |
| Ano: 2004 |
URL: http://orgprints.org/1698/1/1698.pdf |
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| Olesen, Jørgen E.; Hansen, Preben Klarskov; Berntsen, Jørgen; Christensen, Svend. |
| Cereal crop species and varieties differ in competitive ability against weeds mainly as influenced by differences in canopy architecture. The FASSET crop model was used to separate the effects of a number of crop traits on the suppressive ability of winter wheat varieties and the ability to tolerate weeds. The model simulated the competition between different varieties of winter wheat and a sown grass mixture for light, water and nitrogen. Crop physiological parameters of eight varieties and one variety mixture were estimated from measurements in a 3-year field experiment. The parameters estimated were thermal time from emergence to flag leaf appearance, thermal time from flag leaf appearance to anthesis, thermal time from anthesis to yellow ripeness,... |
| Tipo: Journal paper |
Palavras-chave: Cereals; Pulses and oilseeds Weed management. |
| Ano: 2004 |
URL: http://orgprints.org/3654/1/JEOA044.pdf |
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| Hutchings, Nicholas J.; Petersen, Bjørn M.; Olesen, Jørgen E.; Berntsen, Jørgen. |
| The presence of grazing animals contributes to a much greater spatial heterogeneity in the cycling of C and N within grasslands, compared to arable land. This is primarily due to the deposition of excreta in patches rather than evenly over the field. However, an additional source of heterogeneity is introduced because grazing animals do not evenly utilise the grassland. Herbage contaminated by their faeces will tend to be rejected, as will poor quality (low digestibility) vegetation. There is therefore good reason to expect that C and N cycling will be highly spatially variable in grazed grassland. Hitherto, grassland models have assumed C and N dynamics to be uniform within a field. In this paper, modelling is used to investigate the potential effect of... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Air and water emissions. |
| Ano: 2004 |
URL: http://orgprints.org/4132/1/4132.doc |
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| Berntsen, Jørgen; Olesen, Jørgen; Petersen, Bjørn Molt; Eriksen, Jørgen. |
| Introduction Management of nitrogen in dairy systems is especially difficult due to the use of organic manures and the residual effects of the pasture. During grazing a considerable build-up of soil N is often observed. Ploughing of the grassland is therefore followed by a large mineralization that might exceed the demand of the subsequent crop. This might lead to large amount of nitrate being leached. In addition, rotations dependent on organic manures rather than mineral fertilizers are believed to have a higher risk of nitrate leaching. The study present results from simulations with the FASSET model (Berntsen et al., 2003) of nitrate leaching and crop growth in organic dairy systems with two types of manures at two different stocking levels.... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Production systems. |
| Ano: 2003 |
URL: http://orgprints.org/1700/1/12N_workshop%2DI[1].ppt |
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| Olesen, Jørgen E.; Askegaard, Margrethe; Berntsen, Jørgen. |
| Nitrate leaching from crop rotations for organic grain production were investigated in a field experiment on different soil types in Denmark from 1997 to 2002. Three experimental factors were included in the experiment in a factorial design: 1) proportion of grass-clover and pulses in the rotation, 2) cover crop (with and without), and 3) manure (with and without). Two four-course rotations were compared. They had one year of grass-clover as a green manure crop, either followed by spring wheat or by winter wheat. The nitrate leaching was measured using ceramic suction cells. The nitrate leaching did not differ between the rotations, as a change in leaching following the grass-clover was compensated by a reverse effect in the grain crops. Use of cover crops... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Farming Systems. |
| Ano: 2004 |
URL: http://orgprints.org/3859/1/3859.pdf |
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| Chatskikh, Dmitri; Olesen, Jørgen E.; Berntsen, Jørgen; Regina, Kristiina; Yamulki, Sirwan. |
| Local adaptations of the IPCC methodology (http://www.ipcc.ch) are applied in different countries. They include a combination of theoretical, experimental and simulation methods for evaluating the activity and factors indicated N2O emission. The N2O emission from agricultural soil is considered an important source both for environmental impact and non-industrial losses of nitrogen (Petersen, Olesen, 2002). In this study a multifactorial approach, based on dynamic modelling, is used at a farm/field level to estimate N2O emission from grassland. For this purpose an algorithm for modeling of gaseous N2O emission was developed and analyzed. In the algorithm, based on the conceptual process-oriented model HIP (Davidson et al., 2000), both nitrification and... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Air and water emissions. |
| Ano: 2003 |
URL: http://orgprints.org/4130/1/4130.doc |
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| Askegaard, Margrethe; Støvring, Mogens; Berntsen, Jørgen. |
| A two-year field experiment with spring barley in an organic mixed crop rotation showed contrasting results between the two years in the response to the tested factors: Variety, location in the crop rotation, and organic manure application. The yields of the varieties differed due to attacks of different airborne leaf diseases. In one of the years the “high fertility” position of the barley the 1st year after grass-clover gave unexpectedly lower grain yields than the position four years after grass-clover. Finally, the straw-based farmyard manure (FYM) resulted in higher grain yields in one of the years whereas slurry performed best in the other year, though the content of ammonia-N was less in FYM both years. We measured differences in the root... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Cereals; Pulses and oilseeds. |
| Ano: 2006 |
URL: http://orgprints.org/7472/1/Paper_MA.doc |
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| Registros recuperados: 14 | |
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